• Mammoth Grip Sprinkler Spacers. Mammoth Grip Sprinkler Spacers are used to stabilize and accurately install sprinkler heads.
• Armada Technologies Pro48 Solenoid Activator / Chatterbox and Pro210 Tone Probe. Portable, irrigation system tester. Activates valves, tests solenoids, tests wire continuity, chatters solenoids, and has a tone generator for wire identification.
• Sprinkler Buddy Sprinkler Head Indicator. The Sprinkler Buddy keeps grass from growing next to or over the sprinkler head, thus make the sprinkler location obvious in the lawn.

Key to common controller features in the table below:

• Stations. Maximum number of valve stations. The actual number of stations may be less depending on which model is purchased. In most cases you need one station for each automatic valve.
• Programs. Number of programs available. Each program can have different start times, operation days, and run times for the irrigation valve stations. You need to use different programs for areas with different water requirements. For example a lawn might need to be watered every other day, but drought tolerant shrubs might need watering only once a week or less. Without separate programs they would both be watered on the same days and the shrubs might drown. More programs allows more flexibility resulting in water savings and healthier plants. Most homes need at least 2 programs, one for the lawn and one for the shrubs. Few homes need more than 4 programs.
• Smart Controller. A “Smart Controller” adjusts the watering schedule by itself throughout the year. Smart controllers are quickly becoming mandatory by law in much of the Western and Southern USA. To read more on Smart Controllers see the Smart Controller FAQ. If the controller has Smart features the following key indicates what system is used:
  • H Historical. Adjusts watering based on historical water use records.
  • HS Historical with a sensor. Fine tunes historic data using current condition sensor.
  • OS Off-site data via phone, radio, Internet, etc.
  • WS Weather station. Has it’s own weather station.
  • MS Uses a soil moisture sensor.
• Master Valve Has a control circuit for a master valve and/or pump start switch. An important feature if you use a pump.
• Rain Sensor Has a circuit for attaching a rain sensor. Shuts down if rain detected (typically the sensor itself is not included.)
• Non Volatile Memory is non-volatile, retains data without a battery even in a power failure.
• Delay A delay can be programmed between valve stations to allow time for slow closing valves to close fully. Another important feature if you have a pump, or if you have low water pressure.

This page contains an index and links to reviews of automatic solenoid valves commonly used in landscape sprinkler systems and other irrigation systems.

Electric Anti-Siphon Valves

Electric Angle or Globe Valves

Notes for tables above:

• DW means the valve has special features for use with dirty water (caution–dirty is a relative term, if you can SEE the dirt you better get a good filter rather than a DW valve!!!)
• PR means pressure regulating. (Caution–the outlet pressure for the valve must be set at least 15 PSI lower than the incoming water pressure for most pressure regulating valves to work properly.)
• Valves are plastic unless noted as brass. (Do not assume brass is better, but also do not assume plastic is better!)

Common Valve Options:

Latching Solenoids

Latching solenoid option: Latching solenoids are special solenoids used most often with battery or solar operated irrigation controllers. A latching solenoid will not work with a standard irrigation controller. The latching solenoids work on a toggle principle. Each time they get an electrical pulse from the controller they either open or close. So when they get the first electric pulse they open. The next time they get a pulse they close. This saves electricity which is why battery operated controllers use them. The bad news is if they ever get “out of phase” they open when they should close and visa-versa. So the sprinklers run all day and turn off for 15 minutes each night. Opps…

3-way Solenoid

3-way solenoid option: A full explanation of what a 3-way solenoid is would require an in-depth knowledge of the hydraulic principles that make a valve work, which is a bit too much to try to explain here. So let’s just say that a 3-way solenoid is a more complex solenoid that is less sensitive to dirt or other contaminates in the water. 3-way solenoids are used on many dirty water or anti-contamination valves. Warning- most 3-way solenoids spit out a small amount of water each time the valve is opened, so be prepared for a few tablespoons up to a cup or more of water to come out. If installed indoors you’ll need a drain for the water to go into.

Dirty Water Valve

Dirty water option: An important note on “dirty water” and “anti-contamination” valves. “Dirty water” as used in the irrigation industry means water with small amounts of particulates or algae particles. As a general rule if the water looks dirty, then it is too dirty for any standard irrigation valve, including those labeled as “dirty water” or “anti-contamination” valves. You certainly don’t want to feed water into this valve, or any other manufacturer’s “dirty water” valve, that has sticks or twigs in it! Dirty water valves, such as this one, are commonly used for things like irrigation using secondary treated sewage. These valves contain internal screens to prevent debris from entering the small passages inside the valve. But remember that big stuff can still get lodged in the main passageways of the valve. Really dirty “sludge” water contains so much garbage that the screens become clogged, even if they are “self-cleaning”. The bottom line is that if you are pumping really dirty water, such as dairy sludge, you should talk to the valve manufacturer before using any valve. One more tip; when you call, talk to one of their engineering staff or a “troubleshooter”, not a salesperson! Almost every irrigation equipment manufacturer has troubleshooters that know the capabilities of their equipment better than anyone. These folks will generally give you a straight answer because they are the poor saps who have to go out and check out the problem if the valve doesn’t work!

Pressure Regulating

With this option the valve will regulate the downstream pressure to a desired maximum level. Lets say your irrigation mainline pressure is 100 PSI and you want to operate spray heads on the valve circuit controlled by this valve. At 100 PSI the spray heads would bow apart. With this option the valve can be set so that it will always keep the downstream pressure at 40 PSI or less. Like all pressure regulators the outlet pressure you set must be at least 15 PSI lower than the inlet pressure for the valve. If not, the regulator to work accurately or may not work at all. So if your mainline pressure is 45 PSI and you set the outlet for 40 PSI it won’t work very well. If the pressure at the valve inlet is 45 PSI you would ned to set the outlet pressure at 30 PSI (45-15=30). You could set the pressure lower than 30 PSI if desired, just not higher.

How to Select the Best Rotor-type Sprinkler:

Click here for an in-depth discussion of rotor-type sprinklers and what facts you should consider when selecting one. You should read this before reading the reviews or deciding on a make or model to use.

List of Rotors & Reviews:

Click here for a list of minimum standards for a good rotor.
Click here for a description of the feature codes used in the list below.

Rotor-Type Sprinkler Heads
Features in red are optional. They cost extra and may require a special order from the factory.

*Caution: Part numbers for some models don’t follow in a logical order that clearly identifies the body style. Check the description to assure it is the correct sprinkler head.

Other Products related to Rotor Heads:

• Mammoth Grip Sprinkler Spacers. Mammoth Grip Sprinkler Spacers are used to stabilize and accurately install sprinkler heads.
• Sprinkler Buddy Sprinkler Head Indicator. The Sprinkler Buddy keeps grass from growing next to or over the sprinkler head, thus making the sprinkler location obvious in the lawn.

Minimum standards:

I think any that any rotor sprinkler worth spending money on should have the following features:

• Must pop-up at least 3 inches (stream height above top of case).
• Must not be a discontinued or test-run product (generally that means at least one year on the market).
• Must have positive spring retraction for the riser piston.
• Must have a wiper seal on the riser piston.
• Must have a filter screen.
• Must have a closed-case (drive unit not exposed).
• If installed in a play area it should have a rubber cover (a rubber cover is so cheap and such an obvious safety item, I can’t think of a good excuse why all rotors shouldn’t have one!)

Feature key:

The following abbreviations are used in the reference chart below for various features of the rotor models:

• WS = Wiper seal. A wiper seal around the pop-up riser keeps dirt out of the sprinkler and reduces water waste.
• SR = Spring retraction. A spring pulls the pop-up riser back into the body after irrigation.
• FS = Filter screen. A screen installed inside the sprinkler helps protect the nozzle from debris in the water which might get caught in the nozzle. This is not a substitute for cleaning out the pipe when installing! I’ve found that most of these screens are only partially effective. A lot of stuff still gets though. The junk will not clog the nozzle but on water lubricated rotor drive mechanisms it can jam in the gears.
• CV = Check valve. The check valve keeps water from draining out of the pipes through the sprinkler head when the system stops running. A “must have” feature if your irrigation is installed on a sloped area. In general, if the elevation changes more than a foot within the valve zone, I recommend you use rotors with built-in check valves. Without this feature the water in the pipes will empty out through the lowest sprinkler head every time the valve is closed. This creates puddles and mud around the lowest heads and also cause excessive air discharge the next time the sprinklers are turned on. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra). Most check valves can be easily added as a retrofit item after the sprinkler is installed. You just unscrew the top, pull out the guts, snap in the check valve, then reassemble. No need to dig up the sprinkler. Check valve conversion kits can be difficult to obtain, and may require special ordering. If you even remotely think you may need them, it is best to just buy a model with a check valve already installed.
• NP = Non-potable water markings. Purple-colored markings are available for the sprinkler, generally with the label “Do Not Drink” on them. In most cases this is a replacement cap for the sprinkler, some are snap on covers that snap over the standard cap. Purple is the universal color for identifying a water source that is unsafe for human contact. In many places treated sewage and “gray water” (water from canals or untreated waste water from sinks or showers) are used for irrigation water, thus these warning labels are needed. This item may be optional, that is, you will only get it with the sprinkler if you request it (and probably pay extra).
• VR = Vandal Resistant. Has a feature that makes the sprinkler more vandal resistant. In most cases this is a lock screw that prevents easy disassembly or removal of the sprinkler without a special tool, probably an Allen wrench. Sometimes a metal cap is also part of the package. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).
• CC = Closed-Case. This means the drive mechanism that operates the sprinkler is not exposed at any time. An exposed drive unit can get stuff caught in it and jam. Bermuda and St. Augustine grass are particularly tough on open-case rotors as the grass grows into the drive mechanism. An example of an open-case rotor is a impact sprinkler head (the type with the arm that splashes into the water stream to move the stream back and forth.) A pop-up impact head is considered open-case because the mechanism is exposed while it is operating and grass easily gets into the cases. (Professional landscape maintenance people often refer to them as “rat traps”.)
• Arc:40-360° = Adjustable Arc. The first number is the minimum arc, the second is the maximum. If the maximum is not 360°, there is a separate non-adjustable full-circle model you must use for full circles.
• Arcs plates: Means that multiple arcs are available, but only at fixed intervals (not adjustable). A set of plates comes with the head, or is purchased separately, and you install the plate for the arc that best fits the shape of the area watered.
• LA = Low Angle Nozzles. Low angle nozzles are available. These are useful in windy areas. The lower angle means a shorter radius, so the heads will need to be installed closer together. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).
• SS = Stainless Steel Riser. The riser (the part that pops up) has a stainless steel sleeve around it. The stainless steel wears better in sandy soils where the sand can scratch the plastic riser and cause the wiper seal to leak. The stainless steel sleeve may also reduce damage from other sources (like mowers), although I have not found that it really helps that much. Typically the stainless steel sleeve is made from very thin metal. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).
• SO = Shut Off Valve. A small valve inside the sprinkler allows you to shut off the water to the nozzle in order to change nozzles. This is a big convenience on large sprinkler systems where it would be a pain to go shut off the valve so you can replace a nozzle in a sprinkler head. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).
• RC = Rubber Cover. The top of the sprinkler has a rubber cover over it to lessen the chance of injuries should someone fall on it. Highly recommended if you have kids. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).
• Robot. Sometimes called robot sprinklers, these sprinklers direct a stream of water to fall on specific spots. This works something like when you use a hose to water the yard, and you move the no

How to Select the Best Spray-Type Sprinkler:

Click here for an in-depth discussion of spray-type sprinklers and what facts you should consider when selecting one. You should read this before reading the reviews or deciding on a make or model to use.

List of Fixed Spray Type Sprinklers & Reviews:

Click here for a list of minimum standards for a good spray sprinkler.
Click here for a description of the feature codes used in the list below.

Note that many of the sprinkler model series listed include shrub and 2″ pop-up bodies, which do NOT meet my minimum standards.

*Caution: Part numbers for these products don’t appear to follow in a logical pattern that clearly identifies related products. Don’t rely on the part numbers alone!!! Carefully check the descriptions, product labels, and look over the product itself to assure you are getting the correct item.

(NS) means nozzle sold separately.

Other Products related to Spray Heads:

• Mammoth Grip Sprinkler Spacers. Mammoth Grip Sprinkler Spacers are used to stabilize and accurately install sprinkler heads.
• Sprinkler Buddy Sprinkler Head Indicator. The Sprinkler Buddy keeps grass from growing next to or over the sprinkler head, thus it makes the sprinkler location obvious in the lawn.

Minimum standards:

It is my opinion that any spray sprinkler worth spending money on should have the following features:

• Pop-up at least 3 inches (stream height above top of the case).
• Not be a discontinued or test-run product (generally that means at least one year on the market).
• Positive spring retraction for the riser piston. Gravity retraction results in mowed-off nozzles.
• A wiper seal on the riser piston.
• A filter screen.
• Matched precipitation rate nozzles.

Without the above features a sprinkler is not a bargain at any price, maintenance and repairs will cost you more than it would have to just buy a good-quality sprinkler.

Note:

I have not reviewed sprinklers and nozzles separately. It is assumed the sprinkler body will be used with the standard nozzle recommended by the manufacturer. In other words, if you use an ABC brand model ZZZ series body, I assume you will use it with a nozzle supplied by ABC brand for use with their ZZZ series body. The reason I point this out is that the nozzles for many spray-type sprinklers are interchangeable with those made by other manufacturers. They tend to have either “Toro style” nozzles with male threads on the nozzle, or “Rainbird style” nozzles with female threads on the nozzle. In general, I don’t recommend mixing different brands of nozzles and bodies.

Feature key:

The following abbreviations are used in the reference chart below for various features of the spray sprinkler models:

• WS = Wiper seal. A wiper seal around the pop-up riser keeps dirt out of the sprinkler and reduces water waste.
• SR = Spring retraction. A spring pulls the pop-up riser back into the body after irrigation.
• FS = Filter screen. A screen installed inside the sprinkler helps protect the nozzle from debris in the water which might get caught in the nozzle. This is not a substitute for cleaning out the pipe when installing! Most screens are only partially effective.
• RM = Ratchet mechanism. Ratcheting allows the riser to be turned independent of the body. To realign the spray direction you don’t need to turn the entire sprinkler, just the riser. The ratcheting mechanism holds it in the new position. Sometimes called a “friction collar” or “adjustable stem position”.
• MP = Matched precipitation rate nozzles. You can mix various nozzles made by the manufacturer on the same valve zone. For example you could use a 10′ radius quarter circle, 15′ radius full circle, and a 4’x15′ strip spray nozzle all on the same valve zone and the water application uniformity remains constant. Without this feature you get wet and dry areas and lots of wasted water.
• UM = Universal male thread nozzle. This sprinkler uses universal male thread pattern nozzles. That means the nozzle will fit on any brand or model spray sprinkler that also uses universal male nozzles. I strongly recommend that all the spray-type nozzles on a valve zone be made by the same manufacturer. The matched precipitation rates of Brand A nozzles will probably not match those of Brand B.
• UF = Universal female thread nozzle. This sprinkler uses universal female thread pattern nozzles. That means the nozzle will fit on any brand or model spray sprinkler that also uses universal female nozzles. I strongly recommend that all the nozzles on a valve zone be made by the same manufacturer. The matched precipitation rates of Brand A nozzles will probably not match those of Brand B.
• Sediment basin or trap. A sediment basin is a recessed area at the bottom of the sprinkler body where sediment can settle and become trapped. When the sprinkler is turned off, small grains of sand and other particles (sediment) that were caught on the nozzle screen often drop off the screen and settle down to the bottom of the sprinkler. Then the next time the sprinkler is turned on the swirling water rushing through the sprinkler body and riser pushes this sediment back up and eventually it again gets stopped by the nozzle screen. This process repeats each time the sprinkler is run. A settlement basin or trap is a deep recessed area in the bottom of the sprinkler body where this sediment can settle out away from the turbulent flow and it will not be repeatedly blown up into the nozzle screen. This helps the screen stay cleaner and also reduces abrasive wear on the internal parts of the sprinkler that result from sediment repeatedly being swirled up against them.
• CV = Check valve. The check valve keeps water from draining out of the pipes through the sprinkler head when the system stops running. A “must have” feature if your irrigation is installed on a slope or hillside. Without this feature the water in the pipes will drain out every time the valve is closed. This creates puddles or mud pits around the lowest heads where the water drains out. It also causes excessive air discharge the next time the sprinklers are turned on (the sprinklers spit, burp, and cough, which is not good for them or the pipes.) This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra). Most check valves can be easily added as a retrofit item after the sprinkler is installed. You just unscrew the top, pull out the guts, snap in the check valve, then reassemble. No need to dig up the sprinkler. Retrofit check valves can be difficult to find, you may need to special order them from the factory.
• PCD = Pressure Control Discs. These small disks fit into the bottom of the nozzle or are built into the screen. They are essentially a rubber disk with a small hole in it that restricts the water flow. They control the water pressure and flow into the nozzle. They are very handy for reducing the radius of a spray-type sprinkler and they work much, much better than the radius reduction screws on the nozzles. The sprinkler manufacturer will have a chart showing which disc to use with each nozzle to give the exact radius you need. I use PCDs to adjust the radius on all my spray sprinkler systems. If you adjust the radius of a sprinkler using the screw on top of the nozzle, and then the next time you turn it on the sprinkler no longer sprays water, installing a PCD will cure the problem. PCDs are not generic, you must get the specific one made for your brand and model of spray head.
• PR = Pressure regulation. An built-in pressure regulator maintains uniform pattern under varying pressures. These are basically for correcting problems with existing sprinkler systems. Unless installed on a hillside, a well-designed system shouldn’t have pressure variations in it that would require a regulator at the sprinkler. It is generally less expensive to utilize a single pressure regulator at the valve or at the water source. Exception: this pressure regulation feature is helpful when you have sprinklers installed on a steep hillside where the sprinklers at the bottom of the hill will have much more pressure than those at the top. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).
• SI = Side inlet. An optional side inlet allows the pipe to be installed into either the side or bottom of the sprinkler. This allows the use of a shallower trench. Warning: If you use the side inlet it is very difficult to replace the sprinkler if it breaks! On many brands the pressure regulation and check valve features will not work if you use the side inlet. In general I do not advise using the side inlets. All sprinklers that have a side inlet also have a bottom inlet, so having a side inlet isn’t something to avoid when selecting a sprinkler. It is something to avoid using when you install them! Many 6″ pop-ups and most 12″ pop-ups come with a side inlet whether you want it or not.
• NP = Non-potable water markings. Purple-colored markings are available for the sprinkler, generally with the label “Do Not Drink” on them. In most cases this is a replacement cap for the sprinkler, some are snap on covers that go over the standard cap. Purple is the universal color for identifying a water source that is unsafe for human contact. In many places treated sewage and “gray water” (untreated waste water from sinks or showers) are used for irrigation water, thus these warning labels are needed. This item may be optional, that is, you will only get it with the sprinkler if you request it (and probably pay extra).
• VR = Vandal Resistant. Has a feature that makes the sprinkler more vandal resistant. In most cases this is a lock screw that prevents easy removal of the sprinkler without a special tool, probably an Allen wrench. Sometimes a metal cap is also part of the package. This feature may be optional, that is, it is available but you will only get it with the sprinkler if you request it (and probably pay extra).

Select a Product Review Category:

Product reviews are separated into categories based on the type of product. Click on the type of product you want to research below:

Fixed Spray-Type Sprinklers
Spray-type sprinklers spray a fan of water out of the nozzle, similar to a shower head. They are typically spaced up to 18 feet apart in the sprinkler system.

Rotor-Type Sprinklers
Rotor-type sprinklers have one or more moving streams of water that rotate around the sprinkler head. They are typically spaced from 18 to 45 feet apart. Even larger rotors designed for parks and golf courses are spaced up to 90 feet apart. You need a professional designer for these, even a minor design error will result in huge dry spots!

Valves
Electric solenoid valves used for turning on irrigation circuits (sprinklers or drip emitters.) Includes anti-siphon, angle, and globe type valves.

Controllers
Controllers are fancy timers used to turn on and off automatic valves.

Tools, Accessories, Etc.
Accessories, tools, and other products that don’t fit into one of the above categories.

Common Questions about the Listings & Reviews

Are these reviews biased?

Of course! Expect that any evaluation of any product will be biased by the reviewer’s own personal experiences with the product, observation of installations where the product is used, and/or the experiences related to by others.

Why are there question marks in some of the part numbers?

A question mark character (?) in a part number represents a place holder for ANY letter or number. For example, a product for which I list a part number of 531?? could represent any of the following: 53100, 53190, 531AZ, 531ZA, 531A1, 5319A, etc. Using a variable is simpler than showing many different part numbers that are all essentially the same product with only a minor variation, such as different sizes.

Even more confusion: Sometimes manufacturers repackage their products for specific stores using custom part numbers. Some manufacturer’s use part numbers that make little sense at all (at least no logic that I can figure out!) A number of products are re-branded to carry the name of a different manufacturer, so you will find the exact same product with different brand names on it. All of these practices tend to confuse things. I have tried to include each such item under all the names and part numbers used, however it is just not possible for me to know all of them.

Often a small water supply pipe size between the water company’s big water main in the street and your house results in a low flow to the house. This can add a lot of cost to your new sprinkler system, as a lower flow means you will need more valve circuits. This FAQ explains how much benefit to expect from changing to a larger size house water supply pipe, and how to install the new pipe if you decide it would be beneficial. This FAQ is a sub-page to the City Slicker Water webpage, which is part of the tutorial on how to design a sprinkler system. While written in relationship to irrigation systems, the information here applies to any situation where you want to achieve a greater water flow to the house. It also should be helpful if you just need or want to replace the water supply pipe for the house.

Before you begin any digging call 811. This is a FREE service available everywhere in the USA. “Every digging job requires a call – even small projects like planting trees or shrubs. If you hit an underground utility line while digging, you can harm yourself or those around you, disrupt service to an entire neighborhood and potentially be responsible for fines and repair costs.” See the 811 website for more details. They will come out and mark the locations of all the underground utilities for you. In addition to helping you avoid accidentally digging up a utility pipe or wire, this will also help you locate exactly where your existing water supply pipe is located! Again, both the phone call and the service are free.

Before rushing out to replace the existing water supply pipe with a larger pipe, I suggest that you dig up some of the existing supply pipe and see what size it actually is underground. Often a larger pipe size (probably plastic) is used for the underground portion of the pipe, with a smaller size metal pipe at the end where the pipe comes out of the ground or extends into the basement. If all but 5 feet or so of the supply pipe is a larger pipe size, you probably don’t need to replace it. In this case the larger pipe size you found underground can be used for the “New Replacement Pipe Size” when calculating a new Maximum Available GPM using the table below.

Potential New Maximum Available GPM Values

If you don’t have a water meter, use the shut-off valve size
or smallest existing supply pipe size (whichever is smaller) in place
of the water meter size.

New pipe sizes larger than those shown in the table above do not result in a higher Maximum Available GPM value. However, they may help you by reducing the pressure loss, which can also be beneficial. The Sprinkler Design Tutorial will explain this.

* PE pipe is not recommended. PE has a low burst pressure, and generally PEX pipe is now used in situations where PE was formerly used.

“Maximum Available GPM” is a value used in the Sprinkler System Design Tutorial at IrrigationTutorials.com. It is a measure of the maximum SAFE flow that the house water supply pipe can accommodate. It is possible to force more water through the pipe, however doing so may cause major damage to both the pipe and house’s plumbing system over time. See the tutorial on Water Hammer and Air in Pipes for more information on pipe damage.

The table above is only for use in situations where the water is supplied to multiple households by a water supplier, such as a municipal water system. It is not suitable for use when water is supplied from on-site wells, streams, ponds, etc. For calculating how much water is available using an on-site pump (like with a well) see the Country Bumpkin webpage, for gravity flow sources see the Backwoods Water webpage.

Not all types of pipe listed are legal to use in all locations. Local building authorities regulate through building codes what type of pipe may be used. Codes change and it may no longer be legal to replace the pipe with the same type that was previously used. Local specialized plumbing stores may be able to help you with code compliance, however it has been my experience that advice on codes from larger regional and national outlets is often not correct. I recommend that you contact your local building authorities for advice on what type of pipe to use, often this requires just a simple phone call to them. Many will also offer very valuable tips and suggestions, be sure to also ask how deep the pipe must be buried.

How to replace your water supply line:

In most places a plumbing permit is required to replace the water supply pipe or even to simply cut into it. Contact your local building authorities for details.

Remember that the water supply pipe carries the water you and your family drink! It is important to be careful not to get dirt into it when working. After completion of your work be sure to turn on all your water faucets for several minutes to flush out any dirt or other contaminates. You should sterilize the pipes before using the water from them for drinking. There are products available at plumbing stores for this. Be sure to buy the pipe sterilizer and read the instructions before you start work as you may need to put the sterilizer into the pipes before you reconnect them!

Water mains, Goosenecks, and Corporations Stops

The water company has a large pipe someplace out there that is called the “water main”. It is probably 6 inches or larger in diameter and located in the street or alley. From the water main a smaller pipe goes to your property. This smaller pipe is referred to as a “gooseneck”. At the end of the gooseneck is a shutoff valve called a “corporation stop”. The corporation stop is typically installed near your property line. The idea is that the corporation stop marks the dividing point between you and the water supplier. The pipe coming into the corporation stop belongs to the water supplier. The pipe going out of it typically belongs to the property owner. The corporation stop is usually located in a box or at the bottom of a sleeve with a round plastic or metal cap on it. The cap may only be 4″ in diameter and hard to find. Often it will be covered with dirt or grass, so you will need to poke around to find it, try probing the ground with a pitchfork, metal rake, or screwdriver. Look for a mark engraved into the curb or street pavement indicating the location. The corporation stop will probably be buried below the frost line, so it may be several feet deep in colder areas.

Call 811 and they will come out and mark the location of the water gooseneck for you, and it’s free! This is very helpful in finding the corporation stop since it is someplace on the gooseneck. That will narrow your search area. Sometimes they will even mark the location of the corporation stop. The person who comes out to mark the pipe locations generally has detailed plans that show the exact location of everything. If you happen to be there and are friendly, they are often willing to share lots of useful information with you.

The corporation stop (often abbreviated as “corp stop”) serves as the water company shut-off valve for your house. It is usually operated using a special key or wrench in order to prevent unauthorized use. Fortunately, you can buy a wrench for it at most hardware stores. Get out a flashlight and look at top of the corporation stop first to see what shape the operating nut is, as there are several styles. Also note how deep it is so you can get a wrench with a long enough handle to reach it. Most use a slotted wrench that fits over a raised rectangular shaped bar, like the one in the photo below. If you’re really lucky, it will have a normal handle on it, but don’t bet on it! In some cases you have enough room to operate the corporation stop using a standard pipe wrench. Another trick is to use a basin wrench (a special wrench used to install faucets on sinks) to operate it. You will probably also notice a couple of holes on the corporation stop that align with each other when the valve is in the closed position. These allow the water company to padlock it closed if you don’t pay your water bill! Most corporation stops are hard to turn, so you may need to put some muscle into it. You may be able to get the water company to send someone out to close and open it for you. Often they will do this for free (especially if you ask nice, and you have a good record of paying your water bill on time!)

Photo of an underground water service utility box
containing a corporation stop, water meter, & homeowner shut-off valve.

The photo above is of a particularly nice set-up. Not only is there a corporation stop but there is also a homeowner shut-off valve with an easy to use handle. No need to use a special key, the homeowner can turn off the water themselves without tools in an emergency. I cleaned up the inside of this box before taking the photo. A valve box like this will often have ants, spiders and other disgusting stuff in it so be careful when opening them up. I even found a dead turtle in one once!

Sometimes in cold weather areas there is not a corporation stop located outside. The corporation stop is in your house, usually in the basement, crawl space, or a utility room. In this case you’re pretty much screwed, because the water service pipe is likely owned by the water company and even if it isn’t you can’t easily shut off the water to replace it. Before giving up, call your water company directly (use their local customer service number, not 811) and ask if they have a shut-off someplace between their mainline and your house. Maybe you just couldn’t find it. As a last resort, ask them if they will install a new, larger supply pipe for you. Most of the time they will, but they probably will charge you for doing it. Don’t be surprised if they refer you to a plumbing company to actually do the work.

Add a Second Pipe or Replace the Original Pipe?

How you proceed from here depends on the current layout of your water supply, your budget, and future maintenance concerns. Select the method below that best applies to your needs.

The water meter is installed right next to the corporation stop, or you don’t have a water meter.

• You can simply tap into the existing water supply pipe right after the water meter. Then install a brand new larger size pipe to the sprinkler system. The pipe leading to the irrigation system would be the “new” supply line, using the revised GPM from the table above. The existing supply line to the house would remain unchanged, and the existing flow to the house would remain unchanged. Only the sprinkler system would get the increased flow.
• Tap into the existing supply pipe right after the corporation stop/water meter and install a new second pipe to the house parallel to it. About a foot out from the house connect the new pipe back into the old, smaller pipe leading into the house. That way you don’t need to change any of the pipe in the house walls. This creates two supply pipes side-by-side to the house, with the water going through both of them. The advantage is that this saves some money, as the new pipe can be the same size as the old pipe. The water will go through both of the pipes, so the flow will be much greater than previously (but not doubled, other restrictions still exist, such as the gooseneck and corporation stop.) The downside is that you will now have two separate pipes going to the house. That means twice as much pipe that can break or leak someday. Plus the old pipe will still be there and because it is old, it is more likely to leak or break. Because this method creates future problems, it is not recommended by most professionals.
• Remove the existing water supply pipe between the corporation stop/water meter and the house and replace it completely with a new, larger pipe. About a foot out from the house connect the new pipe to the old, smaller pipe leading into the house. That way you don’t need to change any of the pipe in the house walls. This is the most common method used and is generally the best option.

The water meter is installed more than five feet away from the corporation stop (typically inside the house.)

The options for pipe replacement are essentially the same as those above, however in this case you need to replace the pipe between the corporation stop and the meter. Typically in this situation the meter is inside the house. However, if the meter is someplace out in the yard you will also need to replace the pipe between the meter and the house.

It is much easier if you don’t actually replace the short section of pipe that goes into the house through the wall or floor. Reconnect the new pipe to the old, smaller pipe about a foot outside of the house wall. That leaves a short section of the old pipe going into the house, but is a lot easier than replacing the pipe through the wall or floor. The water will squeeze through the short section and it will work fine as long as there isn’t more than 5 feet of old pipe left between the point you connected the new pipe and the water meter. If there is more than 5′ left, you will need to install new pipe through the wall, or replace the old pipe inside the house once it is through the wall. In other words you leave a short section of the old pipe going into the house through the wall. Once inside it is easier to install a new, larger pipe. You will tap in your new sprinkler system as close as possible after the water meter. Unfortunately, you will have to route the new sprinkler supply pipe out through the wall, which means you will have to drill a hole in the wall. Be sure to seal the hole around the pipe with a good quality flexible water-proof caulking compound! The pipe will move as it expands and contracts, so the caulk needs to remain flexible after it has cured. (Do not use cement for sealing the hole! Standard cement, plaster, and concrete mixes are NOT waterproof!)

Other Items to Consider

Plastic pipe must generally be installed at least 18 inches deep, measured from the top of the pipe to the soil level. All pipe should be installed below the frost line. In some areas that might be 4 feet or more deep. Your local building authorities will have specific requirements on how deep the pipe must be.

How do you connect the new pipe to the old? Most professionals use a compression coupling. If you don’t know what that is, ask at a hardware store. If you make a threaded connection between plastic and metal pipe see the How to Connect Plastic Pipe to Metal Pipe FAQ.

Well, that’s it for this FAQ. Have fun, and remember, safety first when digging and working with trenches. Follow all OSHA requirements. See OSHA’s guide to working around trenches.

What Is Low Head Drainage?

Water that flows onto the sidewalk or curb after the sprinklers turn off, but then stops after a few minutes, is due to a phenomena called “low head drainage”. This occurs when the sprinkler system is installed on a sloped area. The slope does not need to be very high, a change of elevation of less than a foot will often create low head drainage. After the sprinklers are turned off, the water in the pipes drains out through the lowest sprinkler heads and is replaced with air. The easiest way to tell if you have low head drainage is to watch the sprinklers when you turn them on. If they spit and spew lots of air when the valve is turned on, then you have a low head drainage problem. Obviously the water that drains out of the pipes is wasted. The spewing and spitting of air every time you turn on the sprinklers also puts a lot of stress on the pipe and sprinklers.

Leaking Valve or Low Head Drainage?

If you have water flowing from a sprinkler head continuously, even when the sprinkler system is off, then the problem is a leaking control valve. The primary difference between low head drainage and a leaking valve is that low head drainage results in water flowing from the lowest sprinklers for a while after they run, but the drainage stops after the pipes are fully drained. (It may take several hours for the water to drain out of the pipes.) If a valve is leaking the water will run out of the lowest sprinkler head all the time, 24 hours a day, every day. A typical indication that the problem is a leaking control valve is moss or algae growing on the sidewalk due to the constant flow of water. Another common sign is puddles of water around the lowest sprinklers that never dry out. To fix the leaking valve you must disassemble the valve, clean it, replace any bad parts, then reassemble it. See How to Repair a Irrigation Solenoid Valve for instructions. It is possible and common to have problems with both a leaking valve and low head drainage. Fix the valve first, then check for low head drainage.

How to Stop Low Head Drainage:

To fix low head drainage you need to have special anti-drain check valves installed at the sprinkler heads. These check valves prevent the water from draining out of the pipes through the lowest sprinklers. In most cases these check valves are built into the sprinkler head. The anti-drain check valve is an optional feature available when you purchase the sprinkler. This check-valve option is available on all major brands of sprinklers. The anti-drain check-valve closes and holds the water in the pipes when the sprinkler system is off. These built-in check-valves don’t cause any drop in performance of the sprinklers, so they don’t have any impact on your sprinkler system design. Many major brands of sprinklers can be retrofitted with a new internal check valve, although the retrofit kits are hard to find. Most pros simply buy a new head with the check valve feature and replace the old sprinkler with the new one.

You can also buy separate check valves that can be installed on the pipe under existing sprinkler heads. These are a lot harder to install, you need to dig up the sprinkler head, remove it, install the new check valve on the riser pipe, then screw the old sprinkler back into the new check valve. Then comes the hard part- the length of the check valve you just added makes the sprinkler sit about 3 inches higher than it was before! So now you need to lower the sprinkler head. There is also another catch to the retrofit type check-valves; they do result in a drop in the sprinkler’s performance. They typically create a drop in water pressure at the sprinkler inlet of 2 to 5 PSI. In addition to the performance drop the retrofit devices are often more expensive than simply replacing the sprinkler with a model that has a built-in check valve.

