A low head that drains briefly after watering may be releasing water left in the lateral pipe. Flow that continues for a long time—or several heads on one zone that keep seeping—usually points to a zone valve that is not sealing.
Match the pattern before opening anything
| Possible cause | Best clue | First check |
|---|---|---|
| Low-head drainage | Lowest head drips briefly, then stops | Time how long drainage lasts |
| Weeping zone valve | Several heads seep long after shutdown | Shut off irrigation water and compare |
| Mainline leak | Wet area remains with controller off | Observe with irrigation supply isolated |
| Damaged head or riser | Leak appears only while the zone runs | Expose and inspect the head connection |
Check these in order
- 01
Time the leak
After the watering cycle ends, note whether the flow slows and stops. Brief drainage at the lowest elevation differs from a steady valve-fed seep.
- 02
Count affected heads
One lowest head favors drainage. Multiple heads in the same zone favor a valve that cannot seal because of debris, diaphragm damage, or a loose manual bleed.
- 03
Isolate irrigation water
If you know the dedicated irrigation shutoff, close it and observe. A leak that stops supports an irrigation-side fault. Do not operate an unfamiliar backflow assembly as a substitute shutoff.
- 04
Choose the correct repair
Use a check-valve head for recurring low-point drainage. For continuous seepage, service the zone valve rather than repeatedly replacing the lowest head.
- Water continues near the foundation or a paved surface.
- The irrigation shutoff cannot be identified.
- The valve must be rebuilt and its exact model is unknown.
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