Valve Won't Close (Stuck On)
A valve stuck open keeps water running continuously on one zone. This is usually caused by debris under the diaphragm or a torn diaphragm that can't seal.
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Symptoms
- One zone runs continuously even when the controller is off
- Water keeps flowing from sprinkler heads after the zone should have stopped
- High water bill
Diagnosis
Debris (pebble, grit) is lodged under the diaphragm preventing it from sealing against the valve seat, or the diaphragm is torn/warped.
Step-by-Step Repair
- 1
First, make sure the solenoid is fully tightened (clockwise). A loose solenoid bleeds water and holds the valve open.
- 2
Check that the manual bleed screw is fully closed.
- 3
If the valve still runs, shut off the main water supply to the irrigation system.
- 4
Remove the valve bonnet screws and lift the bonnet off.
- 5
Remove the diaphragm and inspect the rubber seal and the valve seat for debris, cracks, or wear.
- 6
Clean the valve seat thoroughly. Remove any sand or pebbles.
- 7
Replace the diaphragm if it is torn, warped, or has visible wear on the sealing surface.
- 8
Reassemble and restore water. The zone should now stop when the controller signals it off.
Parts Needed
- •Zone Valve (or diaphragm rebuild kit) × 1
Pro Tips
- A tiny grain of sand is enough to keep a valve from sealing. Inspect carefully.
Prevention Tips
- Flush lateral lines after any pipe repair — debris travels downstream into valve seats.
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