How to Fix Underground Sprinkler Valves


Landscape contractors call underground valves in-line valves. This means the valves have an inlet and an outlet directly opposite of each other or the two line up in a straight line. Contractors group the in-line valves in a manifold with two or more valves or by themselves. Contractors bury the valves in the ground and then place a hard plastic valve box around it to protect the valves from dirt.

Things You'll Need

  • Eyeglass screwdriver
  • Round nose shovel
  • Phillips screwdriver
  • Pipe cutter
  • Teflon tape
  • 2 male adapters
  • Primer
  • Glue
  • Straight coupling
  • Tape measure

Replace the Top Half

  • Turn the valve on using the controller to isolate the problem. Place your fingers on the outlet portion of the valve or the part where the water comes out. If you feel the vibration of water running through the pipes when the valve is off, this indicates a bad solenoid, a torn diaphragm or clogged valve ports.

  • Open the flow control all the way and then close the flow control on top of the valve with your fingers. This might dislodge any debris causing the valve to stick open.

  • Use an eyeglass screwdriver to open the bleeder valve located on the bonnet of the valve. Turn the screw in the counterclockwise direction to turn the valve on. As soon as the valve comes on, turn the screw with the eyeglass screwdriver in the counterclockwise direction turning the valve off. This might also dislodge any debris causing the valve to malfunction.

  • Expose the valve that needs to be worked on with a round nose shovel. Dig down about 3 to 4 inches all around so you can see all the piping going in and out of the valve. Remove the valve box if there is one for better access.

  • Remove the top of the valve by unscrewing the bonnet screws with a Phillips screwdriver. Take the top to your local hardware store to buy the exact valve. All of the internal and moving parts to a valve lie in the top part of the valve, so replacing the top keeps from replacing the entire valve and more importantly keeps you from re-piping the valve.

  • Place the new top on the bonnet and tighten the valve screws with a Phillips screwdriver.

Replace the Valve

  • Replace the entire valve by cutting out the valve using a pipe cutter. This is necessary if the hardware store can not match your valve. You need to replace the old valve with a different one of the same size.

  • Wrap thread seal tape around two male adapters. Wrap the tape three times around the threads. Screw one male adapter to the outlet side and another to the inlet side by hand. Use channel lock pliers to tighten the adapters. Male adapters are threaded on one end and have a slip end on the other which allows the pipe to be inserted and glued.

  • Install a straight coupling to the end of the pipe on the inlet side of the new valve so the new piece of pipe can be glued in. Measure with a tape measure so that only one small piece of pipe is needed on the inlet side. Apply primer to both ends of the straight coupling. After it dries, apply the glue. Install new piping so the new valve can be inserted.

  • Apply primer to male adapters. When dry, apply glue and connect to pipe on inlet side. Apply primer and glue to other side and then insert the remaining pipe into the male adapter on the outlet side.

Tips & Warnings

  • Clean off any debris and dirt around the valve. When working on a valve, the work site needs to be clean so no debris gets sucked into the line and the valve.
  • Check set time on label before you turn water on.
  • Inspect for leaks after you install new valve.
  • Turn off water at the main-line before opening any valve.
  • Turn off the water at the irrigation shut-off valve or the main-line prior to working on the inside of the valve.

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