Where do you buy sprinklers with check valves or retrofit check valve? Check valves and sprinklers with built-in check valves are often not available at discount stores or big box hardware stores. You will probably need to get them from a local irrigation specialty store or online.

A tentative change to the language of the State of California’s Water Conservation Laws will make the use of low-drainage check valves mandatory for new sprinkler systems starting in the year 2010, and may also require retrofit of many older sprinkler systems with check valves. Expect other States where water conservation is an issue to also implement this requirement.

What is Expansive Soil?

Expansive soils can be found in many areas. Expansive soils expand in size when they get wet, and then shrink as they dry out. As the soil expands and contracts it can create enough force to cause major damage to building foundations, patios, and sidewalks. Expansive soils are also sometimes called shrink-swell soils, swelling soils, adobe, clay, or caliche soils. The damage caused by expansive soil is similar to that of frost heave found in northern regions, but it is NOT the same thing!

Identifying Expansive Soil

Soil that cracks or fractures when it dries is often a sign that it is expansive; however a lack of cracks does not necessarily indicate that the soil is not expansive. Other expansive soils take on a popcorn like appearance when they dry, they look like someone spread little lumps of popcorn shaped dirt on the soil surface. Expansive soils are often clay like, becoming very sticky when wet and hard and brittle when dry. The best way to determine if the soil at a location is expansive is to have an expansion test performed by a soil expert. Expansive soils are common in desert areas, and also in river bottoms or valleys formed by sediment. They typically form in areas that were once covered by seas or lakes. For example, they are commonly found in the deserts of Arizona, the valleys of Colorado, and coastal plains like the Los Angeles Basin and the low lying areas around San Francisco Bay. Often your local government building department can tell you if the soil in your area is known to have expansion problems. Links at the bottom of this page lead to websites with maps of expansive soil areas and more information on expansive soils.

Typical cracking of expansive soil when dry.

Limitations of this Article

Use of this information is at your own risk. Expansive soils vary widely so all I can offer here are broad ideas for ways to deal with it. You will need to decide for yourself the appropriateness of these ideas to your situation. If your soil is extremely expansive you should have a Soils or Geotechnical Engineer advise you on ways to deal with it (they are most often listed under the headings “Engineers – Geotechnical” and/or “Engineers – Soils” in your local phone directory.) Because of the extreme and costly damage that can result from soil expansion, you need to use extreme care in how you deal with it. Please see the Terms of Use for this website.

Water and Expansive Soils

Expansive soils either expand or contract as the amount of water or moisture in them changes. It doesn’t matter if the water is from rainfall or irrigation; the damage is the same either way. In a very simplified explanation, the soil pulls water into it, where the water is stored between the tiny soil particles. Since the water takes up space between the soil particles, the area occupied by the soil expands. The key to controlling damage is to keep the moisture level in the soil next to and under foundations, sidewalks or patios at a uniform level of moisture at all times. If the soil is dry, you want to keep it dry, if it is slightly wet, you want to keep it slightly wet. The amount of moisture in the soil isn’t nearly as important as avoiding changes in the moisture content of the soil.

Concrete Materials

When expansive soils are present it is important to use reinforced concrete to resist the soil movement. This is important because no matter how careful you are, there will be at least some minor soil expansion, and you must be prepared for it. Building and wall foundations should be designed by a qualified engineer. This is not a place to cut corners! Seek out qualified help for the design of foundations. Repair of building damage caused by soil movement can be horrifyingly expensive!

All concrete, including sidewalks and patios, should contain steel reinforcement materials such as rebar and steel mesh. Placing steel in the concrete strengthens it and reduces concrete heaving and cracking. Concrete patios should also have thickened edges with rebar in them to resist soil movement. A local licensed architect, landscape architect, engineer, or concrete contractor can advise you on the necessary thickness of the reinforced edge and the type and quantity of steel mesh and rebar to use. Be sure to discuss with them your budget, and how much cracking and heaving you are willing to accept. Often a compromise is required between cost and having a perfect concrete surface.

The use of concrete pavers or bricks is another option for patios and sidewalks in areas with expansive soils. The pavers are installed without mortar. As the soil expands and contracts the pavers simply move with the soil. The disadvantage of this is that the surface may become very uneven as the pavers move and shift. The advantage is that the pavers generally don’t crack like concrete. Another advantage is that if the pavers become uneven you can remove and reinstall them. Removing and reinstalling them is a lot of work, of course!

Controlling Soil Expansion

The most obvious way to keep expansive soils from expanding is to keep water off of them. Rainwater from roofs should be collected in gutters and then piped away from the building. Drainage should direct water away from buildings. The soil should slope away from buildings for at least 5 feet out from the wall, further is better. While this has nothing to do with irrigation, I mention it because it is important to keep all water away from the building, not just irrigation water. Also keep trees and large shrubs at least 10 feet from buildings as the roots can remove moisture from the soil next to the building and cause it to shrink and collapse.

One way that expansion of soils is controlled by architects and engineers is by mixing lime or other anti-expansion products into the soil. Irrigation water will leach lime and other materials out of the soil, which defeats the purpose of the treatment. Be sure to check to see if the soil under your foundation was treated with lime or a similar anti-expansion material prior to building the structure. If the soil was treated, you need to keep irrigation water away from the treated areas if possible. If possible consult with the building designer as to how far away you need to keep the irrigation from the treated area. If you can’t get a recommendation, keep the irrigation at least 5 feet away. Aprons around the building, as described further below, are a good solution when the soil has been treated.

Another way that engineers deal with expansive soil is to remove the soil and then reinstall it in severely compacted layers (usually with lime added), or just totally replace it with non-expansive soil hauled in from someplace else. This is fairly common in residential building. Normally the soil within 3 to 5 feet of the building foundation will be replaced to a depth of 4 or 5 feet. Be careful not to mix soil from elsewhere around the site with this soil. Also be careful not to mix soil amendments into this area as they will change the non-expansive soil properties. It is best to simply not plant anything within 5 feet of the building foundation. Remember that even if the soil around the building has been replaced or treated, you will still have to deal with expansive soil problems under your driveways, sidewalks and patios.

Finally, architects and engineers may seek to control soil expansion by use of irrigation to help maintain a constant moisture level in the soil. This is a bit tricky because if the irrigation ever fails for any reason, expansion or contraction will occur. This method also requires almost pinpoint accuracy in scheduling irrigation. In the real world this is pretty much impossible to achieve.

Most often some type of compromise solution utilizing several of the above methods of controlling soil expansion is used. In these compromise solutions all water (both from irrigation and rainfall) is kept out of a “no-water zone” that extends at least 3 feet away from the foundation, and often 5 feet. Typically an impermeable apron of some sort is used for this. Then irrigation is used at the edge of this “no-water zone” to maintain a reasonably constant moisture level surrounding it. The following paragraphs look at methods of keeping the “no-water zone” dry and irrigating the edge of the “no-water zone”.

Concrete Aprons

Probably the best method of keeping water away from the building foundations is to use an impermeable apron around the building to keep water away from the foundation. One way this is done is to pour a concrete “apron” all the way around the foundation. The apron needs to extend between 3-5 feet out from the foundation. A plastic moisture barrier sheet is placed under the concrete, because concrete is not water-proof and moisture will seep through it. Also water will flow through the concrete at cracks and expansion joints. It is important that the surface of the concrete apron is sloped so water drains out away from the building and does not pool on the concrete surface. When using a concrete apron you need to understand that the expanding soil will break the concrete apron, and cause it too heave. The only purpose for this concrete is to keep water away from the foundation; it is not intended for use as a sidewalk or patio. It is accepted that soil expansion and contraction due to water seeping under the concrete will result in the concrete becoming uneven and broken! If you want plants up next to the building, put plants in containers on top of the apron. If you want to reduce damage to the concrete apron, add a moisture barrier at the outer edge of it as described below.

Plastic/Rubber Aprons

Another way to keep the perimeter areas dry is to use a plastic or rubber barrier and then cover it with rocks, gravel, bark, or some other loose material. This is often visually more pleasing than the concrete apron above, as the loose material covering the apron does not develop ugly cracks, like concrete. The downside to plastic is that it is not as permanent, yearly checks are needed to make sure the plastic does not have tears or holes in it, and the plastic must be periodically replaced as it will wear out over time. Rubber is more durable but also breaks down over time. The thickest plastic/rubber that can be afforded should be used, thicker material will hold up longer. 20mil thick plastic/rubber is often the minimum thickness used. This plastic/rubber material is often sold for use as pond liners. The plastic/rubber apron must be glued at the top to the edge of the foundation so that water will not enter between the barrier and the foundation. Use high-quality glue or double-stick tape that remains flexible when dry. All joints in the plastic/rubber should be overlapped by at least 8 inches and glued or taped together. The plastic/rubber should not be exposed to any sunlight, as sunlight will make it wear out much faster. Cover the plastic/rubber completely with something to keep sunlight off of it. Generally the covering material is at least 3 inches deep over the plastic/rubber. If you cover the barrier with dirt it is likely weeds will grow and create holes in it, so dirt or soil is not a good choice. It is very important to not let weeds grow on top of the plastic/rubber. If you put potted plants on top of the apron area, check often to make sure roots are not growing out of the pots and down into the barrier!

Typical Apron Detail, click on detail to print.

Moisture Barriers

Moisture barriers are most often used to reduce expansion damage to less important structures like hardscape. (Paved landscape features like driveways, sidewalks, and patios are called hardscape. Hardscape can be made from many materials, such as concrete, bricks, flagstone, etc.) Moisture barriers are also used in areas where the soil is only minimally expansive. A moisture barrier keeps water from seeping sideways under the adjacent hardscape, but does not keep water away from the edges of the hardscape. This reduces lifting of the hardscape surface by the expansive soil. It does not prevent the adjacent soil from moving the hardscape sideways, which is why it is not suitable for areas with highly expandable soil. A moisture barrier is a sheet of thick plastic or metal set vertically along the edge of the hardscape. The moisture barrier typically extends at least 24 inches in depth; often 36″ deep barriers are used. The moisture barrier must be glued at the top to the edge of the hardscape so that water will not enter between the barrier and the hardscape. Use high-quality glue or double-stick tape that remains flexible when dry. Moisture barriers should be checked at least once a year to assure the barrier is still firmly glued to the edge of the hardscape. Moisture barriers need to be continuous with no gaps, cracks, or unglued joints between the sections. Typically the moisture barrier sections are both overlapped and glued or taped together at any joints. It is critical that water not be able to get through or behind the barrier. The moisture barrier needs to be thick enough that roots will not easily grow through it and create holes in it. Often 20mil and thicker plastic is used. If metal is used for the moisture barrier it should not be something that will rust.

Typical Moisture Barrier Detail, click on detail to print.

Using Irrigation to Maintain Uniform Moisture

Often Geotechnical Engineers will recommend that irrigation be used to maintain “uniform soil moisture” levels. The theory is that if the moisture level stays uniform at all times, the soil will neither expand nor contract. This is easier to say than it is to do. While irrigation can maintain the needed water in the soil, it takes a top quality irrigation system to apply the water uniformly and it takes skill in timing the irrigations to keep the amount of water in the soil constant and uniform. If the irrigation system is not maintained and operated very carefully, it can worsen the problem rather than help. Remember that the key is keeping the soil moisture at a constant, uniform level. If you decide to keep the soil stable by keeping it moist, you must always keep it at exactly the same level of moistness. If it is ever allowed to dry out or become over-saturated it may cause damage. Because using irrigation to maintain uniform soil moisture is difficult, it is best to use irrigation only in combination with the use of a apron or moisture barrier as described below.

Maintaining Water Uniformity in the Soil

Water content of irrigated soil varies tremendously. Immediately after irrigation the water content is very high, and then it recedes with time until the next irrigation. This is true of both sprinklers and drip systems, but sprinklers add even greater variability than drip. As the water moves down through the soil and away from the heat of the sun and air circulation, it disperses. As a result the moisture level in the soil tends to stabilize and become relatively uniform. Stable and uniform soil moisture is exactly what is desired for reducing the soil expansion problems. This is the reason that foundations of buildings on expansive soil are often 3 or 4 feet deep, extending down to where the soil moisture levels are more stable. But often a 3-4 foot deep foundation is not practical, or for whatever reason was not utilized. Fortunately, water also moves sideways through the soil, not just down. So we can mimic this “soil depth effect” at the surface to some degree by sealing the surface so that water neither enters it nor evaporates from it. This way the water can move sideways out from our irrigation source, and as with moving down, the moisture level will become more stable and uniform as we move away from the water source. All we need to do is block water from entering or leaving the soil at the surface level. This is the theory behind the use of concrete and plastic aprons described above. An apron 3 to 5 feet wide is placed around the entire building. Irrigation is installed at the outer edge of this apron. This keeps the irrigation well away from the foundation and helps maintain moisture levels more uniform near and under the building or patio. When water from rainfall or irrigation enters the soil, it moves sideways through the soil, by capillary action, under the edge of the apron. By the time it has moved 3-5 feet sideways under the apron, the moisture level is dispersed and reasonably stable and constant.

It is critical that the irrigation system be run at regular intervals to keep the moisture level stable. I strongly suggest the irrigation be automated with a timer and checked regularly. You can also use automatic soil moisture sensors to control the irrigation. There are many available on the market, but my experience has been that they are not fool-proof. You can’t just set them and forget them. The oldest type is called Tensiometers. There are also solid state sensors that require less maintenance than the older style Tensiometers. There are constant arguments in the industry as to which is better; I really don’t have an opinion on this. They are heavily influenced by local conditions, particularly soil type and salt content; you will need to do some research to find the one best for your situation. Many of the soil moisture sensors are designed to keep the moisture from dropping below a given level, but do not guard against too much water in the soil.

Drip Irrigation

It is my opinion that you will get the most uniform moisture applications from a drip system. It is important that the drip system uses evenly spaced emitters, generally around 12 inches apart on the tube. There are a number of products that come with emitters pre-installed on a tube at regular intervals. Or you can buy the emitters and tube separate and install them on the tube yourself at uniform spaces. The drip tubes should not be buried unless you use one of the types that use chemicals to prevent root intrusion into the emitters. The only two I know of are Techline (with Techfilter) by Netafim, and DL-2000 by Toro. The drip tube is typically installed 12″ from the edge of the apron. See the Drip Irrigation Design Guidelines for more help with a drip system design. Remember, uniformity of water application is critical to control expansive soils so proper design is very important.

Soaker Hose

Soaker hoses tend to not give very uniform distribution of moisture, and they have a rather limited life span. They may be appropriate for a short term temporary solution prior to installing a more permanent irrigation system. I wouldn’t consider a soaker hose for a permanent solution. If you do use them, the design and operation is similar to drip systems.

Sprinkler Irrigation

Sprinklers may also be used for irrigation around the apron; however the sprinkler spacing must be head-to-head at the edge where the water application needs to be as uniform as possible. Head-to-head means that one sprinkler sprays all the way to the next. So if the sprinkler radius is 12 feet, they should be placed no more than 12 feet apart. The sprinkler heads should be placed at least 6″ away from the edge of the apron. See the Sprinkler Irrigation Design Tutorial for information on designing a high quality irrigation system. Remember, uniformity of water application is critical to control expansive soils so proper design is very important.

Additional Resources on the Web

Here are some good resources for additional study:
Colorado State University Extension- Horticulture Article on expansive soils by C.R. Wilson, J.G. Davis and N. Mejia for Colorado State University Extension- Horticulture.
Missouri University of Science and Technology A very good article on expansive soils with case studies and solutions for foundations and swimming pools. A must-read article if you plan to build a swi

Wind can really mess up an irrigation system. Even a gentle breeze will blow around the water droplets from most sprinklers. Realistically, a slight breeze from time to time is not usually a problem. But if you expect a steady breeze on a consistent basis, you should take precautions in your irrigation system design. This FAQ will guide you through the possible solutions to wind problems.

If Possible, Avoid Using Sprinklers:

The best way to deal with wind when designing an irrigation system is to avoid using sprinklers. Anytime you spray water into the air there’s going to be problems with the wind blowing the water around. This is simply unavoidable. So the best approach is to avoid irrigation systems that spray water into the air. A drip system is ideal, as the water is dripped directly into the soil from the emitters. Subsurface (underground) drip systems will work for most lawns, however subsurface irrigation is not for everyone. It is generally more expensive than sprinklers and requires different maintenance procedures.

Bubblers are also a good solution, as the water is also applied directly at the soil level. Bubblers work by flooding small areas of the ground with water. Bubblers do not work well for lawn areas, however. The difference between bubblers and drip is in how quickly the water is applied. With a bubbler the water is applied faster than the soil can absorb it, so it spreads out and floods the area. Bubblers are great for shrubs planted in groups on flat soil where the water can spread out. They are not good for slopes where the water will flow downhill and away. Drip systems emit water very slowly and the water soaks directly into the soil without flooding. With a drip system only an area about 3 feet (1m) in diameter around each emitter (or dripper) becomes wet (the size of the area varies with soil type and how much water is applied.) So at least one emitter is required for each plant, for larger plants you might need several emitters. Drip systems work well on slopes. See the Drip Irrigation Design Guidelines for more information.

Re-Design Your Landscape:

Another way to deal with wind problems is through the design of your landscape. In windy areas it is common to design landscapes so that there is no lawn directly adjacent to sidewalks, driveways, roads, buildings, or anything else you don’t want to get wet. A typical lawn for a windy area would be designed to look somewhat like a golf green surrounded by shrubs. (Use a rounded shape for the lawn, like a jelly bean or the meandering edge of a mountain meadow surrounded by forest.) The lawn is then irrigated with sprinklers, and the shrubs are irrigated with bubblers or drip irrigation. The sprinklers are adjusted so that the ones on the upwind side spray slightly backwards into the wind, so that the wind blows the water back onto the lawn. In other words a sprinkler that would normally use a half-circle nozzle on the upwind side might utilize a two-thirds circle nozzle so that it sprays back into the wind slightly. On the downwind side the sprinklers are adjusted just the opposite, with the knowledge that water will be blown slightly down wind. So on the downwind side a sprinkler that would normally have a half-circle nozzle might now use a one-third circle nozzle. Because the lawn is surrounded by shrub areas, any water that blows outside of the lawn area will not be wasted.

Sprinklers and Wind:

The remainder of this article will deal with sprinkler systems and the unique challenges that wind presents when designing a sprinkler system.

Don’t Water When the Wind Is Blowing:

I guess it is obvious, but it is an important factor so here it is: the best way to avoid wind problems is to avoid the wind altogether. Even in the windiest locations there are often times of the day when the wind doesn’t blow as much or as strong. This is typically in the early morning hours. Try to design your sprinkler system so that you can irrigate during these reasonably wind-free hours of the day. This may require you to obtain a larger water source, so that you can irrigate more area in less time. Do a little research to see what time of the day the wind blows the least. In many windy areas the wind dies down a few hours after sunset and doesn’t start up again until shortly after sunrise. Use a fully automatic irrigation system and design it so that it can operate during these reasonably wind-free hours of the day.

Will watering at night cause any harm? Watering at night and during early the morning saves water, as there is less evaporation at these times of day. In humid climates watering at night can lead to mold and mildew problems, however this is not typically a problem in windy areas, as the wind tends to quickly dry out the residual moisture on the leaves. A well-established lawn should not need to be watered more than once a day, even in hot, windy areas. Shrubs need watering even less often. So watering at night, rather than during the day, should not be a problem. In hot, windy areas lawns and other plantings will often look wilted by late afternoon, this is often hard to avoid. Watering during the heat of the day typically does not provide much help with this as the problem isn’t a lack of water in the ground. The problem is that the plant simply can’t pump enough water through it’s roots to stay crisp and fresh looking. A healthier plant with more and better roots is the solution to this problem, and watering too frequently can actually cause less roots to grow. During the establishment period for new plantings (typically the first 90 days) it is necessary to water more frequently, a new lawn often needs water every 2-3 hours on a hot afternoon. When establishing a new lawn it is often necessary to hand water some areas when the wind is blowing in order to assure they get enough water.

Sprinkler Head Selection:

Wind impacts sprinklers when it blows the water away from the place where you wanted the water to be applied. This is called wind drift. Two factors have a large effect on the amount of wind drift. The first is the size of the water droplets the second is the size of the water stream.

Spray-type sprinkler heads: Mist and small water droplets are easily blown by the wind. So it is best to avoid sprinklers that create a lot of mist or very small water droplets. Spray-type heads tend to create lots of mist, especially if there is excessive water pressure at the sprinkler head. This can be addressed simply by properly adjusting the sprinkler to minimize the amount of mist created and not over-spacing the sprinklers. A small screw on the top of most spray head nozzles allows them to be adjusted so that there is a minimal amount of mist created. To avoid over-spacing, if the sprinkler company’s literature says the sprinkler has a 15 foot (4,5m) radius, then do not space them more than 15 feet apart! Remember that for the most efficient operation, most sprinklers require 100% overlap of the area watered by each sprinkler. Yes, I know that seems like a lot of sprinklers, but it is the way it works, so get used to it. Each sprinkler needs to throw water all the way to the next sprinkler. Low angle sprinklers are generally less affected by wind, however you need to use a sprinkler with at least a 4″ pop-up height so that the low-angle spray does not hit the grass.

Rotor type sprinkler heads: Like the spray-type heads they must be spaced so that there is 100% overlap of the watered areas. When using rotor-type sprinklers avoid models that use less than 3 gallons per minute (11.4 l/min) flow. The higher flow rates of larger nozzles result in larger water droplets that are not blown around as easily. Rotors that have multiple streams of water are called stream rotors. Stream rotors can be identified by their appearance when operating, the streams of water look like spider legs rotating around the sprinkler. Stream rotors tend to have very small water streams that are easily moved by the wind. It is probably best to avoid them if you must irrigate when the wind is blowing. The closer the water is to the ground the less likely it is to be blown by wind. So try to avoid sprinklers that have high trajectories. Low angle sprinklers are less affected by wind. The farther the water has to travel through the air, the more likely it is to be blown off-course by wind. Thus in windy areas it is best to use shorter radius sprinklers.

My preference is to base the selection of either rotors or spray-type sprinklers on the size and shape of the area. I generally use rotors in areas where all the dimensions are more than 20 feet (6m). In narrower areas I use spray-type heads. Both sprays and rotors have issues with wind and in my opinion neither provides a clear advantage in windy areas. When dealing with wind, I have found that the type of sprinkler isn’t nearly as critical as proper spacing and adjustment.

For more on sprinkler head spacing see the Sprinkler Spacing Page of the Sprinkler Irrigation System Design Tutorial for the correct method of designing a sprinkler system. Wind makes it critical that you design the system properly; the wind leaves you with no room for error in your sprinkler spacing or pipe sizes.

Valve Zones for Windy Locations:

Design your irrigation system so that the perimeter edges on the up-wind and down-wind sides are controlled by separate valves. Wind problems tend to be the worst along the up-wind edge of the irrigated area. In this area the wind blows the water away from the edge, leaving it dry. The next worst area for wind problems is on the downwind edge, where the wind tends to blow the water out of the irrigated area. Put the sprinklers on both these edges on their own separate valve circuits if possible. This allows you to run those valves during more reliably wind-free times of the day. It also allows you to increase or decrease the watering time in those areas to compensate for the wind problems. If cost or another factor makes it difficult to separate both edges, then try to separate only the up-wind edge to the extent possible. It’s OK to fudge a little and include a few heads that aren’t on the edge on the same valve circuit with the ones on the edge.

Tighten Spacing On the Upwind Edge:

As previously mentioned, wind problems tend to be bad on the upwind edge of the irrigated area. One means of dealing with this is to place the sprinklers closer together on the upwind edge. There is no room for sprinkler spacing errors on the upwind edge. If you’re using spray type sprinklers I suggest a maximum distance between sprinklers of 12 feet. Spray type heads used at 12 foot spacings have water droplets that are considerably larger and less susceptible being blown by the wind. If you are using rotor type sprinklers try to keep the spacing slightly closer than head to head. That means the water from one rotor should spray all away to the next rotor along the upwind edge. Don’t stretch the spacing at all. When in doubt, reduce the space between heads and add another sprinkler head. On the upwind edge it is always better to have more heads than to have less.

Wind Detectors:

To avoid irrigating during times when the wind is blowing you can use a control system that detects wind. One method of doing this is to install a wind speed monitor nearby. It detects high wind speeds and shuts off the irrigation. It does this in a non-smart way; it just shuts off the power to the valves and irrigation stops. This is a really effective method but there is a drawback- the irrigation gets skipped and the landscape may dry up if the wind blows for several days! So if you use a wind detector like this you need to keep an eye on it, wind can make the landscape dry out fast. Some high-end irrigation controllers are smart enough to know that the irrigation was shut down and will attempt to reschedule it at a wind free time. Finally, some irrigation controllers have a remote programming feature where the irrigation schedule is calculated and controlled by a company for you on a subscription basis. In this case the company determines that the wind is blowing in your area based on a wind detector, a nearby weather station, or the weather forecast. When the wind blows hard enough to be a problem they shut off the irrigation and reschedule it for you.

That’s it. These tricks and techniques should help you to have a better irrigation system in windy areas. Remember, the best trick is to avoid the wind by irrigating when it isn’t blowing!

A master valve is an automatic valve, typically an electric solenoid type valve, that is installed at the point where the irrigation system connects to the water supply. The master valve is wired to a special “master valve circuit” on the irrigation controller. (Sometimes this circuit is called a “pump start circuit”. Both types of circuits work similar or identical, and can be used for a pump and/or a master valve.) The irrigation controller turns the master valve on and off. Most, but not all, irrigation controllers have a master valve circuit built in to them.

How a master valve works:

Zone valves are the individual valves that operate a group of sprinklers or drip emitters. A typical irrigation system has several zone valves. Typically one zone valve is turned on at a time, and controls the irrigation in a specific area of the yard. Whenever one of the irrigation zone valves is told to open by the controller, the controller also signals the master valve to open. So the master valve is a little like a back up valve, or a fail-safe valve. The purpose of the master valve is to shut off the water to the irrigation system when none of the zone valves are operating.

Benefits of master valves:

• If a zone valve develops a leak, or doesn’t close, the master valve will act as a back-up to shut off the water. Note that the water will still be on as long as any other zone valves are on. But when all are finished watering, the master valve will shut off the main water supply to the entire irrigation system. While this does not eliminate the water loss or damage, it may minimize it.
• If the mainline pipe (the pipe from the water source to the zone valves) breaks, the water will be turned off at the end of the irrigation cycle and this may minimize water loss and damage. This is especially useful if the mainline is on a hillside, where a leak might cause massive erosion and property damage. Again, the water will still be on as long as any other zone valves are on, so it only will stop the flow when the entire irrigation system is off.
• Some of the more expensive irrigation controllers can use a flow sensor in combination with a master valve to detect leaks and shut off the entire irrigation system. The controller memorizes how much water is used by each valve zone. If the flow sensor shows that the water use is higher than expected, indicating a leak, the controller detects the change in flow and closes the master valve. Unfortunately, most commercial landscape maintenance companies I have dealt with do not know how to use one of these sensor systems, and they disable the sensor. This has happened about 90% of the time on projects I have used these systems on.

Disadvantages of master valves:

• Leaks are more likely to go unnoticed and not get repaired when a master valve is used. This is because most irrigation systems run at night, when nobody is around to see the leak. During the day, when the irrigation system is shut down by the master valve, the leak is not noticed and goes unreported. My experience is that most property owners, homeowners and, yes, even professional landscape maintenance providers, do not regularly check the irrigation systems for proper operation. They make repairs only when damage becomes extreme or someone complains. No, this is not how it should be done, but sadly it is what I see 90% of the time. For this reason a master valve can actually increase the amount of water wasted when a leak develops.
• Master valves lead to premature failure of both PVC and PE (poly) mainlines. This is due to the stretching and contracting of the pipe each time the system is pressurized and then depressurized. This problem is greatly exaggerated at higher water pressures (over 65 PSI or 4,5 bars).
• A master valve can increase the severity of water hammer if the mainline has a pinhole, or one of the zone valves has a slight leak, or if the zone valves close slower than the master valve. This is due to the water draining out of the mainline. When the master valve opens and the pipe refills, the water charges through the empty pipe at a very high velocity, slamming into the tees and ells and causing damage to the pipe system.
• A master valve is one more item that can fail and require maintenance, plus it adds to the initial cost of the irrigation system.

What type of valve should be used for a master valve?

Any electric solenoid valve can be used as a master valve, except for anti-siphon valves. Anti-siphon valves may not be used as master valves. (You should never install an anti-siphon valve in a location where there is another valve downstream of it, if you do it will break the anti-siphon part of the valve.) Many professionals like to use brass valves for master valves due to the higher pressure rating and a general attitude that “if it’s brass it must be better”. I don’t feel that a brass valve is necessary unless you can’t find a plastic valve with a high enough pressure rating. Note that the pressure rating of the valve should be at least double the expected water pressure in the irrigation system. So if you have 75 PSI, or 5,2 bars, of water pressure the valve should be rated for at least 150 PSI, or 10,4 bars. If the master valve is installed before the irrigation system filter, then a “contamination-proof”, “self-filtering”, or “dirty water” valve would be the best type of valve to use as the master valve. These are expensive valves that have a small built-in filter to help protect the valve from dirt, which is a major cause of valve failure. If a valve with a filter is too expensive, a valve featuring a “self-cleaning metering rod” or “self-flushing ports” would be the next best thing. At a minimum the master valve should be equal in quality to the zone control valves. I typically install a filter upstream of the master valve, so most of the time I use the same valve model for the master valve as I use for the zone control valves. If you are designing an irrigation system that uses hydraulically operated zone valves, you will want to use a hydraulic operated master valve rather than an electric solenoid type. Hydraulic operated systems are rare, so if you don’t know what I’m talking about it doesn’t apply to you!

Where to install the master valve:

The master valve can be installed anywhere you would like. It can be before or after the backflow preventer and or the pressure regulator (if used). A few water districts do not allow any valves to be installed before the backflow preventer, but most don’t care. I typically place them in an underground box after the backflow preventer and the pressure regulator. In most cases, putting it after the pressure regulator allows the use of a less expensive valve with a lower pressure rating. In freezing climates the basement, utility room, or a heated shed is a good place for them. If you need to repair the master valve it will spill water when you open it, so make sure it is not installed in a location where a little water spilling out will cause harm. Some master valves spit water out of the valve when they are manually turned on. I suggest that the master valve not be used as the emergency shut off/winterization valve for the irrigation system. Use a separate ball valve installed before the master valve for that. Like all electric valves, sooner or later it will need to be repaired, and you will need to shut off the water while you fix it.

My opinion; when should you use a master valve?

If your mainline is located in a place where a leak might cause severe property damage or a danger to the public, you should use a master valve. If you are willing to pay the price of a flow monitoring irrigation controller with a flow sensor, a master valve can be used as a water conservation measure. The controller should be programmed to shut the master valve only if a leak is detected, and not at the end of every irrigation cycle. For a typical residential irrigation system, and even many commercial systems, I don’t think the benefits of a master valve outweigh the risks or justify the cost. Many water districts in areas with limited water supplies require the use of master valves as a water conservation measure. I absolutely oppose the use of master valves as a water conservation measure when not used with a flow sensor and appropriate irrigation controller. My experience indicates they actually result in an increase in wasted water!

Help, I Need More Water!

How can I get more water out of my existing water supply pipe? How can I increase the minimum available GPM for use in my irrigation design? These questions and variations of them are among the most frequently-asked questions I hear. A typical question would be something like this: “I have a 5/8″ meter and a 3/4″ copper supply, so according to the Sprinkler System Design Tutorial I only have 10 GPM available. This doesn’t seem like very much, so I did a bucket test and got 18 GPM from it! So why can’t I use the 18 GPM figure from my bucket test for my Initial Design Flow?” Well, the answer is you can use that higher value. Of course, you can also jump off a cliff if you want to, but it isn’t a wise choice. There is more involved in determining your Design Flow than just measuring water in a bucket. The good news is that you MAY be able to use a higher flow. The bad news is it isn’t easy or fast to determine if you can! So be patient, and read on. I know this is a long tutorial, but there are a lot of variables and I want to try to give you enough information to make a good decision.

The rest of this FAQ assumes your water is coming to you from a water supplier. If you pump your own water from a well, stream, or pond the only way to increase your water flow is to install a newer and/or larger pump, larger pipe leading to and from it, and possibly drill a deeper well. You will need to see the Irrigation Pumping Systems Tutorial for details on how to do that.

GPM definition: GPM is the standard unit of flow used in the USA, it means “gallons per minute”. This tutorial uses GPM as the flow measurement. Metric countries use liters per minute (l/m) to measure flow. Multiply GPM x 3.78 to get liters per minute.

There are obvious advantages to having a higher flow rate available for your sprinkler system. Increasing your available water supply will reduce the number of valves you need, which could result in a less expensive controller, less wire, and, in general, a lower cost. The best way to increase the amount of water you have available is to have the water supplier install a larger pipe to your property. But in most cases these good options are expensive or not even possible. So the next best solution is to try to force more water through the existing pipe. Unfortunately, there is a lot of really bad advice floating around on how to determine the maximum flow for your sprinkler system. Most sprinkler contractors and sprinkler design guides focus on keeping the short-term costs down. After all, they want to make a sale, and the best way to do that is to have the lowest price. They will save you a few bucks up front when buying your system at the expense of hundreds or even thousands of dollars in repairs later on. The theory is that you are happy you saved money today– and they won’t be around when you are unhappy later! I don’t play that game, so we’re going to look at the risks, and then you can decide if it is worth it.

The Problems with Higher Flows

First, this FAQ assumes you have already worked through the process of calculating your flow used in my Sprinkler System Design Tutorial, and that you want to use a higher flow than what was recommended there. If you haven’t read through at least the first 3 pages of that Tutorial, I recommend you do it before continuing here. The tutorial describes the best way to determine how much flow you will have to work with in designing your sprinkler system.

Keep in mind that what we are discussing here is the maximum available GPM flow. The maximum available flow is the starting point for your design. The actual GPM you should use for your irrigation system may be lower than this value for any number of reasons. As you work through the tutorial above, you will be able to determine the actual GPM you should use.

Now let’s take a look at the significant risks involved in using a higher flow, so you know what you are getting into. The Maximum Available GPM figures I recommend in the Sprinkler System Design Tutorial are set at the maximum safe flow for your pipe size and type, as recommended by the vast majority of experts and the pipe manufacturers.  It is correct that you can get a lot more water through that pipe. No doubt about it. You can force an almost unlimited amount of water through a pipe if you put enough pressure on the water. But is that wise?

