Tag Archives: anti-siphon valve

Drip System Detail Drawings

Some sample drawings to assist you

A Typical Drip System using Anti-Siphon Valves

Miscellaneous Drip Irrigation Part Installation:

Drip Flush Valve

Hard Piped Emitter

Valve Installation & Wiring:

Automatic Control Valve with Filter and Pressure Regulator

Anti-Siphon Valve

Valve Wiring to Controller

Filter Installation:

Auto Flush Disk Filter

Backflow Preventer Installation:

This is a good method for installing a valve and backflow preventer on a trellis, arbor, or other elevated structure:
Atmospheric Vacuum Breaker Backflow Preventer

Pressure Vacuum Breaker Backflow Preventer

Reduced Pressure Backflow Preventer

Double Check Backflow Preventer

Installing an Anti-Siphon Valve

Anti-siphon valves are the primary type of valve used for residential irrigation systems.   There are several very important rules that apply when you are using or installing an anti-siphon valve.  They MUST be installed in the correct way or they will not work!!

Quick & Dirty Summary

  • Anti-siphon valves must be installed 6″ higher than the highest sprinkler head or emitter outlet.
  • The anti-siphon valve inlet pipe must meet local plumbing code requirements for exposed pipe.  Generally that means using metal pipe such as copper, brass, or galv. steel.
  • No other on/off valves may be installed on the downstream side of an anti-siphon valve.
  • Anti-siphon valves may not be left “on” or “open” for more than 12 continuous hours at any time.
  • The optional “Flow Control” feature is worth paying more for.  It will probably save you more time and money than the extra cost it adds to the valve.  Plus most anti-siphon valves without flow controls are poor quality.
  • To avoid nasty surprises, avoid using a water supply for your irrigation system that passes through a house inside the walls, under floors, or through the attic.

Keep reading for in-depth details and answers to “why?”

Continue reading Installing an Anti-Siphon Valve

Irrigation Valves

This page explains everything you need to know about irrigation valves!

There are many different kinds of irrigation valves available. You will need at least two different types for your irrigation system.

1. Emergency shut-off valve:

This valve should be installed at the closest point possible to your water source, that is, the location where you tap in for the irrigation system. Without this valve you will need to shut off the water to the entire house when you want to work on the mainline or irrigation valves. The most commonly used valves for this purpose are “gate valves” because they are inexpensive. Unfortunately the cheap gate valves you’re likely to find in your local hardware store also tend to fail after a very short period of time.  I recommend that you use a “ball valve”, or if you need a really big shut off valve (over 3 inch size) use a “disk valve” or “butterfly valve”. These cost a bit more but are much more reliable and will last several times longer. So if you pay twice as much for a ball valve it’s probably still the best deal! If you want to use a gate valve make sure that it is a “wedge” type and buy a good quality one (it will probably cost more than a ball valve.) There’s nothing worse than trying to repair a system when you can’t shut off the water completely.  OK, that’s about all you need to know about emergency shut-off valves.  The rest of this page is about Irrigation Control Valves.

2. Irrigation Control Valves:

These are the valves that turn on and off the sprinklers, they also may be used for drip irrigation systems. Other names sometime used for them are irrigation valve, sprinkler valve, solenoid valve, and lawn valve. Sometimes they are incorrectly called Garden Valves.  A garden valve is a manual valve that you connect a garden hose to.

Globe Valves vs. Anti-Siphon Valves

You have two basic styles of control valves to choose from.


Globe or angle valve:

This valve is available in any size and is commonly installed underground in a box or vault. Since it doesn’t incorporate a backflow preventer you must provide one separately. See the article on backflow preventers. The globe style valve is the most common used valve on commercial and larger size sprinkler systems.

Anti-siphon valve:

Available only in 3/4″ and 1″ size. This is the most common used valve style for homeowners. The anti-siphon valve incorporates a backflow preventer into the valve. This saves a considerable amount of money, as backflow preventers are very expensive. The anti-siphon valve MUST be installed above ground and MUST be at least 6″ higher than the highest sprinkler head. This means that if you want to use anti-siphon valves you will have to locate the valves at the highest point in your yard, and run a water supply pipe to them from the water source (this water supply is called a “mainline”). The mainline pipe leading to the anti-siphon valves should be buried 18″ deep to protect it.

Valve Operation/Control Systems

Manual, Hydraulic and Solenoid Valves:

The sprinkler valves may be manually operated or they can be remotely controlled (automatic valves.) Manual control is simple, the valve has a handle that you use to turn it on and off using your hand as the power source. Remote control valves are either electric or hydraulic operated using a timer or other signaling device to tell them to open and close. Today almost all of sprinkler control valves are electric powered solenoid valves. The electric solenoid valve operates on 24 volt alternating current (vac) and is turned on and off by a timer called an “irrigation controller” or often just “controller”. Anti-siphon, globe, and angle valves styles are all available as automatic valves.

Solenoid Valve and Controller Compatibility

Pretty much all 24 volt valves and controllers are compatible with each other.  The most common exception to this rule is valves operated by controllers that are battery or solar powered. (By battery powered I mean they are not plugged into a power source other than the battery.  Many controllers have a battery to prevent program loss in case of a power failure, these are not “battery operated”.) So in most cases you can buy a brand “X” controller and it will work fine with brand “Y” valves. You can even mix two or more brands of valves together if for some reason that appealed to you.  For example the irrigation system where I test valves and controllers has many different brands all running together.  If the valve is not “universal” or compatible it will typically have a warning on the packaging.

Flow Control

I strongly recommend that if you are going to use automatic valves, you select a valve model that has a manual flow adjustment control feature on it. Don’t confuse the flow control with a manual on/off switch. The flow control is a separate handle (sometimes a screw) in addition to the manual on/off control on the valve. This flow control feature is not found on many of the less expensive “budget” valves. The flow control bypasses the automatic valve features allowing the valve to be closed in an emergency by turning a handle just like a standard manual valve. More important is that it also allows the valve to be “throttled”, that is, the water flow may be adjusted to any rate desired. This ability to adjust the flow rate is very useful in many different situations, both when installing your sprinkler system and later when managing it.  It can literally make the difference between being able to make a troublesome valve work and having to remove and replace it!  I very strongly suggest that this is a feature worth the extra cost.


