How to Replace an Irrigation Valve

Inspect the valve and determine the size of the valve. Measure the inside diameter of the inlet to the valve with a tape measure. Turn off the water to the valve at the main. This will isolate the valve and allow work to be done. The size of the valve will determine your pipe size and fitting sizes.

Valves in a valve box need to be dug out with a shovel. If the valve is located above ground, go to Step 7. Dig around the valve so that you have adequate room to work and expose piping on the inlet and outlet sides of the valve. This may involve removing the irrigation box and setting it aside.

In-line valves sit between the inlet and outlet piping. Cut the valve free of the pipe on the outlet and inlet sides with a pipe PVC cutter. Cut 6 inches out from the inlet and outlet. This will give you room to glue in new piping. Remove the old valve and set it aside.

Rebuild the inlet and outlet piping for the new valve. Primer a straight coupling/slip on the inlet and outlet side. The slip means that the coupling is not threaded on either side and pipe can be slipped on and then glued. Cut two pieces of pipe approximately 6 inches long. Primer these pipe pieces and when dry. Then apply glue and insert the pipe into the straight couplings.

Prepare the valve for insertion. Wrap Teflon tape three times around the threads of the two male adapters. Screw the male adapters into the inlet and outlet sides with channel lock pliers. Primer the male adapters and wait for them to dry prior to gluing them to the pipe.

Check the fit of the valve. Place the valve between the two pipes to check this fit. Cut any excess pipe and then glue the valve into place. Check the label for glue setting times before testing.

Anti-siphon valves are easier to fit because they lie on top of the inlet and outlet pipes; this eliminates Step 3. To replace anti-siphon valve, cut it with pipe cutters. Make the cut as close to the inlet and outlet of the valve. Complete Step 5 and then check that your valve remains 6 inches above the highest sprinkler. If not, you will need to raise the piping.

Glue the new valve onto the inlet and outlet pipe and follow the instructions for set time on the glue before testing for leaks.