Scrubbing

Velocity is the measurement of the speed at which the water is moving through a pipe. In the USA irrigation industry we measure this speed in feet per second (abbreviated feet/second or ft/sec). Flowing water is a funny thing, it seems rather harmless, but at very high velocities bad things begin to occur inside pipes. The first is what is called “scrubbing”. Scrubbing is essentially the wearing away of the inside of the pipe one molecule at a time.  It results from a number of different factors, but it’s easiest just to picture the water as being very slightly abrasive.  It just scrubs away at the pipe.  As the water moves faster and faster, this effect gets considerably worse.  Therefore, most industry sources recommend that you limit flow velocities to less than 7 feet/second, if possible. If the pipe is larger than 2″, the recommended maximum velocity drops to 5 feet/second. Scrubbing is also worse in metal pipes, the slicker surface of plastics reduces the problem. Scrubbing combined with corrosion is the primary reason that copper pipes in houses develop pin holes over time and need to be replaced.

Water Hammer

The second problem that occurs at high velocities is “water hammer”. Remember the Jan & Dean song Dead Man’s Curve?  Let’s say you have a really fast Model A hot rod (what a thrill, can I hitch a ride?) You decide to take it out for a ride on Sunset Blvd. It would be safe to drive at 35 MPH, stupid at 50 MPH and sure death when you hit Dead Man’s Curve at 80 MPH!  In the same way, the water in your pipes can go pretty fast, but what happens when it hits that curve?  How about if it hits a wall? The answer is called “water hammer”.

Water hammer is caused when a valve quickly closes on the fast-flowing water in the pipe. For a great mental image of this, picture a large, very heavy, very long truck full of bananas driving straight into the face of a cliff.  Got the image?  Bananas everywhere!  One last thing to be aware of is that water hammer problems are much more likely if you have water pressure over 60 PSI. If you want to read more on water hammer I have written an entire tutorial on the topic. You can read it here: www.irrigationtutorials.com/waterhammer.htm.

So can you use a higher flow?  Sure, you can.  But all bets are off.   I know it saves a lot of money if you can use a higher flow and have a few less valves.  But if you get a good case of water hammer, you can bet you are going to regret it.  When a sprinkler valve shuts off at 4 AM in the morning and it sounds like the house was just hit by a truck, your spouse may hit you!  Or maybe you’ll just ignore the noise until the morning one of the hoses under a sink blows off due to the pressure surge, and the house is flooded.  Then you may just wish you had spent a little more money on your sprinkler system! Scrubbing, on the other hand, is pretty easy to predict. If you exceed the recommended flows in the tutorial, you are going to get scrubbing damage, especially if you have copper pipe. What is next to impossible to predict is how much damage will be caused. As you increase the flow, the scrubbing gets progressively worse. It also depends on the type of pipe you have and how well it was assembled back when they built your house. If, in general, you have noted that your house is poorly constructed, you might want to think long and hard about this! But if the scrubbing isn’t major, and the pipe and workmanship are good quality, it takes years and years for it to become a problem. How many years varies widely, but more than 10 years seems to be a reasonable expectation.

Well, at this point you need to decide how much risk you want to assume to save a few dollars. Unfortunately, I can’t help you with this. It has to be your decision. So below I’ll give you some new maximum flow rates, and also explain how to do a water hammer test.

Ready to Proceed?

OK, you understand the risks and you want to proceed anyway. The Maximum Design Flows that I give in the Sprinkler System Design Tutorial are based on maintaining a flow below 7 feet/second. Some people in the industry say you can go up to 10 feet per second, especially with smaller pipe sizes. I have never heard anyone with any training recommend a flow higher than that. The maximum flow values in the table below are based on 10 feet/second velocity.  Flows over this value pretty much guarantee you will see major damage in the pipe.

Remember that the maximum flow must be based on the most restrictive pipe that the water passes through on the way to your sprinkler system. For example, let’s say your house has a 1″ PVC pipe that brings the water from the water company mainline out in the street to your house. When the pipe reaches the house, it changes to 3/4″ PEX pipe through the house. In this case if you tapped into the 1″ PVC pipe, then the 1″ PVC pipe would determine the maximum flow. This is because the water going to the sprinklers goes directly from the 1″ PVC pipe into the sprinkler system. You wouldn’t need to consider the 3/4″ PEX because the water never passed through it. However, if you tapped into the water supply inside the house after the pipe becomes 3/4″ PEX, then the PEX pipe would determine the maximum flow because the PEX pipe has a lower maximum flow than the PVC. The most restrictive pipe that the water actually passes through determines the maximum flow.

“What if the smallest pipe is really short? Won’t the water just squeeze through without problems? After all, a lot of water squeezes through a valve, and the opening in a valve is pretty small, right?” Yes, that is correct, and you can squeeze the water through. The problem is the scrubbing. A valve is made with a heavy body so it can stand up to the wear, but pipe, particularly copper, is not. My advice is to replace the small pipe section with a larger pipe. But yes, you can squeeze the water through if it is less than 3 feet long and you accept that the pipe will wear out faster.

NEVER EXCEED THESE FLOWS!
(GPM at 10 feet/second)

Notes on using the table above:

CTS means “Copper Tube Size”, IPS means “Iron Pipe Size”. SDR means Standard Dimension Ratio (the ratio of the pipe wall thickness in relation to the diameter of the pipe).

If your pipe is larger than 1″, you should have plenty of water, stick with the flows in the tutorial! Larger pipe sizes are much less forgiving of high-velocity flows.

What type of plastic pipe is it? PEX and PE are both polyethylene products. There is a lot of confusion over these two products. True PEX is a stronger form of cross-linked polyethylene that has become popular with plumbers in recent years. Both PEX and PE are flexible, and both have a glossy appearance and slick surface. So how do you tell which one you have? Older PE is almost always black, and in most cases PEX is not black. The surest thing to look for are the letters “PEX” printed on the tubing. Making things even worse, white PEX looks a lot like PVC, especially if it is old or dirty! PEX is easily scratched with a fingernail, PVC scratches, but not easily. PEX was not invented until the ’70s, and it is seldom found in homes built before 1975. (It wasn’t officially sold in the USA until 1985. Of course, if your house has been remodeled, you could still have it in a older house.)

PEX tubing. Don’t confuse it with PE or PVC!
Note the labels “PEX” & “SDR-9”.

PVC plastic pipe is almost always white or gray and is more rigid than either PEX or PE. Another type of PVC called CPVC is sometimes used inside homes and often is found in older mobile homes. It is similar to regular PVC, but will be labeled “CPVC” and most often is a yellowish, gold, or tan color. CPVC in homes is usually copper tube size (look for “SDR-11” printed on the pipe), but is also sometimes IPS (SCH 40). Confused yet? Your best bet is to find lettering on the pipe that says what type it is.

CRITICAL! Your maximum flow MUST be based on the most restrictive pipe size and type between the water company’s mainline and your sprinkler system. Even if you use a 1″ PVC pipe for your irrigation system, if you are tapping into a 3/4″ copper pipe to get the water, then the 3/4″ pipe determines the maximum flow. Think of it this way- you may have a huge mouth, but if you are trying to suck soda through one of those tiny straws used to stir coffee you will not get much soda! The pipes leading to your irrigation system are like that tiny straw. The smallest, most restrictive one determines how much water gets through.

Water Hammer Test:

If you’re going to try using a higher flow, you need to perform a water hammer test. I know this takes time and effort, but it is necessary.

This test is absolutely critical if you plan to tap into a pipe that comes out of the side of your house, like a hose bib. This is because you don’t know what size pipes they used inside the walls of your house. Just because the plumber should have used a big pipe doesn’t mean he did. Maybe he ran out of the correct size of pipe and didn’t want to make another trip back to the shop to get pipe, so a small pipe he has handy gets installed. Who knows. All I know is it happens.

Understand that no test is perfect. This test will identify if water hammer will occur under the conditions which you run the test. Conditions can and do change. If you happen to run the test while your water company’s water pressure is abnormally low, you could get a false negative for water hammer. Plus other things can cause water hammer, such as designing your sprinkler system wrong. I do not guarantee that a negative result with this test will mean no water hammer will occur in your sprinkler system.

Tip: If you aren’t familiar with the terms used here, see the Glossary and the Understanding Fittings pages. Also, a picture is worth a thousand words, so here’s a diagram of what I am about to try to explain!

1. Go shopping! Here’s a few of the items you will need:
   • Pressure gauge 0-100 PSI (or higher.)
   • 1″ electric irrigation valve (make sure it has a flow control on it, and it is best if it is the same brand and model you plan to use for your irrigation system.)
   • 1″ brass ball valve.
   • 3 nine-volt batteries.
   • 1″ pipe (more on what type and how much pipe is discussed later)
   • Whatever fittings you need to connect it all to the house water main as described and shown in the diagram above.
   Read all of these instructions, think it through, and make a list before you go shopping to avoid a second trip to the store. You should be able to find all of these items at an irrigation supply store or the plumbing and irrigation sections of most home improvement centers. Tip: lay out all the parts on the floor of the store to be sure you have everything you need and that all the parts will fit together.
2. Tap into the water supply pipe at the point where you want to take your irrigation system water from (the “Water Source Point of Connection” in the diagram above.) You will reuse this tap for your irrigation system water supply, so it won’t be wasted. Keep in mind that the further this tap is from where the water supply pipe enters your property, the more chance you have of creating water hammer problems! The worst possible place to tap into is a hose bib sticking out of the side of the house. The best place to tap into is the supply pipe right after the water meter (if you have one.) The second best place to tap into is right after the main water shut-off valve for your house’s water supply.
3. Install the ball valve as close as you can to the tap point, but make sure it is in a easily-accessible location. This will become your emergency/winter shut-off for the irrigation system, so it will be permanent. You won’t remove it after the test, so do a good job of installing it!
4. Install a 1″ section of pipe going from the ball valve to the pressure gauge location. Suggestion: it will be easier if the pressure gauge and electric irrigation valve are above ground. This pipe can be as long as you like, but should not be less than 12″ long. It can have as many directional changes as needed to get it above ground or outside of the house. If part of this pipe will be inside your basement or crawl space, it should be the same type of pipe that is used inside the rest of your house. In may places it is not legal to use PVC or PE pipe inside or under a house. Even if it is legal I don’t recommend it.
5. Install a tee (a fitting, shaped like a “T”, that adds an outlet to a pipe) and attach the pressure gauge to the outlet of the tee. Most pressure gauges come with a hose adapter on them, which has 3/4″ female hose threads. Most pipe has IPS threads, which are not the same as hose threads. However, you can attach the 3/4″ hose connection onto a 3/4″ plastic male pipe thread with a little force (ie; use a wrench.) This is only temporary, so it will be OK. Do not leave the pressure gauge permanently connected. Remove it after you are done with your test. All but the most expensive pressure gauges will “stretch” over time and stop working accurately if you leave them connected to a water source.
6. Install another short section of pipe after the pressure gauge and then install the electric valve. Note that water may spill from the valve during the test, so it is best if the valve is installed outside.
7. Now install as much 1″ pipe as needed to go from the electric valve to some place where you can dump a lot of water and not make too big of a mess. We’ll call this the “blow off” pipe. This pipe is temporary, so just lay the pipe on top of the ground. This pipe can be up to 100 feet long, if needed. Remember you will need to get a 5 gallon bucket under the pipe outlet, so you may need a few ells in the pipe to go up over the top of the bucket. If you used PVC pipe, let the glue dry for an hour before proceeding.
8. Now slowly open the ball valve to the full-open position. Check the pressure reading on the pressure gauge and write it down. This reading is your static water pressure. You will use it when you design the sprinkler system. If you use my Irrigation Design Tutorial, this will be your “Design Pressure”
9. Now test and break-in the electric valve. Close the flow control on the valve. Next, manually open the electric valve using the on/off lever on the valve (on some valves you do this by turning a knob or loosening a bleed screw, see your valve instructions). Wait 30 seconds, then open the flow control to the fully-open position. The water should start flowing as you open it. Let it run for at least a minute, then turn the manual on/off lever to the off position. It may take up to two minutes for the water to stop flowing through the valve. Don’t panic, this is normal. If the electric valve still does not close after a couple of minutes, it probably has an air bubble caught in it. Again, this is very common with brand new valves. Try re-closing the flow control on the valve, then reopen it. If this doesn’t work, another trick is to go press your hand over the outlet of the pipe to create some back pressure on the valve. (You will get wet doing this!) Once you have it working, break in the valve by opening and closing it a few times, using the manual on/off lever.
10. Now the flow test! Open the electric valve using a test battery setup (see below.) To do this just touch the wires from the valve to the end terminals of the test battery chain. With the wires connected to the batteries the valve should open. When disconnected, the valve should close (again, it may take a couple of minutes to close).  Open and close the electric valve several times to break in the solenoid.
11. Next, open the electric valve using the batteries. Check the pressure gauge. If it shows less than 35 PSI, then slowly close the flow control knob/handle on the electric valve until the pressure on the gauge moves up to 35 PSI. Once the gauge is reading 35 PSI (or more) go measure the flow coming out of the end of the pipe using your bucket (see method below.) If the flow is higher than the maximum flow you determined using the table above, close the flow control knob/handle a little and retest. Continue closing the flow control knob/handle until you get the flow down to (or below) the maximum flow.
12. Finally– it’s time to test for water hammer! Close the electric valve by disconnecting the battery. Did you hear a bump, bang, or multiple bumps when the valve actually closed? If so, that is water hammer. A soft thump heard at the valve is OK. All valves make some sound when they close. What you don’t want is a very solid-sounding thump, multiple bumps, or any loud noise that you can hear in the house. Anything that sounds like a hammer hitting the pipe is bad. Now that you have it all set up, run the test several times late at night when it is quiet and again very early in the morning during the most likely time you will be irrigating.  Do you hear any water hammer at those times?  Listen both at the valve and inside your house.  If you do hear water hammer, you need to reduce the flow a little , (close the flow control knob/handle a little more) then repeat the test. Continue until you reach a flow where you don’t hear any water hammer. This flow is the maximum flow you should use for designing your irrigation system.

Bucket Method GPM flow test:

Get a 5-gallon bucket. Old paint buckets work great. Since most 5-gallon buckets actually hold more than 5 gallons of water, you will need to calibrate the bucket as follows: Find an accurate measuring container, and measure out 5 gallons of water into your bucket. Then mark the water level on the side of the bucket with a marking pen so you can easily see it.  The test is simple. Put the bucket under your water outlet pipe and time how long it takes to fill the bucket to 5 gallons.  The formula for calculating the flow in GPM is: 300 divided by the seconds it takes to fill a 5 gallon bucket = GPM.

Guys- don’t use your wife’s favorite kitchen measuring cup!

Battery test setup:

Use 3 standard 9-volt batteries (the rectangular type with snap connectors on top.) Using the male and female snaps on top of the batteries, snap all three of them together in a chain. This creates a home-made, portable, 27-volt valve tester. Now touch the valve solenoid wires to the end terminals on your battery chain. The valve should open. Easy. Cheap. And it works great!

Using a chain of 9 volt batteries to open a valve.

“Smart Controllers” are controllers that automatically update the watering schedule to allow for changes in water needs throughout the year. So a smart controller will automatically reduce the watering times as the weather gets cooler and less water is needed. Then as the weather begins to warm up, the controller will add more watering time. The way this typically works is that you set the controller for a default maximum watering time, based on the hottest time of year. Then the controller reduces that time amount by a percentage value when less water is needed. There are several methods used by different controllers to determine how much to reduce the watering time. Some controllers may allow for use of more than one method. Here’s a list of the common methods used by smart controllers to determine the watering time:

• Historical. Uses historical weather and water use data for your area to determine what amount of water is required. Typically it only resets the time monthly. While the historic data is not perfect, it still gives significant water savings for most users. You will periodically need to manually override the automatic controller settings, especially if you have unusually hot weather for the month. To setup the controller on some models you simply enter your zip code and it accesses the historic data from it’s memory. On others you have to initially key in the historic data from the user’s manual or a website. Due to the lower cost of this type of smart controller, often it will give you the best financial return on your investment. This is especially true for a small residential irrigation system.
• Historical with a sensor. Uses historical data to determine an initial reduction in watering time, but then further adjusts the time based on a sensor. Typically a temperature sensor is used. If the daily high temperature is higher than the historical data says is normal, it adds more time, if the temperature is lower, it reduces the watering time. This gives more accuracy that the historic data alone will.
• Off-site data. Uses water and/or weather data provided by a remote provider. The controller uses a radio, Internet, or phone connection to obtain the data from either a central data provider, or from a local weather station. Generally there is a subscription charge for the data service and there may also be charges for the telephone, Internet, or radio link. Accuracy is dependent on where the data is obtained from (garbage in, garbage out). If the data comes from a nearby weather station it can be very accurate. If it comes from a central data base of historic data that is expertly manipulated for current conditions it can be very accurate also. So with this type of smart controller you need to ask the provider exactly where the data would come from for a controller installed at your location.
• Weather station. This controller has it’s own weather station that you install with it. It uses real-time data from the weather station to adjust the watering times. It is very accurate if it uses a good weather station.
• Moisture Sensor. A moisture sensor (often more than one) is placed under the irrigation system to measure the actual amount of moisture in the soil. The irrigation time is based on the amount of moisture present. I’m going to get flamed for this, but I wouldn’t be honest if I didn’t tell you that moisture sensors have not been well-accepted by professional turf managers. This is at least in part due to a lack of long-term reliability of the sensor units. There are several types of sensors available. Some require regular maintenance, others do not. There are advantages and disadvantages to each type of sensor. Do some research, as different types of sensors work better with some types of soils than they do with others. Be prepared to spend some time calibrating the sensors and making adjustments. With that said, this is a very accurate method of determining watering times.

Some companies sell add-on equipment, such as moisture sensors, that can be used with any brand of controller to make it “smart”.

With all smart controllers there is an initial shake down period of a few months when the controller will need weekly adjustments. During this time you fine-tune the controller to your actual conditions. After that the controller takes care of the adjustments.

In order to make good decisions about which sprinkler products will work best for you it is necessary to have some basic knowledge of how sprinklers work and what the various options available to you are. Therefore the following is intended to give you the background necessary to understand the terminology used in my reviews.

Sprinklers fall into one of two types based on the method they use to apply water to the ground; spray-type (sprays) or rotor-type (rotors.) Spray-type sprinklers are the type of sprinkler that spray a fixed water pattern similar to how a shower head works. Rotor-type sprinklers use a rotating stream (or multiple streams) of water to apply the water to the ground. Spray-type sprinklers (also called “spray heads” and “sprays”) are typically used for smaller areas. Rotor-type sprinklers (most often simply called “rotors”) are used for larger areas (generally more than 18′ in width.)

Rotor-Type Sprinkler Basics

Rotor is the term used to describe the various sprinklers which operate by rotating streams of water over the landscape. The example which most people are familiar with is the “impact” rotor sprinkler (often improperly called a “rainbird”, Rainbird is the actually the trade name of a sprinkler manufacturer.) The impact sprinkler is mounted on a bearing that allows the entire sprinkler body to spin in circles. It is rotated by the impact of a swinging arm which repeatedly strikes the body of the sprinkler, causing it to rotate slightly each time. You probably know the impact sprinkler best for the distinct sound it makes when operating– tooka, tooka, tooka, tic, tic, tic, tic, tic, tooka, tooka, tooka, etc… You may run into rotor-type sprinklers called “cam drives” or “ball drives”. These are also impact sprinklers, however the impact is caused by either a cam or a ball bearing inside the body of the sprinkler. With ball and cam drive rotors only the nozzle moves. Most of these ball and cam drive sprinklers are no longer sold, but a few, like the Rainbird R-50 (they don’t call it a ball drive, but it is) are still available. While impacts do an acceptable job of irrigating, the jerky motion of the impact drive tends to make them rotate in a less than uniform manner. Thus the impact rotors have now been almost completely replaced by gear-driven rotors, which are very quiet, rotate smoothly, are lower maintenance, and much smaller in size. As with cam and ball drives, only the nozzle on a gear-drive moves. The water moving through the sprinkler spins a turbine, this turns a set of gears, which turn the nozzle. These gear-drive rotors have one or more streams of water which rotate silently across the landscape. The prettiest of these are the multi-stream rotors (or “stream-rotor”) where multiple streams of water rotate over the landscape one after the other. Multi-stream rotors are fascinating to watch but tend to be higher maintenance than the other types of gear-drive sprinkler heads.

Most rotors now come with a set of nozzles rather than a single nozzle. Often these nozzles come attached to what is called a nozzle tree. Just remove the nozzle you want from the tree and install it in the rotor. Save the rest of the nozzles, you may need them later. Multiple nozzles are a big advantage, as you can change to a different size nozzle if needed to help balance your system. Say you have a dry spot between rotors. You might be able to green it up by installing a larger nozzle in the rotors surrounding the dry spot. Some rotors, however, still come with a single, pre-installed nozzle, and some come with stripped down nozzle trees (with only a few of the available nozzle sizes on them.) If you want the whole set of nozzles with these less expensive models, you must purchase them separately. A preinstalled nozzle or limited nozzle tree is common with many of the prepackaged rotors sold at discount stores.

I need to mention a new type of sprinkler, which I am classifying as a rotor since it utilizes a moving stream of water. However, it operates a little different from a traditional rotor. Sometimes called robot sprinklers, these sprinklers direct a stream of water to fall on specific spots. This works something like when you use a hose to water the yard, and you move the nozzle of the hose around to make the stream of water fall on different spots. The size and shape of the area to be watered is programmed into a computer, the computer then controls the sprinklers, telling them where to move the stream and how much water to apply in each spot. Typically they use an electric motor to move the nozzle.

What situations work best with rotor-type sprinkler heads?

Typically rotors are used for sprinkler spacings from 18 feet to 55 feet apart. There are rotors available that can be spaced closer than 18 feet but they are generally not cost effective, as a spray sprinkler will work well at this spacing and cost less. There are also rotors available for spacings farther apart than 55 feet but they are typically only used for golf courses. Most rotors require a lot more water pressure to operate than spray-type sprinkler heads. When selecting a rotor keep Stryker’s Rule in mind; “the water pressure at the rotor head (in PSI) must exceed the distance (in feet) between the heads.”) Thus if you want to space rotors 35 feet apart you will need 35 PSI of pressure at the rotor. (Caution: you will actually need more pressure than 35 PSI to run the system due to pressure loss in the pipes and valves between the water source and the sprinkler. Figure a minimum of 15 PSI more will be required for the pipes and valves.) The small rotors sold for residential use work best at 25 to 35 foot spacings, although with careful design some models can be spaced up to 50 feet apart. As a general rule you should hire a professional designer if you need sprinkler spacings greater than 45 feet. Designing with larger sprinklers requires specialized knowledge as many unique factors must be considered in the design process.

How a Typical Gear-Drive Rotor Works

Water enters the base of the sprinkler. From there it passes through a filter screen and then through a turbine. The water turns the turbine, which powers a set of gears, which rotate the sprinkler nozzle. The water then passes up through the body and exits through the nozzle. Generally the nozzles can be removed and there are numerous nozzle sizes available. At the nozzle there is a radius reduction screw. With most rotors this screw also doubles as the set screw that holds the nozzle in place.

Reducing the Radius and Dealing with Coverage Problems

As the radius reduction screw is turned clockwise the end of the screw comes into contact with the stream of water exiting the nozzle. This distorts the water stream and results in a reduction of the radius. Many people in the irrigation industry refer to this screw as the “break-up screw” because it “breaks up” the water stream. There is a temptation to play around with this screw setting in an attempt to create a better water pattern. However, most modern rotor-type sprinklers are designed to give optimum uniformity with the radius reduction screw not in contact with the water stream. Therefore you should only turn the screw so that it contacts the water stream if you need to reduce the sprinkler radius. Be warned- most people look at the stream of water exiting the nozzle and feel it is not giving a uniform pattern. So they mess with the radius reduction screw trying to get a “better pattern”. Unfortunately, this most often hurts rather than helps. The fact is that without training the average person can’t tell when the water pattern is best by simply looking at it. The moral is if you don’t need to reduce the radius of the stream, then leave the screw in a position where it does not contact the water stream! With that said, there is a situation where the screw does need to be used to break up the water stream to improve the pattern. It occurs when the water pressure (PSI) at the rotor is below the optimum level (indicating in most cases that the system wasn’t designed correctly). You can’t tell if this is a problem by looking at the stream, so look at the ground around the sprinkler. If you have a low pressure problem the sprinkler will create a donut-shaped water pattern on the ground. There will be a very small green area right around the sprinkler head where water leaks from the head. Then there is a dry area for several feet (the donut hole), with a wet area farther out. This creates a pattern on grass shaped like a huge green donut, with a small bit of green in the very center. If this is happening you will need to use the radius adjustment screw to break up the stream so that more water falls closer to the rotor. If there are dry patches located midway between two rotors, but no donut pattern, that usually means the rotors are spaced too far apart, or the radius adjustment screw is too far into the stream. Try backing off the radius adjustment screw until the screw does not contact the water stream. If that doesn’t fix the dry spot try using a larger nozzle size in the rotors adjacent the dry spot. Unfortunately in most cases these simple efforts to fix the problem just result in creating a new problem. For example, using a larger nozzle may cause the pressure to drop and create the previously mentioned donut pattern problem. If new problems are created you will either need to live with dry spots, or spend some serious money making major repairs. Major repairs that are often needed include adding a booster pump to create more water pressure, relocating the rotors so that they are closer together, replacing the pipes with larger size pipes, or a combination of these.

Pop-Up vs. Shrub Style Heads

Rotor bodies come in two basic styles, “pop-up” and “shrub” style. Pop-ups do just what the name implies, the sprinkler body is installed below ground and the nozzle is lifted up above ground on a riser when the sprinkler is operating. After the irrigation is complete, the riser and nozzle are pulled by a spring back down into the sprinkler body. Since the body is typically installed below ground, the sprinkler becomes more or less invisible when it is in the “down” position. This has two advantages. The first is that the sprinkler does not detract as much from the appearance of the landscape. The second advantage is that the sprinkler is not as likely to trip someone, or be damaged by yard care equipment such as lawn mowers.

Recommended Pop-Up Heights

• Bermuda grass, dethatched yearly – use 3” or 4” pop-up.
• Bermuda grass, dethatched less often – use 4” pop-up.
• Fescue, bluegrass, rye grass – use 4”, 5” or 6” pop-up.
• St. Augustine or any grass planted near blowing sand – use 5” or 6” pop-up.
• Low ground cover – use 5” or 6” pop-up.
• Medium height ground cover – use 12” pop-up.
• Shrubs- see discussion below.

The 12 inch bodies work good for taller ground covers and low shrubs. Generally in a landscape design shorter shrubs are used at the edges of planters and larger, taller shrubs are used farther back in the area. So 6 or 12 inch pop-ups at the perimeter will often provide adequate coverage.

Shrub-Style Rotor Sprinklers

Shrub-style sprinkler bodies are mounted above ground level on a vertical pipe. This allows the sprinkler to be elevated above the level of the plants, where it can spray water over them. Shrub-type sprinklers are most often used in areas with tall, dense shrubs. Shrub-type bodies should not be used next to sidewalks, paths, driveways, lawn edges, or anywhere near places people walk or play. This is because the shrub sprinklers may trip people, or worse, someone may fall on one and be impaled (more likely just badly bruised, but the injury is still significant.) Not a pretty thought. For this reason I recommend, as do almost all professionals, that shrub-type spray heads only be used when there is no other option. If you have tall shrubs adjacent to a sidewalk you should consider replacing them with ground cover or lower growing shrubs. I use shrub-style sprinklers mostly on inaccessible hillsides where we are trying to grow plants for erosion control. I typically install them 36″ above ground to reduce problems with people tripping over them or falling onto them. Often I attach them to a large post to make them more visible. One of the arguments often given for using shrub style sprinklers is cost savings. Cost wise, I have found that shrub-style sprinklers are no less expensive than pop-up style bodies once you include the cost of the riser pipe and a stake to keep the sprinkler from wobbling. In order to make a shrub-style sprinkler cost less than a pop-up you must install it within 6″ of ground level. That is the height that makes it most dangerous.

A Brief History of Rotors

Nothing essential to read in this section, it’s provided for those who are curious. The earliest rotors were impact types, and Rainbird was one of the earliest sprinkler companies. Although several companies made similar products, the name Rainbird came to be almost synonymous with impact sprinklers. But impacts had problems in turf areas where pop-up style sprinklers are needed. The drive arms were large and to make a pop-up style of rotor required a huge case (called a bucket) for the sprinkler to retract into. They required a lot of maintenance because grass would grow into the cases and interfere with the arms. These large impact pop-ups are commonly are called “rat traps” in the industry. It was realized that a better solution was needed. In an attempt to create a smaller, closed-case (no exposed moving parts) rotor, cam and ball drive rotors were invented, primarily made by Buckner and a company named Safe-T-Rain. The “Safe-T-Rain” name resulted from the idea that their ball drive rotors were smaller than the impact rotors and presented less of a hazard. Both cam and ball drives also use an impact to turn the sprinkler, but now at least all the moving parts were smaller and internal. But they also wore out quickly and were never really widely accepted by the turf grass industry.

In the mid 70’s the first turbine powered gear-drive sprinklers came along. The Toro and K-Rain companies pioneered the gear drive industry. Toro used a sealed gear train filled with oil and their Toro S700 was the dominant residential size gear-drive for a number of years. They worked very well, but they were really difficult to adjust and the oil-filled gear boxes leaked oil and were expensive to manufacture. About the same time Rainbird introduced the very inexpensive, all-plastic Mini-Paw impact sprinkler. The Mini-Paw was smaller than other impact rotors due to a unique design of the impact mechanism. The Mini-Paw quickly became the biggest seller in the residential rotor market. Unfortunately the Mini-Paws didn’t hold up very well and had the standard impact sprinkler problem of high maintenance costs.

The next innovation in rotor design was water-lubricated gear-drives. These were inexpensive, reliable, and easier to adjust than the Toro models. Hunter, Nelson, and K-Rain quickly came to dominate the entire rotor market. Rainbird desperately needed a sprinkler to compete with these gear-drive rotors, and introduced the R-50, a variation of a ball-drive. The R-50 was a moderate success, but it was hard to adjust and the early models had a lot of maintenance problems. Rainbird then introduced the T-Bird, their first gear-drive rotor. It was essentially a first try and had problems. Finally, on the third try, Rainbird came out with the 3500 and 5000 series gear-drive rotors and belatedly joined the others. Now, finally, all the major irrigation manufacturers have a good gear-drive rotor available.

So what’s next for rotors? The latest innovation is the micro-rotor. This tiny rotor is the size of a spray sprinkler nozzle and fits on a standard spray sprinkler body. This makes it less than half the size of the other rotors, and much less expensive. Developed by the Walla Walla Sprinkler Company and sold under the name MP Rotator, this micro-rotor is a stream rotor type (multiple rotating streams of water.) It is driven by a turbine, but does not have a gear box. To keep the sprinkler rotating at a slow, steady speed it utilizes a sealed gel-filled clutch. The thick gel slows the speed of the nozzle. Rainbird recently introduced a mini-rotor also, and other manufacturer’s will follow. Only time will tell if this will be the next big thing in rotors.

What to Look for in a Good Quality Rotor

I recommend using a gear-drive rotor, or for smaller areas a turbine-driven micro-rotor. Pretty much all of the gear-drive rotors hold up well and perform well. The biggest problem with the gear-drive rotors is adjusting the arcs. Nelson makes the easiest to adjust but has a problem with the cap that covers the adjustment collars coming off. The Toro S700 has the hardest arc to adjust, and everyone else falls someplace in between. The bottom line is to be prepared to get wet when adjusting any rotor! The good news is that every one of the gear-drive rotors currently on the market has essentially the same basic features, so any of them will meet what I would consider the minimum requirements; a 3″ pop-up height, a good wiper seal, stainless steel retraction spring, sturdy plastic body and cap.

Rotor-Type Sprinkler Radius and Spacing

The radius of a rotor-type sprinkler is determined by the water pressure at the rotor inlet and the nozzle used. Most rotors come with several nozzles. More nozzles gives you better control and helps avoid over-watered areas. For a standard rotor you need to use a different nozzle for each arc, so you need one size nozzle for a 1/4 circle, another for 1/2 circle, another for 3/4, and another for full circle. So for even a simple sprinkler system you need at least 3-4 different nozzle sizes! If you also need different radius distances you will likely need even more nozzles. With stream rotors you don’t to use different nozzles for each different arc, so they don’t come with multiple nozzles.

The sprinkler manufacturer will list the radius for each sprinkler nozzle they make on the packaging, or on a separate reference chart (but please read the next paragraph before relying on that data.) Most also have performance data charts on their websites. The radius will vary based on the water pressure and flow, more pressure and flow will result in a larger radius. So for a typical nozzle you will see a table that gives the various radius, pressure and flow combinations for the nozzle (see example below.) If you can’t find the desired radius, get the nozzle with the next size larger radius than you need. The radius can be reduced by means of the radius adjustment screw on the top of the sprinkler nozzle. Some nozzles are designed to spray the water at a very low angle. Be careful of these nozzles, if you have mounded areas or hillsides they may spray water into the ground. It is best only to use low angle nozzles in relatively flat areas.

A big problem with all of the rotors is that they don’t perform as well in actual use as the manufacturer’s performance data tables suggest. The problem is that the radius the manufacturer measures on their indoor test range is not accurate out in the real world where the wind blows. Competition forces them to aim for the largest radius possible at the lowest possible pressure and flow. But the gallonage and pressure have a huge effect on how effectively the water is distributed. For example, a low gallonage, low pressure nozzle is going to be much more effected by wind (even wind so slight you don’t even notice it) than a higher flow, higher pressure nozzle. So you need to be careful. Unfortunately it takes lots of experience to know what works and what does not. Because of competition, the advice you get from the manufacturer’s literature and help lines has, in my opinion, stretched the limits considerably. So, based on my experience I am providing you with nozzle GPM/pressures combinations I recommend you use for various situations. I very strongly suggest that you follow these recommendations. In some cases I have provided more specific recommendations in my reviews. If you don’t follow them you may very well regret it! Many people before you have made this mistake, please don’t join them. Fixing the problem if you use the wrong nozzles can be very expensive! People are really unhappy when I tell them what is needed to fix the problem.

As a general rule I advise against spacing rotors more than 45 feet apart unless you have a professional irrigation consultant design the system. Most contractor’s and “free design services” don’t have the design knowledge to handle a design of this complexity, you need to find a designer with lots of experience. I’m not trying to make anyone look bad, I just have a lot of experience fixing problems on these large radius systems, and have noted that the problems almost always resulted from poor original design. Wide spacings simply bring many difficult design problems with them.