  • Using the manual flow control you can manually force the valve closed if it sticks open. The manual on/off switch will not close the valve if it is stuck open. Failure to close automatically is one of the most common valve problems, so there’s a good chance that someday you will use the flow control to force closed a valve that is stuck open.
  • If your flows are on the low end of the valve’s operation range, it may be helpful to throttle down the flow control to make the valve close faster and more reliably. Without the flow control feature you may have a lot of problems in this situation, you will probably have to replace the valve.
  • Partially closing the flow control will make the valve close faster, which is not something you want to do normally, but sometimes it is desirable. On automatic systems it is common for the next valve to open before the previous one fully closes. The resulting loss of pressure due to two valve circuits being on at the same time can cause the first valve to never fully close. A flow control on the valve can help correct this problem.
  • Buy valves with the flow control feature.  Just do it.  Don’t be one of the many people who later makes some lame excuse to me, like “the guy at the store, who normally works in the paint department but was filling in for the day on the irrigation aisle, said it was a waste of money!”

Should You Use Metal or Plastic Valves?

Sprinkler valves come in both brass and plastic models. Most valves used today are plastic, but brass is not out of the picture. There is no doubt that a brass valve will last longer in most situations, especially if installed above ground in the sunlight. From an operational point of view both are reliable, especially for automatic systems. For manual valves my experience is that plastic valves wear out fast and have a very short life. Brass will last much longer. If you use plastic valves above ground you may wish to consider building a cover for them to protect them from sunlight, which can destroy the plastic over time.

Two types of plastic material are used for valves. Glass-reinforced nylon is the best, it is tougher, more resistant to impact, and has a higher pressure rating. PVC is used for lower cost valves, it still is pretty strong, although that really depends on how thick the plastic is! A few valves use ABS plastic or polyethylene, especially for minor parts like screws or caps. Both of these plastics are less strong and are typically used for parts with little stress on them. I recommend avoiding valves with “solvent weld” connections (the pipe glues directly into the valve.) If the valve fails, they can be difficult to replace. Only the cheapest valves come with solvent weld connections. Hmmm… cheap valves fail more and with glued ends are harder to replace- sounds like a bad idea.

Jar Top or Traditional Top Held on with Screws?

OK, just personal opinion here, but I don’t see any advantage to a jar top valve.  Yes, they seem to work as well as a top with screws holding it on.  They primarily are only found on cheaper valves.  The only selling point I have heard for them is that they are supposed to be faster to open for repairs.  Are you repairing it that often?  I hope not! But I guess if it is a cheap valve…?  My experience is that by the time the valve is old enough to need repairs the jar top has seized up and it takes a strap wrench to get the top off.  Personally I prefer using a simple screwdriver to remove a few screws as opposed to wrestling with a strap wrench in a tight spot like a valve box.


Today’s valves are pretty maintenance free. Almost all automatic valve failures result from installation or design problems. Ignore the following and you will hate your valves regardless of what type or brand you buy!

Join the “Hall of Regrets”! Simply ignore the following advice, then send me your “I’m an idiot, I wish I’d listened…” sob story. I’ll add it to my collection and shed an alligator tear or two for you!

  • Dirt in the irrigation pipes. Inside the valve there are very small water passages that lead to and from the solenoid. Water must flow freely through these small passages. If a grain of sand or glob of algae gets into these passages it can block them and the valve will fail to open or (more likely) fail to close. It is critical to flush all the dirt out of the pipes before installing the valves. A 100 to 200 mesh filter installed at the water source connection can also help keep out contaminates that come in with the water supply. You may be surprised to learn that most water companies have considerable amounts of sand in their pipes. When you install a new sprinkler system the higher flows stir up this sand and then it gets into your new system. That’s why I suggest to you in the installation tutorial to flush for so long. You have to get the sand out of both the sprinkler system pipes and the water supply pipes! I can’t stress this enough! It’s like a cheap low-flow toilet. You have to flush, flush, and flush again!
  • Almost all valve solenoid failures are caused by water getting into the solenoid. The water gets into them through the wires. The solenoid wires have multiple strands of wires twisted together with insulation around them. Because they are twisted there are very small gaps between the wires which form passages along the length of the wire. Water is sucked up through these small passages and deposited into the solenoid by capillary action. Thus it is critically important that the wire splices on the valves be completely water proof so that water can’t be sucked into the solenoid through the wires. You should water-proof the wire splices right after you test the valves! No kidding, a single drop of water on the bare valve wire end can be quickly sucked up into the solenoid and will ruin the solenoid. The Installation Tutorial has more on this.

Valve Size and Pressure Losses:

Emergency Shut-Off Valve:

The pressure loss through the emergency shut-off valve is not significant enough to worry with. We will ignore it. The emergency shut-off valve should be the same size as the pipe it is installed on. If a smaller size shut-off valve is used then you do need to worry about losing pressure through the valve. Probably about 2 PSI would be a safe assumption of the pressure loss.

Automatic Valves:

WARNING!!! If you use the wrong size automatic valve, the valve may not work! READ THAT AGAIN! Let it sink in. The correct valve size often will not be the same size as the pipe it is connected to.

The pressure loss in an automatic solenoid valve is the primary energy source used by the valve to open and close the valve.  The electricity sent to the valve solenoid is just used to jump-start the process, the real force used is the water pressure.  If the valve doesn’t have enough pressure loss it will not have the energy needed to close by itself.  Always size automatic valves based on the flow rate using the manufacturer’s chart as a guide. Never assume that the valve should be the same size as the pipe! It is very common for the valve to be a different size than the pipe it is installed on. I have seen some rare cases where a 3/4″ valve was the proper size for the flow through a 2″ pipe!!! If you absolutely must guess, use the next solenoid valve size smaller than the pipe size and assume a pressure loss of 6 PSI. Never guess if your flow is less than 5 GPM, always use a chart! Many automatic valves won’t work at all at flows below 5 GPM!

