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What To Do When Your Sprinkler System Leaks While Turned Off

So your sprinkler system is off, but your sprinklers are still leaking water. The two most likely culprits are a leaking valve or low head drainage. But which is it?

The main difference between Low Head Drainage and a leaking valve is that Low Head Drainage results in water leaking from the lowest elevated sprinklers for a while after they run, but then the leakage stops after the pipes are fully drained, which may take several hours. If a valve is leaking, then the leakage will continue to flow all the time without stopping. Look for moss or algae growing on the walkway or the curb. This is a common sign that your control valve is leaking.

Picture of a Sprinkler Spray and that is leaking with the valves off.
illustration of a valve

How To Fix A Leaking Valve:

  1. Disassemble the leaking sprinkler valve
  2. Clean it
  3. Replace any worn or broken parts
  4. Reassemble the valve
  5. If necessary replace the valve with a new one

Shop for valves and repair parts here.

How To Stop Low Head Drainage:

When water continues to flow from one or more sprinkler heads for a few minutes after you turn your irrigation system off, it’s Low Head Drainage. Usually, this occurs when an irrigation system has been installed on a slope. A difference in elevation of less than a foot, within a zone, will often create Low Head Drainage. Once the sprinkler zone shuts off, the water in the pipes drains out via the lowest sprinkler head within the zone and the pipe fills with air.

To stop Low Head Drainage, you need to have special anti-drain valves installed at the sprinkler heads. Now in some cases valves are built into the sprinkler head. It is an optional feature when you purchase the sprinkler and is available on most major brands of sprinklers. Most people just simply purchase a new sprinkler head with the check valve feature and replace the old with the new.

Rain Bird 1804 SAM with built-in check valve.

Hunter Adjustable Arc CV Rotor with built-in check valve.

Another option to stop leaking sprinklers is purchasing separate check valves. You can install them on the pipe under the existing sprinklers. Although much harder to install, it will accomplish the same goal. You will need to dig up the sprinkler head, remove it, install the new check valve on the riser and then screw the old sprinkler back into the new check valve.

You will then need to lower the sprinkler head to the appropriate level since the check valve will raise the sprinkler about 3 inches. The pressure typically drops about 2-5 psi in this instance.

If you are looking for irrigation angle valves, you can find them here. Angle valves have a 90-degree angle between their inlet and outlet pipes.