How to Fix a Leaky Lawn Sprinkler

Turn off the water to the irrigation system. Shut off the electrical power to the sprinkler system as well.

Open the system's valve box. Use a hand trowel to clean out any mud accumulated there. Stuff some rags inside the box to absorb any water that remains.

Remove the wire connectors on the low-voltage electrical line. Twist the solenoid valve loose by hand. Hold it so that any water inside it drains out.

Use a screwdriver to take the bonnet, or top, off the solenoid. Remove the spring and diaphragm gasket that sit on the solenoid valve. Don't allow the spring to fall out of the solenoid as you open it. Put the spring and the screws in a safe place.

Examine the diaphragm gasket for damage. You may not need to replace the gasket if it has no visible damage. Wipe it off and look for small pieces of debris that may be preventing the solenoid from operating properly. If necessary, place a new gasket on the solenoid valve. Set the spring on top of it. Replace the bonnet. Tighten the screws on the bonnet by turning them clockwise.

Twist the solenoid back into position in the valve box. Use waterproof wire nuts to reconnect the low-voltage electrical line.

Remove the rags from the valve box. Fill the box with clean, crushed rock. Close the valve box.

Turn the electrical supply and water back on to the sprinkler system. Check for leaks.