Important! Rotors require what is know in the industry as “head-to-head spacing”. Head-to-head spacing means that the water from one sprinkler must spray all the way to the next sprinkler in all directions- to the right, left and also to the head(s) across from it. This is very important, spacing the sprinkler heads too far apart is one of the most common design errors, and it is almost impossible to go back and correct the problem later without spending tons of money. Simply stated if the radius is 30 feet you need to space the rotors no more than 30 feet apart, less in many cases. The sprinkler design tutorial gives a more in-depth description of the importance of head-to-head spacing. Head-to-head spacing is critical for avoiding dry spots and disease problems. With spacings wider than 45 feet it is often necessary to use spacings even closer than head-to-head.

Matching Precipitation Rates

Standard rotors (the water stream moves back and forth) require a little more design effort. To make this easier I have suggested which nozzles you should use in many of my reviews of specific rotors. In those cases you should simply use the nozzles I recommend. You should also use the free on-line Sprinkler System Design Tutorial when you actually design your system! This is just background information, the tutorial will guide you through the design process step-by-step. However, this information will help you understand why it is important that the rotor you choose to use should come with a large selection of nozzles.

The precipitation rates for standard rotors are not matched, so you must select the right nozzle size for each rotor based on the radius, pattern, and flow of the various nozzles available. Here’s an example of a performance chart for a typical standard rotor. (Don’t actually use this chart, it is just a sample! Each brand and model has it’s own chart, you need to use the correct chart.)

Sample Rotor Nozzle Performance Chart

The chart above shows four nozzles (for many rotors there will be more nozzles available.) For each nozzle it gives the radius and GPM combinations that result at different water pressures. Remember this is the water pressure at the sprinkler, which will be less than the water available water pressure due to pressure lost in the pipe and valves.

Let’s consider a 60 foot x 60 foot square lawn area (see image below.) Nine rotors would be required to water this area as follows: In each of the four corners there would be a 1/4 circle rotor (4 total). At the mid-point of each side there would be a half circle rotor (4 total). In the exact center of the lawn there would be a single full circle rotor. Each rotor would need a radius of 30 feet. This would provide the desired head-to-head spacing.

Rotor Spacing Example for 60′ x 60′ Lawn
(Using 30′ Radius Rotors)

Yes, this is how many rotors you need to water a 60 foot square lawn! No need to write and ask me if I made a mistake. Nope, I don’t get kick-backs from the sprinkler companies for helping them sell more sprinkler heads. There are a number of good reasons for all the overlap, if you really are interested you can take a couple of classes at your local university in physics and hydraulics. OK, I’m guessing that doesn’t sound very interesting to you, so let’s just move on.

As you recall from the description of a standard rotor, the rotor shoots a stream of water that rotates one way around the rotor, then reverses back the other direction, covering the same area again (except for a full circle rotor, which just moves continuously in a circle.) This back and forth motion creates a problem- since all the rotors turn at the same speed. So in the time it takes the full circle rotor to make one complete rotation, the 1/4 circle rotor will have gone back and forth over the same area 4 times. So if you use the same size nozzle in all the rotors the area watered by the quarter circle rotor would have 4 times more water applied to it than the area watered by the full circle rotor. This will not work! The area around the corners would turn to mud while the area in the center of our lawn would be dry! Therefore, to compensate we use a smaller nozzle in the corners and a larger one in the center. The full circle nozzle will need to have a GPM four times higher than that of the quarter circle. Using our 60 foot square lawn and the Sample Rotor Nozzle Performance Chart above we would select the following nozzles:

One thing you will notice is that these nozzles are not a perfect solution. To be perfect, all the radii would be identical and the GPM values would be exact multiples of each other (ie; all radii would be 30 feet and GPM values would be 1.1, 2.2, 3.3, and 4.4 GPM.) Unfortunately perfection is not attainable, so we must settle for the next best thing. In this case the GPM values are close enough to being multiples of each other. Because the radii are all larger than we need, it will be necessary to reduce the radius of each rotor after it is installed by using the radius adjustment screw. Now you can understand why a rotor that includes a lot of nozzles is better than one that only includes one nozzle. If you go to a typical discount retail store you will find a lot of rotors that only come with one nozzle. Now you know why that is not such a good deal for most yards. No doubt a lot of you are thinking to yourself, “so that’s why the middle of my yard is as dry as an old bone and the corners are swamps!”

Stream rotors have matched precipitation rates, so you don’t have to deal with the different nozzles for different arcs problem. If you are designing with them you will use the same nozzle for all the sprinklers that have the same radius. A chart provided by the manufacturer will tell you the GPM for each rotor based on the pattern used (ie; quarter circle, half circle, full circle.) This makes designing with stream rotors a bit easier than with standard type single stream rotors. Select stream rotor nozzles based on the radius desired. Most stream rotors do not have a radius adjustment feature, so the radius can’t be changed except by changing the nozzle. Here’s an example of a nozzle chart for a stream rotor:

Sample Stream Rotor Nozzle Performance Table

From the nozzle chart you start by selecting the radius you want. The table tells you the pressure you will need and the GPM that the sprinkler will require. So if you need a 21 foot radius you would select nozzle #02. The chart then tells you that you will require 35 PSI at the rotor and for a half circle pattern (180°) the flow used by the rotor will be 1.44 GPM.

Special Situations

Most rotor-type sprinklers are available with a number of optional features. Here are some situations where you should consider using a rotor sprinkler with optional features.

Slopes & Check Valves. If your yard is sloped you should use sprinklers with built-in check valves. An elevation change that exceeds the depth of your pipe is enough to make the use of check valves advisable. In other words, if one side of the yard is more than a foot lower than the other, and you plan to bury the pipes less than a foot deep, you should use check valves. I use them on all my projects as the default. Most manufacturer’s built-in check valves will work up to an elevation difference of 10 feet height. If the elevation difference between sprinklers is greater than 10 feet you will need to add an additional adjustable low-drainage prevention check-valve under the sprinkler. The purpose of the check valves is to prevent the water from draining out of the pipes through the lowest sprinkler head each time the water is turned off (this is called “low-head drainage”.) Low head drainage creates mud pits around the lowest heads, and also allows water to drain onto sidewalks causing algae and moss to grow. Plus each time you start up a valve zone the sprinklers will sputter and spit as the air is pushed out, which is bad for the pipes, hard on the sprinkler, and wastes water.

If you use check valves and you are in a cold winter area where you winterize your sprinkler system, you need to have your sprinkler system winterized by blowing the water out of pipe with air. Another option is to remove the check valves before you winterize the system, however this is a lot of work. The check valves trap the water in the pipes and the sprinkler heads where it will freeze and break the pipes and the sprinkler heads.

Play areas. When using rotors in play areas you should use rotors with rubber covers. The rubber cover helps reduce injuries caused when someone falls on the sprinkler.

Extremely sandy soil. Some rotors are available with stainless steel sleeves around the pop-up riser. This helps keep the riser from becoming scratched by sharp sand particles. Deep scratches in the plastic can prevent the riser from easily moving up and down. Generally this is not a big problem except in very sandy areas.

Recycled (also called reclaimed) water. When using recycled water the rotor should be equipped with an optional purple-colored cap. Recycled water is usually treated sewage or grey water (wash water.) Many cities are now installing separate water systems that carry recycled water for use with irrigation systems, especially in areas where water is scarce. In general, human contact with recycled water should be avoided. The purple color is the universal identifier of the presence of recycled water.

In order to make good decisions about which products will work best for you it is necessary to have some basic knowledge of how sprinklers work and what the various options available to you are. Therefore the following few paragraphs are intended to give you the background necessary to understand the terminology used in my reviews. The background information below is much more in-depth than that in the tutorials, so even if you have read the tutorials you should still look through this page.

Fixed Spray-Type Sprinkler Basics

Sprinklers fall into one of two types based on the method they use to apply water to the ground; fixed spray-type (sprays) or rotor-type (rotors.) Spray-type sprinklers are the type of sprinkler that spray a fixed water pattern similar to how a old-fashioned shower head works. Rotor-type sprinklers use a rotating stream (or multiple streams) of water to apply the water to the ground. Spray-type sprinklers are also called “fixed spray heads”, “spray heads” and often just plain “sprays”. Most of the professionals I know call them “spray heads”, and you will note that is the term I use also. They are typically used for smaller size areas. Rotor-type sprinklers are used for larger areas (generally more than 18′ in width.)

Where should spray heads be used?

Spray heads work best for smaller areas and areas with tight, curving edges. I like to use them for anything less than 25 feet wide. Although rotors are available for areas as narrow as 18 feet, spray heads tend to be more economical in these smaller areas than rotors. Another advantage of spray heads is their relative simplicity. There is not a whole lot to go wrong with one. By far the most common problems result from clogged nozzles, a problem that can be almost totally eliminated by flushing the pipes thoroughly prior to installing the spray heads and installing a filter on your sprinkler system. (Install the filter upstream of the automatic sprinkler system valves so the valves benefit from filtered water too!) Although most spray heads come with a small filter screen that installs under the nozzle, in my opinion these filters are not sufficient. I recommend installing a 100 mesh filter at the water source for ALL sprinkler systems.

How a Typical Spray-Type Sprinkler Works

Water enters the base of the sprinkler and passes up through the body to the nozzle. On the way to the nozzle the water passes through a filter screen. As previously mentioned I do not suggest that you rely on this screen for filtration, consider it a backup to your sprinkler system filter. Do not remove the filter screen, some spray type sprinklers will not work properly without the screens! After passing through the screen the water enters the nozzle and passes through a small valve. This valve is operated by a screw on top of the nozzle, which is known as the “radius adjustment screw”. As you turn the screw the valve closes slightly. This causes the water to speed up as it tries to force it’s way through, resulting in an increase in turbulence and friction. This turbulence and friction causes a drop in the water pressure. The pressure drop in turn causes the radius of the sprinkler to be reduced. From the radius adjustment valve the water continues up into the nozzle and is sprayed up against a plate or through a small slit(s), which causes the water to fan out as it leaves the nozzle. This is what creates the fan-like spray pattern typical of a spray head. The shape and size of the plate or slit is what determines the nozzle pattern and angle. Some spray nozzles have adjustable plates or slits that allow the spray arc to be adjusted.

A typical spray head consists of two separate parts, a body and a nozzle. Often these are sold separately, but sometimes retail stores package them together. Typically various different nozzles are available, anywhere from just a few different patterns and radii combinations, up to hundreds of variations. In most cases all of a manufacturer’s nozzles will fit on all of their spray head bodies.

Pop-Up vs. Shrub Spray Heads

The bodies come in two basic styles, “pop-up” and “shrub” style. Pop-ups do just what the name implies, the sprinkler nozzle is attached to a riser which lifts the nozzle up into the air when the sprinkler is operating. After the irrigation is complete, the riser and nozzle drop back down into the sprinkler body. Since the body is typically installed below ground, the sprinkler becomes more or less invisible when it is in the “down” position. This has two advantages. The first is that the sprinkler does not detract as much from the appearance of the landscape. The second advantage is that the sprinkler is not as likely to trip someone, or be damaged by yard care equipment such as lawn mowers.

Recommended Pop-Up Heights

• Bermuda grass, dethatched yearly – use 3” or 4” pop-up.
• Bermuda grass, dethatched less often – use 4” pop-up.
• Fescue, bluegrass, rye grass – use 4” or 6” pop-up.
• St. Augustine or any grass planted near blowing sand – use 6” pop-up.
• Low ground cover – use 6” pop-up.
• Medium height ground cover – use 12” pop-up.
• Shrubs- see discussion below.

The 6 inch height bodies are the primary height I use for my projects in both lawn, shrub, and most ground cover areas (I use a lot of low growing ground covers with 4-6 inch mature height.) The 12 inch bodies work good for taller ground covers and low shrubs. Keep in mind that with shrubs you don’t always need to throw the water over the top of the shrub. When the shrubs are first planted they are small and a 6″ height will spray over them. As the shrubs grow they begin to block the spray, but by this time the shrub has developed a good root system and will seek out the water. Generally in a landscape design shorter shrubs are used at the edges of planters and larger, taller shrubs are used farther back in the area. So 6 or 12 inch pop-ups spaced 10 to 12 feet apart at the perimeter will usually provide adequate coverage.

Shrub-Style Spray Sprinklers

Shrub-style sprinkler bodies are mounted above ground level on a vertical pipe. This allows the sprinkler to be elevated above the level of the plants, where it can spray water over them. Shrub type sprinklers are most often used in areas with tall, dense shrubs. Shrub type bodies should not be used next to sidewalks, paths, driveways, lawn edges, or anywhere near places people walk or play. This is because the shrub sprinklers may trip people, or worse, someone may fall on one and be impaled (more likely just badly bruised, but the injury is still significant). Not a pretty thought. For this reason I recommend, as do almost all professionals, that shrub type spray heads only be used when there is no other option. If you have tall shrubs adjacent to a sidewalk you should consider replacing them with ground cover or lower growing shrubs. I use shrub style sprinklers mostly on inaccessible hillsides where I am trying to grow plants for erosion control. I usually install them 36″ above ground to avoid problems with people tripping over them or falling onto them. One of the arguments often given for using shrub style sprinklers is cost savings. Cost wise, I have found that shrub style sprinklers are no less expensive than pop-up style bodies once you include the cost of the riser pipe and a stake to keep the sprinkler from wobbling. In order to make a shrub style sprinkler cost less than a pop-up you must install it within 6″ of ground level. That is the height that makes it most dangerous. Your homeowner’s insurance rates will likely go through the roof if someone trips on a sprinkler and files a claim for injuries. This will be far more expensive than the cost would have been to use pop-up sprinklers!

Spray-Type Sprinkler Radius

The radius of a spray-type sprinkler is determined by the nozzle used. The sprinkler manufacturer will list the radius for each sprinkler nozzle on the packaging, a separate reference chart, or their website. The radius will vary based on the water pressure, more pressure will result in a larger radius. So for a typical nozzle you will see a table that gives the various radius, pressure and flow combinations for the nozzle (see example below.) Most spray head nozzles have a radius between 4-15 feet, some are claimed to have a radius as great as 21 feet, but I would urge caution using a radius over 15 feet. It’s a physics problem, water simply doesn’t spray further than 15 feet very well or evenly. When selecting a nozzle, look for one with a radius as close to your desired radius as possible. If you can’t find the desired radius, get the nozzle with the next size larger radius than you need. The radius can then be reduced by means of a radius adjustment screw on the top of the sprinkler nozzle. As the adjustment screw is closed, the water pressure at the nozzle is decreased, this results in the radius and flow of the sprinkler being reduced. For example, if you wanted to water a 14 foot wide area you would install a 15 foot radius spray head and use the radius reduction screw to reduce the radius to the desired 14 feet. With most nozzles the radius can be adjusted down to almost nothing, however I don’t recommend reducing it by more than about 40% when using the radius adjustment screw. Further reduction can cause coverage and operation problems. Often times a nozzle with a severely reduced radius will stop working on warm days. This is because the heat causes the radius reduction screw to expand, which causes the flow to be completely shut off. One last thing to watch for when selecting a nozzle is the angle of spray. Some nozzles are designed to spray the water at a very low or even flat angle. Be careful of these nozzles, if you have mounds or hillsides they may spray the water into the ground. It is best only to use low angle nozzles in flat areas.

Spray-Type Sprinkler Spacing

As a general rule I advise against spacing spray-type sprinklers more than 18 feet apart. Spacing them farther than that often gives unsatisfactory results. Spray heads require what is know in the industry as “;head-to-head spacing”. This means that the water from one sprinkler must spray all the way to the next sprinkler in all directions– to the right, left and also to the head across from it. This is very important, spacing the sprinkler heads too far apart is one of the most common design errors, and it is almost impossible to go back and correct the problem later without spending tons of money. The sprinkler design tutorial gives a more in-depth description of the importance of head-to-head spacing. Head-to-head spacing is critical in lawn areas for avoiding dry spots and disease problems. In shrub and ground cover planting there is more room for fudging, you can generally space the heads at up to 60% of their diameter of water throw. Examples: Using a 15′ radius head for lawn areas you should not exceed 15′ between sprinklers. Using 15′ radius spray heads for shrub areas you should not exceed 18′ (30′ diameter x 0.6) between sprinklers.

Sample Spray Nozzle Performance Table (this sample is for a Toro nozzle)

Pattern	Part No.	20 PSI	30 PSI	40 PSI	50 PSI
	12Q	11′ – 0.40 GPM	12′ – 0.50 GPM	13′ – 0.60 GPM	13′ – 0.63 GPM

Example: From the chart above you can see that this nozzle at 30 PSI will have a radius of 12 feet and a flow of 0.50 GPM (gallons per minute). If you wanted to operate this nozzle at 25 PSI you would need to extrapolate the data from the chart. For example for this nozzle 25 PSI would give 11.5′ radius and 0.45 GPM flow.

Reducing the radius of a nozzle.

As previously noted you can reduce the radius of most nozzles using the radius reduction screw. This allows you to use the nozzle in a smaller area. A common question I am asked is what happens to the flow of the nozzle when you decrease the radius? The answer is that the flow (GPM) is reduced, but not by much. In most cases you can just ignore it and use the full radius flow. If you really want to find out how much the flow would be reduced, simply refer back to the manufacturer’s performance chart for that nozzle. As previously mentioned, the radius reduction screw works by reducing the water pressure in the nozzle. If you look at a performance chart it will give you the radius at various pressures. Make sure you are using the right chart for the nozzle you plan to use. Find the radius on the chart that you plan to create using the radius reduction screw. The chart will show you the flow the nozzle uses at that radius.

Example: Let’s say you install the nozzle shown in the table above in a situation with 30 PSI, but you only want it to throw 11 feet. You would use the radius reduction screw to reduce the radius to 11′. According to the chart at an 11 foot radius the nozzle would use a flow of 0.40 GPM.

Matched Precipitation Rates

Most spray heads now have what are called “matched precipitation rates”. Matched precipitation (ppt) rate nozzles mean that the nozzles can be mixed and matched on the same sprinkler zone without concern that one might apply more water than another. Back in the bad old days, only nozzles with the same radius were matched. So you had to use all the same radius nozzles on each valve circuit. But now with matched ppt rate nozzle sets, you can use the radius that works best. So you can use 8 foot, 12 foot, 15 foot, and strip nozzles on the same valve circuit and you will still get nice uniform coverage (provided you don’t exceed head-to-head spacing, that is!) You don’t even begin to know how much easier this makes designing a sprinkler system! There are two exceptions you need to keep in mind however. First, only those nozzles in a manufacturer’s set that are labeled “matched precipitation” are matched. Most manufacturer’s also make nozzles that are not matched to the others. So make sure they are labeled “matched precipitation”. Second is that all the nozzles must be made by the same manufacturer. Each manufacturer uses a different precipitation rate as the default one for the nozzles to match. So don’t mix manufacturer A’s nozzles together with manufacturer B’s nozzles on the same valve zone, even though they both may be labeled “matched ppt”.

Misting and Fine Tuning:

All spray-type sprinklers will mist and waste water if the water pressure exceeds the levels listed in the performance data tables. Some misting is normal. To determine if the misting is excessive adjust one sprinkler as follows:

• Turn the radius reduction screw on the nozzle until the radius is less than head-to-head coverage.
• Now open it back up until head-to-head coverage is obtained.

The sprinkler is now operating efficiently, and you will be able to observe the normal level of mist. If all the heads are misting too much, you should use the flow control on the valve rather than the radius reduction screws to reduce the misting. Simply follow the steps above, but close and open the valve flow control rather than the radius reduction screw. If only a few are misting, use the radius reduction screw on the sprinkler.

Special Situations

Most spray-type sprinklers are available with a number of optional features. Here are some situations where you should consider using a spray-type sprinkler with one of these optional features.

• Slopes. If your yard is sloped you should use sprinklers with built-in check valves. An elevation change that exceeds the depth of your pipe is enough to make the use of check valves advisable. So if you are installing the pipe 12″ deep, and one side of the watered area is 18″ higher than the other, you should use check valves. I use them on all my projects as the default, they aren’t very expensive. Most manufacturer’s built-in check valves will not work if the elevation difference is greater than 10 feet. If the elevation difference between sprinklers is greater than 10 feet you will need to add a separate adjustable low-drainage prevention check valve under the sprinkler. For built-in check valves look for sprinklers with the “CV” feature in my list of sprinkler features.
• Radius under 6 feet. If you are reducing a nozzles radius to less than 6′ consider using an optional Pressure Control Disc to reduce the radius rather than using the built-in radius reduction screw. This does not apply to nozzles that are designed to spray less than 6 feet such as strip sprays and short radius nozzles. It only applies when you plan on using the radius reduction screw to reduce the radius of a nozzle that is designed to throw more than 6 feet. Look for sprinklers with the “PCD” feature in my list of sprinkler features.

Optional Features

Check Valves (CV). The most popular option for spray heads are built-in check valves. If your sprinkler system is being installed in an area where the elevation change exceeds the depth you are burying the pipe you should probably use sprinklers with this feature. Example; if the elevation change is 10 inches and you are burying the pipes 6 inches deep, you should use check valves. But in this same situation if you were burying the pipes 12 inches deep you would not need them.

The check valve prevents water from draining out of the pipes through the sprinkler head after the valve closes. When the water drains out of the pipes it is replaced with air. The next time you turn on the sprinklers this air must be expelled from the pipes, so for the first couple of minutes the sprinklers spit and spew air. This puts a lot of stress on the pipe and the sprinklers. As the water rushes into the pipes it slams into the ells and tees where the pipe changes direction. The air also messes up your uniformity as some sprinklers are watering the lawn while others are just blowing air out! The last problem is that the water that drains out of the sprinkler heads after the valve closes has to go somewhere. So it either runs across a sidewalk or driveway and grows moss and mold, or it makes a big mud puddle around the sprinkler head.

There is one large misunderstanding in the industry about check valves that you should be aware of. Many people, even professionals, erroneously believe that check valves will prevent water from running out of the heads if the valve leaks. This is absolutely not true. If the valve is leaking when it is closed, water will still run out of the lowest head, even if you have check valves installed in the head. This is because the water leaking from the valve is pressurized, and the pressurized water has sufficient energy to force open the check valves. The bottom line is that if you have a leaky valve, the water is going to come out of one of the sprinkler heads and check valves will not stop that. Now this is such a prominent “urban sprinkler legend” that I know a few people out there are going to want to argue with me about it. So before you fire off an angry email to me please test it out yourself. Install a valve zone with check valves on all the heads. Then open the valve just a tiny bit, just as if it were leaking. Now check out the water leaking out of the heads!

Pressure Control Discs. These small disks fit into the bottom of the nozzle or are built into the screen. They are essentially a rubber disk with a small hole in it that restricts the water flow. They control the water pressure and flow into the nozzle. As the water pressure presses against the soft rubber of the disc, the disc deforms and the hole gets smaller, thus reducing the flow through it. They are very handy for reducing the radius of a spray-type sprinkler as they work much better than the radius reduction screws on the nozzles. The sprinkler manufacturer will have a chart showing which disc to use with each nozzle to give the exact radius you need. You will probably need to go to an irrigation specialty stores to purchase these. The Pressure Control Discs can be easily retrofitted into existing sprinklers.

Other available features and options for spray-type sprinklers are described on the spray sprinkler listing page.

Why a Filter?

Water filtration is important for all irrigation systems. Now before someone argues with me, yes, some sprinkler systems are used to spread solids, such as treated sewage, for disposal. But even those in my experience have incorporated some form of filtration upstream of the system to prevent solids which are too large from entering the system.

Filters can help extend the life of, and lower the maintenance on, your sprinkler system. For drip systems they are a necessity to prevent emitters from becoming plugged. Even if small sand particles can pass through your system without clogging it, they cause wear on the equipment. Automatic valves contain very small water passageways in them which can become plugged resulting in the valve failing to either open or close. A small grain of sand caught in a spray nozzle can result in a dry, dead spot in a lawn.

While sand is probably the first thing most people think needs to be filtered out of the water, organic materials can be just as important to remove. Algae can grow inside the system, especially in drip tubes. Another situation occurs when a small piece of organic matter snags somewhere in a valve, fitting, emitter, or sprinkler. The organic matter by itself may not be large enough to be a problem. But soon another piece comes along and gets caught in the first. Then a very small grain of sand that would normally have passed through the system without problems becomes caught in the organic matter. Soon a large build-up of crud forms and the flow is blocked. Have you ever had the hose on your vacuum cleaner clog up with a wad of hair, small objects, and dirt? Each one of those objects went into the hose, so they should have made it through to the canister. But they didn’t because they all got caught together. The same thing happens in your irrigation system. How about a small fish or a clam? They go into your system when they are small (often as eggs) and once in there they grow! Laugh if you want, but I’ve seen it many times! Freshwater clams are very common in city water systems. That’s right, there’s a very good chance that every time you get a drink from the faucet you’re drinking clam water! Yuck… (but be realistic, has it killed you yet? Or perhaps you’ve never eaten clam chowder? Or maybe you should take a look in your cat or dog’s bowl at what THEY drink without getting sick. The truth is that your body processes dirt much better than your irrigation system does!)

Types of Filters

Filters are broken down into different categories dependent upon the method used to filter the water. A brief description of the most common types follows.

Screen filters:

Screen filters are probably the most common filters and in most cases the least expensive. Screen filters are excellent for removing hard particulates from water, such as sand. They are not so great at removing organic materials such as algae, mold, slime, and other unmentionables! These non-solid materials tend to embed themselves into the screen material where they are very difficult to remove. In other cases they simply slide through the holes in the screen by temporarily deforming their shape.

Screen filters are cleaned by flushing them with a stream of water or removing the screen and cleaning it by hand. Depending on the flush method used you will probably have to periodically hand clean the screen to remove garbage not removed by flushing. Several methods of flushing are common. The simplest is a flush outlet. The outlet is opened and it is hoped that the debris washes out of the flush outlet with the water! An improved variation on this is the directed-flow flush. Again a flush outlet is opened, but in this case the structure of the filter is designed so that the flush flow rushes over the face of the screen sweeping the debris along with it. Somewhat like hosing off a sidewalk with a strong stream of water. This is the most common method found in inexpensive filters. The most effective method of flushing is the backwash method, but these filters are typically more expensive. In this method the flush water is forced backwards through the screen for a very effective cleaning. This is accomplished by either using two filters side-by-side (the clean water from one is used to flush the other) or by “vacuuming” the screen with a small nozzle which is moved over the screen by a mechanism in the filter, “sucking” the debris off of it. (Although it is referred to as vacuuming it is really a form of backflush. The water is forced backwards through the screen by the water pressure in the system, not by a true vacuum.)

Cartridge Filters:

Cartridge filters are essentially a variation of the other types listed here, depending on what the cartridge is made of. Most cartridges contain a paper filter which works just like a screen filter. Most also remove organics well because the paper texture is rough enough to snag the organic matter. While some cartridges can be washed, most of them you simply replace when dirty.

Media Filters:

Media filters clean the water by forcing it through a container filled with a small, sharp edged, “media”. In most cases the media material is uniform sized, crushed sand. The water passes through the small spaces between the media grains and the debris is stopped when it can’t fit through these spaces. Media filters are best for removing organic material from the water. This is where the importance of the sharp edged media comes into play. These sharp edges snag the organics which would otherwise slime and slither their way through the small spaces. This is why it is important to use sharp media. Whenever someone tells me their media filter doesn’t work my first question is always “where did you get your media material for the filter?” Their answer is almost always something to the effect of “uh…, I just used some sand from the creek up the road, why?” River, beach, and creek sand tend to have rounded, soft edges and are not suitable at all for media filters! Media filters are the type of filters most commonly used for high volume cleaning of water from rivers and lakes. They are used by both large farms and municipal water systems. They most often are 3 to 6 foot diameter rounded tanks sitting on short legs, and are almost always in groups of two or more. I’ve seen municipal water systems with media filters that are over 12 feet tall and 10 feet in diameter! They tend to be a wee bit large and heavy for the average homeowner! Media filters are cleaned by backflushing. The force of the water going backwards through the filter lifts and separates the media which frees the debris and washes it out through a flush valve. Because a small amount of media is often washed out too, it is necessary to periodically add some more to the filters. Because sand is not easily flushed out of them, media filters are not good for situations where the water contains a lot of sand. The sand will not flush out and soon the filter will be completely filled with sand which you will have to remove by hand. Media filters must be carefully matched to the system flow rate for proper operation. Always consult the media filter manufacturer’s literature for proper sizing procedures!

Disk Filters:

Disk filters are a cross between a screen filter and a media filter, with many of the advantages of both. Disk filters are good at removing both particulates, like sand, and organic matter. A disk filter consists of a stack of round disks. The face of each disk is covered with various sized small bumps. A close up view of the bumps reveals that each has a sharp point on the top of it, somewhat like a tiny pyramid. These bumps are very small, thus a typical disk looks a lot like the old vinyl 45 RPM records! Because of the bumps, the disks have tiny spaces between them when stacked together. The water is forced between the disks, and the particulates are filtered out because they won’t fit through these gaps. The organics are snagged by the sharp points on the bumps. For automatic cleaning of the filter the disks are separated from each other which frees the debris to be flushed out through a flush outlet. For less expensive disk filters you must remove the disks and hose them off.

Centrifugal Filters:

Also known as “sand separators”, centrifugal filters are primarily for removing particulates, such as sand, from the water. They are great for situations where a lot of sand is present in the water as they don’t clog up nearly as quickly as other types of filters. The dirty water enters the filter where it is swirled around the inside of a cylinder. The centrifugal force causes the sand particles to move to the outside edge of the cylinder where they gradually slide down the side to a holding tank at the bottom. Centrifugal filters are reasonably inexpensive, very simple, and are very effective for removing sand from water. Because many wells pump sand up along with the water you will often see a centrifugal filter installed on a large well. Some centrifugal filters are designed to be installed inside the well. These typically are attached to the bottom of a submersible pump. It is not unusual for a very small amount of sand to pass through a centrifugal filter. For drip irrigation systems I always add a “backup” screen filter when using a centrifugal filter as a safety precaution. A centrifugal filter used in combination with a media filter after it is an excellent combination. The centrifugal pulls out the sand, the media filter then removes the organics. This combination is very often used in municipal water treatment, where a third activated charcoal filter may be added to remove chemicals. Note that the centrifugal filter selection must be carefully matched against the system GPM or the filter will not work correctly. Always consult the manufacturer’s sizing guidelines when designing a centrifugal filtration system for your irrigation system.

Tutorial continues below…

Filter Recommendations

So which filter to use? There is no fixed answer. Your budget, water quality, and availability of the filter and parts must all be considered. Screen filters are generally the least expensive. If you have a city water supply with nothing more than a periodic grain of sand or flake of rust in it, a screen filter will be fine in most cases. Sometimes a combination of more than one type of filter will be needed. For a smaller size system a disk filter would remove both sand and organics, but you might need to frequently clean it! Here are some suggestions based on the source of your irrigation water:

How much Filtration do you need?

What we are asking here is what’s the smallest size of particle that needs to be removed from the water by the filter? The amount of filtration you need is dependent to a large degree on what type of irrigation you have. For example, drip irrigation systems need a much higher degree of filtration in order to protect the emitters from plugging. For most applications the amount of filtration is measured by the “mesh size” of the screen or maximum size in “microns” of an object that can pass through the filter. There is a mesh vs. micron conversion table at the bottom of this page.

You always want to use the highest level of filtration that is practical. Even if your sprinkler system can easily handle a fairly good size grain of sand without clogging, removing that sand grain is still advantageous as it will eliminate the wear on the system caused by the sand grain as it passes through. The balancing factor is that the more particles removed the more often the filter clogs up and needs to be flushed. Excessive flushing can waste water and energy, so a trade off is necessary.

Rule of Thumb Guidelines

Drip Systems:

The drip emitter manufacturer will specify in their literature the level of filtration required. I almost always take it one level greater. (That is, I remove even smaller particles than they recommend.) I generally never use anything less than 100 mesh or 150 micron.

Sprinkler Systems:

A 70 mesh filter will remove most particles capable of plugging a sprinkler nozzle, however, I like to use a 100 mesh (150 micron) and often use a 150 mesh (100 micron) filter in order to also remove the particles that can cause wear on the system and damage the valves.

All Irrigation Systems:

Bottom line- I would suggest using at least a 100 mesh (150 micron) screen or equivalent in the filter. I suggest you run the water through a filter before it reaches the control valves. Small grains of sand are one of the most common causes of control valve failure, especially when using the standard electric solenoid valves used on most irrigation systems. My experience is that the savings in valve repairs will pay for the cost of the filter over the next 5 years. With a cost benefit like that it is pretty hard to argue against installing a filter!

Approximate Filter Size Equivalents

The values in the table above are rough equivalents. While the Micron is a standard metric measurement, the term Mesh is rather subjective, especially for values over 300. For example, I’ve seen both 500 mesh and 700 mesh screens that have equal filtration, that is, they both filter out particles down to 30 microns in size. The problem is related to the size of wire from which the screen is manufactured. The mesh designation is based on the number of wires in one linear inch of the screen. So two screens can have the same mesh, but if one is made with thicker wire than the other, the one with thicker wire will have smaller openings between the wires. Therefore, micron is a much more accurate measurement for use in determining the size of particle that can (or can’t!) pass through a filter.

Sprinkler Heads are not Seating:

Here’s what to do if some of the pop-up style sprinkler heads on your landscape sprinkler system do not fully pop-up. Sometimes none of the heads fully pop-up, sometimes only one or two are partially popping up and the rest are working correctly. This is a fairly common problem, but there are a number of possible causes to examine. This article will take you step-by-step through the process of finding the problem and fixing it. Let’s start with a couple of photos to help familiarize you with the names of the sprinkler parts used in this article:

Typical Modern Pop-Up Sprinkler Head

Parts of a Typical Pop-Up Spray Sprinkler
From left to right:
Nozzle, Cap, Wiper Seal, Riser, Retraction Spring, Body

Step-by-Step Instructions:

1. Check all the valves to make sure that none of them are partially closed. A partially closed valve will reduce the water pressure and water flow to the sprinklers and this will cause them to not fully pop-up.
   
