How to Repair a Leaking Anti-Siphon Sprinkler Valve

What You'll Need
Hack saw
Replacement anti-siphon valve for your sprinkler system
PVC Pipe and Couplers
PVC Primer
PVC glue

If the anti-siphon sprinkler valve on your sprinkler system is leaking, you may be able to stop the leak by simply tightening the screws on the valve with a screwdriver. However, more often than not, a leak in an anti-siphon valve will require that the valve be replaced. Fortunately, replacing a leaky anti-siphon valve on your sprinkler system is a relatively easy DIY task that you can perform in just a few minutes. This easy to follow how-to guide will show you everything you need to know.

Step 1 - Turn Off the Water

Turn off the water to the sprinkler system by shutting off the isolation valve from the water main or closing the main shut off valve where the meter is located. Usually, the water meter will be near the street or road in front of your home.

Step 2 - Saw Off the Pipe Connected to the Anti-siphon Valve

Take a hack saw and cut off the piece of PVC pipe that runs into the bottom of the anti-siphon valve. Many anti-siphon valves are also attached to the first sprinkler head in your sprinkler system. Therefore, you'll need to cut off the piece of PVC pipe that runs into the bottom of the first sprinkler head as well.

Step 3 - Purchase Replacement Anti-Siphon Valve

Take the old anti-siphon valve to your local home improvement center and purchase a replacement. If possible, purchase a replacement anti-siphon valve that is the exact same size as the old one. However, if you're unable to find a replacement that is the exact same size, you may be able to use a PVC reducer coupler to help match up an anti-siphon valve that uses a PVC pipe of a different size. If you are unsure, ask someone in the plumbing department as they should be able to help you.

Step 4 - Cut Pipe and Attach Couplers

Now that you have your replacement anti-siphon valve, you can begin installing it. First, you'll need to make up for the pipe height that was lost by cutting the piece of PVC pipe when you removed the old valve (the anti-siphon valve needs to be higher than the sprinkler heads). So, first attach a coupler to the top of the sawed off PVC pipe. Use PVC primer and glue on the edges of the pipe and inside the coupler. Then, cut off a short 2 or 3-inch section of PVC pipe and insert it into the coupler. Do the same on the piece of pipe that is used for the first sprinkler head.

Step 5 - Install New Anti-siphon Valve

After you've installed the new couplers and PVC pipe pieces, you can go ahead and install the anti-siphon valve. To do this, you just need to use some primer and glue on the top of the pieces of PVC pipe and inside the fittings of the valve. Press the valve fixture onto the two pieces of PVC pipe that you sawed earlier. Make sure the first pipe goes into the anti-siphon side of the fixture and the second piece goes into the first sprinkler head that is attached to the anti-siphon valve.

Step 6 - Turn On the Water

Turn the water back on and test the installation. If you have followed the above instructions, the new anti-siphon valve should not leak.