How to Stop a Sprinkler Valve That Won't Shut Off
If you notice water slowly seeping from a sprinkler zone or pooling near the valve box when the system is supposed to be off, you have a valve that isn't sealing. Unlike a zone that fully runs, this is a slow weep — but it wastes water around the clock. Here's how to stop it.
Why a valve leaks when closed
When commanded off, a healthy valve's diaphragm presses against its seat to stop all flow. A slow leak means something is preventing a complete seal:
- Debris on the seat: a grain of sand or grit holds the diaphragm open slightly.
- A worn or warped diaphragm that no longer seals fully.
- A scratched or damaged valve seat.
- Slightly high pressure forcing water past a marginal seal.
How to fix it
Shut off the irrigation water, then open the top of the valve (the bonnet). Clean out any debris from the diaphragm and seat, inspect the diaphragm for wear or warping, and replace it if needed — it's a low-cost part. Reassemble, turn the water on slowly, and confirm the weeping has stopped.
Check the flow-control and pressure
Some valves have a flow-control adjustment; make sure it isn't holding the valve cracked open. If excessive pressure is the issue, a pressure regulator may help. Persistent leaks after a new diaphragm can mean a damaged seat, requiring valve replacement.
When to call a pro
If cleaning and a new diaphragm don't stop the weep, our irrigation team can rebuild or replace the valve.
Frequently asked questions
Why does my sprinkler valve leak when the system is off?
Something is preventing a full seal — usually debris on the seat or a worn diaphragm. Cleaning or replacing the diaphragm typically fixes it.
Is a weeping valve worth fixing?
Yes — a slow constant leak wastes water 24/7 and keeps soil soggy. The fix is usually quick and cheap.
Arbol Roble has cared for Inland Empire landscapes since 1997, serving Rancho Cucamonga, Ontario, Fontana, Eastvale, Corona and Riverside. Request a free quote or browse our residential and commercial services.
About the Author
The Arbol Roble team are licensed landscaping and irrigation professionals (CSLB License #1077455) serving Rancho Cucamonga, Ontario, Fontana, Eastvale, Corona, Riverside, and the greater Inland Empire.