   
   Typical Solenoid Valve Controls
   • Many electric solenoid valves used to operate the sprinkler circuits have a flow control handle, knob, or screw on them that allows the valve to be manually closed or throttled. If your valves have a flow control, check and make sure it is completely open. The flow control on most valves is on top of the valve and centered in the middle of the valve. Turn the handle counter-clockwise to open it. If water starts coming out, STOP turning it and retighten it! If water comes out it is a manual bleed screw used to manually open the valve, not a flow control. For the location of the flow control check the valve owner’s manual. (If you don’t have one, search for a owner’s manual at the valve manufacturer’s website.) Many low-cost valves do not have a flow control.
   • Try manually opening the electric solenoid valve. There should be a lever (often labeled with “open — close” on it) or small bleed screw on the valve that allows you to bypass the solenoid and open the valve. If there is a bleed screw open the screw until a small stream of water comes out, but do not remove the screw completely, it is very hard to get back on if you remove it. If the heads pop-up fully when the valve is manually opened then the problem is inside the valve. Clean the valve. See How to Repair a Irrigation Solenoid Valve.
   • Check any other valves to make sure they are fully open. There may be a shut-off valve at the point where your sprinkler system connects to the house water system, check it. There may also be a valve where the house water connects to the water company pipes if you have a municipal water supply. Look for any valves that may be partially closed. I was called to consult on an apartment complex where the water supply had suddenly lost pressure. The sprinklers were not popping up, and when the sprinkler system was turned on the showers in the 2nd floor apartments stopped working! They had looked and looked for a problem. I traced the problem back to the street, so we called the water company. They discovered that the pipes in the street had been worked on a few days earlier. In the process they had partially closed a valve on the pipes, and forgot to reopen it!
2. Next, turn on a single valve that has heads that will not pop up.
   • Sometimes a grain of sand will wedge in the gap between the pop-up riser and the cap of the sprinkler, causing the sprinkler riser to jam part way up. Press the pop-up riser on the sprinkler head down firmly, but gently, with your foot so that it is pushed all the way back down into the body (you may get wet doing this!) Then release it so it pops back up. Repeat this 4 or 5 times to loosen and flush out any sand grains caught between the riser and the cap.
   • Check for excessive blow-by of the sprinkler riser. When the riser comes up a small amount of water squirts out of the gap between the riser and the cap, this is called blow-by. A small amount of blow-by is normal, it lubricates the seal and helps clean dirt and grass off of the riser as it goes up and down. To check the blow-by have someone turn on the sprinkler valve while you watch the riser on the sprinkler as it comes up. A little water gurgling out between the riser and cap is normal. A lot of water coming out between the riser and the cap is not normal. To determine what is normal compare several sprinklers, looking for one that squirts considerably more water than the others, indicating excessive blow-by. If you are still not certain, replace one sprinkler with a brand new sprinkler and then compare it to the others. If the sprinklers have excessive blow-by they should be replaced. Be sure to use the same brand and model of sprinkler heads for replacements. Different brands and models are NOT compatible with each other. Each manufacturer uses different water application rates for their sprinklers and you will get over-watered and/or dry spots if you mix brands together.
   • No water should come out from between the riser and the cap when the riser is in the fully extended position. Turn on the sprinklers and check each one for leakage between the riser and cap. Make sure the riser is fully up when you check. If the riser does not come up all the way, pull it all the way up with your hand. Hold the riser up while checking if it will not stay up by itself. Check all the sprinklers, as a leaking sprinkler near the valve can cause a different sprinkler that is farther from the valve to not fully pop up. If there is leakage between the riser and the cap when the riser is completely up, the riser seal is bad, the riser is scratched, or the cap is scratched. Replace the sprinkler.
3. Turn off the water and try pulling up the riser on the sprinkler with your hand. There will be resistance due to the retraction spring, but the riser should move easily up and down without catching or hanging up. Sometimes the riser on the pop-up and the seal around it become badly scratched from sand particles. The surface becomes so rough that it causes the riser to not move freely in and out of the sprinkler body. The only solution for this is to replace the sprinkler. If you try to use sandpaper on the riser to smooth it out you will just create excessive blow-by, so don’t waste your time.
4. Has your water pressure dropped? This often happens when new construction occurs nearby and the water system must supply water to more homes or businesses. If you have your own water supply with a pump the water pressure and flow may drop as the pump gets old and worn out. When the water pressure drops, the sprinklers may no longer pop-up fully. If you get your water from a water provider, call them and ask if the water pressure in your neighborhood has dropped recently. If it has, ask if this is just a temporary problem that will go away in a few days. (Often the water pressure drops temporarily when repairs are being made to pumps or pipes.) Often the water pressure in municipal water systems will go up and down depending on time of day or day of the week. Often water pressure is low between 5-8 AM when lots of people are taking showers and watering lawns. Try changing to a different watering time or day to see if the water pressure is higher (if you ask them, the water supplier can often suggest a good time when pressures are higher.) If you have a pump of your own, like in a well, then call your pump service company and have them check the pump out. If you discover the water pressure has permanently dropped you have a serious problem. Your sprinkler system was apparently designed for a higher water pressure that is no longer available. Your choices are to add a booster pump to create more water pressure for the sprinkler system or to modify the sprinkler system to use less pressure.
   
   • Booster pump: If you add a booster pump I strongly suggest you purchase a pre-assembled pump system from a sprinkler supply specialty store. These units come with everything you need, you just pipe it to your system and plug it in. Pumps are tricky, you can waste a lot of money in a hurry if you do it wrong. There are a number of pumps sold through hardware and catalog stores that are called “sprinkler pumps”, most of these are designed to run a single sprinkler head on a hose. I get a lot of sad stories from people who bought one of these and then discovered it wouldn’t do the job. Then they sell it to someone else on Ebay, and the cycle repeats itself. Save yourself a lot of grief and buy a packaged complete pump system that includes the right size pump with all the starters and safety switches you need. Warning: some municipal water systems do not allow the use of booster pumps, check with your water provider.
   • Modify sprinkler system: To modify the sprinklers to use less pressure and water you will need to reduce the number of sprinklers on each valve circuit. Remove a sprinkler from the valve circuit(s) having problems and install a plug in the pipe where it was connected. Turn on the valve and test to see if the sprinklers now work correctly. If they still do not pop-up and spray correctly go back and remove another sprinkler, then test again. Continue removing sprinklers until the other sprinklers start working properly. Now you will have to reinstall those sprinklers you removed. You will need to install a new valve for them and install new pipes to them from the valve, creating a new valve circuit. Yes, I am aware that is a lot of work!

The steps above should have identified the problem and fixed it. Now would be a good time to give the sprinkler system a full tune-up. See Sprinkler System Tune-Up.

Once a year you should give your sprinkler system a “tune-up”. Most people do this at the start of the irrigation season. First we’ll look at some necessary definitions, then I’ll tell you how to tune-up your sprinkler system.

Spray-type sprinklers (often simply called “spray heads” or “sprays”) are the sprinklers that create a fixed fan-shaped spray pattern, somewhat like a shower nozzle spray.

Spray-Type Sprinkler Heads

Rotor-type sprinklers (called “rotors”) are the sprinklers that have one or more streams of water that rotate over the landscape. Some have a single stream that goes back and forth, or just goes in a complete circle. Another type are called “stream rotors”, these have several fingers of water that rotate around the sprinkler in the same direction and look like spider legs. The bottom line is that if the sprinkler has a stream of water that rotates, it is a rotor-type sprinkler.

Rotor-Type Sprinkler Heads with Single Stream.

A valve circuit or valve zone is a group of sprinklers that are all turned on and off by the same valve. Sometimes the term hydrozone is also used, although this is not a totally correct useage. Most sprinkler systems have several valve circuits, each controlled by a different valve. The valves might be manually operated, or they may be automatic valves that are turned on and off by a controller (sometimes called a timer or irrigation clock). On the controller the valve circuits may be called valve stations. Unfortunately the lack of uniform names makes it confusing.

Sprinkler System Tune-up Step 1:

Check for problems. Turn on each valve, one at a time, and carefully inspect your irrigation system. Look for wet spots that indicate there might be a leaking irrigation pipe. Repair any leaks.

Replace controller battery. Most irrigation controllers have a back-up battery that maintains the time and program during power failures. Typically it is a standard rectangular shaped 9-volt alkaline battery. Check the battery in the irrigation controller. Replace it if it is not fully charged, or if it is more than a couple of years old. The battery is often located behind the front panel of the controller. Depending on the model, you may need to remove some screws or unhook a latch to open the panel and get to it. Check your owner’s manual. Here’s a bit of trivia to stick in the back of your brain until needed: if the controller no longer shows the correct time after a power failure the problem is likely that a battery needs to be replaced in it.

Straighten any sprinkler heads that are leaning to the side. In most situations sprinkler heads need to be installed so that they are perpendicular to the ground to work correctly. On a level area this means they would be positioned straight up and down so that they do not lean towards any side. If they lean to one side they may create dry spots and also waste lots of water. On slopes the general standard is to position the sprinkler heads perpendicular (at a right angle) to the slope. However you need to use comon sense here. On steep slopes you may want to lean the heads slightly toward the top of the slope. With the sprinkler turned on, look at the spray pattern. If the uphill side is spraying almost straight up into the air, you need to lean the sprinkler a bit toward the top of the slope, otherwise the water is just spraying straight up and all falling in the same place, or blowing away. When a full circle sprinkler head is located at the bottom of a slope it is a common problem for it to spray directly into the ground on the downhill side. You may need to lean it a little toward the top of the slope to correct the problem. I typically lean the sprinklers slightly toward the top of the slope on my systems, but most experts do not agree with me on this, so I may well be wrong.

Replace any broken or malfunctioning sprinklers. Straighten any sprinklers that are leaning. Be sure to replace broken sprinklers with the same brand and model as the other sprinklers on the same valve circuit. If some of the sprinklers are already mis-matched you need to replace them so that all the sprinklers controlled by any single valve are matched. Mixing different brands and types of sprinklers together on the same valve circuit is a common mistake made by do-it-yourselfers. Most brands and models of sprinklers are not compatible with any other brands or models. While there are exceptions, most manufacturers use different flow rates in their sprinkler heads than their competitors. (It makes sense doesn’t it? They want you to use their sprinklers for replacements, not the other guys! You can’t use Chevy parts in a Ford either.) Mixing different brands and models of sprinklers together on the same valve circuit can result in huge amounts of water wasted. Mixing them is like putting a heavy kid and a light kid on a teeter-totter. It doesn’t work! If the original brand used is not available, you have two choices:

1. See if you can find a model with the same flows for the same exact pressure and radius of throw. This takes a lot of time if you do it yourself. You could save some time and effort by asking for help at a professional irrigation store (your local big-box store is generally not a good place to ask for help on this issue), or see if I have reviewed the sprinkler model you are using. In my reviews I often mention other compatible models. Important note; just because a part will screw on, that doesn’t mean it is a match. It just means it has similar size threads, which are standardized. You can fit a Hunter brand spray nozzle on a Rainbird brand body, but the Hunter nozzle is not a performance match with the Rainbird nozzles.
2. Change all the sprinklers to another model. Often option (2) is not a bad idea, if the sprinklers are no longer available they are likely pretty old, or they weren’t great to begin with (that’s why they aren’t sold anymore?)

It should be obvious that if you can’t mix different sprinkler models on the same valve circuit, then you should also never mix spray-type heads and rotor-type sprinklers on the same valve zone. Mixing rotors and sprays together on the same valve is even worse than mixing brands and models! Spray-type heads put out twice as much water as rotors given the same size area! If you mix them together the grass near the spray-type sprinklers will be drowning, while the grass around the rotors has just barely enough water to keep it alive! (I’m getting over-excited and using too many exclamation marks.) Check it out yourself, you will see the area around the spray heads is really wet compared to the area around the rotors.

Clarification- we are discussing why you should not mix different brands or models of sprinklers together on the same valve circuit. Check the definition of valve circuit again at the top of the page if you are not clear about this. You MAY use different brands and types if they are on different valve circuits. So you could have one valve circuit with Rainbird spray heads on it and another valve circuit with Hunter rotors on it. That would be OK. Also, the don’t mix them rule is only for sprinklers. You can use a different brand of valve for each valve circuit without problems most of the time. In most cases the automatic valves don’t have to be the same brand as the controller either.

Sprinkler System Tune-up Step 2:

Clean spray-type sprinklers. If you have spray-type sprinklers start by removing the nozzle from each head and cleaning the screen. The screen will be under the nozzle, you may need a bent paper-clip to use as a hook to pull it out. An old toothbrush works good for cleaning the filter. Reinstall the filter and put the nozzle back on. Next, turn on the sprinklers and look for partially blocked nozzles. The fan-shaped spray of water out of each nozzle should be even and uniform across the entire width. Uneven gaps in the fan indicate a grain of sand is stuck in the nozzle, remove the nozzle and carefully clean it. To clean plastic nozzles use a plastic or wood tool (like a toothpick) rather than a metal knife blade. Try not to scratch plastic nozzles when cleaning them, even a small scratch can ruin the spray pattern. If you have any doubts just replace the nozzle with a new one. Most pros don’t bother trying to clean nozzles, they scratch so easy it’s just faster and cheaper to replace them rather than waste the time trying to clean them.

Sprinkler System Tune-up step 3:

Adjust spray-type sprinklers. On top of each spray-type nozzle is a small radius adjustment screw. Turn the adjustment screw to adjust each of your spray-type sprinklers so that they don’t spray onto sidewalks or walls. If spray-type heads are creating a lot of mist try partially closing the adjustment screws on them (turn the screw clockwise to reduce the misting.) You will likely discover that you can turn the screw considerably without it actually reducing the spray distance. Partially closing the adjustment screw will reduce the water pressure inside the nozzle, which will cut down on how much mist is created. After adjusting, make sure that the spray from the nozzle still goes all the way to the next sprinkler. When sprinklers are properly spaced and adjusted the water from each sprinkler should spray all the way to the next sprinkler in each direction. This is how sprinklers are designed by the manufacturers to be spaced. I know it seems like a waste but there is actually a reason it is necessary that is related to the physics of water application, but you don’t really want a science lesson now do you? Take my word for it, there should be 100% overlap of the watered areas. This is true for both spray-type sprinklers and rotor-type sprinklers. In the industry we call this “head-to-head spacing”. If you don’t want to take my word for it, call a sprinkler manufacturer’s help line and ask them.

Adjustment Screw on a Spray-Type Sprinkler

Sprinkler System Tune-up Step 4:

Clean rotor-type sprinklers. Most pop-up gear-driven rotors have a filter in them that can be cleaned. Gear driven rotors are identified by the very quiet operation and the water stream that moves smoothly as it rotates. The water stream on a gear-driven rotor always rotates at the same speed. However getting to the filter is difficult, you must unscrew and remove the cap on the top of the rotor. When you remove the cap the nozzle and drive assembly will be attached to it and come out with it. Look for the screen on the bottom of the drive assembly you just pulled out. The problem is that when putting the drive assembly back into the body, you often will get more dirt into the body than you just removed from the screen! Thus the final condition is worse than when you started. So I don’t recommend cleaning the screen on rotors unless you are having problems with them. If you do clean them be very careful that dirt does not get knocked into the body when you put the cap back on. A weak water stream from the rotors, a reduction in the distance the water throws, or dry spots in the lawn that never were present before would all indicate the screen may be clogged and you should clean it. Be aware that all of those problems can result from other causes also, so cleaning the filter screen is not a guarantee cure!

Impact drive rotors: Impact drive rotors are the ones that have an arm that swings back and forth, hitting the water stream. The impact of the arm striking the water stream causes the nozzle to rotate slightly, thus the name “impact drive” or simply “impacts”. Impacts are easily identified by jerking movement of the water stream, and the sound they make as the arm strikes the water going forward; chuk, chuk, chuk, chuk, and then reversing direction; tikka, tikka, tikka. The water stream moves faster when it reverses direction. Pop-up impact sprinklers often have large diameter cases due to the size of the impact arm. The pop-up impact drive rotors also often have a screen, however it requires a special tool to get to it. You will need to go to a irrigation specialty store to get the tool. Generally this is not worth the effort. The simple impact sprinklers mounted above ground on a pipe do not generally have a screen.

Impact Driven Rotor (mounted on pipe above ground)

Sprinkler System Tune-up Step 5:

Adjust the rotor-type sprinklers. For rotors the most common adjustment error is to try to create even coverage by breaking up the water stream using the radius adjustment screw. On a typical rotor the radius adjustment screw is located on top of the sprinkler, just in front of the nozzle. When turned the screw drops down into the water stream causing the stream to deform. This deflects the water stream and reduces the distance it shoots from the sprinkler.

Most newer rotors give the best, most uniform, coverage when the screw is not touching the water stream at all. This is not true of older rotors (at least 20 years old) and really cheap rotors that don’t have engineered nozzles. Often these inexpensive rotors require the radius adjustment screw be used to break up the stream. Most turbine/gear-driven rotors have engineered nozzles and don’t need any adjustment to break up the water stream. Don’t worry if it looks to you like most of the water is falling at the edge of the pattern, this is normal. Most people can’t see the small droplets of water that fall in the area closer to the sprinkler head, so it looks to them like the sprinkler is out of adjustment.

Turn the adjustment screw clockwise until it is touching the water stream (you will notice the stream change shape when the screw contacts it.) Now turn the screw counter-clockwise just enough that it is not touching the stream. This is the proper default position, unless the sprinkler is spraying too far you should leave it in this default position. Warning: the adjustment screw also holds the nozzle in place on most gear-drive rotors. Stop turning the screw when it no longer touches the water stream. If you turn the screw too far, or remove it, the nozzle will fly out and you may never find it! OK, now if the stream of water is going too far, you can turn the screw clockwise until the distance is reduced to keep it within the irrigated area. Use the radius adjustment only if you need to actually reduce the radius so the water doesn’t spray on something like a sidewalk or the house.

 
 
Typical Gear-Drive Rotor Radius Adjustment Screw Locations:
A – Silver screw near edge, above nozzle.
B – Silver screw near edge, above nozzle.
C – Screw under a rubber flap, near edge, above nozzle.
D – Stream rotor nozzle, screw is in center of sprinkler.

 
On rubber top rotors the adjustment screws are under rubber flaps. Push the screwdriver through the slits on the rubber cap to reach the screw under the flap.

Check the yard in a week or so. Dry areas located midway between the rotor heads usually indicate the adjustment screw is too far into the water stream, or the sprinklers are spaced too far apart (check the manufacturer’s recommended spacing.) If a yellow “donut” shaped dry area develops around the sprinkler this indicates that you either have one of those cheap rotors without engineered nozzles, or the rotor sprinkler does not have enough water pressure. Typically lack of water pressure is because the pipe that leads to the rotor is too small, or there are too many sprinklers on the valve circuit. This is a design problem, but it is a bit late for easily correcting it now. If donuts appear, try adjusting the radius screw so the end of the screw just slightly touches the water stream. That should cause more water to fall in the dry donut area. You may need to experiment with different settings until you get the best possible results.

If you don’t want to wait for dry spots to appear in your lawn, there is a short-cut way to check the adjustment and coverage uniformity of your sprinklers. Place identical-size cups, more or less evenly spaced, throughout the area watered. The cups should be between 5 and 10 feet (1,5m to 3m) from each other. Keep the cups at least 3 feet (1m) from any sprinkler heads, if they are closer than that to a sprinkler you will get inaccurate results, also keep the cups at least 12″ from the edge of sidewalks, curbs, patios, or other paved surfaces. Disposable plastic or foam cups work good but tend to get knocked over by the water stream. Here’s a trick- place a stake made from a piece of stiff wire (ie; a wire coat-hanger) next to each cup and use a couple of rubber bands or masking tape to strap the cup to the stake. Run the sprinklers for a few minutes so that the cups are at least 1/4 full, if you have rotors the slowest moving one should make at least 5 passes over the cups. Now compare how much water is in the cups. When the sprinklers are properly adjusted each cup should have about the same amount of water in it. Be warned, it is not always possible to get it perfect if there is an underlying design problem with the sprinkler system. If you want to try to fix the design problem, try creating a new design following the method in the Sprinkler Design Tutorial. Then compare the optimal design you just created with what is actually installed. You may see some possible ideas for improving the system.

Here are detailed instructions for things you can do that will reduce the amount of water your irrigation system uses, with a few extra landscape related tricks for saving water, and a warning regarding water savings and snake oil thrown in at the end of the article.

Jump down to:
  Landscape Ideas for Saving Water
  Water Savings & Snake Oil

Water Saving Tips & Ideas for Irrigation Systems

Have your irrigation system audited. Some water providers will conduct an irrigation audit for you either free or at minimal cost. Check with your water provider. If not, your local water provider can likely provide a list of irrigation auditors in your area. You can also look for a Certified Landscape Irrigation Auditor using the An irrigation audit is the first step for those of you who are not “do-it-yourselfers”, especially if you get it from an independent auditor who is not also a irrigation contractor or maintenance provider. Regardless of who does the audit, the auditor should carefully examine and test your irrigation system. They should then create a report for you detailing the condition of the system, including a list of recommendations for repairs and improvements. Some auditors also will provide you with an irrigation schedule showing how often and how long you should water during each month of the year. For a full list of things that are usually done in a standard irrigation audit, see the Recommended Audit Guidelines produced by the Irrigation Association. After you have your audit in hand, you can then get quotes from landscapers for performing the repairs and improvements you want done. When hiring an auditor be sure to ask what tests they will perform. Some auditors do not follow the standards set by the Irrigation Association.

Adjust your irrigation controller (timer) run time for seasonal changes in weather once a month. Simply making a monthly change to the irrigation operation times can save more water and money than any other thing you can do. It costs nothing but a few minutes of your time each month. Most controllers even have a % key that makes changing the time quick and reasonably painless. Put a reminder on your calendar so you are reminded each month. Even greater savings come with weekly time adjustments, but monthly will provide the most return in water savings for your time invested. To learn more on the topic, see the Irrigation Scheduling Tutorial.

Run your irrigation system during the morning hours, especially if you use sprinklers. Less water is lost to evaporation when the temperature is cooler, plus in most areas the wind doesn’t blow as hard in the mornings. Watering in the evenings can lead to turf and plant disease problems because the water sits on the plants all night, especially in humid climates.

If you irrigate with automatic sprinklers, program your irrigation timer so that it waters in 2-3 short cycles rather than a single long period of time. Allow the water to soak in to the ground between the cycles. Almost all professional irrigation managers water their turf in cycles. For example, if you normally water for 15 minutes, try this; water for 4 minutes, wait 30 minutes or more for it to soak in, then water another 4 minutes, then wait again, then water another 4 minutes. Now you have watered a total of 12 minutes rather than 15. Even with the reduced total watering time, chances are you will see a significant improvement in how good your lawn looks. The reason cycling works so well is that almost all brands and types of sprinklers apply water much faster than it can actually soak into the ground. So after about 5 minutes of running, most of the water begins to build up on top of the soil and then it just runs off into the gutter or to a low spot in the yard. Cycling the irrigation gives the water time to soak into the ground and reduces water run-off, it also will help reduce the wet spots in the lawn where lawn diseases get started.

Give your sprinkler system a tune up. This is another reasonably inexpensive step that gives a good return on your investment. See the Sprinkler System Tune-Up FAQ for instructions on tuning up your sprinkler system.

Make sure tall grass, groundcovers, or shrubs are not blocking or deflecting the water spraying out of the sprinklers. The water from sprinklers heads that pop-up less than 3 inches high is often deflected by tall grass around the sprinkler head. When the water pattern is deflected by tall grass or leaves it results in uneven watering and water waste. With tall grass it may appear that the water spray is forcing it’s way through the grass without being deflected, but this is an illusion. You can only see the large, heavier drops of water that are not easily deflected. The smaller droplets that you can’t see are being blocked, and that creates uneven watering patterns. The industry standard for lawns is to use sprinkler heads with a pop-up height of 4 inches or more. Turn on the sprinklers right before the next time the lawn is scheduled to be mowed and see if the grass around the heads is blocking the spray. If it is, consider replacing the sprinkler heads with a model that pops up higher. (See the next item down this list, about relocating sprinklers, for tips on flexible risers that allow you to more easily move or replace a sprinkler.)

Shrubs and groundcover that have grown since the sprinkler system was installed may also block the spray of sprinklers. If you don’t want to replace or raise the sprinkler heads, trim the shrubs around the heads so that the spray is not blocked. In shrub areas it is not always necessary for the spray to go over the top of the shrubs. In many cases it is OK for the water to spray into the side of the shrubs, especially if the shrubs are 6 feet (2m) or more away from the sprinkler. Shrub roots will often grow out to where the water is. If the shrubs are not wilting and are healthy, then there is no need to change the sprinklers. If you want to really save a lot of water consider changing the sprinklers in shrub areas to a drip system, which will use even less water. More information on drip systems is found farther down in this article.

Relocate sprinklers so that they are between 4 and 6 inches (10-15cm) from the edge of sidewalks, curbs, patios, etc. in lawn areas. In shrub areas they can often be 12 inches (30cm) from the edge, especially with a mature landscape. This will reduce the amount of spray onto the paved surface and will not create a dry area along the edge of the lawn. It will also reduce the amount of damage that trimmers cause to the sprinkler heads. Almost all stores that sell irrigation equipment will have flexible riser pipes made for relocating sprinklers. Using the flexible riser pipe makes relocating the sprinklers much easier, and the flexible pipe allows the sprinklers to move if a car or heavy lawn mower hits them without breaking a pipe or the sprinkler.

Fix leaking valves. Look for water running onto sidewalks or over curbs after the sprinkler system is turned off. If water flows constantly when the sprinkler system is off (often there will be mold or algae growing on the cement or ground) that indicates that a valve is not fully closing. A valve that doesn’t close usually is caused by a small grain of sand stuck inside the valve. Clean, or simply replace, the valve. See the FAQ on How to Repair a Irrigation Solenoid Valve.

Fix low head drainage. Do your sprinklers spit and spew air mixed with water for a short period each time they are turned on? This is caused by a phenomena called “low head drainage”. Low-head drainage occurs when the sprinkler system has been installed on a sloped area. After the sprinklers are turned off, the water in the pipes drains out through the lowest sprinkler heads and is replaced by air. The water that drains out is wasted, and often flows into the gutter or creates a muddy area around the lowest sprinkler head or drip emitter. Then the air is violently forced out the next time you run the sprinklers. This puts a lot of stress on the sprinklers and pipes. The easiest way to tell if you have this problem is when you turn on the sprinklers. If they spit and spew air when the valve is turned on, then you have low head drainage. See the FAQ on Stopping Low-Head-Drainage & Sprinklers that Spit Air.

Install a Smart controller. A Smart controller does the work of periodically adjusting the sprinkler operating times for you. It changes the run times to reflect the current water needs of the plants. Some water companies will assist in the purchase price of a Smart controller. See the separate FAQ on Smart Controllers for more information about Smart Controllers.

Install a rain switch. A rain switch is a simple rain sensor. When it detects measurable rainfall, it turns off the automatic irrigation valves. You can buy a rain switch almost anywhere irrigation products are sold, most will work with any brand of irrigation controller or timer and any brand of valve. You mount the rain switch on the side of the house, on a pole, or on a fence in a location where water will fall on it but sprinkler water will not hit it. Then you run 2 or 3 wires from the rain switch to the controller. The exact installation instructions vary depending on the brand and model of the rain switch.

Install a filter on your irrigation system. A filter saves water (and money) indirectly. Most valve and sprinkler malfunctions result from contaminants in the water supply. Typically this is small grains of sand, pipe scale, or small fresh-water snails. All of these are common in many public water systems. Installing a simple screen filter at the water source (before the valves) will greatly reduce the frequency of sprinkler system breakdowns and save water. A filter is one addition to your irrigation system that almost always pays for itself within 5 years. The cost of a single valve repair can be much greater than the cost of buying and installing a filter. See the Irrigation Water Filtration Tutorial for more information.

If your irrigation system is located in an area where hard frosts occur make sure you properly winterize it each year before the cold weather hits. See the Winterizing Your Irrigation System tutorial for details.

Switch to newer sprinkler heads. Technology in sprinklers has advanced over the last 20 years and many new sprinklers are more water efficient than the older models. Generally this option is only cost effective if you have a very old sprinkler system, or if your original sprinkler system was poorly designed. Small stream-rotor nozzles that fit onto spray-type sprinkler bodies are being heavily advertised as being more efficient than old style spray heads. A couple of popular brands of these stream rotor nozzles are the Hunter MP Rotator and the Rainbird Rotary Nozzles. A word of warning; while they are indeed more efficient than a standard spray nozzle, it is only a marginal efficiency gain and switching nozzles is probably not cost effective if you have a good sprinkler system. However these rotary nozzles can provide a significant benefit for poorly designed sprinkler systems where spray type heads were spaced too far apart or the pipes are too small. This is because these new rotary nozzles achieve a greater radius than was possible with the old style nozzles while using less water. So if you have a sprinkler system and you give it a tune-up, but it still has dry spots, changing to the stream rotor nozzles may help. Measure how far apart your sprinkler heads are, then select the rotary nozzle that has a radius equal too the distance between sprinklers. So if the sprinklers are 20 feet apart get nozzles that have a 20 foot radius. Replace all of the nozzles, don’t try to mix the rotary nozzles on the same system with older nozzles- they are not compatible. It may help, and it may not. You might want to buy the nozzles at a the store with a generous return policy. That way if they don’t fix the problem you can return them. Not all spacing problems can be repaired using stream rotor nozzles. You may need to add more sprinklers, or just totally redesign the sprinkler system to fix the dry spots.

Switch to drip irrigation for watering shrubs. Drip irrigation is about 20% more water efficient than sprinklers are. It is easy to install, and reasonably inexpensive. See the Drip Irrigation Design Guidelines for more information.

Do you have an alternate source of irrigation water you could use? Water from creeks, ponds, and shallow wells are all examples. Grey water from roofs and sinks is another source if you have very limited irrigation needs. These are typically not easy solutions. You need to do a lot of research before you do anything. Completely design out the system and make sure you have enough water- and make sure you have a legal right to the water! There are way too many tanks, barrels, and pumps sitting around unused because someone got all excited and bought stuff without researching how much water was really required. Also, digging your own well is not legal in many locations, and requires a government permit to do it pretty much everywhere. If you punch an illegal well out in your yard and it pollutes the aquifer you could lose everything you own paying for the environmental damage. If you dam up a creek and kill some endangered whatever you could find yourself in a lot of trouble. There was a time when you could do whatever you want on your own property, but those days are long gone. Right or not, that is the way it is.

Some sprinkler head models have built-in pressure regulators. The pressure regulators save water by reducing the water pressure at the sprinkler head nozzle. If too much water pressure is present, the sprinklers tend to create too much mist and give uneven coverage resulting in water waste. These built-in pressure regulators are available as an option on many higher quality spray-type sprinklers. Rotor-type sprinklers seldom need pressure regulation, so this feature is not generally available on them. In order for the pressure regulators to work you must have excessive pressure! If you do not have excess pressure, the pressure regulators may actually harm your system’s performance. If you are a homeowner and considering retrofitting your sprinkler system using pressure regulating sprinkler heads, turn on the sprinklers and look carefully at the sprinkler head farthest from the valve. If it is not creating a considerable amount of mist, it is unlikely that the pressure regulators will help you save water. So what would be a typical situation where pressure regulating sprinklers would be used? A typical use of pressure regulating sprinkler heads is for a valve circuit on a steep hillside. In this situation the sprinklers at the bottom of the hill will have excessive pressure due to the effect of gravity on the water pressure (take my word for it, this is too complex a topic to cover here.) Using pressure regulating sprinklers on these lower sprinkler heads would cause them to perform better. If the highest sprinkler is not more than 6 feet (2m) higher than the lowest sprinkler on the same valve circuit, pressure regulating sprinklers will probably not be of much help.

Tip: On a typical sprinkler system (that is not on a hillside) you can get almost the same result obtained from switching to pressure regulating sprinkler heads by simply properly adjusting the system. For instructions on how to do this, see the Sprinkler System Tune-Up FAQ. I would strongly suggest that you try properly adjusting the sprinklers first, before you spend a lot of money on pressure regulating sprinkler heads. My experience is that very few sprinkler systems will benefit significantly from the use of the pressure reducing sprinkler heads. If you do have too much water pressure it is usually better to install a single pressure reducer valve on the entire irrigation system, or install pressure reducing valves. Excessive pressure is damaging to the entire sprinkler system, so it is better, and often cheaper, to reduce the pressure in the whole system.

Automated emergency shut-off devices save water by automatically shutting off the water when something in the irrigation system breaks. There are several different types of these devices available. Before we get into specifics, understand that these devices do not save water during ordinary operation of the irrigation system. They only prevent water waste when something breaks. In many cases they simply are not cost effective, so the suitability of these devices must be examined on a case-by-case basis. Automated emergency shut-off devices are often used on irrigation systems where a break or valve failure could cause serious damage (such as an irrigation system watering a steep slope, where a break could cause massive erosion.) They also are used often in locations where a leak might go undetected for days, such as a vacation home or remote location.

The first of these devices is a irrigation controller with the capability of monitoring flows. The controller works in conjunction with a flow sensor and master valve. The master valve is an electric solenoid valve that is installed on the mainline near the water connection point, where it can shut-off all the water flowing to the entire irrigation system. The master valve is typically installed right after the backflow preventer. The flow sensor is installed on the mainline pipe after the master valve. Be sure to follow the manufacturer’s directions when installing a flow sensor as it will not work accurately if it is not installed exactly as recommended. The flow sensor is connected by wires (often using special communications cable rather than standard wire) to the irrigation controller. Some controllers use a wireless signal to communicate with the flow sensor. The controller used must be a model that is capable of monitoring the flow sensor and responding to the input from it. Typically this feature is only found on higher-end controllers. If you’re interested in this type of system, select the controller first. The controller manufacturer will then have specific recommendations as to the type and model of flow sensor and master valve to use. Follow the manufacturer’s recommendations.

Here’s how it all works: When water flows into the irrigation system the flow sensor measures the rate of that flow. The controller is set in learning mode, where it monitors the flow sensor output and memorizes how much flow occurs at any given time of the day when everything is working correctly. Once it has a history of correct flows, it then monitors the flow at all times and compares the current flow with what is normal. If it detects an abnormal flow (either too high or too low), it signals the master valve to close. This shuts off water to the entire irrigation system. Most of these controllers will then sound an alarm to alert you. Some will even phone you, email you, or send a text message with an alert. So if a mainline were to break, the flow sensor would show a higher than normal flow, and then the controller would respond by closing the master valve, shutting down the entire system, and alerting you. Most of these controllers will also detect a valve that is broken, as well as any number of other problems.

The second type of shut-off devices are simple mechanical devices that either install under, or are built into, a sprinkler head. These are often called “geyser preventers”, a reference to the geyser-like spray of water that occurs when a sprinkler head or nozzle is broken off. These devices are flow activated. If the sprinkler head or nozzle should break off, it will result in a much higher water flow. The higher velocity of this increased flow through the shut-off device causes a valve in the device to close, which shuts off the water supply to the broken sprinkler. Some shut off devices screw directly into the pipe tee under the sprinkler head. The sprinkler riser is then screwed into the shut-off device, and the sprinkler is attached to the riser. (A “riser” is the short length of pipe that connects the sprinkler to the water supply pipe. Most risers are made so that they will bend or twist if the sprinkler is hit or bumped. This ability of the riser to bend or twist greatly reduces how often sprinkler heads break off.) Another type of shut-off devices are built into the bottom of some models of sprinkler heads and are often called “valve-in-stem shut-off devices.” The limitations of the built-in devices is that since they are inside the sprinkler they will not work if the entire sprinkler head breaks off, which is a common problem. Keep in mind that neither of these types of mechanical shut-off devices will detect a broken pipe, they only work if the sprinkler breaks. Also be sure to investigate carefully the details on any shut-off device you’re considering purchasing. While some devices completely shut off the flow when a break is detected, others simply restrict the flow, but do not completely shut the water off when the sprinkler breaks.