The size of the automatic valves is determined by the manufacturer’s recommended flow range, together with the pressure loss through the valve at the selected flow. You will need to get the valve manufacturer’s flow chart for the model of valve you plan to use. This information should be on the valve packaging. If you can’t find it on the package, try the valve manufacturer’s website or ask for a data sheet on the valve at the store where you buy the valve. (At discount home improvement stores you are likely to get a blank stare from the employee if you ask for a data sheet!)

Some valves don’t appear to have data sheets available anywhere, so as a last resort I’ve assembled some data for you based on my own research for some of the more popular ones. You will find it in the reviews on this website, Click Here.  That said, if the valve manufacturer doesn’t provide this necessary information it shows an extreme lack of professionalism, I would be very reluctant to use the product!

If you can’t find pressure loss and flow range information for the valve you want to use, I strongly suggest you use a different brand of valve. After the valve is installed is not a good time to discover it’s the wrong size and won’t open or close automatically!

Example: let’s say you are going to use an automatic anti-siphon type valve. Your Design Flow is 20 GPM, so for now we will assume the flow through the valve will also be 20 GPM. (If it turns out the flow will be less, you can resize the valve later.) The manufacturer’s flow chart would look something like this:


Doesn’t Work Valve Company, Inc. – Valve Performance Data

5 GPM 10 GPM 15 GPM 20 GPM 25 GPM
3/4″ Anti-Siphon Valve 5.0 PSI 5.5 PSI 6.0 PSI 8.0 PSI
1″ Anti-Siphon Valve 2.5 PSI 3.5 PSI 3.0 PSI 4.0 PSI 9.0 PSI

Warning: The chart above is not real. DO NOT USE THESE VALUES!

The example chart above tells us that the pressure loss for our valve at 20 GPM flow would be 8.0 PSI if we used a 3/4″ valve and 4.0 if we used a 1″ valve. So we could use either one. The pressure loss information from the chart would be the number that you write into your Pressure Loss Table on the “_____ PSI – Valves” line. So if we decided to use the 3/4″ valve, the value would be 8 PSI. But what if after adding all the pressure losses in the loss table, you discover that the losses are too high? In that case you could go back and change to a 1″ valve. That would reduce the pressure loss down to 4 PSI, rather than 8. With that said, as a general rule I try to avoid losing more than 6 PSI through a valve. So I would not use a 3/4″ valve in the example above if it were my sprinkler system. Why? Valves need pressure drop for them to work correctly, but really high pressure losses are hard on the valve. As the pressure loss through an automatic valve increases, the speed with which the valve closes also increases. Thus a high pressure loss can cause the valve to snap closed extremely fast, and that is bad for the entire sprinkler system. Plus the water is moving extremely fast through the valves at those higher pressure loss rates, resulting in more wear on the valve seats. The result is that the valve will fail earlier.

If you looked closely at the chart above you may have noted a couple of interesting items. First, and most obvious, is that no pressure loss is given for a 3/4″ valve at 25 GPM. This is because that flow is outside the acceptable range for the valve. You should not use the valve for that flow. The next item is less obvious, but if you look closely, you will notice the pressure loss for the 1″ size valve is less at the 15 GPM than it is at the lower 10 GPM flow!  No, it isn’t a mistake.  It is very common for valves to have higher pressure losses at very low flows, so don’t panic if you notice this on a flow chart, it’s not a misprint.

Can a valve be smaller than the pipe it is connected to?

As you move through the tutorial you will find that even though the valve will handle a certain flow, that flow is often too high for the same size of pipe. So it is very common to have a valve that is one, or even two, sizes smaller than the pipe it is installed in. In fact it is so common that they actually make special pipe fittings (connectors) for this. For example they make a PVC plastic male adapter that glues onto 1″ pvc pipe, but has 3/4″ threads to allow you to install a 3/4″ valve on a 1″ PVC pipe. They also make one that glues onto 1 1/4″ pipe but has 1″ threads.

For Manual Valves:

Manual valves are much more forgiving than automatic valves. You don’t need to worry about having enough pressure to allow the valve to close by itself, it uses “elbow grease” to power it! However, you still need to find out what the pressure loss through the valve will be so you can enter it in your Pressure Loss Table. As with the automatic valves, you use a chart provided by the manufacturer for this. Follow the same procedure given above for automatic valves. Unfortunately, pressure loss data for manual valves can be hard to find as many manufacturers don’t provide it. As a general rule, allow 2 PSI pressure loss for a globe or angle type manual control valve, 5 PSI if it is an anti-siphon valve. Manual irrigation control valves should be of the “angle” or “globe” type with replaceable rubber seats. Never use a gate valve as a control valve. Gate valves are not made to be regularly opened and shut. Many gate valves will start leaking after as little as 10 uses!

Want to use a manual valve now but change to an automatic valve later? No problem. Simply design for the automatic valve, but use the manual one instead. Then you can replace it later when you want to automate the system. Another way to do this is to install the automatic valve and simply operate it manually using the manual on/off lever. If you do this, then later you just install a controller as well as wires between the controller and the valves and you have an automatic control system.

This article is part of the Sprinkler Irrigation Design Tutorial
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How to Remove a Valve Zone from Sprinkler system

Q.  I have 3 zones for my sprinkler system.  I need to remove the valve/pipe/heads from one of the 3 zones in my backyard.

A. You may not even need to turn off the irrigation system water for this project.  But it is a good idea to know how to turn it off.  You never know when you may need to.

Definition:Zone valve” when used in irrigation, is the valve that turns on and off a group of sprinkler heads.  In most cases the zone valve is an electric activated valve and has a solenoid with wires leading into it on top of the valve.  The wires connect the zone valve to the irrigation controller (sometimes called the “timer” or “control box.”)  The power to the valve is typically 24 volts AC.  It usually will not harm most people if they touch a live wire, but it will give you enough of a shock that you will never want to do it again!  Obviously if you have a pacemaker or sensitivity to electrical current you will want to be extra careful around the wires.  If you touch your cell phone to a bare wire it may become an expensive paperweight.

