Why Are My Sprinkler Heads Leaking When the System Is Off?

A sprinkler head that leaks after the system shuts off is usually caused by low-head drainage or by an irrigation valve that is not sealing completely. The timing, duration and location of the water help distinguish normal drainage from a valve problem.

What is low-head drainage?

Water remaining in a zone’s lateral piping can move downhill after the valve closes. The lowest sprinkler head may continue dripping or draining until that trapped water is gone. This usually tapers off rather than continuing indefinitely under full pressure.

When leakage points to a valve problem

If water continues for a long time, returns repeatedly between watering cycles, or several heads remain pressurized, the zone valve may be allowing water to pass when it should be closed. Debris, diaphragm damage or internal wear can prevent a valve from sealing.

See how to tell if a sprinkler valve is bad and why a sprinkler zone keeps running.

Why only the lowest head may leak

Gravity sends residual water toward the low point. That is why a single downhill head can drain even though the valve has closed correctly. Check valves in compatible sprinkler heads can sometimes reduce this type of drainage.

What homeowners should observe

  • How long the leaking continues after shutdown.
  • Whether the water gradually slows or remains pressurized.
  • Whether the leaking head is at a low point in the yard.
  • Whether the problem occurs after every watering cycle.
  • Whether the valve box is also wet.

Could a broken pipe cause this?

A downstream leak can create wet soil while a zone runs, but persistent water emerging from a sprinkler head while the zone is supposed to be off more directly raises the question of drainage or unwanted flow through the valve.

When repair makes sense

If leakage does not taper off, creates recurring puddles, or appears to be pressurized, valve diagnosis makes sense. Fort Mill Irrigation provides sprinkler valve repair and sprinkler head and nozzle repair.

Frequently asked questions

Is a little dripping after watering normal?

It can be, especially from the lowest head on a sloped zone. Normal drainage should eventually stop.

Can a bad valve make one head leak?

Yes. A small amount of water passing through a valve can travel to the lowest outlet and appear at only one head.

Does replacing the sprinkler head fix it?

Not if the actual problem is unwanted water passing through the zone valve. The source of the water should be identified first.

Need help with sprinkler heads that leak when the system is off in Fort Mill or a nearby community? Call or text Fort Mill Irrigation at (803) 710-8008.