Separate plants into hydro-zones. A hydro-zone is an area where all the plants use more or less the same amount of water and have the same sun and wind exposure. For example, lawn in the sun would be one hydro-zone, the lawn in shaded areas would be another hydro-zone, lawn in the sun on a windy hill-top would be yet another hydro-zone. (The lawn in shade uses less water than the sunny area, the windy hill top uses more water than the sunny area. Wind dries out the grass quickly, similar to how a blow-dryer dries your hair quickly.) The irrigation is separated so that each hydro-zone area is watered by a different valve. This allows you to water each hydro-zone individually for just the right time to apply the water needed by the plants, without over-watering.

Landscape Ideas for Saving Water:

Mow your grass at a higher length (so that it is longer.) While there is some debate about whether this saves much water, scalping the grass off at a low height is definitely not good for the vigor and health of the grass. Longer grass has deeper, stronger roots and is more resistant to disease and drought. Most grass should be mowed to a length of no less than 3 inches. See the next item.

Dethatch and/or aerate your lawn. Lawn aeration helps assure that the water can penetrate easily into the soil, over time the soil surface can become very compacted and water will not easily penetrate it. Aerating also provides air to the roots of the grass, which is necessary for healthy growth. Thatch build-up on the soil surface under the grass blades can actually repel water. How often you need to dethatch or aerate the lawn depends on the type of grass, whether you remove lawn clippings, the type of soil, the climate, and how much you fertilize. (Fertilizer helps feed the bacteria that break down thatch into humus, but too much fertilizer can cause excessive growth and an increase in the amount of thatch.) Dry spots at the higher areas of the lawn are often the first sign you need to dethatch or aerate the lawn. To check take a hose and lightly water the dry area. If the water does not penetrate into the soil quickly you need to either aerate or dethatch, or both.

Reduce the use of fertilizers. Fertilizers encourage rapid growth which results in higher water use. Cut back on fertilizer application amounts to the minimum needed. More frequent application of fertilizer in smaller doses will also help. Try to avoid the green up then yellow off then green up cycle of fertilizer application. Some people find that using an automatic fertilizer dispensing system gives them the green yard they want without wasting fertilizer. Fertilizer injection isn’t for everyone, you need to be willing to calibrate the system and keep watch on it. Consider your neighborhood and risks involved, will wind blow the fertilizer filled spray into neighbors yards? Will kids get into the sprinklers and come into contact with the chemicals?

Add a layer of mulch to shrub beds. A 2 or 3 inches deep layer of mulch, such as wood chips, bark, almond hulls, or even decorative rock, reduces water use and also reduces the number of weeds.

Reshape your landscape to use less water. Often a minor change can not only refresh and improve the appearance of your landscape, it can also save water. Look around at your yard layout, especially the size and location of lawns. Can you remove or shrink the size of the lawn areas? Lawn uses much more water than the same size area planted in shrubs or groundcover. Does your lawn go right up to the edge of the house or fences? If it does, you can save water and help your house siding and fences to last longer by reducing the size of the lawn so that it is at least 3 to 4 feet away from fences and walls. Irrigation water spraying on the side of a house or fence can cause all kinds of expensive problems. Try creating a curved meandering edge on the lawn area to mimic the look of a meadow; it gives a much more esthetically pleasing look than a straight edge. Then add a foundation planting of low-growing shrubs with drip irrigation between the lawn and the house or fence. For more design ideas go down to the local hardware or book store and pick up a couple of books on landscape design. Another idea is to visit model homes, often they have good water-efficient landscape layout ideas. When you find something you like, copy it!

Have you looked at the new synthetic lawns and golf greens? Many of them look very good and are very durable, they are much improved from the old fake grass “carpets” of the past. Synthetic grass isn’t going to meet the needs of everyone, but they sure save a lot of water compared to a real grass lawn!

How about replacing old high-water using shrubs with shrubs that are less thirsty? Visit a local nursery with knowledgeable staff who can help you select good plants that use less water for your yard. Use of native plants can be particularly water and environmentally friendly, but isn’t necessary to get a water saving landscape. You also don’t need to go to a “weeds and twigs” look just to save water. While a desert landscape may use almost no water, even a lush-looking landscape that mimics a forest can be designed to use minimal water. If you want a small garden area of high water use plants, locate it in a shady area with protection from wind. Even high-water-use plants will use much less water if they are planted in a shady area where they are protected from strong winds.

Water Savings & Snake Oil

As attention has shifted to saving water, irrigation companies have assigned their marketing departments and sales staff to push for any water saving connection possible that will sell products. “Irrigation specialists” are suddenly everywhere offering services to help you revamp your irrigation system to save water. Unfortunately, along with the many legitimate products and companies a few “snake oil” salesmen are bound to sneak in, trying to turn a quick profit at your expense. In the past few months I have seen a number of questionable claims. Before you fork over your money or sign on the line, ask a few questions:

• How does this product work? What feature about it saves water and how? An ad I recently saw in an irrigation trade magazine promoted a product as “water saving” but failed to disclose that the product would save water only in very specific situations found on very few irrigation systems.
• Will this product work with your irrigation system? Will it fit? A client of mine was recently told (by a city agency) he should switch his spray-type sprinklers to the new stream rotor nozzles to save water. These stream rotor nozzles have a minimum radius of 10 feet. His sprinkler system uses sprinklers with a radius of 8 feet and less. If he had made the requested change it would not have saved any water, it would have resulted in massive water waste!
• Does the firm proposing this service have extensive irrigation experience and knowledge? A lot of landscapers who have never installed a sprinkler are suddenly irrigation experts.
• Is this cost effective? Spending $100.00 to save $10.00 worth of water may be admirable but is it a wise move? (Yes, it may be in some situations.)
• Be wary of claims that you will save some large percentage of water. Most of the claims I have seen of 50-80% savings were based on the assumption that you have a really terrible quality irrigation system and that you leave it set to water for the maximum amount all year, even when snow is on the ground. In that case simply turning it off in winter could net you a 50% savings. So beware of blanket claims.

Free Irrigation Equipment!

Many water providers, particularly in drought areas in the USA, are offering discounts, coupons, and rebates on water-saving irrigation equipment. Some are even providing this equipment for free to local customers. Before you purchase any irrigation equipment, be sure to check with your local water provider to see if they are offering any freebies. You do like free stuff, don’t you? I do!

When a solenoid valve (also called an electric valve or automatic sprinkler valve) fails to close it is almost always because something is stuck inside it. This might be a grain of sand, a small twig, a insect, or even a tiny snail. To fix the valve you need to disassemble and clean it. When a valve fails to open it is usually due to a bad solenoid or bad wiring, although in rare cases a grain of sand stuck inside the valve or a ripped diaphragm inside the valve. The following instruction tell how to disassemble, clean, and inspect the automatic valve.

To clean the valve:
As you disassemble the valve be sure to note how all the parts fit together so you can get it back together correctly! I strongly suggest you make a sketch and take notes. Each brand and model of valve is slightly different. The valve shown in the photos here is an anti-siphon type valve, which is a type commonly used on home sprinkler systems. The cap structure on the right side of this valve is the anti-siphon device.

Typical Anti-Siphon Type Solenoid Valve

Remove the solenoid from the valve. Most solenoids unscrew counter-clockwise to remove. When removing the solenoid watch that the spring loaded plunger inside it does not pop-out and fall into a mud puddle. On most newer valves the plunger is held “captive” so it won’t fall out when the solenoid is removed, but sometimes even those ones come loose. Once the solenoid is removed, push in on the end of the spring-loaded plunger in the solenoid. It should spring gently back out when released, and it should slide in and out smoothly when pressed several times in a row. If the plunger doesn’t move easily and smoothly, replace the solenoid; it is damaged and can’t be repaired. Do not apply any oil or lubricant to the solenoid plunger, if it is sticking it is not repairable, replace it.

Solenoid Removed, Showing Plunger

Remove the valve lid, most are held in place by several metal screws. Some models of valve have lids that screw off like the top of a jar, turn counter-clockwise (lefty losey) to remove this type of lid. You may need to use a strap wrench to remove the jar-top style lids. All valves have a spring under the lid, don’t let it fall out into the mud! Remove the spring and set it aside.

Valve Lid Screws

Removing Valve Lid Screws

Watch that the Spring Does Not Fall Out When Removing the Lid

Look for the tiny passages, called “ports”, inside the valve lid. These ports lead from the bottom of the lid to the area where the solenoid was attached. The exact location of the ports varies with each valve brand and model. Make sure these passages are not clogged with a grain of sand or whatever. Be careful you do not scratch or enlarge these passages when trying to get the sand out! Do not try to drill out these ports to clean them or make them larger.

Ports in Lid

Remove the rubber diaphragm from the valve. Make sure it is not cracked or broken, if it is replace it. Some valve models also have a port in the diaphragm, check to see if there is one, if so make sure it is clean. On some valves the port in the diaphragm has a metal pin that runs through it, the purpose of the pin is to keep the port clean. The pin should slide freely in the port. The diaphragm in the photo below has a separate, removable seat gasket attached to the bottom of it with a screw. On many valves the rubber seat gasket and the diaphragm are one piece and the seat gasket is not removable. Make sure the seat gasket or diaphragm seat does not have anything stuck on it, like a grain of sand or twig. If the gasket surface is scratched or torn replace the gasket or diaphragm.

Examine the valve seat in the bottom of the valve body. The seat is the part of the valve body that the gasket presses against to stop the water flow through the valve. Make sure the seat is not scratched or pitted, if it is the valve will leak when closed. On some valves the seat is replaceable. On some brass valves the seat can be ground down with a special tool to remove pits and scratches. However, for most valves if the seat is scratched or pitted, the valve is not repairable and must be replaced.

Rubber Diaphragm and Gasket

With the valve disassembled turn on the water to flush any remaining sand and crud from the pipes upstream of the valve. Turn it on full blast, and run it for a minute or two, you need to get everything out of that pipe. Turn off the water, and dry yourself off. I know you don’t want to get wet, but don’t skip flushing the pipes and valve body, this is an important step!

Carefully clean everything, then reassemble the valve. Some valves have a separate lid gasket or o-ring that needs to be cleaned or replaced before being reassembled. If there are any o-rings, I strongly suggest you lubricate them before reassembling using K-Y Jelly or a similar product. Lubricating o-rings is optional, but recommended as it keeps them from crimping during assembly. If the o-ring crimps it will be ruined and will leak. K-Y Jelly is a water-based lubricant that you buy in the feminine hygiene department of a supermarket or drug store. (Don’t ask for it at the hardware store unless you want to give the employees a good laugh at your expense. Yes, I admit I fell for this back when I was first starting out in this business, it’s a favorite plumber gag to send the new guy out to buy the K-Y Jelly!) Do not use vaseline, silicone, oil or any petroleum based products on the valve, they may damage the seals and also may clog the ports in the valve.

Use K-Y Jelly to Lubricate Rubber Parts of the Valve
Do Not Use Petroleum-Based Products!

When attaching the lid, avoid striping out the lid threads and warping the lid as follows: When inserting the screws that hold the cap on, start with one of the screws next to the solenoid. Insert the screw in the hole then turn it counter-clockwise (losey lefty) until you feel a slight click as the screw finds the threads. Then reverse direction (righty tighty) and lightly tighten it. Then insert the second screw on the opposite side of the valve lid. Like the first, find the threads then just lightly tighten the screw. Continue with one screw on one side and the next on the other until they are all in. Now go back and tighten them all, going in the same order you inserted them. Do not over-tighten the screws on plastic valves, you will strip out the threads.

If you’re blessed and didn’t mess up something the valve should work correctly now.

Suggestion: Your valve has already failed once, chances are that means something in the water got stuck in it, which means there is sand or whatever in the water supply. Consider installing a filter upstream of the valve to keep out the sand and crud in the future. Typically the cost of a valve repair is greater than the cost of installing a filter. See the Irrigation Water Filtration Tutorial.

Buzzing solenoids are usually caused by insufficient voltage reaching the valve solenoid. Unfortunately there are many things that can cause insufficient voltage. To determine what the problem is requires testing for each of the possible causes.

First off, what’s a valve solenoid? The valve solenoid is the small device attached to the valve that the wires lead to. It is what makes the valve open and close when an electrical signal is transmitted to it by the irrigation controller. The solenoid is actually a electro-magnet that operates a plunger, which serves as a pilot valve, but that is not important for what we want to do here. It is normal for the solenoid to make noise, it clicks when the valve is turned on or off. It also is normal for a very soft buzzing sound to be heard when the valve is activated, but you should not be able to hear it unless you put your ear near it. If you can easily hear it buzzing, that is not normal.

Solenoid on an Electric Anti-Siphon Type Valve

What’s an irrigation controller? “Irrigation controller” is what we in the irrigation industry call the timer that is used to automatically control the irrigation system. The controller has a valve circuit (often called a “station”) for each of the valves it operates. It turns on the valves by sending a 24-volt current to the valve from the circuit/station.

General suggestion: Purchase new valves and controllers from a store that will allow them to be returned. Some of the diagnostic routines listed here are trial and error. Purchasing from a store that has a generous return policy will allow you to return an item if you find it wasn’t the problem.

Irrigation test equipment can be purchased that will test the controller, valve, and/or wiring. The procedures below do NOT require that you have a tester, but a tester does make it easier. If you don’t have a tester(s) and want to look into buying one, see the Reviews – Accessories, Tools, and Other Products section of this website. It has reviews of some valve testing products.

The procedures that follow require the use of an electric valve activator. Most valve testers have a built-in valve activator. If you don’t have a valve tester, you can make your own valve activator very easily. For complete instructions on making a simple valve activator see this link: Irrigation Valve Activator.

OK, let’s get started.

Test #1

Are there multiple valves operated by the same irrigation controller? Do they all buzz? If not, go to test #2.

• If all the valves buzz when they are turned on, it may just be that the valves you have normally buzz. Some brands softly buzz during normal operation. You might try calling the valve manufacturer’s customer service number and asking about it. If the buzzing isn’t soft or normal, the problem is probably a bad controller or a bad common wire. (The common wire is usually a white color, and it is connected to all the valves.) If you have an irrigation tester that includes a controller circuit/station output test, use it to check the controller output. If the test indicates a bad controller, replace the controller.
• To check the controller without a tester, disconnect the common wire and one of the valve wires from the controller, connect them to your valve activator, and turn the valve on using the activator. Does the valve solenoid buzz now? If not, the problem is very likely the controller, try replacing it. Buy a new controller from a store that will allow you to return it if it turns out it isn’t the problem. If replacing the controller does not stop the buzzing continue to next step.

Test #2

Sometimes there is just a loose or incomplete wire splice or connection causing the buzzing. Turn on the valve using the controller. Go to the buzzing valve and check the wire connections. If they have the twist or screw-on type wire connectors, try tightening them by turning the connector clockwise. If they are a different type of connector, just twist the wires around a bit, or push them firmly into the connector to see if you can make a better connection. If the buzzing stops then you simply have a bad wire splice. Turn off the valve using the controller. Remove the old splice and make a new splice using a NEW connector. Be sure the splice is water-proof or your next problem will be a rusted-out solenoid! Water can be pulled up into the solenoid from a non-waterproofed splice. The water is pulled through the tiny spaces between the multiple wire strands by capillary action. Not properly water-proofing of the wire splices is the #1 cause of solenoid failure! Taping the splices with electrical tape will NOT sufficiently water proof them. Use special water-proof connectors that you can buy at any hardware store.

If messing with the splices doesn’t work, disconnect the wires completely from the valve (you may have to cut the wires.) Strip some insulation off the end of the valve’s wires. If you have a valve tester, connect the tester to the valve and test the valve. If the test shows a bad solenoid, replace the solenoid or the valve.

If you do not have a tester (or if the tester indicted a good solenoid) connect the valve activator to the wires. Turn on the valve using the valve activator. The valve should open and there should not be any buzzing.

• If the valve does not buzz when activated the problem is either that the wires from the controller to the valve are bad, or possibly the irrigation controller itself is bad. Proceed to test #3.
• If the valve still buzzes when turned on with the activator, the solenoid on the valve is dirty or bad. Turn off the water, then take the solenoid off the valve and clean both the solenoid and the area it came out of on the valve. Most solenoids are connected to the valve with threads, just unscrew the solenoid to remove it. The solenoid has a spring loaded plunger in it, watch that it does not pop out when you remove the solenoid.

With the solenoid removed turn on the water for a few seconds to blow out the passages in the valve. When you do this water should spray out of the area where the solenoid was (protect your face, often bits of sand, plastic, or metal will fly out with the water.) If water doesn’t forcefully spray out of the valve, turn off the water and check that the tiny passages in the valve lid under the solenoid are not blocked. Use a small piece of wire to push any trash caught in the passages out, but be very careful, do not scratch the sides or top of the passages. Do not try to clean the passages by drilling them out with a drill bit. You probably will need to remove the lid from the valve to clean the passages. Most valve lids are held on with screws (the lid in the photo above has numbers stamped on the side of it and is held on with silver screws), however, some lids screw off like the top of a jar. If you do remove the valve lid, make a drawing of how all the valve parts under the lid fit together as you remove them, so you can reassemble it! Clean all the parts and put the valve lid back on after you are done. If you leave even a single grain of sand inside the valve, it may cause the valve to fail and then you will have to reclean it!

Clean the solenoid, and check the plunger. If you push on the end of the plunger it should easily slide into the solenoid. It should spring back out when released. If the plunger does not move easily or the spring does not push it back out, replace the solenoid. In my experience trying to clean or repair the plunger doesn’t provide a long-term fix.  Make sure the area of the valve lid under the solenoid is still clean, then put the solenoid back onto the valve.

Now try testing the valve again using your tester/activator. If it still buzzes the problem is a bad coil in the solenoid and it is not repairable. Replace the solenoid or the whole valve. If the valve is more than 10 years old and isn’t a top quality valve, you probably should just replace the entire valve, it is getting pretty old.

Test #3

Go to the controller and disconnect the common wire and the valve wire for the valve that buzzes from the controller.

If you have an irrigation tester that includes a controller circuit output test, use it to check the controller output on each circuit/station. If you find bad circuits, mark them as bad and use other circuits if you have extras. If you don’t have any extra valve circuits you will need to replace the controller.

If you don’t have a controller circuit/station tester, connect your valve activator to the valve wires at the controller and use it to turn the valve on.

• If the valve is still buzzing, you likely have a bad wire or wires between the controller and the valve. Replace the bad wire(s) or use a work-around solution. (See below.) If you decide to replace wires, before you dig trenches or string new wires through difficult to access locations like a crawl space or an attic, just lay down temporarily wires between the controller and valves. By running temporary wires between the controller and valves you can confirm that bad wires are the problem and also determine which wires are bad. Wire is expensive, so for temporary wires I suggest buying a packaged wire rather than a custom-cut length off of a large spool. Don’t cut the wire, just leave any extra wire coiled while doing the test. Strip off just enough insulation on the ends to make your connections. Most stores will take packaged wire back as a return if you haven’t actually cut it to a shorter length. Simply disconnect the old wires and hook up the new temporary wires in their place. Once you have identified which wires are bad you can cut the wire to the proper length and install the new wires in their permanent position. If the valve still buzzes with a new wire, it’s time to replace both the valve and the controller with new ones, if you haven’t already.
• If the valve does not buzz when activated with your valve activator, you probably have a bad controller circuit/station. Try swapping the valve onto a different controller circuit. At your controller, disconnect the wire for one of the valves that is not buzzing, and hook the wire for the buzzing valve up to that circuit. If the valve solenoid still buzzes after being switched to the new circuit, it means the wire to the valve is probably bad. See the procedure for replacing the wires in the paragraph above. If it doesn’t buzz anymore, it means the controller circuit that the valve was previously connected to is bad. If you have a spare circuit on the controller, you can use it to control the valve. If not, you will need to replace the controller.

Work-Around Solutions for Bad Wires

If you have bad wires that you don’t want to replace there are a number of products made to provide a solution using the wires you have.

2-Wire Controllers. If you have at least 2 good wires you can use a controller that utilizes only 2 wires. These controllers hook all the valves up to the same 2 wires, and a special decoder is installed at each valve. The controller turns on the valves using a signal sent to the decoders.

Wireless Controllers. There are some controllers that use wireless transmitters to control the valves.

Battery & Solar Powered Controllers. These controllers are installed at the valve location and are powered by batteries, sometimes with a solar battery charger.

Double Up Devices. These are devices that allow you to install two valves on the same wire. They each work slightly different so you will need to do a little research to figure out which would work best for you.

End

You can easily make a simple valve activator or valve tester to turn on electric irrigation valves in the field. It’s easy. Cheap. And it works great!

Take 3 standard 9-volt batteries (the rectangular type with snap connectors on top.) Using the male and female snaps on top of the batteries, snap all three of them together in a chain. This creates a home-made, portable, 27-volt “valve activator”.

Remove the splices from your valve wires.  Now attach the valve solenoid wires to the two open end terminals on your battery chain.  The valve should open.

For a more professional approach you can purchase irrigation valve activators/testers that will not only activate the valve, but will also test that the wires and solenoids are within acceptable performance standards. See the Reviews – Accessories, Tools, and Other Products section of this website for reviews of some available products.

Plastic to metal connections are made using threaded connections. A plastic male thread is used to connect to metal female threads.

Do not use a plastic female threaded connector with a metal male connector! The joint will almost always leak or break.

The standard IPS type threads used on pipe and fittings are not uniform in diameter. For example, if you look closely at a male pipe thread you will notice that the diameter at the first thread on the end of the fitting has a smaller diameter than the last thread. Likewise with a female thread the first thread at the end has a larger diameter than the last thread. There is a good reason for this. When you are screwing the threads together it actually does get tighter! As the threads are screwed together it starts to compress the male fitting while stretching the female fitting, resulting in a very tight joint that doesn’t leak. This is why it gets so much harder to turn the pipe as you continue to tighten the joint. However this creates a problem if you are joining two different materials together. If one is softer than the other, then the softer one will do all of the compressing or stretching. Compressing is generally not a big problem, but stretching too much can be bad news for the strength of the material. To adjust for this effect, female threads on fittings and valves are often reinforced by making them thicker. Look at a typical metal female fitting like a coupling and you will notice the reinforced end. For plastic valves they not only use thicker plastic, they sometimes will place a metal ring around the female end, or put fiberglass reinforcement in the plastic.

Plastics like PVC create more of a problem since plastic easily stretches compared to almost all metals. Because of this, you should (almost) never use a female PVC fitting with a male metal fitting. Since the male metal thread is harder, the male threads don’t compress and all the “give” comes from the female PVC. The result is the female PVC is stretched beyond it’s strength limits by the hard metal, resulting in tiny stress cracks and leaks. The exception I hinted at is that there are some specialty plastic fittings available that have a combination of heavier plastic and metal reinforcement rings to give them sufficient strength to withstand stress cracking. Typically these fittings are only used on large agricultural, park, and golf course irrigation systems.

There is also another type of threads called “acme threads” that do have uniformly sized threads. These are the type of threads used on items that need to be easily disassembled, like jar lids.

Sealing Tapes and Pipe Dopes

When making threaded joints you need to use a sealer/lubricant. This is a product that helps seal the joint and also serves as a lubricant to make it easier to screw the male end into the female. The standard products for this are either Teflon pipe dope, Teflon tape, or PTFE tape. For sprinkler systems Teflon or PTFE tape is preferred. If pipe dope gets into the pipes the water will carry it to the sprinklers and it will gum them up (using pipe dope also voids the warranty on most sprinklers.) Some pipe dopes made for metal pipe are not compatible with plastic. They will harm the plastic resulting in future failure. Stick to Teflon or PTFE materials that are labeled for use on plastic.

If using pipe dope spread it on the male threads. Try not to get any on the last thread on the end, so it doesn’t get squeezed into the inside of the pipe. Put a good thick coat on starting with the second thread from the end. Most pros use Teflon pipe dope because it is faster and takes less thinking than Teflon tape to install. (Teflon tape must be put on in the correct direction or it comes off.) But they pay the price with ruined sprinkler heads they have to later replace.

Some Teflon tape, sold typically at discount suppliers, is very, very thin. If you can hold the tape up to a light and see the light through it you have some very thin tape and you will need to use a lot more of it. Use about 9-10 wraps around the male threads when using the cheap thin tape. I find it is actually cheaper to buy the more expensive thicker tape.

For good-quality tape it takes 3-4 wraps around the male threads to create a good seal. Don’t put tape on the first thread and you will find it easier to get the joints started. Pull the tape tight around the threads as you put it on, but don’t stretch it too much. You should be able to see the shape of the threads through the tape. Wrap the tape around the pipe threads in the same direction as the female threads will screw on. (Clockwise if you are looking at the end of the male threads.) If you go the other direction the tape will tend to come off as you try to thread the ends together.

I prefer to use the pink colored “extra-heavy”, “full density” PTFE tape. I almost never use pipe dope.

Water Pipe Noise and Things that go Bump in the Night.

Is your sprinkler system making odd noises? That sound may be water hammer, but then again, there are other things that create noise in water pipes. Air in the pipes can cause them to make sounds which are easily confused with water hammer. In a few cases I have dealt with, the thumping turned out to be loose pipes striking each other. What I will attempt to do in this tutorial is take you through a few steps to determine the source of the sound and then suggest some remedies. I will start with the easy fixes (that are, unfortunately, less likely to work) and then move on to tougher ones (which are more likely to work.)

Many years ago I was called in to consult on a large high school irrigation system that was having water hammer problems. The water hammer was literally blowing apart the system. Two guys were working full time just repairing the pipe breaks! They had tried for months to fix it and numerous irrigation equipment salesmen had checked it out. They had spent hundreds of dollars on adding additional equipment which was supposed to cure the problem, such as air vents, and a “huge water hammer arrester”. But the problem continued. We looked at the original plans for the system and the problem was almost immediately obvious. The water was flowing through the system backwards! Apparently someone decided to move the well location from one end of the property to the other. They didn’t bother to redesign the sprinkler system, they just ran the water through it from the other direction. Unfortunately, that meant the water started out in the smallest pipe in the system. I suggested they add a second pipe next to the small one that was restricting the flow. They did, problem solved, no more water hammer! They could have saved thousands of dollars in repair work and unneeded equipment. The moral of the story is always look for the source of the problem before you try to fix it.

A quick disclosure before continuing- these explanations are intended for the average Joe. All you physicists and engineers out there need to relax. I realize these are not perfectly accurate scientific explanations. There are other websites that dwell into the nitty-gritty details with lots of formulas that will make your day. You’ll find one at http://www.lmnoeng.com/WaterHammer/WaterHammer.htm. It has lots of formulas! The majority of the people reading this do not want to deal with scientific theory and mathematical problems, they just want to know how to quiet things down so they can sleep at night!

Some of the solutions I mention in this tutorial may not meet plumbing codes in some areas. Plumbing codes and standards vary from city to city. It is always best to check with local building department officials before modifying the plumbing inside your home.

Identify the Problem

The first thing to check is the water pressure in your house. You can buy a pressure gauge for this at most hardware and home improvement stores. Attach the gauge to the cold water outlet for your washing machine. (Some water will spill out of the washing machine hose when you remove it, so hold a towel under it.) Turn off the water for anything in the house that uses water. This includes all the faucets in the house, ice makers, reverse-osmosis type water purifiers, and make sure the toilets aren’t filling. Any water running in the house may cause an inaccurate reading on the gauge. Turn on the water faucet that the gauge is attached to, and then read the water pressure on the gauge. That’s all there is to it!

Pressure Gauge attached to laundry outlet.

After the test turn off the water and disconnect the gauge. (Some water will spill out of the gauge when you remove it so hold a towel under it when you remove it.) The pressure reading you get from the gauge should be 60 PSI or less. Pressures higher than 60 PSI can be the source of the noise problem. But just as important, water pressures higher than 60 PSI can cause a lot of other plumbing problems too. So if the pressure is higher than 60 PSI you need to fix that first. The solution for high water pressure is to install a pressure reducing valve on the pipe that brings water into your house. (Pressure reducing valves may also be called “pressure regulators” or “pressure regulating valves” depending on the brand of valve and where you buy it.) If you already have a pressure reducing valve it is probably broken. They tend to break or wear out after about 10-15 years of service. You can try adjusting it to see if it is just set wrong, however be prepared for the need for an immediate replacement if you do this. If one of the parts inside the pressure reducing valve is broken, the valve may jamb closed when you try to adjust it. If this happens you will need to replace the valve immediately! To adjust the pressure on the valve you turn the bolt that protrudes from the bell shaped part of the valve (see photo below). When selecting a new pressure reducing valve make sure you get a brass-body model similar to that shown in the photo below. Warning: installing or replacing a pressure reducing valve involves a moderate to high level of plumbing skill, you may want to hire a plumber for this if you are not experienced with plumbing. Typically it requires cutting pipes. (Yes, the pressure on the gauge in the photo above is 112 PSI. The pressure reducing valve on my house was broken when I took the photo. So it happens to all of us.)

Pressure Reducing Valve/ Pressure Regulating Valve/ Pressure Regulator
No, it’s not installed upside down. This particular valve is installed on a pipe where the flow is going up.

If the water pressure is less than 50 PSI, then the next thing to check is for loose pipes that may be bumping each other, making noise. In the case of loose pipes the sound will usually become much louder as you approach the source. In one instance a tutorial user wrote me to say that he discovered that the problem was a backflow preventer that wobbled when the irrigation system was running and bumped the side of the house. So start by listening for a sound source and looking for anything loose. It would be frustrating to spend tons of money trying to fix what you thought was a water hammer problem only to discover the fix was to stuff a 50 cent piece of foam between two pipes!

When water moves through a pipe it makes noise. Although it might seem to be a smooth flow, the water inside the pipe actually churns and tumbles as it moves through. The normal sound of water moving through pipes is a steady, even sound. The best way to know what it sounds like is to go turn the bathtub water on full blast, then go to other rooms of the house and listen. (Don’t let the tub overflow!) Some newer bathtubs don’t use enough water to make the pipes “sing” so you may have to turn on several faucets at the same time to create enough volume. The sound you will hear is the normal sound of water flowing through the pipes. If that is the sound you are hearing that is bothering you, then unfortunately, there is little you can easily do about it. Water makes more noise as it moves faster through the pipes. Replacing the pipes with larger pipes will reduce or even eliminate the noise you can hear. But that is a huge undertaking.

A continuous thump, thump, thump noise, consisting of evenly spaced thumps when the water is running may be caused by a under-size water meter. The noise may also be a tapping sound. The noise may appear to come from the water heater as the tank amplifies the sound. Check the water meter, you will likely hear the noise coming from it. The solution is to install a larger meter.

A pipe that is changing temperature will clunk as it expands or contracts. The noise results from the pipe suddenly shifting position. This is common inside a house when hot water is turned on. The hot water flows into the cold pipes causing them to expand. But this temperature change related noise may also occur in less expected times and locations. For example a water pipe that supplies irrigation water may pass through an attic or crawl space where it may get hot on a warm day. When the irrigation comes on cold water is pulled into the pipe, causing it to contract and make noise. The key to pipe expansion/contraction related noise is that the clanking noises are not uniformly spaced, they occur randomly. The noise is generally noticeable but not loud. The noise occurs soon after water is turned on someplace and stops after a minute or two as the pipes reach the new temperature. Installing insulation on the pipes may help reduce the noise. Loosening straps that hold the pipes in place may also reduce the noise by allowing the pipe to slide easier as it expands and contracts. Often there is little you can do to completely eliminate this type of noise and it is something you will just have to live with.

Air in the pipes can cause an awful lot of noise! It can be much worse to listen to than true water hammer. The noise of air in the pipes is often a vibrating sound or a rapid ticking sound similar in pace to a machine gun firing. (At least what one sounds like in the movies.) Air in the pipes can be really difficult to get rid of. Air tends to get trapped at high points of the pipe system where it is difficult to push out. As the water moves in the pipes it breaks the pockets of air up into tiny bubbles. Then the water flows past the bubbles, leaving the air still in the pipe. These tiny bubbles moving around, and expanding and contracting, are that rapid vibrating sound you hear. (Everyone who has been to Hawaii knows how annoying the sound of Tiny Bubbles can become after a few repetitions.)

Water hammer can also be the source of the noise. Water hammer can be a big thump that shakes the house, or a series of banging noises starting with a loud bang followed by several “echoes”. The best way to identify if the noise is water hammer is to ask yourself “when does it happen?” If the noise occurs when you open a valve or a faucet, it is probably air in the pipes. If it occurs when a valve closes or the washer changes cycles, it is probably water hammer. If it occurs when a pump starts, it could be water hammer, air in the pipes, or both. Although opening valves can sometimes create water hammer, this typically only occurs with valves larger than 3″ in size, and even then it is reasonably rare. In fact, in my 20+ years in the business I have never actually seen water hammer caused by a valve opening.

So here’s your noisy pipe checklist:

• Noise when a valve closes = water hammer.
• Noise unrelated to valve opening or closing = air in pipes or loose pipes moving around and striking objects.
• Noise when a pump starts = water hammer and/or air in pipes.
• Loud single thumps or multiple quick bumps, then no noise. This tends to be water hammer.
• Vibrating and prolonged noises tend to be air in the pipes.
• A continuous, uniformly spaced tap, tap, tap noise when water is running may be caused by an under-size water meter.
• As hot water flows into a cold pipe, or cold water into a hot pipe, the pipe will expand or contract and make noises. This will create a clunking noise that goes away in a minute or two once the pipe fully changes temperature.

Air in the Pipes

There are only two ways I know of to get the air out; push it out by increasing the water velocity (speed), or open the pipe and release the air.

To push the air out you need to temporarily increase the water velocity to the point the water “sweeps” out the air bubbles. To increase the velocity you need to turn on as many water outlets as possible. That creates a high water demand and the water velocity goes way up. As the water rushes through the pipe the trapped air is swept along with it and out of the pipe.

If the air is in the irrigation mainline (a mainline is the pipe upstream of the circuit control valves) you should be able to increase the velocity by manually opening two or more of the circuit valves at once. Most electric irrigation valves can be manually opened by twisting a lever under the valve’s solenoid (the thing the wires go into), or by partially unscrewing a bleed screw on top of the valve. Do not remove the bleed screw, just slowly turn it until the valve opens. Open all of the valves at the same time if you need to. Let the water run for a while to give it a chance to push all the air out. When you close the valves close them one at a time. Closing them all at once can cause a pressure surge that can damage your irrigation system. Don’t be surprised if the valves take a long time to close, this is fairly normal when more than one valve is opened at the same time. If the electric valves won’t close, slowly turn off the main water supply to the irrigation system, wait one minute, then slowly turn it back on. They should now be closed.

