How to Fix a Leaky Sprinkler Valve and Get Your Irrigation System Back on Track

Before you begin working on your sprinkler system, make sure there’s no water or electricity flowing through it. Start by cutting off your sprinklers’ water supply at the system’s main shut-off valve. 

Not familiar with your irrigation system’s shut-off valve? It’s typically a ball valve attached to a copper pipe that goes into your home at ground level and may be in a utility room, crawl space, or basement. If it’s not in any of these places, look for it outside, buried in your irrigation control valve box.

After that, shut off the power to your sprinkler system at the circuit breaker box.

Your next step is to open the valve box that houses the problematic valve. You can usually lift it from the corners, but if you have trouble opening it, look for a slot on the side to insert a screwdriver and pop the lid off.

Depending on the setup of your sprinkler system, there may be multiple valves in one valve box. Before proceeding with the next steps, make sure you know which valve is faulty. If only one valve is clearly wet or dripping into the valve box, that’ll be easy. However, identifying the right valve is a little tricker if your only clue is that the sprinklers in its zone won’t turn off or if there’s low water pressure in that zone.

To figure out which valve corresponds to that zone, you’ll first need to turn on the water and power again. Then, going valve by valve, gently twist the solenoid on each valve (which will activate its respective sprinkler zone) until you find the irrigation valve that controls the zone that won’t shut off.

With the water and power disconnected, remove the solenoid from the sprinkler valve. Usually, this just involves unscrewing it in the counterclockwise direction.

Using a soft, damp cloth or gentle brush, clear any dirt or debris from the solenoid and the opening where it sits in the valve.

In some cases, just washing off the solenoid might fix the problem. But while you’re in the valve box, it’s a good idea to clean out the sprinkler valve as well.

To do this, take off the top of the valve, either by untwisting it or removing its screws or bolts. Set these parts aside on a clean cloth. Then, continue disassembling the valve by removing the diaphragm, spring, and o-ring and placing them on the cloth as well. (It’s important to put these pieces back together in the right order, so if it helps you remember, snap a photo with your smartphone or jot down some notes with a pencil and paper.)

Take your damp cloth or brush to clean each of these parts. If anything looks particularly worn down, you may need to buy a replacement.

When all of the pieces are clean, rebuild the valve together and place it into the valve box. Next, switch on the power and slowly rotate the shut-off valve to turn on the water again. 

Using your irrigation system controller, turn on the sprinklers in the faulty valve’s zone and head outside. Hopefully, your original problem—for example, a leaky valve or low water pressure—is solved. But if the issue persists, you may need to replace the solenoid.

Make sure the water and power is turned off before replacing the solenoid.

At the valve box, disconnect the wires from the top of the solenoid, taking a picture or writing down where each one goes so that you can reference it later. Remove the solenoid from the valve and set it aside. Attach the wires to the new solenoid and insert it into the valve. Put the valve back in the valve box.

Slowly turn on the water and flip on the power before testing the sprinklers again. If it still doesn’t work, it’s time to call an expert.