Shut off the water. (Optional, if you are not going to remove the zone valve you don’t need to do this.)  Turn off the water to the entire sprinkler system.  Many sprinkler systems have a main shut off valve that turns off all the water to the sprinkler system.  Look around for the shut off valve.  It may be in a box underground.  Often it it near the location where the pipes enter the house.  Often it it in a basement if other water pipes are located in the basement.  Once you found a possible shut off valve, turn on one of your sprinkler zone valves so you can see that the system is running.  Now try turning off the possible shut-off valve.  It the sprinklers stop running you know the valve shuts off water to the sprinkler system.  Now check and see if it also turned off the water to the house.  If it did, you just found the house main water shut off valve.  You may not find a valve that turns off only the sprinkler water.  A lot of homeowner installed sprinkler systems don’t have them.  You may just have to turn off all the water to the house in order to work on the sprinkler system.

The easiest way is to leave the zone valve installed and not remove it.  Just plug it.  I’ll tell you how to do that first.

Identify the valve.  Now you need to figure out which of the sprinkler zone valves is the one you want to remove.  Hopefully you know where the valves are.  If not, see the article on how to find missing valves.   To determine which valve you want to remove, you manually turn on the zone valves (without using the control box) and see which one turns on the sprinkler you want to remove.  On top of your zone valves is a solenoid, written on it you will see ON/OFF arrows.  Turn the solenoid in the “ON” direction about 1/4 turn or so.  This should open the valve and the sprinklers should come on.  Note: Some valves have a lever that turns them on and off, some have a bleed screw you partially turn to make them manually open.  Each valve make and model is a little different, so you may have to use some deductive skills to figure out how to manually open your valve.  By turning them on one at a time you should be able to determine which valve operates the sprinklers you want to remove.  When finished, turn off the valve by by reversing the procedure you used to turn it on.  If your valve uses a bleed screw to open it, DO NOT completely remove the bleed screw.  Just unscrew it slowly until the valve turns on.

Typical sprinkler zone valves.
Typical sprinkler zone valves.

3. Now that you know which valve you want to remove, carefully dig the dirt away from the valve and expose the pipe on the downstream side of the zone valve. If you clear the dirt off the top of the zone valve it should have a flow direction arrow someplace on the valve body that points toward the outlet side.  (It may be on the side of the valve, using a small mirror makes it easier to find it.)

Once you know which direction the water flows through the valve, cut out a short section of the pipe right after the valve. Water may squirt out when you make the first cut into the pipe, so be prepared to get some muddy water sprayed at you!   A lot of water may drain out when you cut the pipe, depending on how much water was in the pipes and the slope of your yard.   You may have to bail water out of the hole with a bucket to remove it.  With the pipe section removed you can now use a wrench to unscrew the remaining pipe from the valve outlet.  Take the pipe section you removed from the valve (with the threads on it) to a hardware store and buy a threaded plug of the same size and a roll of Teflon tape.  Wrap several layers of the Teflon tape sealant onto the threads of the plug and then put the plug into the valve outlet opening.  Hand tighten the plug, then use the wrench to tighten it another half turn.  Do not overtighten it, if you overtighten the plug the valve body may split open.  Now that valve zone is plugged off.  You can remove the wires for that valve from the controller if you wish.  Now remove any of the pipe or sprinklers you want from that valve zone.

You can remove the entire valve if you want to.  I didn’t have you remove the valve because that does not require you to turn off the water to the entire sprinkler system, which is easier for most homeowners to do themselves.

To remove the entire valve:  Turn off the water to the entire sprinkler system.  Then manually turn ON the valve you want to remove, the sprinklers will come on for a few seconds then slowly shut off as the water discharges from the pipes and the pressure is released.  If the sprinklers keep running the water is not shut off!  Now follow the directions above.   Once the outlet pipe section is cut and removed, cut the wires off the valve, then unscrew and remove the entire valve.  Seal the ends of the wires with PVC glue or silicon caulk/sealer if you think you may ever want to use them again.   Put a threaded cap on the pipe that formerly connected to the valve.

Removing sprinklers.  To remove a sprinkler you can sometimes just grab the top of it and turn it counter-clockwise.  It will unscrew from the pipe below it and then you can lift it out of the ground.  Often you will need to dig away grass from it so you can twist it out.  In most cases you don’t need to dig a big hole around the sprinkler head, just dig away enough dirt and grass to allow you to grip the sprinkler.  Fill in the hole with dirt after you remove it.  Assuming you are abandoning the pipes, there is no need to cap the pipe off below the sprinkler, just leave it there.  If you don’t plan to ever use it, it doesn’t matter if it gets dirt in it.

Removing Pipes.  Most of the time we just leave the pipes in the ground.  They are a lot of work to remove and most of the time they don’t bother anyone if left buried.  If the pipes are not very deep you can often pull them up using “brute force”.  Dig down to expose the end of the pipe, grab the end and pull it up out of the ground.  If there is thick lawn you may need to cut a slit in the lawn surface to allow the pipe to be pulled up easier.  Use a edger to cut the turf directly above the pipe.  A string trimmer with heavy string in it may be able to cut the turf.  It may use up a lot of string!

I don’t recommend using a vehicle to pull the pipe out, but I know some will try it.  If you do this and get yourself injured or killed, you will be featured in those “knuckleheads in the news” columns!  If you try attaching a rope to the pipe and the other end to a garden tractor or truck to pull the pipe out of the ground – be very careful.  Wear protective clothing, gloves, eye protection and a hard hat.  Keep everyone else far away.  Have someone there watching from a distance who can call 911 if you get hurt!  Here’s why I say you shouldn’t do this:  Plastic pipe breaks suddenly and violently when pulled hard.  If the pipe or rope breaks while pulling on the pipe both the rope and the pipe can whip around violently and cause injury or damage, ie; break a window.  The white hard PVC plastic pipe can shatter and release small, very sharp pieces of plastic that act like shrapnel and cut like dozens of little knives.  If the pipe does not come out easily and you see the rope stretching, STOP, it’s going to break!  Don’t be an idiot, use common sense and extreme care.