If the noise only occurs when an individual sprinkler valve (always the same valve) is opened the air may be in the lateral pipe (the pipe downstream of the valve.) In that case you will need to temporarily remove some of the sprinkler heads on that valve circuit in order to increase the water velocity. Remove the 3 sprinkler heads furthest from the valve and then open the valve to flush out the air. If that doesn’t get it out try removing more sprinklers. After the air is flushed out, put the sprinkler heads back on. If that fixes the problem temporarily but it returns after the next time you irrigate, then the problem is that the water is draining out of the pipes through the sprinkler heads after each irrigation. This is probably because one or more sprinkler heads are lower than the others. When the water drains out, air gets back into the pipes. To prevent this you need to install “anti-drain check valves” at the inlet of each sprinkler head. The anti-drain check valve is a small spring-loaded check valve. The check valve holds back the water so it doesn’t drain out. It does not effect the performance of the sprinkler head noticeably. Many sprinkler heads are available with this feature built-in to the sprinkler. Some brands also have retrofit kits available that allow the check valves to be easily installed in existing sprinklers. The built-in anti-drain check valves do not effect the performance of the sprinkler at all.

If the air is in your household pipes try turning on all the faucets in the house and then flush all the toilets. Again, give it a few minutes to push that air out. If you know where the water supply comes into your house turn off the faucets starting with the one closest to the water supply entry point, then close them one at a time moving away from the entry point. As you come to a toilet when you are moving through the house turning off faucets, flush it again, then wait two minutes before closing the next faucet. Don’t forget the faucets on the outside of the house!

If the above procedures didn’t get the air out…

Next try a water hammer arrestor. This often doesn’t work with air problems, but it’s worth a try. At your local hardware or home store look for a pre-packaged water hammer arrestor that attaches to a standard washing machine cold-water outlet. The ones I have seen come in one of those clear plastic display packages, and look like a copper tube with hose connections. Check the return policy of the store before you buy it, if you can, buy it someplace where they will take it back if it doesn’t work. Make sure you keep all the packaging. Install it per the directions on the package. If it doesn’t work, remove it and return it.

If the air can’t be pushed out, and the water hammer arrestor didn’t work, you will need to find where the air is trapped in the pipe and “open the pipe” to release it. Air rises above water, so the air is likely trapped in a high spot in the piping. Try to visualize how your irrigation system is laid out. Are there any obvious high points where air might be trapped? If you can identify a likely high point turn off the main water shut-off valve and open a faucet or valve to release the water pressure. Then cut the pipe at the high point and install a tee on it with a small valve on the tee outlet. A compression type tee may be easier to install. A 1/2″ valve, or even a smaller one if you can find one, will work fine for the valve. Do not use a gate valve! Gate valves tend to leak easily. Ball valves work good. See the drawing below. The valve needs to be on a short nipple, a few inches above the pipe as shown. (Stop snickering, in the irrigation business a nipple is the name of a short length of pipe. If you really like to giggle at odd names read the glossary.) Close the faucet and turn the water back on. The air will rise to the highest point which is the short upright nipple under the valve. You can then open the valve just a little bit to let the air escape. Some water is going to come out too, so be prepared for it to squirt! After releasing the air put a plug in the outlet of the valve for safety.

Sometimes you will get all the air out and everything will be fine for a while, then without warning, the air noise will return. This is because the water coming into your house or irrigation system sometimes has air trapped in it. Have you ever filled a glass of water from the kitchen faucet and noticed it was a milky white color? But after sitting for a while it turns clear. That white color most likely was caused by tiny bubbles of air in the water (at least I hope it was!) This air can get in the water lots of ways, it is fairly normal and doesn’t by itself mean your water is polluted or not drinkable. But this air does tend to rise out of the water when the water is sitting in your pipes, and it can form an air pocket in the pipe after a while. This causes the wonderful air noise you enjoy so much to return. If this happens often you can add a “continuous venting” type air vent in place of the valve in the drawing above. The air vent needs to be the type that releases air while under pressure. The type of air vents that are made for most irrigation systems will not work. The type you want has a float connected to an arm that uses a lever to open and close a small valve that allows the air to escape. The correct vent type is often called an “air eliminator” or “air relief valve.” Look for that term “continuous venting”. Most plumbing supply stores will have one. A 1/4″ size one should work fine.

Water Hammer

True water hammer is essentially the sound of a “water wreck” occurring. It happens when moving water suddenly changes speed. Water hammer can be caused by a pump starting or a valve rapidly opening, however in the vast majority of cases it results when a valve closes. Sometimes you can create it simply by closing a faucet very fast. Many single lever household sink faucets will allow you to slam them closed fast enough to cause water hammer. Closing the same valve slowly will not cause the water hammer. However, more often the valve causing the problem is an automatic valve such as is used on an irrigation system. Since most dishwashers and washing machines use the same type of valves as irrigation systems, you will sometimes get water hammer when the dishwasher or washing machine fill valve closes. So for this tutorial I am going to focus on water hammer caused by closing valves. Even though these so-called “electric valves” appear to be powered by electricity, they actually use water pressure as their major power source. The electric solenoid on the valve operates a tiny “pilot valve”. The water flow from this tiny valve is then used to open and close the bigger valve using hydraulic pressure. This works well, but leaves a minor engineering problem. It is very hard to get these valves to close slowly! Engineers have made some great progress but they still haven’t fully defeated what I call the 80/20 problem. The 80/20 problem is that valves close slowly until they are about 80% closed, then they tend to snap fully closed in a millisecond! This causes the water in the pipes to suddenly stop moving. Now we all know the story of Jack and Jill, and the reason Jack fell down is that water is heavy (and perhaps Jack was paying too much attention to Jill , and not enough to his bucket, but I’m getting off-track here.) A column of water moving through the pipe at 7 feet per second carries with it a tremendous amount of weight and momentum. While it’s not a perfect example, the one commonly used is to think of the water in the pipe as a big freight train going through a long tunnel. The valve closing is like blocking the end of the tunnel with thousands of tons of rock. When the train slams into the blocked end of the tunnel there is going to be one horrific crash! The faster that train is moving, the worse the crash will be. Thus the problem with water velocity in the pipe. The faster the water is moving, the worse the crash is going to be when the valve closes. That crash is the cause of a big thumping noise when the valve closes. Secondary thumps that follow are essentially “echoes” in the pipe.

Now that thumping sound would be bad enough, but a unique property of water makes the problem much worse than just an annoying noise. Water is essentially non-compressible (it compresses a little bit, but not much.) So all the energy it carries with it when it slams into the closed valve has to go someplace. So the energy creates a brief, but enormous, spike it the water pressure in the pipes. This spike can easily double or triple the water pressure in your system. The pressure spike occurs so fast that a standard pressure gauge will not even register it. But this increased water pressure doesn’t just hang around the vicinity of the valve. It passes as a shock wave back through the pipe at (almost) the speed of sound in water, seeking a way out. This creates stress on the pipe, and if there is a weak point in the piping the pressure surge will find it. So each time the water hammer occurs it is putting stress on the pipe, which weakens the pipe. If you hear the noise in your house, then the pipe in the house is being damaged, even if the source of the surge is someplace else. It shock wave travels through the water in the pipe. So what kind of damage does it do? Consider a standard rubber balloon. You blow up the balloon then let the air out. You do this again and again. Each time the balloon gets stretched a little more and weakens. After being blown up many times the balloon simply bursts. You didn’t blow any more air into it than before, it just was weakened by the constant expanding and contracting. The pipes in your home and irrigation system stress in a similar manner when exposed to these pressure spikes. Where is the most likely weak spot where it will break? In my experience the first pipe to go is in the house, not the sprinkler system. It is often the tube connecting a toilet or sink to the household water system, which is usually a hose or thin wall pipe. The result is a flooded bathroom. If you made an error in installing the irrigation system and forgot a clamp or didn’t get a good strong glue joint you may see a leak there. A small pinhole leak in plastic irrigation pipe or hose very quickly enlarges to the diameter of a pencil. Points where the pipe changes direction also take a beating as the pressure surge wants to continue in a straight line rather than go around the bend. There is one last frustrating problem with water hammer, which is that the sound you hear often appears to be coming from someplace other than the point where the water hammer was created. This is because sound travels very well through the pipe and the water in it. So you can’t rely on your ears to find the source of the water hammer.

Water hammer is influenced by three variables, understanding these variables will help you find the source of your water hammer problem.

The first variable is the length of the pipe the water is traveling through. We can’t do much about the length of your pipes, assuming that you can’t move your house closer to the water source. But it is an important factor in creating water hammer, so it is useful to take a look at it, especially as it relates to the pipe size. For example, in some situations you can force a high rate of flow through a small pipe without problems, provided the length of the pipe is short, say, a few feet. The shorter the pipe, the smaller it can be. Knowing this will help you when you try to identify the source of the water hammer. So keep in mind that a small pipe may not be a problem if it is a very short length.

The second variable is time, or specifically how fast the water is being stopped. When a closing valve is causing water hammer, time is how long it takes for the valve to close. Most irrigation valves take several seconds to close. Theoretically this would not cause a problem, as several seconds is very slow when dealing with water hammer. The problem is that 80/20 ratio I mentioned previously. The valve may take a few seconds to go from full open to full closed, but it has a tendency to snap closed when it gets down to that last 20%. Realistically the actual closing time of a typical irrigation solenoid valve is around 1/2 to 1 second as best I can tell. But it varies greatly, even when testing the same valve. For example, an irrigation valve closes much faster if there is higher water pressure present. It also closes faster as you increase the flow through the valve (increasing the flow creates a greater pressure differential across the valve, which causes it to close faster.) So a valve that would not cause a water hammer problem at a low flow and low pressure, will cause all kinds of problems if you increase the flow through the valve and/or the water pressure.

The third factor that influences water hammer is the velocity of the water. The faster the water is traveling in the pipe, the greater the water hammer. It is this last factor which is easiest for us to correct in a sprinkler system, so most of the suggested solutions for water hammer will be aimed at reducing the water velocity.

Be aware that there are many “quick fix” devices that are supposed to fix water hammer problems for you. My experience has been that air vents, air traps, and water hammer arresters seldom work with automatic irrigation systems. Irrigation systems, particularly sprinkler systems, tend to have much more severe water hammer problems than that found in household plumbing. These devices are made to stop water hammer that is caused by household uses and they will often cure the problem in those cases. But I have never seen one fix water hammer caused by an automatic sprinkler system.

Now you need to do some detective work. Take the time to do some research. Listen for the water hammer noise. What’s happening when, and especially just prior to, the time when the sound occurs? Water hammer is set off by something, it doesn’t just occur randomly. Chances are a irrigation valve closes when the sound occurs. Closing irrigation valves are the source most of the time. Another frequent cause is the fill valve on a dishwasher or washing machine closing. Once you know what happens, you can focus in on it as the potential source of the problem.

Solutions for Water Hammer Caused by Washing Machines and Dishwashers:

If the noise occurs when a washing machine or dishwasher valve closes the problem is that the appliance is demanding more water than one or more of the pipes supplying to it can safely handle. We’ll try the cheapest solution first.

• This is the cheapest solution but not really the best. I would only use it as a temporary fix. Try partially closing the shut-off valve for the appliance. Start by closing it half way. If that doesn’t get rid of the noise close it a little more, keep repeating until the noise stops. Closing the valve reduces the flow to the appliance, and thus reduces the velocity in the pipes. Unfortunately many dishwashers and washing machines use a fill timer rather than actually measuring if the washer is full. Sometimes when you close the valve partially the washer doesn’t get enough water and the clothes or dishes don’t get clean. So check to see if closing the valve is creating cleaning problems. If it is, reopen the valve a little and try again.
• There should be a short tube that leads from the shutoff valve to a appliance. Often this tube is a piece of 1/2″ hose or a 3/8″ copper tube. This tube should not be more than three or four feet long, if it is longer the tube may be part of the problem, so try replacing it with a larger tube.
• The next trick to try is installing a AA-size water hammer arrester on the pipe at the shut-off valve. While these devices are seldom useful for irrigation systems, they often do work with appliances because the water demand is not nearly as high as a sprinkler system. You can get a water hammer arrester at just about any plumbing supply store. At your local hardware or home store look for a pre-packaged water hammer arrestor that attaches to a standard washing machine cold water outlet. The ones I have seen come in one of those clear plastic display packages, and look like a copper tube with hose connections. Check the return policy of the store before you buy it, will they take it back if it doesn’t work? Make sure you keep all the packaging. Install it per the directions on the package. If you are installing it on a dishwasher fill, you will probably need some adapters to make it fit. If it doesn’t work, remove it and return it.
• Air chambers are pretty much worthless, none of the building codes recognize them any more for water hammer control. An air chamber is just a long section of vertical tube with a cap on the top of it. The idea is that air is trapped in the tube and absorbs the water hammer shock. They may work for a while, but they become water-logged with time. They also need to be huge, generally at least 3/4″ size and several feet long.. So if someone suggests one, I recommend not wasting your time and money.
• The last option is to tear out the walls or floors and install a new, larger pipe to the appliance. Before you do that run a test. Get a 3/4″ heavy duty garden hose. It will cost a lot, but at least you can reuse it in the garden. Hook up one end to the flush outlet on your water heater, and connect your appliance to the other end. Then run the appliance, the water hammer should be gone. If the water hammer is still there, then the pipe in the wall is not the problem.

Typical dishwasher shut-off valve under a kitchen sink.
The silver tube looped around the valve is the water supply to the dishwasher.
Gray is the dishwasher power cord. White pipe is the dishwasher drain pipe.

Solutions for Water Hammer Caused by Irrigation Systems:

The easiest solution is to lower the water pressure for your entire irrigation system. This doesn’t really get rid of all of the water hammer, but it will sometimes reduce it to a level you can live with. Of course often when you lower the pressure enough to stop the water hammer the sprinkler system stops working too. Lowering the pressure has two effects. It lowers the water demand of the sprinklers, which in turn reduces the velocity in the pipes. That actually reduces the water hammer. Lowering the pressure also reduces the overall surge pressure when the water hammer occurs. That simply reduces the severity of the water hammer, but doesn’t get rid of it. To test if this will eliminate the noise, simply go to the main shutoff valve for the sprinkler system. (If your sprinkler system doesn’t have a shut-off you will need to install one.) Close it down until it is about 50% closed. Now run the sprinkler system. If the water hammer is still there, close the valve a little more and repeat. Continue this until the water hammer goes away. When the water hammer is gone, check your sprinklers. Are they still operating correctly? If they are operating correctly the water from any single sprinkler should be spraying almost all the way to the adjacent sprinkler head (you need about 80% overlap of the water between sprinklers to keep from getting dry spots.) So if the sprinklers are 18 feet apart the water from each one should be covering an area at least 14.4 feet out from the sprinkler (18 x 0.80 = 14.4). If the water is not going far enough you will get dry spots, so this solution will not work. If the sprinklers seem to be still working good leave the valve partially closed for a few days. Do any other problems shown up? Like the showers don’t work in the house or dry spots show up in the lawn? If not you should go to the plumbing store and buy a good quality, brass bodied, adjustable pressure reducing valve. Install it right after the shut-off valve that you partially closed. Then open the shut-off valve fully and adjust the pressure reducing valve until the pressure is at a level where the sprinklers work right but the water hammer isn’t a problem. You should not leave the shut-off valve partially closed for more than a couple of weeks. Most of those valves are not designed to be left permanently in a partially closed position. Also the pressure reducing valve is designed to compensate for changes in the incoming water pressure to your house. The shut-off valve can’t do that. If only one valve zone of the sprinkler system creates water hammer you can try partially closing the flow control stem on the irrigation control valve. If that works, the flow control may be left in a partially closed position permanently, it will not harm the valve.

If you have an automatic sprinkler system you may be able to get rid of the water hammer by simply changing the order in which the valves operate. Simply find out which valve uses the least water. This will probably be the one with the least sprinklers, but not always. Some sprinklers use more water than others. Once you know which valve uses the least water, rewire the controller so that the valve that uses the least water is the last valve to run. If you don’t know which one uses the least water just try all of them in the last position. Since water hammer is directly related to flow, the valve that uses the least water is much less likely to cause water hammer when it closes. The reason putting this low flow valve last works is because most irrigation valves close slowly. So typically valve #4 will not have completely closed when the next valve, #5, opens. So when valve 4 snaps closed it creates a shock wave (water hammer), but the wave passes harmlessly out of the system through valve circuit #5. Don’t worry if you didn’t understand how that works, just try switching the valve order on the controller and see if it gets rid of the water hammer problem! (My thanks to Larry Welch for pointing this trick out to me!)

The next step is to try a water hammer arrestor. As noted before, this often doesn’t work with sprinkler related water hammer, but it’s worth a try. At your local hardware or home store look for a pre-packaged water hammer arrestor that attaches to a standard washing machine cold water outlet. The ones I have seen come in one of those clear plastic display packages, and look like a copper tube with hose connections. Check the return policy of the store before you buy it, will they take it back if it doesn’t work? Make sure you keep all the packaging. Install it per the directions on the package, try putting it on a hose bib close to the point where the irrigation system connects to the house water. If you have a hose bib on the irrigation system mainline, that is an even better place. Or you can tap into the irrigation mainline to install it. If it doesn’t work, remove it and return it.

If the noises were caused by an irrigation valve, then it is likely that someplace between the water source and that valve the water velocity is too high. Too much water is trying to squeeze itself through the pipe. To get through the pipe the water moves faster (higher velocity) and the faster it goes, the worse the water hammer gets. You have to reduce the speed of that water to get rid of the water hammer. Here are some ways to do that.

The irrigation valve may be too small. This is seldom the problem, but I mention it because it is possible. If the valve is the same size as the pipe it is installed on (say, 1″ pipe with a 1″ valve) then it is extremely unlikely that the valve size is the problem. If the valve is one size smaller than the pipe (say, 1″ pipe with a 3/4″ valve) then there is a very small chance that the valve is the problem. It is normal to use a valve one size smaller than the pipe, so this is still is not very likely a problem. If the valve is a couple of sizes smaller than the pipe then there is a reasonable possibility that a larger valve will fix the problem. Also, cheaper valves often snap closed faster than more expensive ones. So a cheap undersized valve might be a good possibility as the water hammer source. It might be worth the effort of replacing the valve.

This next option was once a good one, but now it seldom works because very few of these old sprinklers are still around. Really old sprinkler systems (15 years or more) used sprinklers heads that had a much higher water demand than today’s sprinklers. Typically these sprinklers were made of solid brass. Thanks to engineering advances newer sprinklers have similar performance but use much less water. You could try replacing the old sprinklers with the new, low-flow sprinklers. Start by doing some research. Note the sprinkler manufacturer’s name and the sprinkler model number of the existing sprinklers and do a search for that name and number on the Internet. If the sprinkler is no longer made that’s a good sign. If you can find it check with the manufacturer to find out what the GPM of the sprinkler is. GPM is the gallons per minute of water the sprinkler uses. Next check how far apart the sprinklers are installed from each other. Take that number and multiply it by 0.80. So if the sprinklers are 18 feet apart you will get 18 x 0.80 =14.4 Round up, so use 15. The replacement sprinkler will need to have a radius equal to that number, so in this case it will need a 15 foot radius (not diameter). Go to the store and look for sprinklers that cover that radius. Then check the GPM demand of the new sprinklers. If they use less water than your current sprinklers you can replace the old sprinklers with new ones. It may get rid of the water hammer. It may not. But even if it doesn’t work you get a better irrigation system. Note that if you are using pop-up sprinklers always use the ones with retraction springs. I recommend at least a 3″ pop-up height to reduce maintenance problems.

Splitting valve zones is another method of getting rid of water hammer. If only one of the irrigation valves is causing water hammer the easiest solution is to reduce the amount of water that valve is using. That will reduce the velocity and the water hammer will stop. To do that you need to reduce the number of sprinkler heads the valve operates. The easiest way to do that is usually to install a second valve and connect half the sprinklers to it. That’s likely going to mean doing some trenching and installing some new pipe. So before you do that, you should run a simple test to make sure it will fix the problem. Remove half the sprinklers controlled by the valve and put a cap on the pipes where they were. Now turn on and off the valve several times to test for water hammer. If possible test the valve multiple times at different times of the day over a period of a week. If the water hammer only occurred at certain times of the day be sure to test at those times. For example, often water hammer problems are much worse at night, so it’s a good idea to test a couple of times late at night. If the water hammer is gone, it worked! If the water hammer is still there you may need to remove even more sprinklers. If you remove all the sprinklers and the water hammer is still there, that valve is obviously not the problem! If the water hammer goes away when you reduce the number of sprinklers, then you will need to install a second valve and pipe to provide water to the sprinkler heads that were removed. Make sure the second valve has the same number or less sprinkler heads as the original one. You don’t want to create another water hammer problem! You may even have to install 3 valve circuits where there was one originally.

If the water hammer occurs when several valves close you can split each of them into two or more valves as described above. But you may find that it is easier to install a new, larger pipe to all of the valves. Remember, when water hammer occurs due to a closing valve it is because the water is going too fast in a pipe someplace on the upstream side of the valves. In order to understand this next procedure you need to be familiar with the relationship between your house plumbing and your sprinkler system and you need to know some terminology.

• Your water comes to your neighborhood in large “water mains” (pipes), usually located in the street, that supply the entire neighborhood with water. These pipes are owned by the water provider.
• From the water main a smaller pipe known as a “gooseneck” carries the water to your property line. This is also owned by the water provider.
• Often there is a buried valve known as a “corporation stop” at the point where the gooseneck reaches your property. There may also me a water meter right after the corporation stop. In northern climates the water meter and maybe even the corporation stop will be installed within the house (usually in the basement) to protect it from freezing. The corporation stop marks the end of the water company’s pipe and the start of your private household pipe.
• The pipe from the corporation stop to the faucets in your house is the “house water supply pipe“. This is usually a single pipe that branches off to all the faucets when it gets inside the house.
• The pipe running from the house water supply pipe to the irrigation system valves is called the “irrigation mainline“. The irrigation mainline connects to the house water supply pipe at some point. Where is anyone’s guess, I’ve seen just about every possibility over the years. There should be a shut-off valve at the point the irrigation system connects to the house water supply. Should be… but often there isn’t. If there isn’t you should consider adding one.

So now it’s time for more detective work. (In this case detective work also means “hard work”.) You need to check all the pipes the water passes through on the way from the water main to the valves to see if there is a “bottleneck”– a section of pipe that is smaller than the others. You will need to check all of the pipes previously mentioned; the gooseneck, the house water supply pipe and the irrigation mainline. You only need to check the pipes in a direct line between the water provider’s water main and the source of the water hammer (most likely the irrigation valves.) To understand this think of all the pipes as if they were roads. Imagine you want to “drive” from the water main to the irrigation valve and you want to take the most direct route. The water also will take the most direct route. So the pipes you want to check are those on that direct route. Don’t worry about any pipes that branch off to elsewhere. The water won’t take any side trips to see the local sights. Like I said, this is going to take some detective work to figure out which pipes the water is going through and where they are! This may require digging a lot of small “test holes” to find buried pipes and determine what size they are. If you are lucky, you will find a section of pipe that is smaller than the others. This is likely the source of the problem, replace it with a bigger pipe. Remember, any of the pipes may be the one that is too small. It could be the gooseneck, the house water supply pipe, or the irrigation mainline.

Here’s a quick tip: if the irrigation mainline hooks up to the location of a former hose-bib on the side of the house, the pipe leading to the hose-bib is almost always the problem. Typically when the house is built, the plumber just runs a 1/2″ pipe to hose-bibs to save money. A 1/2″ pipe is big enough for a hose to water the Petunias, but not big enough to supply a sprinkler system! . Unfortunately many do-it-yourself sprinkler installers do not know this, and some of those stupid “design your own sprinkler system” brochures you get at the hardware store even show people using a hose bib to connect the sprinkler system to. A lot of sprinkler system repair guys have gotten rich thanks to those stupid brochures! Stupid, stupid brochures! OK, I need to calm down and get back on track.

There are numerous materials that pipe is made from. The most common are copper, steel, galvanized steel, PVC, polyethylene, and a new product called PEX.

• PVC is usually white (sometimes gray) colored plastic.
• Polyethylene (also Polybutylene) is normally black. Polyethylene, often called “poly” or “PE”, is more soft and flexible than PVC, and has a slightly “oily” feel. You can scratch poly with a fingernail, but not PVC (unless you’re using that “tough nails” stuff on them, in which case you can use them to rip out concrete.)
• Copper is copper colored when new but often turns green if exposed to the weather.
• Steel looks like, um…, steel. You know what steel looks like, right? A magnet sticks to steel but not copper.
• PEX is a type of polyethylene, it is flexible like the Polyethylene, but much stronger. It will normally say “PEX” on it, and be a color other than black. Often it is white or blue. and may look a lot like PVC, especially if it is old and dirty! In the absence of the words PEX on the tube, check the diameter of the tube. PEX is typically made to have the same outside diameter as copper tube. Another way to tell is to look for the fittings that connect plastic (non-threaded) pieces together. PVC pipe will be glued together, PEX tube will use barbs with clamps, or compression fittings. If still in doubt, go to a plumbing supply store and check out actual samples to compare with what you have.

To determine the size of the pipe, grab a piece of string about 6″(152mm) long. Strip away any insulation on the pipe, so you can get at the pipe and wrap the string around it. Measure how many inches of string it takes to go around the pipe once. The string length is the circumference of the pipe (yikes, bad memories of high school geometry!). Using the circumference we can calculate the diameter of the pipe, which allows us to calculate the pipe size, zzzzzzzzzz….. Let’s forget all those calculations! Based on the string length use the table below to find your pipe size.

For Copper and PEX Tube & Pipe
2.75″ (70mm) = 3/4″ pipe
3.53″ (90mm) = 1″ pipe
4.32″ (110mm) = 1¼” pipe
5.10″ (130mm) = 1½” pipe

For Steel Pipe or PVC Plastic Pipe
3.25″ (83mm) = 3/4″ pipe
4.00″(102mm) = 1″ pipe
5.00″(127mm) = 1¼” pipe
6.00″(152mm) = 1½” pipe

For Flexible Polyethylene Pipe
2.96-3.33″ (75-85mm) = 3/4″ pipe
3.74-4.24″ (95-108mm) = 1″ pipe
4.90-5.57″ (124-141mm) = 1¼” pipe
5.70-6.28″ (145-160mm) = 1½” pipe

So what if you didn’t find a pipe that was smaller than the others? In this case all of the pipe may be restricting the flow. To fix it you may need to replace all of the pipe. But I would suggest that you start with the pipe that would be easiest to replace. After you replace it test for water hammer. If it is gone, great! If not, go to the next section of pipe. Chances are you can’t replace the gooseneck, since it does not belong to you. Fortunately it is often a short length running just from the water main out in the street to your property line. If it is very short like this the water hammer may well go away or be greatly reduced without replacing it.

There are two ways to fix the small pipe problem.

1. One way is to remove the small pipe and install a larger one in it’s place. If you replace the existing pipe I suggest that the new pipe be two sizes larger than the old one, just to be safe. Using a pipe two sizes larger will not harm anything and it will not reduce your water pressure. See the discussion of pipe sizes at the bottom of this page.
2. The other way to reduce the velocity in the small pipe is to simply install a second pipe next to it and run the water through both pipes. Using this second method results in half the water going through each pipe, so the velocity in both of them is much lower. This is usually cheaper to do than replacing the pipe. The second pipe should be equal in size or larger than the original pipe. Tap the new pipe in as close as you can to the ends of the existing small pipe. This will leave you with a short section of small pipe on either end, which will cause some flow restriction. However it probably will not be enough to cause water hammer. The restriction caused by this short section of small pipe would be similar to that found when the water passes through a standard valve, which also restricts the flow.

Now one last thing. Since we are essentially guessing that the small pipe is the source of the problem, I can’t promise you that replacing it will get rid of the water hammer. Unfortunately there is not an easy way to test this method without actually installing the new or second pipe. If the pipe you are thinking of replacing is buried, before going to a lot of work digging up pipes, try a test installation with the new pipe on top of the ground. Then test for water hammer. If that fixes the problem, then you can dig a trench and put the new pipe in the trench.

For reference, here are the common pipe sizes available in the USA: 1/2″, 3/4″, 1″, 1 1/4″, 1 1/2″, 2″.

Impact of changing to a Larger Pipe Size:

Did someone tell you that using a larger pipe will reduce your water pressure or make things “not work right”? One of my (many) pet peeves is that a lot of people in the industry will tell you that you need smaller pipes because “the smaller pipe squeezes the water and creates more pressure”. No, no, no! It doesn’t work that way! Using a larger pipe size will not reduce the water pressure or hurt your irrigation system or your house water system. There is a common misconception out there that if you use a bigger pipe the water pressure will be reduced and the sprinklers and your washing machine will stop working. This is not true and I am on a personal campaign to kill this ugly myth!. So please forgive me for ranting a little. It is a lie! An old sprinkler installer’s tale. Anyone who tells you this doesn’t know what he or she is talking about. Now every time I write this I get flamed by someone in the industry who doesn’t agree. Instead of flaming me, I challenge you to simply prove me wrong! Do a little research. Look up the Bernoulli principle and you will see that it says that if flow is constant the water pressure decreases as the pipe gets smaller. You can even try it yourself using a fun, online interactive toy built by physicist Mark Mitchell located here. (Warning this page loads slow and requires JavaScript. But it is worth the wait!) The bottom line is that you can’t “squeeze” more pressure out by using a smaller pipe. Let’s face facts, misunderstanding this is probably the problem that got the small pipe there in the first place. So you already have problems because someone bought into that lie, don’t repeat the error! It’s so important I’m going to repeat it. You can’t hurt your system by using a larger pipe. But if the new pipe isn’t big enough, you will still have water hammer and that will hurt your system. Remember, this is a very common myth. I have even heard from readers who tell me that the tech support people at a major sprinkler manufacturer have been spouting this little untruth. I sure hope that it wasn’t true. If you talk to someone at a tech support line and they tell you this myth, please ask them nicely to check their facts. They need to stop spreading these false theories or more people are going to wind up with water hammer problems. Now with all that said, there is a rare reason for using a smaller pipe. I wouldn’t mention it but some other expert will call me on it if I don’t. Sometimes the water is going through the pipe so slowly that silt and other stuff in the water settles out and slowly plugs the pipe. The higher velocity in a smaller pipe keeps stuff from settling out. But this is a very, very, very unusual situation. If you are having water hammer problems there is almost zero chance of this being an issue for you. Your problem is high velocity, not low velocity.

Don’t forget about spring “start up” procedures!

The Basics

Winterizing your irrigation system is really pretty simple:

1. Turn off the water to the irrigation system at main valve.
2. Set the automatic irrigation controller to the “rain” setting.
3. Turn on each of the valves to release pressure in the pipes.
4. Drain all of the water out of any irrigation components that might freeze.

Be sure to check out the glossary if you find a term you don’t understand!

Well, you could probably figure out those basic steps without my help! What you want is details, so let’s get to it. Depending on where your irrigation system is located you need to take different approaches to winterization.

Select your location:
Temperate Climates
Cold Climates

Temperate Climates

These are areas where it doesn’t freeze or a typical freeze lasts for only a few hours. If it snows the snow melts in an hour or so. Ice may form at night but quickly melts in the morning. If you have hose bibs or water pipes on the outside of your house chances are they are not wrapped in insulation to keep them from freezing (because they don’t need to be!).

Ahh, the joys of Southern California living! Here we consider anything below 60 degrees (F) much too cold and we pull out the parkas and throw a log on the fire! Well, OK, I live in the southern fringe of Central California, but I’m only about 2 blocks from the ocean so it almost never freezes here. However, throughout most of Southern California, like other temperate regions, we can get hard freezes during the early morning hours. Any freeze can cause damage to an irrigation system, so precautions need to be taken.

Here’s the procedure for all temperate climate areas:

1. Shut off the water supply to the irrigation system. The main shut off valve for your irrigation system needs to be “freeze proof”. That means it should be below the frost line, inside a heated room, wrapped with insulation, or somehow protected from freezing. It doesn’t do much good if the shut-off valve freezes and breaks! So what happens if you don’t have a main shut-off valve for your irrigation system? Then you’ll need to install one! (duh!)
   
2. If you have an automatic system then you will need to “shut down” the controller (timer) also. Most controllers have a “rain mode” which simply shuts off the signals to the valves. The controller continues to keep time, the programming information (start times, valve run times, etc,) isn’t lost, and the clock continues to run, all that changes is that the valves don’t come on. An alternative to using the rain mode is simply to shut off the power to the controller. If you do, you’ll need to reprogram the time, and maybe all your other settings too, in the spring! How much electricity is saved by turning it off? That depends. Solid state controllers use very little energy-about the same as a night light. Mechanical controllers use more- as much or more than a 100 watt bulb in many cases. My rule of thumb is that if the controller has a digital time display you should use the rain setting on the controller. If the controller uses a dial, like a analog clock face, turn off the power to the controller to save electricity. If a pump is wired to your controller you should disconnect the power to the controller rather than using the rain shut down feature. There is a remote possibility that the controller could damage the pump by accidentally starting it while the system is shut down.
   
3. In temperate areas it is not necessary to remove the water from the underground pipes since it doesn’t freeze that deep. Hooray!
   
4. If you have gear-drive rotor sprinklers installed above ground the water needs to be drained out of them or they may freeze and rupture. Often the water will drain out on its own. If the water doesn’t drain out you will need to install a drain valve somewhere on the sprinkler supply pipe so you can drain the water out. A 1/2″ valve will work fine. Another option is to remove the rotors and shake the water out of them, then replace them (or store them inside for the winter). Many rotors have a built in check valve that prevents the water from draining out, so you have to remove them and shake the water out. So if you have any gear-drive rotors mounted above ground be sure to check to make sure the water has drained out of them.
   
5. Any above ground piping needs to be insulated. You can buy self sticking foam insulating tape to wrap around the pipe which works fine. You can also install the foam insulating tubes commonly sold at home supply stores on them. (Buy a couple of extra lengths of foam for the kids, they love to use them for “sword” fights. Also, if you have a low doorway the foam tubes make great bumpers to keep you from getting your brains knocked out when you forget to duck on your way out the door!)
   
