If water keeps flowing after the controller is switched off, the controller is no longer commanding the valve. The usual cause is a valve held open by debris, a damaged diaphragm, a loose solenoid, or an open bleed screw.
Match the pattern before opening anything
| Possible cause | Best clue | First check |
|---|---|---|
| Manual bleed left open | Problem began after valve work | Inspect bleed screw and solenoid position |
| Debris on valve seat | Zone started sticking after supply work | Shut water off before valve service |
| Torn diaphragm | Valve cannot seal after cleaning | Match replacement to exact valve model |
| Controller output stuck on | Valve closes when controller wire is removed | Have the terminal output tested |
Check these in order
- 01
Turn the controller off
Set the controller to OFF rather than merely cancelling a program. If flow continues, treat the problem as a mechanical valve fault until testing proves otherwise.
- 02
Stop the irrigation water
Use the dedicated irrigation shutoff if its identity and operation are known. Avoid forcing old handles or dismantling a backflow preventer under pressure.
- 03
Check external valve controls
With water off, verify that the manual bleed is closed and the solenoid is seated according to the manufacturer. Do not overtighten plastic parts.
- 04
Inspect internally only when matched
Photograph the valve orientation, identify its model, and use the correct diaphragm kit. Springs and ports must return to their original positions.
- You cannot stop the water promptly.
- The shutoff, backflow device, or valve is cracked.
- Water is approaching the house, street, or electrical equipment.
Sources and review notes
General maintenance logic is checked against EPA WaterSense outdoor irrigation guidance. Product controls and disassembly steps vary by model; use the current manufacturer manual for your exact valve, controller, or sprinkler head.
Published and last reviewed: August 26, 2026