If you can’t pull the pipe up and you absolutely can’t just abandon it in place, the only way I know of to get it out is to dig it out.  Ugghh.  Lots of work.



Creating Water-Proof Irrigation Wire Connections

Water-proofing your irrigation system’s wire splices is one of the most critical tasks in any installation or repair that involves wire splices.  The splices need to be completely water-proof.  Taping them up with electrical tape will NOT work for this!  The electrical tape will allow water into the splice as it becomes old, brittle, and the adhesive on it dries out.  If you don’t water-proof your splices it WILL cause your valve to fail!  Don’t save a buck on a wire splice and ruin a $20 valve! I’ll explain in detail why waterproofing is so important later, first let’s get down to the details on how to make a good waterproof wire splice.

General Things That you Need to Know about all splices!

Caution:  The methods described below are intended for low-voltage wires of 24VAC or less, such as those used in typical irrigation system controls.  They should not be used for higher voltages.

DO NOT BURY SPLICES directly in the ground.  Put a box around them to protect them and to help you find the later.  A small plastic utility box works fine.  Glue a large steel washer to the bottom of the box lid using epoxy.  This will allow you to find the box with a metal detector if grass grows over it.  Splices are the most likely place a wire will short out in the future, so a box makes the splices easier to find and repair.

2-wire irrigation systems:  These are a newer type of system that uses only 2-wires to control all the valves.  The irrigation controller sends a signal through the valves to a decoder at each valve.  The decoder then allows power to the valve solenoid only when told to by the controller.  These types of systems depend on electrical “signals” sent from the controller through the wire to the decoder.  Any voltage leak at a splice can severely impact the signal and cause the system to malfunction.  For this reason splices for 2-wire systems need to be made much more carefully.  Many of the 2-wire manufacturers have specific splice methods they require be used in order to protect your warranty.  Be sure to use these if required!

Not sure if your system is 2-wire?  As i write this in 2013, 2-wire systems are seldom used on residential systems, but they are also gaining popularity and will probably start showing up soon, first on larger systems.  The controller case normally will be clearly labeled as “2-wire”.  A 2-wire system will also have a “decoder unit” installed on the wires at each valve.  Standard irrigation control systems have two wires going to each valve.  But in a standard system one of the wires goes to a single valve and only that valve.  So if you have 4 valves there will be 5 wires (1 common shared by all the valves, + 1 individual wire to each of 4 valves = 5 wires.)  On a 2-wire system with 54 valves there would be only 2 wires and each valve would have a decoder unit installed on it.  The presence of a decoder to be installed at each valve is the best way to tell if it is 2-wire.

The best way to make the splice is to use special water-proof splice connectors that you can buy at any hardware store.  These are made for sealing outdoor wire connections and work very well.  There are many different styles and types available.

Water-Proof Twist On Connectors – “Nut” Style or “Wing” Style

Most of the connectors currently used by pros consist of an twist on type wire connector that is filled with a water sealing grease.  Sometimes these are called water-proof “nut” or “wing type” connectors.   These are inexpensive and very simple to use. Here are general instructions for use since a lot of these inexpensive connectors are sold without instructions.  If instructions came with the connectors please use those instructions, as they are intended for the actual connectors you bought!

  1. For every 3 connections you need buy 5 connectors.  Why?   Because you will probably make several bad splices, and you will have to remove those connectors and toss them in the trash.  They can’t be reused because when you remove them a lot of the sealer comes out with the wire.   (If you look close most connectors actually say “do not reuse” or similar language on them.)
  2. Start by stripping the insulation off the end of the wires to expose the bare metal wire.  Do not strip off too much insulation, the exposed  bare wire should be about 1/2 the length of the connector body.   You can splice 3 wires together easily using a single connector.  It’s OK to put 4 or 5 wires in a connector, but be warned that it gets a lot more difficult getting the wires to stay in the connector when you use more than 3 wires.
  3. Place the bare ends in one hand and using your other hand, align the wires side-by-side, so the ends of the bare sections are lined up together.  Those ends need to all go into the connector together at the same time, so hold the wires tight and don’t let them slip out of position.  Do not try to insert an additional wire into a wire connector that already has wires spliced together in it.  You need to remove all the wires and redo the splice to add more wires.
  4. Push the connector down over the bare ends of the wire.  Twist the connector clockwise to screw it on.  Hold the wires firmly in position as you twist the connector over them.  The connector has threads, a spring, or barbs inside it that will grab the wires and cinch them together tightly as you twist it on.  Stop twisting when you feel substantial resistance.
  5. Hold the connector in one hand and tug on each of the wires with the other to make sure the wires are secure and will not pull out.  If a wire feels loose or pulls out, disassemble the entire splice and try again.   Use a new connector as some of the sealer will probably be lost when you remove the connector, and it needs all the sealer for a good seal.   If the wires still pull out after another try you are probably using the wrong size connector.
  6. Finally make a visual inspection of the splice.  The insulation on the wire should be fully inserted into the sealer gel or grease.  No bare wire should be visible.  That’s all there is to using twist on wire connectors, they are very quick and easy.

The connector size is important when using twist on connectors!   Be sure you buy and use the correct size connector for the wire sizes you are splicing. The package will list the various wire size combinations that the connector works on.  The connector colors indicate the connector’s size and most are standardized.  Here are some general guidelines.  Warning: There are some brands that do not follow these color guidelines so double check the instructions on the package!

Connectors for #18 wire.  Most residential irrigation systems use #18 size wire, this is the size of most of the multi-wire underground irrigation cables sold in hardware stores.   Unfortunately the colors for these connectors are not standardized.  Most I have seen are dark blue or black.  Make sure it says it will connect 2- #18 wires.