6. Insulate backflow preventers and valves (or remove and store them) if they are above ground. You can also use insulation tape for this. Do not block the air vents and drain outlets on backflow preventers! A cheap trick is to get some R-11 fiberglass insulation and wrap it around the valve or backflow preventer. (Crumpled up newspaper will also work for emergency insulation!) Then place a heavy duty plastic trash bag over the whole thing to keep it dry and use duct tape to hold it all in place. (For a more permanent installation you may want to use heavier plastic than a trash bag!) Don’t seal the bag tightly, allow for an air passage at the bottom so water can run out and air can flow in! Just wrap it tight enough to keep the bag and insulation from blowing off. Insulation will not work if it gets wet! You can also buy ready-made insulation blankets for your valves and backflow preventers at most sprinkler supply stores. (You may need to special order them.) These consist of a large bag made from fiberglass filler sandwiched between soft vinyl cloth, much like a sleeping bag. This insulated bag goes over the backflow preventer and ties or padlocks in place. One brand that I have used is “Polar Parka”. They get a free plug because they sent me a small sample insulation bag, about the size of a bed pillow! I carry it in my truck where I use it as an emergency pillow, a hand warmer, or a great place to put six-packs of soda to keep them cold during the summer!
   

The nice thing about all the above items is that you can do them once, then you never have to worry about it again. The insulation can stay in place all year long and you don’t ever need to worry about winterizing again. (Which isn’t to say that you should neglect your irrigation system. You should still do pre-season maintenance each year in early spring! See the section on Spring start-up procedures.) After all, isn’t that why you choose to live in a nice, temperate climate location?

Cold Climates

Chances are if you live in one of these climates I don’t need to provide a definition of “how cold is cold” for you! If you ever need to shovel snow, or if ice forms and doesn’t melt for days on end, then you are in an area where you need to take some major measures to protect your irrigation system from freezing.

Here’s what you need to do if you live in a cold climate area.

1. Shut off the water supply to the irrigation system. The main shut off valve for your irrigation system needs to be “freeze proof”. That means it should be below the frost line, inside a heated room, wrapped with insulation, or somehow protected from freezing. It doesn’t do much good if the shut-off valve freezes and breaks! What if you don’t have a main shut-off valve for your irrigation system? Then you’ll need to install one! (duh!)
   
2. If you have an automatic system then you will need to “shut down” the controller (timer) also. Most controllers have a “rain mode” which simply shuts off the signals to the valves. The controller continues to keep time, the programming information (start times, valve run times, etc,) isn’t lost, and the clock continues to run, all that changes is that the valves don’t come on. An alternative to using the rain mode is simply to shut off the power to the controller. If you do, you’ll need to reprogram the time, and maybe all your other settings too, in the spring! How much electricity is saved by turning it off? That depends. Solid state controllers use very little energy-about the same as a night light. Mechanical controllers use more- as much or more than a 100 watt bulb in many cases. My rule of thumb is that if the controller has a digital time display you should use the rain setting on the controller. If the controller uses a dial, like a analog clock face, turn off the power to the controller to save electricity. If a pump is wired to your controller you should disconnect the power to the controller rather than using the rain shut down feature. There is a remote possibility that the controller could damage the pump by accidentally starting it while the system is shut down.
   
3. Remove the backflow preventer, remove water from the risers, and cap the risers. (If you are lucky you can siphon the water out of the risers. More likely you will need to pump it out. I’ve found a wet/dry shop vacuum works fine with a few modifications. The hose on the vacuum is usually to large to work, you will probably need to rig a smaller hose onto it using duct tape.) Drain the water out of the backflow preventer and put it in storage for the winter. (You can reinstall it after the water’s drained out if you want to, but I prefer to store it out of harm’s way.) If you have valves installed above ground you need to drain the water out of them, it’s a good idea to remove and store them also. An alternate method is to install pipe heating cables on the above ground valves and backflow preventer then install insulation over the heater cables. Of course you’ll have to pay for electricity to run the heaters all winter, and if the electrical power goes off for an extended period… crack!
   
4. While we’re on the subject of backflow preventers, your backflow preventer, along with any above ground pipe, should have permanent insulation installed on it. This is to protect it from those unexpected early and late season freezes! Those freezes are generally light, so insulation will give you the protection you need. Backflow preventers are very expensive to replace. A few years back an unexpected freeze resulted in so many broken backflow preventers that for a short period it was impossible to buy one due to lack of availability! One way to insulate the pipes and backflow preventer is to use the self-stick foam insulation tape which is available at most hardware and home supply stores. Do not block the air vents and drain outlets on backflow preventers! A cheap trick is to get some R-11 fiberglass insulation and wrap it around the valve or backflow preventer. (Crumpled up newspaper will also work for emergency insulation!) Then place a heavy duty plastic trash bag over the whole thing to keep it dry and use duct tape to hold it all in place. (For a more permanent installation you may want to use heavier plastic than a trash bag!) Don’t seal the bag tightly, allow for an air passage at the bottom so water can run out and air can flow in! Just wrap it tight enough to keep the bag and insulation from blowing off. Insulation will not work if it gets wet! You can also buy ready-made insulation blankets for your valves and backflow preventers at most sprinkler supply stores. (You may need to special order them.) These consist of a large bag made from fiberglass filler sandwiched between soft vinyl cloth, much like a sleeping bag. This insulated bag goes over the backflow preventer and ties or padlocks in place. One brand that I have used is “Polar Parka”. They get a free plug because they sent me a small sample insulation bag, about the size of a bed pillow! I carry it in my truck where I use it as an emergency pillow, a hand warmer, or a great place to put six-packs of soda to keep them cold during the summer!
   
5. Now you need to remove the water from the pipes and sprinklers so that it won’t freeze and break the pipe. There are two ways to do this, drain the water out through drain valves, blow it out using air, you can even suck it out sometimes with a shop vacuum (that’s a lot of work though, you’ll have to empty the shop vac over, and over, and over…!). Blowing out the system is the best method to use. I will detail how to do both blow the system and/or drain it, but I want to stress that blowing out the water is not a project I would recommend attempting for the average homeowner. I recommend that you hire a professional to do it for you. If you don’t want to pay someone to blow the water out, then install drain valves and use the drain valve method below!
   
   Drain Valves:
   • In order to properly drain out your irrigation pipes you need to have drain valves installed at the appropriate locations. This means you will need at least one drain valve upstream of the valves, and one drain valve downstream of each valve. Note that you can’t legally install a drain valve upstream of the backflow preventer(s). The reason for this is that the drain valve creates a point at which contaminates can enter the pipe, and there is no backflow preventer to keep them out of the drinking water supply. That means if you are using anti-siphon valves or atmospheric vacuum breakers you will not be able to have a drain valve on your mainline! Normally you will want to install the mainline deep enough that it will not freeze. Remember- your mainline between the water source and the backflow preventer must comply with all codes that relate to potable water (a fancy term for drinking water) lines. If you are really lucky you can install the mainline so that it slopes down to the vacuum breakers and will drain itself if you remove them. In some areas you may not even be allowed to drain them out through the open pipe end as there is a small possibility that this could also allow contaminates into the pipe. Drain valves can either be manually operated (you open the valve before the first hard freeze) or they can be automatic.
     
   • Remember three important things. First, you need a drain valve at EACH low point in the piping- despite what you may have seen at the amusement park mystery house, water will not flow uphill! Second, if there is not a sprinkler at the high points in the piping you will also need a valve at the high point to let in air. The water won’t flow out unless air can get in! The final thing to remember is that if you use manual drain valves you’re going to need to get to the valve to open it- and it’s probably going to be cold and miserable on the day you decide the irrigation system needs to be winterized! So put the valves in a nice, big, easily accessible box and write down the locations of all the valves so you know where to look for them. When it’s snowing outside you don’t want to have to go hunting for the drain valves! You need about 1/4″ per foot of slope to drain the pipes efficiently. If you work it right you will only need a single drain valve for each lateral. Most installers will try to install the pipe so that the lowest point in the circuit is just after the remote control valve. From there the pipe slopes up to the sprinkler heads. That way you can install the drain valve at the same location as the control valve, and they will both be easy to locate and winterize. Then you install a large valve box over both the control and drain valve. It’s also a good idea to dig a 12″ diameter pit, 24″ deep under each drain valve and fill it with gravel. Then when you release that extremely cold water out of the pipes it has somewhere to go besides up your shirt sleeves and pant legs!
     
   • Automatic drain valves. Automatic drain valves open by themselves each time the pressure drops in the pipe. So at the end of each irrigation cycle the automatic drain valves will open and the water left in the pipes will drain out. Sounds good, right? Well it is and it isn’t. The problem is that automatic drain valves tend to stick closed if they don’t have a chance to open regularly. So if you use one upstream of a valve (on the mainline) it will stay closed during the entire irrigation season (because you keep the mainline pressurized all the time) and will likely stick closed when you turn off the water at the end of the season! Thus, even if you choose to use automatic drain valves you should still install manual drain valves on the mainlines. Downstream of the valves on the lateral pipes sticking isn’t a big problem because the automatic drain valves get a chance to open after each irrigation cycle when the pressure drops. But that also means that all the water drains out of the pipes at the end of each irrigation cycle, every time you run the sprinklers, all season long! I don’t like that, because it creates two problems. The first is that it wastes water. The second is that refilling with water after each irrigation is tough on the piping. Have you noticed spewing, spitting, and banging noises when air comes out of the sprinklers? That’s the water slamming into each of the ells and tees in the piping as it fills the pipe! And that is NOT good for the pipe or the sprinklers. A few times a year is one thing, but every time you run the sprinklers…? So I recommend manual drain valves for most people. Now, are you the forgetful type or a procrastinator of the worst kind? Yeah, you know who you are! In that case use the automatic drains. The wear and tear caused by the automatic drain valves is less expensive than replacing pipes that broke in a freeze.
     
   • The water will not drain completely out of the valves. You will need to either completely disassemble and dry out the valves or remove them and store them inside. I suggest removing and storing them and disassembling them can get you into big trouble if you don’t know exactly what you’re doing. Removing them can be pretty easy if you install unions or other specialized devices on them that make them easier to remove. Ask a sprinkler supplier about these or look in the installation tutorial. Don’t forget to cap the pipe ends where they connected to the valves after you remove the valves to keep garbage and critters out of the empty pipes!
     
   • Some sprinkler heads must also be drained out because water becomes trapped in them. This is common among sprinklers with built-in check valves, such as many better quality pop-up rotors have. Also heads installed using the inlets on the side of the sprinkler body (called side inlets) will not drain by themselves. I don’t recommend using side inlets when installing sprinklers as they cause a number of maintenance problems, this being just one. If you’re not sure if you have this type of sprinkler, remove the cap from one of them and see if there is water trapped down in the sprinkler body. If so you need to get the water out of there, which may mean removing the sprinkler and shaking it out! Or try vacuuming it out with a wet/dry shop vac. For sprinklers with side inlets you can install an automatic drain valve in the bottom inlet of each one so they will drain by themselves, but this gets pretty expensive. Since draining out these types of sprinklers is a lot of work you would probably be better off just paying a professional to winterize your system for you by blowing it out as described below.
     
     
   
   
   The Blow-Out method:
   • This is not a method I recommend for amateurs! It is not a project for the average “do-it-yourselfer”. Almost all big sprinkler systems such as golf courses and parks are winterized using compressed air. But one tiny little mistake– and you will no longer own a sprinkler system. You will now be the proud owner of a bunch of buried plastic shards! So I recommend leaving this method to the professionals. If you try it and one of your sprinklers is launched like a bottle rocket, don’t come crying to me!
     
   • In order to blow the water out of the pipes you will need an air compressor, and it can’t be just any air compressor! It needs to be a big, BIG air compressor. Probably bigger than that compressor you already own. In other words that high pressure, low volume compressor you use in the shop is not the right compressor to use! (Did I mention this isn’t a project for the average do-it-yourselfer?) How big you ask? For a really small irrigation system (3/4″ PVC pipe or 1″ poly pipe) you will need at least a 20 cubic feet per minute air compressor. And that is so small that it is not going to do a very good job! Most experts recommend nothing smaller than a 50 cubic feet per minute compressor for a home sprinkler system. Professionals often use a large gas or diesel powered compressor that can discharge over 125 cubic feet per minute of air and can blow out a pipe as large as 3″ diameter. For pipes over 4″ they use a 250 cubic feet per minute compressor. Note: SCFM means “Standard Cubic Feet per Minute” and for our purposes here, it’s the same thing as CFM. SCFM is a measure of CFM at a specific temperature and altitude.
     
   • Here’s what you should NEVER use. Do not use an air tank filled with compressed air or gas. Do not attempt to create more air flow by filling an air tank, then attempting to blow out the system with large bursts of air from the tank. Do not try to connect the exhaust pipe of your car (truck, boat, cow) up to the sprinkler system. Do not try to use a leaf blower or a vacuum cleaner with the flow reversed. Forget about using your electric tire pump (most of them have a hard enough time just inflating a tire!).
     
   • Each sprinkler system is different. I strongly suggest renting an air compressor rather than buying one until you have found an air volume that works well for you. Many variables effect the proper selection including local altitude, temperature, and type of pipe. Besides, it’s probably a whole lot cheaper to rent one once a year.
     
   • Start by removing the backflow preventer (for anti-siphon valves remove the whole valve). Hopefully the backflow preventer is installed right after the irrigation shut off valve where your irrigation system taps into the water supply. If it isn’t you’re in trouble. You could install a blow out fitting (usually a tee with a 1″ side outlet, and a short length of pipe with a threaded cap on it) for connecting the compressor up to right after that shut off valve. Unfortunately, in most places you can’t legally install a blow out fitting upstream of the backflow preventer(s). The reason for this rule is to protect against the possibility of some idiot hooking up some piece of equipment to the blow out fitting that would allow a pollutant to get into the pipe. Once in the pipe the polutant could then be sucked into everyone’s water supply (there’s no backflow preventer to stop it upstream of the backflow preventer! OK, sorry, I know you’re not stupid, and I didn’t need to explain that.) Now, come on you say, what’s going to be hooked up to it that would pollute the water? Well, a good example would be an air compressor. (Opps… !) When you blow out that pipe out you are blowing more than air in, you are also blowing compressor oil into the pipe! Yuck. So if you do decide to go ahead and blow out the pipes upstream of the backflow preventer, and your family all come down with a bad case of the trots the next day don’t say I didn’t warn you! (Nothing like a little compressor oil to lubricate the old human plumbing system.) Fortunately, if your irrigation system is installed correctly you shouldn’t need to blow out the mainline upstream of the backflow preventer! Allow me to explain (like you have a choice!). The mainline between the water source and the backflow preventer is supposed to be installed in compliance with all codes that relate to potable water pipes (potable is a fancy term for drinking water). One of the requirements found in most plumbing codes is that potable water lines must be installed below the frost line to keep them from freezing, or some other method must be incorporated in the design to prevent freezing (such as a pipe heater). If your mainline upstream of the backflow preventer isn’t designed not to freeze, see if you can figure out some way to drain the mainline (see the drain valve section above). If that won’t work you may need to reinstall the pipe deeper, or install a pipe heater. Another option is to relocate the backflow preventer so that it is right after the irrigation shut-off valve so there isn’t any mainline upstream of the backflow preventer. For more information on backflow preventer types to use see the backflow preventer page.
     
   • Next, connect the air compressor to the backflow preventer riser (on the downstream side). Do not blow air through the backflow preventer or through a pump, you could damage them! It is important that the air compressor has a pressure regulator valve with an accurate gauge on it. Do not turn on the compressor yet! If you have anti-siphon valves you’ll skip this step (but don’t skip the warnings!).
     
   • Safety first! Plastic pipe is not designed to hold compressed air! Air does not behave the same way as water in a confined space. Weird and unexpected things happen! Put on eye protection and keep everyone away from the sprinkler heads. If the air becomes trapped by a pocket of water in the pipes it can suddenly “burp” free with enough force to explode the sprinkler heads! Always increase the air pressure in the pipes slowly. Never attempt to blast out the water with a sudden burst of air. If you can’t get the water out with a steady flow of air, then you need a higher capacity air compressor.
     
   • Using the automatic controller (timer), turn on the last valve that is furthest from the backflow preventer. Only turn on one valve at a time! If one valve is considerably higher in elevation than the others you may want to start with it rather than the last valve. But in most cases the last valve is the first one you should blow out. If you have manual valves just open the valve manually. If you have anti-siphon valves (which you removed earlier), you will not be able to open the valve (because you removed it?) So instead you will now need to hook the compressor hose up to the downstream side of one of the valve risers.
     
   • Turn on the compressor and slowly increase the pressure. Carefully monitor the air pressure, never allowing the pressure in the irrigation system to exceed 50 PSI! You probably won’t even need 50 PSI to blow out all the water. The lower you can keep the pressure, the better. Watch the temperature also! Air heats up as it is compressed (physics 101). The air can be very hot when it leaves the air compressor, hot enough to melt the plastic sprinkler pipe! It may be necessary to add some extra length of hose between the compressor and the connection to the sprinkler system so the air can cool a bit before entering the sprinkler system piping.
     
   • Allow the air to run until all the water is blown out and only air is exiting through the sprinkler heads. Don’t blow air through the system any longer than necessary. If it takes more than 2-3 minutes for the water to get out, stop the compressor and let everything cool down for a few minutes, then start again. Be patient! Keep watching that pressure and temperature! The first valve will probably take a lot longer to blow out than the others because most of the water in the mainline pipes gets blown out of the first valve zone.
     
   • After only air is coming out of the sprinklers, turn off the air compressor, and then turn off the valve. Open the next valve, turn back on the compressor and repeat the blow-out procedure. Continue until all the valve circuits have been blown out. Note that if you have anti-siphon valves you will need to switch the compressor hose to the next valve riser.
     
   • Never turn off all of the valves while the compressor is still running! A valve must be open at all times. The goal is to blow OUT the sprinklers not blow UP the sprinklers!
     
   • When all the valves have been blown out it is a good idea to repeat the entire process again, starting with the first valve.
     
   • If you have a mainline section upstream of the backflow preventer that you are planning to blow the water out of, nows the time. Hook up the compressor to the blow out fitting just downstream from the irrigation system shut-off valve and blow the water out through the backflow preventer riser. Set out the Pepto-Bismol where the family can get to it easily!
     
   • Put the automatic controller into “rain mode” when you’re finished blowing the system out. (Or you can turn it off if you wish.) Install threaded caps over the open ends of the backflow preventer risers, anti-siphon valve risers, and any blow out fittings to keep garbage and critters out until spring. Store the backflow preventer inside for the winter.

Spring start up procedures.

This is just as important as winterization, but nobody ever asks me about it! When you first turn on your sprinkler or drip system in spring you should always flush it out. During the winter many small critters take up residence in your sprinklers, emitters, tubes, and pipes. Often they manage to squeeze in, only to be unable to get back out when spring comes. Whether they crawl down to a smaller pipe and get wedged, or grow, or whatever, I don’t know. But I do know they get in there and they get stuck! So you need to get them out. To do that open the ends of drip tubes and flush ’em out by turning on the water. For sprinklers remove the nozzles from, at the least, the last head on each pipe (better yet, remove them all) and run the water. When you think the water has run long enough, you’re only half way done. Let it run twice that long! The biggest mistake in flushing is not letting the water run long enough. When done, make sure that standing water doesn’t drain back into the pipes, taking dirt back in with it! You may need to put a temporary piece of hose or pipe onto the flush outlet to drain the water to a different area. Make sure the hose is as big or bigger than the pipe, you don’t want to restrict the flow!

After flushing, check the system out by running it. Look for clogged emitters or nozzles. I don’t recommend cleaning plastic sprinkler nozzles, replace them with new ones. Cleaning them leaves small scratches which mess up the spray pattern and create dry spots. (So that’s why you have more and more dry spots each year! Who would have known! And you thought using that screwdriver to pry out the sand grains was a brilliant idea!) Calcium buildup on sprinkler nozzles can be removed using one of the many calcium remover products available for kitchen use. I’ve never tried it but I’ve been told that soaking them in drain clog remover also works. If you try it let me know if it works!

Check for leaking valves. Often the flexible seals dry out over the winter and leak when the water is turned back on. This is also a good time to think about giving your plants some fertilizer. They just woke up from a long nap and they’re HUNGRY! Did you miss Little Shop of Horrors? Feed them, but not too much!

Check the controller for proper run times for each station. If it has a back-up battery replace it with a fresh one. Almost all solid state controllers use ALKALINE back-up batteries and will not work right with other kinds- if in doubt use an alkaline type battery. The battery on some controllers is located behind a face plate where you can’t see it (why do the manufacturers do stupid things like that?), so if you don’t see a battery, remove the wiring compartment cover and look for it in there. A few of the high-end controllers have built in battery chargers (look at the batteries, they should be labeled “rechargeable” if the clock has a built in charger). Most newer controllers now come with non-volatile program memory and long-lasting batteries to keep the clock running during a power outage. These batteries are like the ones in your computer, they last for years, you may never need to change them.

If you have a sprinkler system, give it a spring tune-up. See the Sprinkler System Tune-Up instructions.

Special thanks to the following industry experts who provided input for this tutorial! (I admit it! We don’t do much winterizing here in Southern California and I needed all the help I could get!) The following list is in random order.

• Mark B. Story Sr., President, Brampton Irrigation Inc., Ontario, Canada.
• Keith Vereeke, Spring Brook Irrigation, Holland, Michigan, USA.
• Don Turner, Education Manager, Hunter Industries.
• Dale W. Hansen, National Sales Manager, Landscape & Turf Division, L.R. Nelson Corp..
• Rain Bird Technical Services, Rain Bird National Sales Corp.
• Gary McLauchlin, City of Vancouver, Washington, USA.

Introduction:

Proper irrigation scheduling is a tricky skill that surprisingly few landscape professionals have mastered. By far the largest loss of plant materials on new landscape projects is the direct result of improper irrigation scheduling. You may be surprised to learn that the most common irrigation scheduling problem is not too little water, or even too much water, it is watering too frequently. Many of the common turf grass and landscape shrub diseases are made worse by, or even may be the result of, watering too frequently.

Smart Controllers: The Arm Chair Method.

Before getting into the details of irrigation scheduling, it should be mentioned that there is an easier way. More and more irrigation control systems will do most of the work for you. These irrigation controllers (sprinkler timers) are commonly called “Smart Controllers”. After the initial set up, these Smart Controllers automatically adjust the watering times depending on the water needs of the plants. See the Smart Controller FAQ for more information. I highly recommend you look into purchasing a Smart Controller. If you live in a drought area contact your water supplier to see if they have any programs that will assist you in the purchase price of a Smart Controller. Some water suppliers will pay for part or all of the controller cost!

Understand the Water Needs of Your Plants.

Plant roots need a combination of both air and water to survive. Some plants, like ivy, can grow in a jar of water. Others will die if the roots are wet for longer than 24 hours. Thus, irrigation scheduling must begin with an examination of the plants to be watered. Irrigation scheduling for water-loving plants is easy, you just give them as much water as you can find or afford. Since most problems related to irrigation scheduling involve irrigation of the more drought-tolerant plants the rest of this discussion will focus on these plants. Fortunately, almost all plants will perform well under these irrigation scheduling guidelines. As with anything, there are some exceptions. If in doubt, check with your favorite nursery, or a landscape plant encyclopedia.

At this point it may be helpful to understand the needs of drought-tolerant plants. These plants are often native to arid climates where it rains heavily for short periods, followed by long periods with no rain at all. The drought tolerant features of arid region plants allow them to survive and even thrive under these feast or famine water conditions.

Drought tolerant plants may be found growing in all types of soils, from sand to clay. Sandy soils do not hold moisture well, and drain quickly. They are the easiest soils to grow drought tolerant plants in when irrigation is available. Clay soils hold water tightly for long periods of time, and cause the most problems with over-watering. Watering needs to be much less frequent in clay soils to allow the drying time between irrigations that these plants need.

Never Water if the Soil is Wet!

Irrigation scheduling is simply a matter of close observation and dedication. Ideally, the irrigation control clock should be adjusted on at least a weekly basis to conform with current weather conditions, but even with monthly adjustments plants can be maintained healthy and happy.

The first basic irrigation scheduling rule for drought-tolerant plants is never water if the soil is still wet. The old rule for landscape care was “if it doesn’t look right, water it”. This is often the worst possible thing to do. Plants wilt for any number of reasons other than needing water. Wilting for some perennials happens on hot afternoons no matter how much water they have.

Wilting in drought tolerant plants is often the first sign of too much water. (The roots die from too much water, then the plant wilts from lack of water uptake by the roots. Sort of ironic isn’t it?) Wilting can also be caused by any number of other diseases or even insect damage. Some drought tolerant plants fold their leaves on hot afternoons to conserve water, which can be mistaken for wilting. So never assume a plant needs to be watered because it looks wilted. Check to see if the soil is wet first.

When You do Water, Don’t be Stingy!

The other rule for irrigation scheduling is when you do water, don’t be stingy. Saturate the soil throughout the entire planter. The soil should be completely saturated (the technical term is that the soil has reached field capacity) to a uniform depth of at least 6 inches. The primary feeder roots for most plants will be growing throughout the top 6 inches of the entire planter, not just under the plant’s foliage. These feeder roots are so small that they are not even noticeable in the soil! The plant’s lower roots are primarily to physically support the plant, although these lower roots can sometimes take up water if they need to.

Cycle Your Sprinklers.

If you’re irrigating using sprinklers, the water will probably start to run off into the gutter, or into a low spot, before the soil is wet to a 6 inch depth. This is because the sprinklers put out more water in a given amount of time than the soil can absorb. In technical terms the precipitation rate of the sprinklers is greater than the infiltration rate of the soil. (Both, by the way, are measured as inches/hour in the U.S.A.) Fortunately, solving this problem is easy. As soon as the water starts to run-off, just turn off the sprinklers! Wait an hour or so for the water to soak in, then run the sprinklers again until run-off once again occurs. Continue this run-stop-wait-run cycle until the soil is saturated to a 6 inch depth. This process is referred to as cycling the sprinklers. Almost all sprinkler systems need to be cycled for proper irrigation.

Technical note: in large areas of turf you may not notice the run-off because the water doesn’t run into a gutter or over a sidewalk, but runs off to the lowest area in the lawn. It’s still critically important to prevent the run-off. If you don’t, muddy, wet areas will result where turf diseases will thrive, mosquitoes will breed, and your mower will leave ruts.

Avoid Cycling Drip Systems.

With drip systems the goal of saturating the soil 6 inches deep in the entire planter is the same, but a different approach is necessary to achieve the goal. Drip emitters slowly trickle water into the soil at the location of each emitter. Because the water comes out of the emitter so slowly it easily soaks into the soil, making saturating the soil to a 6 inch depth easy. The problem with a drip system is saturating the soil throughout the entire planter area, not just the soil directly under the emitter. To saturate the entire planter area the water has to move outward in the soil from the emitter locations. In all but the sandiest of soils the water can be forced to move at least 36 inches in each direction away from the emitter through a combination of positive displacement and capillary action. To achieve the positive displacement part of this action it is necessary to avoid cycling the drip system. Run the drip system as long as possible at a time. Create small berms if necessary to control run-off. In some clay soils you may need to cycle the drip system like you would a sprinkler system to avoid run-off, but try to keep it down to just one repeat cycle if possible. Remember, if you can’t achieve saturation of the entire planter area, you at least want the wetted area around each emitter to be as big as you can make it in a single 24 hour period! You may even need to add more emitters to achieve the goal. If you do add more emitters, space them at least 36 inches apart. Remember, the goal isn’t to add more water to the areas that are already wet, the goal is to wet more AREA for the roots to grow in.

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Quick Index by Formula Type:

Metric to U.S. System Conversions
U.S. To Metric Conversions
Area and Distance Conversions
Water Pressure Conversions
Flow and Water Volume Conversions
Pump Calculations
Miscellaneous Irrigation Formulas

Metric to U.S. System Conversions, Calculations, Equations, and Formulas:

• Millimeters (mm) x 0.03937 = inches (“)(in)
• Centimeters (cm) x 0.3937 = inches (“)(in)
• Meters (m) x 39.37 = inches (“)(in)
• Meters (m) x 3.281 = feet (‘)(ft)
• Meters (m) x 1.094 = yards (yds)
• Kilometers (km) x 0.62137 = miles (mi)
• Kilometers (km) x 3280.87 = feet (‘)(ft)
• Liters (l) x 0.2642 = gallons (U.S.)(gals)
• Liters (l) x 0.0353 = cubic feet
• Bars x 14.5038 = pounds per square inch (PSI)
• Kilograms (kg) x 2.205 = Pounds (P)
• Kilometers (km) x 1093.62 = yards (yds)
• Square centimeters x 0.155 = square inches
• Square meters x 10.76 = square feet
• Square kilometers x 0.386 = square miles
• Cubic centimeters x 0.06102 = cubic inches
• Cubic meters x 35.315 = cubic feet

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U.S. to Metric Conversions, Formulas, Calculations, and Equations:

• Inches (“)(in) x 25.4 = millimeters (mm)
• Inches (“)(in) x 2.54 = centimeters (cm)
• Inches (“)(in) x 0.0254 = meters (m)
• Feet (‘)(ft) x 0.3048 = meters (m)
• Yards (yds) x 0.9144 = meters (m)
• Miles (mi) x 1.6093 = kilometers (km)
• Feet (‘)(ft) x 0.0003048 = kilometers (km)
• Gallons (gals) x 3.78 = liters (l)
• Cubic feet x 28.316 = liters (l)
• Pounds (P) x 0.4536 = kilograms (kg)
• Square inches x 6.452 = square centimeters
• Square feet x 0.0929 = square meters
• Square miles x 2.59 = square kilometers
• Acres x 4046.85 = square meters
• Cubic inches x 16.39 = cubic centimeters
• Cubic feet x 0.0283 = cubic meters

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Area and Distance Conversions, Equations, Calculations, and Formulas:

• Acre x 43560 = square feet
• Inches x 0.0833 = feet
• Feet x 12 = inches
• Square mile (“Sections”) x 640 = Acres
• Miles x 5280 = feet
• Circumference of circle x 0.3183 = Diameter of the circle
• Diameter of circle x 3.14 = Circumference of circle
• Diameter squared x 0.7854 = Area of circle
• Radius squared x 3.14 = Area of circle
• Miles x 1760 = yards
• Square Miles x 259 = hectares
• Square kilometers x 100 = hectares
• Acres x 40.47 = areas
• Hectares x 100 = areas
• Areas x 100 = square meters
• Yards x 3 = feet
• Acres x 4840 = square yards

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Water Pressure Equations, Conversions, Formulas, and Calculations:

• Feet head (of water) x .433 = Pounds per square inch (PSI)
• Feet head (of water) x 0.3049 = meters head (of water)
• Feet head (of water) x 0.0295 = atmospheres
• Feet head (of water) x 2.988 = kiloPascals
• Meters head (of water) x 3.28 = feet head (of water)
• atmosphere (Atm) x 1.013 = 1 bar (b)
• atmosphere x 14.696 = Pounds per square inch (PSI)
• bars x 1.033 = kilograms per square centimeter
• bars x 14.67 = Pounds per square inch (PSI)
• bars x 100 = kiloPascals
• Kilograms per square centimeter x 14.223 = pounds per square inch (PSI)
• Pounds per square inch (PSI) x 2.31 = feet head (ft. hd.)
• Pounds per square inch (PSI) x 0.0703 = kilograms per square centimeter
• Pounds per square inch (PSI) x 0.06895 = bars
• Pounds per square inch (PSI) x 0.06805 = atmospheres
• Pounds per square inch (PSI) x 2.31 = feet head (of water)
• Pounds per square inch (PSI) x 6.896 = kiloPascals
• kiloPascal x 0.145 = Pounds per square inch (PSI)
• kiloPascal x 0.01 = bars
• kiloPascal x 0.334 = feet head (of water)

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Flow and Water Volume Formulas, Conversions, Calculations, and Equations:

• U.S. Gallons per minute (gpm) x .1337 = Cubic feet per minute
• Cubic feet per minute x 7.48 = U.S. gallons per minute
• Cubic feet per second x 448.8 = U.S. gallons per minute
• U.S. gallons per minute x 0.00223 = Cubic feet per second
• Acre inches per hour x 453 = U.S. gallons per minute
• British Imperial gallons x 1.201 = U.S. gallons
• U.S. gallons x 0.833 = British Imperial gallons
• Acre feet x 325,850 = U.S. gallons
• Acre inches x 27154 = U.S. gallons
• Velocity in feet per second = (0.408 x GPM) / Inside diameter of pipe in inches, squared
• Q=AV (quantity = area x velocity) (“the basic equation of water flow”)
      (example: quantity in cubic feet per second = square feet of area x feet per second velocity)
• One inch of water depth = 0.62 gallons per square foot of area
• GPM x 226.8 = liters per hour
• cubic feet per minute x 1699 = liters per hour
• acre inches per hour x 1712.3 = liters per minute
• acre feet x 1231.7 = cubic meters
• acre inch x 102.64 = cubic meters
• velocity (feet/second) x 0.3047 = velocity (meters/second)
• velocity (meters/second) x 3.281 = velocity (feet/second)

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Pump Calculations, Conversions, Equations, and Formulas:

The following formulas assume 55% pump efficiency (the standard assumption).

Note: Horsepower is Brake horse power for an electric motor. Do not use for fuel-powered pump engines!

• GPM = (horsepower x 2178) / feet head
• Feet head = (2178 x horsepower) / GPM
• Efficiency of pump = (GPM x feet head) / (horsepower x 3960)
• Horse powers x 745.7 = watts (W)
• Water flow (in cubic meters per second) = 0.55 x pump power (watts) / pressure (pascals)
• Water flow (in liters per second) = 5.43 x pump power (kilowatts) / pressure (bars)

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Miscellaneous Irrigation Formulas, Conversions, Equations, and Calculations:

Sprinkler Precipitation Rate

Note: “head spacing” is the distance between sprinkler heads. L = length between heads in the row, W = width between rows. Therefore “head spacing ” = L x W. Use the GPM value for a full circle sprinkler. So if your sprinklers are all half circles, you need to double the GPM value so it is equivalent to a full circle value. Precipitation rate result will be in inches per hour. The common abbreviation for precipitation rate is “ppt”.

Precipitation rate for square sprinkler spacing:

(GPM of full circle sprinkler x 96.3) / head spacing in feet = precipitation rate

Precipitation rate for triangular sprinkler spacing:

(GPM of full circle sprinkler x 96.3) / (head spacing in feet x 0.866) = precipitation rate

Example: A irrigation system with sprinklers arranged in rows. The rows are 30 feet apart and the sprinklers are 25 feet apart in the row. The sprinkler heads are arranged in a triangle pattern. Each sprinkler head uses 6 GPM. The calculations for precipitation rate would use the formula above for triangular spacing:

(6 x 96.3) / (30 x 25) x 0.866 = ppt

multiply the numbers in the parenthesis to get-
577.8 / 750 x 0.866 = ppt

do multiplication before division-
577.8 / 649.5 = ppt

finally do the division-
0.89 inches per hour = ppt

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