Detecting Water Leaks Underground in Laguna Hills, CA

Underground leaks hide because soil absorbs water. The first sign is often your bill, not a puddle. By the time a lawn goes soft, the leak may have been running for weeks.

The good news is that a few simple checks tell you whether a leak exists before you call anyone.

Signs of a buried leak

• A water bill that rises with no change in how you live.
• A lawn patch that is green, soft or sunken while the rest is normal.
• Low pressure at every faucet in the house.
• The sound of running water when everything is off.
• A meter box that is full of water.
• Warm water in the ground over a hot water line.

A meter test you can do in two minutes

1. Turn off

   Shut off every tap, appliance and irrigation system that uses water.

2. Read

   Open the meter box and look at the small leak indicator or the dial.

3. Wait

   Check again after fifteen minutes without using any water.

4. Compare

   If the indicator spins or the numbers rose, water is leaking somewhere.

To tell if the leak is before or after the house shutoff, close the main valve at the house and check the meter again. If it still moves, the leak is in the buried line between the meter and the house.

How a plumber locates the leak

A pressure test confirms that the line is losing water. Acoustic equipment then listens along the pipe route for the hiss of escaping water. A ground microphone on the surface finds the loudest point, and a correlator can pinpoint the leak between two contact points.

Leak location follows industry practice for pressure testing, and repairs follow the Uniform Plumbing Code (UPC) as California adopts it. Once the spot is found, a small excavation exposes the pipe. That keeps digging, and the repair to your yard, as small as possible. Our leak detection service uses this method.

What a repair involves

For a full run of failed pipe, see water service line repair.

Irrigation leaks versus service line leaks

A yard has more than one water line. The service line brings water from the meter to the house, and the irrigation system has its own pipes and valves. A wet patch near a sprinkler head is more likely an irrigation leak, and a wet patch along the path from the meter to the house is more likely the service line.

To separate them, close the irrigation shutoff or the irrigation backflow valve, then repeat the meter test. If the meter stops, the leak was in the irrigation system. If it keeps moving, the service line or the house plumbing is losing water.

Write down the meter reading before bed and again in the morning. If no one used water overnight and the number changed, a leak is running while you sleep.

How long a leak can run before it shows

A small underground leak can run for months. Soil absorbs the water, and the pipe may sit deep enough that nothing reaches the surface. A leak of only a few gallons an hour adds up to a large volume over a month.

That is why bills matter. Compare this month's use to the same month last year, and call your water district if the difference has no explanation. Early detection costs less than a repair that follows months of soil washout.

What to do while you wait

If the line serves a home in Laguna Niguel or Laguna Woods, tell the dispatcher so the correct district is contacted.

Local questions, answered

Written by the Laguna Hills Express Plumbing team. Last updated November 10, 2026.