Connectors for #14 & #12 wire.  Larger irrigation systems and commercial irrigation often use individual #14 wires.  Sometimes #12 will be used for irrigation systems with very long distances between the controller and the valve.  Most often these connectors are yellow.   Note: Most of the yellow connectors I have seen will NOT connect a single #14 wire to a typical valve solenoid wire.  For this you will probably need the smaller #18 wire connectors above.

Twist-On Waterproof Wire Connectors. Wing Style on left (blue), Nut Style on Right (black).




Mechanical Clip Style Non-Stripping Connectors

Clip style is a catch-all name I use for the various types of connectors that use a mechanical clamping system to grab and bite into the wire.  Typically with this type of connector you push the wire into a round slot on the connector, and then squeeze some type of clamp that bites into the wire to hold it in place.  Some require pliers to squeeze the clamp into the wires.   The most popular of these types of connectors for irrigation use is the Blazing Snaploc BVS Series wire connectors and the 3M Scotchlok 314 series connectors.  These connectors are more expensive but make a very secure connection almost always on the first attempt.  You won’t need to buy nearly as many extras for bad splices.


Container Type Connectors

These connectors are a two piece, two step system.  You connect the wires together using either a standard twist type wire connector, a crimp sleeve, or even soldering the wires together.  Then you shove the splice into a container filled with a water-proofing grease or jell and snap a retainer lid closed to hold the splice inside the container.

A variation on this type of connector is the original waterproofing method used back when I started in the business.   You mixed a 2-part epoxy resin in a small plastic envelope and then shoved the splice into the envelope so it was covered in resin.  The resin was allowed to harden creating a solid water-proof seal.  Unfortunately the resin was a carcinogen.   I don’t think these are sold any longer.


How to Fix a Automatic Irrigation Valve that Won’t Open

Check The Dumb Stuff.

If the valve won’t open at all, or doesn’t fully open, start with the obvious things just to be certain. I know, any idiot knows better, but even us pros periodically overlook something really simple and obvious.

Tip: There are labeled photos of some of the more popular valve models showing the various valve controls (such as flow-controls, on/off levers, and bleed screws) mentioned in this article at this page:  Anti-Siphon Valves with Parts Labeled.

  • Is the water supply turned on?
  • Is there a shut off valve on the water supply that may have been closed?  Once I had a system I couldn’t get to work, couldn’t find any closed valves, but still no water to the sprinklers.  Turned out the city water company had closed a valve in the street for street work they were doing and forgot to reopen it!
  • Check the flow control on the valve to make sure it isn’t closed or partially closed.  It is often desirable for the flow control to be left partially closed, but if it is restricting the flow too much that could be the problem.  On some valves the flow control doesn’t have a handle, it is just a small screw in the valve lid.  If unsure, look up your valve model at the manufacturer’s website to see if they have a drawing of the valve showing a flow control device location.  Unfortunately, some inexpensive valves do not have a flow control device.

Manual Operation Test

Try manually opening the valve, using the on/off lever on top of the valve body.  Some valves use a bleed screw to manually open them, so if you don’t see a lever labeled on/off or open/close, look for a screw, typically the screw has a knob handle to allow it to be twisted by hand.  Do not fully remove a bleed screw!  Just turn it about 1-2 to 1 full turn, water will squirt out from under the screw and the valve should open.  Some valves have both a bleed screw and a on/off lever, on those valves I generally use the bleed screw as I have found it works better if the valve is being stubborn.  If the valve opens correctly and fully when using the manual open lever or  bleed screw, then the problem may be electrical.  If the valve does not open fully when using the manual open feature, skip over the next section on electrical problems.

Basic Electrical Tests

If you don’t have a valve actuator test unit, start by making yourself a home-made valve activator using three nine-volt batteries.  See my page with full instructions for making a irrigation solenoid valve activator (it’s easy and only takes about 2 minutes!)

Valve Electrical Tester
Home Made Valve Actuator for Testing Solenoid Valves

Now use your actuator to test your solenoid and wires:

  • NOTE:  make sure you are using fresh, brand new batteries in your actuator!  It takes a lot of amperage to open a valve and worn or old batteries won’t do the job.  Don’t waste your time tracking down false results caused by bad batteries!!!
  • Note #2:  24 VAC does not feel good if you shock yourself with it, especially if you are wet.  Don’t touch bare wires without rubber gloves on!
  • Disconnect the wires from the valve solenoid.  Touch the valve solenoid wires to the terminals on your activator.  The valve should open.  If the valve fully opens then the problem is NOT the valve, the problem is with the wires leading from the controller (timer) to the valve, or possibly the controller is broken.  Continue with the next step.  If the valve does not open, then skip the rest of the electrical diagnosis items.  The problem is with the valve or the valve solenoid.
  • Controller problems are very rare, it is much more likely the problem is a broken wire.  Do NOT try to test the controller by using a wire to create a short-circuit “spark” between the terminals!  You may fry your controller!  First reread the controller manual on how to wire the valve circuits and make sure you don’t have them wired wrong.   Optional: You can test the controller using a multimeter if you have one and know how to use it.  The controller output to the valves is 24 VAC.  Most modern controllers will show a positive test for 24VAC even if the circuit is off, you need to test the circuit with a load.  Don’t panic if you don’t know what that means or don’t have a multimeter.  Just go to the next step.
  • You can test the wire very simply.  If the wires from the controller to the valve are disconnected from the valve reattach them to the valve solenoid now.
  • Next remove the wires for the common and the “lead” wire circuit to your valve from the controller terminals.
  • Attach your valve actuator to the 2 wires at the controller end, just like you did to the solenoid wires.  The valve should come on.  If it doesn’t open, or only opens partially, the wires from the controller to the valve are either damaged (cut or short circuiting), or you are testing the wrong wires.  Are you sure you have the correct pair of wires for this valve?  That’s often the problem with a newly installed system!  It’s pretty easy to get the wires mixed up, especially if they do not have color-coded insulation.  Another source of the problem may be damaged insulation on the buried wire.  If the insulation on the wire has been removed or damaged someplace along the length of the wire it can cause a voltage leak.  A nick or partial cut in the wire may cause resistance to the current in the wire.  These wire problems cause the solenoid to not receive sufficient power to fully open the valve.
  • If the valve does turn on fully the problem is the controller.  Most modern controllers are not user repairable.  If it is under warranty contact the manufacturer for instructions.  They may ask you to do some additional tests.  If the controller is not still under warranty you can contact a professional irrigation repair outfit for a repair quote.  For most low-cost homeowner controllers it is cheaper to just replace the controller with a new one.  If your current controller is not a Smart Controller you should consider replacing it with one.  A self-adjusting Smart Controller will save you a lot of water and effort.


