An Underground Water Leak at a House

Testing the Plumbing

• When you notice that a water leak has started underground, first determine the source of the leak. Some of the house’s pipes run underground, as does the water supply pipe. You may employ a simple test to determine if the plumbing is the source. First, turn off anything in your house that uses water, closing the shutoff valves for toilets and sinks and turning off your freezer’s ice maker. Take note on your house’s water meter where the needle points. Wait 30 minutes and then check where the needle is pointing. If the needle has not moved, then the plumbing is not the source of the leak.

Supply Pipe Testing

• The supply pipe that runs from the municipal water system to your house’s plumbing sits underground and could be the source of the water leak. To test if the supply pipe is the cause, you must close the main valve. Watch the water meter for another 30 minutes to see if the needle moves. If you see any movement in the needle, the supply pipe is the source of the leak. A professional plumber must dig around the supply pipe to locate and repair the leak.

Sprinkler System

• If your house has an underground sprinkler system or a water supply pipe that runs underground to a hot tub or swimming pool, you need to investigate the possibility of the sprinkler system being the source of the leak. Locate the main valve for the sprinkler system and use the long key to close the valve. Test that the water is shut off by turning on the sprinklers. Watch the area of the leak, as well as the water meter, for half an hour to see if the leaking continues.

Pipe Leak Sources

• Underground pipes may leak for a number of reasons. A pipe that sits next to a rock can rub against the surface of the rock constantly, as the water in the pipe shakes or shifts it. The rubbing eventually ruptures the pipe, leading to the leak. If the pipe is newer, improper installation such as loose joints between the pipes can also lead to leaks. If water is left in sprinkler pipes during the winter, the water may freeze and cause the pipes to split. Pipes also eventually wear out, giving way to corrosion or the constant pressure from being underground.