Fixing Sprinkler Head Leaks: Low-Head Drainage vs. Valve Issues

If you're noticing water pooling around certain sprinkler heads throughout the day—especially after the system has run—you're likely dealing with one of two common issues. The solution depends on whether the leaking heads are at the lowest point of your system.

Low-Head Drainage (Most Common on Slopes)

If your property has a slope and water leaks from the lowest sprinkler heads, you're experiencing low-head drainage. This happens because gravity pulls residual water out of the pipes through the lowest heads after the zone shuts off. The fix is straightforward: install sprinkler heads with built-in check valves (sometimes called "SAM" or "seal-a-matic" heads). These prevent water from draining out when the system is off.

Leaky Control Valve

If the leaking heads aren't at a low point, the problem is likely a faulty zone control valve that isn't sealing completely. To fix this:

1. Shut off the main water supply to the irrigation system.
2. Disassemble the problematic valve (typically in a valve box).
3. Thoroughly clean all internal components, paying special attention to the area under the solenoid.
4. Inspect the rubber diaphragm for tears, holes, or deterioration—replace if damaged.
5. Reassemble the valve and test the zone.

Most valve leaks stem from debris preventing the diaphragm from sealing or a worn diaphragm. Regular maintenance and cleaning often resolve the issue without needing a full valve replacement.