Valve Cleaning and Repair

If you’ve tested the controller and wires and they are OK, then the problem is with the valve itself.  You have two choices:  remove and replace the valve, or  disassemble the valve to look for problems.  Which way you go depends on which is easier for you to do.  I generally try to clean the valve rather than replace it at this point.

Replacing a valve:  Removing and replacing a valve can be a big job if the valve is fully installed.  Basically this is a swap out, take a photo of the old valve before you remove it, then remove it and install the new one in it’s place.   You probably will need to cut the pipe on the outlet side of the valve so you can turn the valve body to unscrew it from the inlet pipe and get it out.   Some valves are installed so close together that you need to cut the pipe on both the inlet and outlet sides, this is especially true of anti-siphon valves.  Once the old valve is out, you install a new one in the same location.  Finally you need to repair the pipe if you cut it.  If the pipe is PVC they make special couplers for repairing pipes that make the job easier.  Remember to completely water proof all the wire splices!

Note: a lot of anti-siphon valves are not properly installed.  Even sprinkler installation companies don’t use the care they should to insure correct installation, and a incorrect installation may be the source of your valve problems.  See the article on How to Properly Install an Anti-Siphon Valve to help you get it  in right this time!

Clean & Repair a Valve: Most people try to repair the valve rather than replace it.  I really think a repair is often easier at this stage.  If you do proceed with disassembling the valve be sure to notice how all the parts fit together so you can reassemble it when done.  Tip: take photos of the valve and how the parts fit together as you disassemble it!

  1. If the valve is more than a couple years old you might want to purchase a repair kit for the valve make and model (see bottom of this page for examples of what to look for.)
  2. Turn off the water supply to the valve.  Remove the solenoid by unscrewing it.  Note: each manufacturer’s valve is slightly different, but the basics are the same.  Your valve may look different from the Water-Master brand valve shown in these photos.
    Remove solenoid
    Remove solenoid

    The bottom of the solenoid has a spring-loaded plunger in it.  After removing the solenoid hold it in one hand and press the plunger in with your little finger.  The plunger should spring back out when you release it and move freely in and out without catching or jamming as you press on it.  If it doesn’t the solenoid is defective, see the manufacturer’s warranty info for how to proceed with replacement.  If the solenoid is fine clean the bottom of the solenoid with a clean towel.

    Check solenoid plunger
    Check solenoid plunger. Warning: plunger may spring out on some models!

    Next clean the little socket area in the valve lid that the solenoid screws into and make sure there aren’t any sand grains or bits of plastic loose in that area.  Using compressed air (that canned air used to dust computer parts works great, some people can blow sufficient air with their mouths using a drinking straw…) gently blow air toward the ports (tiny holes) in the bottom of the solenoid socket.  Keep the air outlet a couple inches away from the ports.  Do not place the end of the air outlet against the ports!  If you jam the air outlet down on them and blast air from a can or air compressor into the valve you will burst the rubber valve diaphragm inside the valve!!!  You just want to gently blow any loose debris out of the ports and socket.   Now screw the solenoid back on hand tight.  Do not over-tighten it, do NOT use a wrench.  It has a seal so you don’t need to crank on it to keep it from leaking.  If you over-tighten the solenoid and force it too far in it will distort the plastic and the plunger will jam.  Now with the solenoid back on, don’t bother to rewire it yet.   Turn on the water and check to see if the valve works manually.  Sometimes the solenoids aren’t installed correctly and this is all it takes to fix the problem.  If the valve now works rewire it and you’re done.  If the valve still doesn’t work go to step 2.

  3. Remove the solenoid again.  Now remove the valve’s lid or cap.  The lid or cap may screw off like a jar lid, or it may be held in place with screws.  If it is the jar lid type you may need a strap wrench to remove the lid.  (They market these jar lids as “easy to remove”, I’ve found few of them actually are.)
    Solenoid Valve Lid Screws
    Solenoid Valve Lid Screws
    Remove lid screws or turn lid to remove if a "jar top" lid.
    Remove lid screws or turn lid to remove if a “jar top” lid.

    A rubber diaphragm sits under the cap and there is a spring between it and the cap, watch for the spring that it doesn’t get lost.  Be very careful not to let dirt get into the valve body while the cap is off, put a piece of kitchen cellophane wrap or something similar over it to keep out dirt.

    Remove the lid, watch that the spring does not pop out and get lost!
    Remove the lid, watch that the spring does not pop out and get lost!
  4. Once the cap is removed look at the cap.  There are tiny holes, called ports, that go from under the solenoid to the bottom side of the cap/lid.  Make sure none of those ports are blocked by a bit of manufacturing plastic or dirt.  You can use a tiny piece of wire to clean them, be very careful not to scratch the plastic or enlarge the hole.  Sometimes one of the ports is not drilled all the way through.  In that case the valve is defective, see your warranty information for how to replace the valve. I have known people who have successfully used a tiny drill bit held in their hand to very carefully drill a blocked port clean.  If you are very careful this may work, BUT it may void your valve’s warranty!   One guy had 6 valves all with the same partially drilled port, clearly a manufacturing error.  He drilled them by hand and every one of them worked afterward.  Your call on that one.

