How to Test an Underground Sprinkler for Leaks

Locate your water meter. The meter has a glass case around the dial and may be located on the side of your house or in an underground meter box. If the meter is underground, use a screwdriver to remove the screw in the lid and pull the lid off to expose the meter.

Turn off all devices inside and outside of your home that use water. This includes faucets, showers, hoses, washing machines and dishwashers. Turn off the underground sprinkler system. This usually involves shutting off the controller and the two valves at the double check valve assembly; check the manufacturer's installation instructions for your particular system. It is critical that no devices are using water during the leak test.

Look at the meter and note if there is a small colored triangle or round disc on the dial, often referred to as a "leak indicator." If it is moving, it means there is water running somewhere along your plumbing. Since you have turned off all the water sources, this would indicate a leak. If your meter does not have such a device, look to see if the hand on the dial is moving. If so, that indicates a leak is present somewhere in your plumbing system. Proceed to Step 5. If neither the leak indicator nor the dial hand was moving, continue to Step 4.

Confirm your findings. Note the position of the dial hand on a piece of paper. Wait 10 minutes and return to the meter and note the position of the dial hand again. If the position of the dial hand remains the same, you have no leak anywhere. If the hand has moved position, this indicates the presence of a slow leak. Continue to Step 5.

Turn off the main water valve. It is generally placed near the meter or where the water line enters the home. Recheck the meter. If the dial hand or leak indicator has now stopped moving once the main water valve has been shut off, this indicates that the leak is located in the house. If the dial hand or leak indicator is still moving, this shows that the leak is outside.

Turn the main water valve back on. Immediately check the water meter again to see if the leak indicator or dial hand has stopped moving. If it has, then the leak is located in the sprinkler system.

Follow the layout of the sprinkler system and look for any wet spots or pooled water on the surface, which will indicate the site of a leak. Check for broken drip emitters and sprinkler heads as well.