    Check the small ports in the lid for obstructions in them.
    Check the small ports in the solenoid valve lid for obstructions in them.  The shape and location of the ports varies with each valve make and model,  there will be two separate ports.
  5. The lid or the diaphragm may also have s small screen filter built into it.  Look carefully they are small and hard to see.  This is a feature found primarily on a few more expensive brands.  At the time I am writing this most Rainbird valves have a tiny filter molded into the diaphragm, so if it is a Rainbird valve be sure to look for it.  If there is a screen be sure it isn’t clogged up.  A toothbrush works good for cleaning the screens.

    Clean two sided white plastic filter with a toothbrush.
    Clean two sided white plastic filter in Rainbird valves with a toothbrush.
  6. Check the rubber diaphragm for any cracks, tears, rips, or holes in it.  It should be flexible and in very good condition.  If not, replace it.  Repair kits with replacement diaphragms are sold at some hardware stores, all irrigation stores, or may be obtained online.
  7. Reassemble the valve when you are finished cleaning the parts and checking for blocked ports.  Everything goes back in the same place it came from.  Be very careful not to get dirt into the valve when reassembling it.  Lubricate all the o-rings using standard KY Jelly (not the heating/stimulation types.)  Do not use oil or silicone lubricants!  KY Jelly is water-based and will not destroy the rubber seals like oil based products will.

    Standard KY Jelly, purchase at any drug store in the feminine hygiene dept.
    Standard KY Jelly, purchase at any drug store in the feminine hygiene dept.
  8. It should work correctly now.

Ads for Typical Repair Parts:

(Amazon has lots more repair parts, for many brands, this is just a start! Hardware & home improvement stores in some areas also carry valve repair parts for a few common models. Dedicated irrigation stores usually stock common brand parts and can order just about any brand or model.)

Valves Downstream from Anti-siphon Valve?

Q.  I have manual shut-off valves installed downstream from my electronic anti-siphon valves.  I installed them to turn off the water to parts of my yard where I grow annuals and only need to water for a few months out of the year.   I would really appreciate it if you would explain why valves downstream cause the anti-siphon valve backflow prevention to fail.

A.  If there are some sprinklers that are not shut off by the downstream valves (ie; there is always a sprinkler that will be on when the anti-siphon valve is on) then you should be fine.  The key to this is that when the anti-siphon valve is closed the water remaining in the pipe downstream of the anti-siphon valve MUST become depressurized.  Depressurizing normally occurs when you shut off the anti-siphon valve and the remaining water pressure in the downstream pipes is released through a sprinkler.   But if you have a valve downstream of the anti-siphon valve it will trap pressurized water in the pipe between the anti-siphon valve and the downstream valve and not allow it to “depressurize”.  Note that sprinkler heads with built-in check valves will also hold the water pressure in the pipe.  That is why when using anti-siphon valves you should remove the check valve from at least one of the sprinklers on each valve circuit (normally you would remove it from the sprinkler on the circuit with the highest elevation.)  the check valves are easy to remove from the sprinklers, normally you just unscrew the sprinkler cap and lift out the riser assembly.  You will see a rubber washer attached to the bottom of the riser assembly, pull it off.  That rubber washer is the check valve seal, with it removed the check valve won’t work.   Now reassemble the sprinkler.

How an anti-siphon valve works:
The  anti-siphon valve works by use of a little air vent that is located on the downstream side of the actual valve.  Look at the anti-siphon valve you will see there is a large cap directly above the water outlet of the valve, the air vent is under this cap.  If you look closely at the lower perimeter of the cap you will see holes or slits that allow the air to move in and out of the vent.  When the anti-siphon valve is turned off the pressure drops in the pipes downstream from it as the remaining water flows out of the sprinklers.  When the pressure drops the little air vent drops open and lets air into the pipe right behind the valve.   This air goes into the pipe and breaks any siphon effect (“anti-siphon”) so that sprinkler water can’t be drawn backward through the valve into the potable water supply.

(Water from the sprinkler pipes can be siphoned back into the water supply system when pressure is lost in the water supply system.  For example, the water company might depressurize their pipes to make repairs.  It doesn’t happen frequently, but it does happen.  When the pressure drops the flow reverses and water from the sprinkler pipes, along with dirt and other yucky stuff, can be sucked in through the sprinklers and then into the water supply system.  When the pressure returns that dirty sprinkler water may go back into the sprinkler system, but it may just as easily go to your kitchen or bathroom sink.  So why wouldn’t the closed anti-siphon valve stop this from happening?  After all the purpose of a valve is to stop water from flowing through it when it is closed, right?  Yes, of course, if the valve is a manual valve.  But electric solenoid valves are “directional” valves.  What that means is they are designed to stop the flow when the water is flowing in one direction only.  When the water flows backwards they don’t fully close!)

What the downstream valve does:
If you have another shut-off valve after the anti-siphon valve, then the water on the downstream side of the anti-siphon valve will stay pressurized even when the anti-siphon valve is closed.  This water pressure holds the little air vent in the closed position so it can’t let in air, and therefore the siphon effect is not broken.  This means the anti-siphon part of the valve will not work.  Even worse, when the little vent is held closed for days at a time due to the constant downstream pressure, it eventually just sticks in the closed position.  Then even if the pressure drops the anti-siphon won’t work.

My Friend or Irrigation Person Says This is All Just Something  YOU Made Up!
Unfortunately, this wrong practice of installing valves after an anti-siphon valve is pretty common in the irrigation industry.  I’ve been called some pretty ugly names over this issue.  Fortunately for me, you don’t have to take my word for it.  Tell your friend/buddy/pal to read the box the anti-siphon valve came in.  It says right on it “do not install valves downstream” or something similar.  If you don’t have the box or it didn’t come in one, then go to the manufacturer’s website and find the anti-siphon valve installation instructions.  You will find that same warning.  Here’s a sample from Rainbird if you want to check for yourself:  Rainbird Anti-siphon Valve Operation Manual. See the section that starts with the heading “CAUTION”.