How to Find an Underground Water Leak

The water line from your meter to your house is out of sight and out of mind until it leaks. Because the water drains into the soil, an underground leak can run for months. Here’s how to confirm one, narrow down where it is, and avoid digging up the whole yard.

Signs of an underground water leak

• Soggy, spongy or sunken ground between the meter and the house
• A strip of grass that’s greener or grows faster than the rest
• Water pooling near the meter pit or where the line enters the house
• Low water pressure throughout the house
• Muddy or cloudy water, or air sputtering from faucets
• A higher water bill with no change in use
• The water meter moving while nothing is running

Step 1: The shutoff test

This test tells you, for certain, whether the leak is in the buried line.

1. Turn off all faucets, appliances and the irrigation system.
2. Check the water meter. If it’s moving, there’s a leak somewhere.
3. Close the main shutoff valve where the water line enters your house. It’s often in the basement, a utility room, a crawl space or near the water heater.
4. Watch the meter again for 15–30 minutes.

Result	What it means
Meter stops	The leak is inside the house (fixtures, walls or under the slab)
Meter keeps moving	The leak is in the buried service line between the meter and the house, or in an irrigation line that tees off it

If you have a sprinkler system, close the irrigation valve too. A leak in the sprinkler mainline looks the same on the meter. See how to find a sprinkler leak.

Step 2: Trace the line’s path

You can’t find a leak on a line you can’t locate. The service line usually runs in a fairly straight path from the meter to the point where it enters the house. Walk that path and look for:

• wet, soft or sunken soil,
• grass that’s greener or lusher,
• water surfacing at a driveway joint, sidewalk crack or the foundation.

Keep in mind: water travels. In sandy soil or along the gravel bed around the pipe, the wet spot can appear a few feet from the actual leak, or not at all.

Step 3: Pinpoint without digging

Once the leak is confirmed in the service line, the goal is to mark the exact spot so only one small hole is dug. Professionals use:

• Acoustic listening: a ground microphone is moved along the line to find where the leak noise is loudest.
• Leak noise correlator: sensors at two access points, such as the meter and a hose bib, calculate the leak’s position from the noise’s travel time.
• Tracer gas: for PVC, PEX and poly lines, which carry sound poorly, the line is filled with a safe hydrogen/nitrogen mix that rises through the soil above the leak.
• Line location: mapping where the pipe actually runs, which is not always where you’d expect.

Read the details in how professional leak detection works.

What causes underground water line leaks?

• Freeze–thaw cycles and frost movement in central Indiana winters
• Tree roots wrapping or pressing on the line
• Age and corrosion, especially in older galvanized or copper lines
• Failed fittings on plastic lines
• Soil settling or heavy loads, such as vehicles over a shallow line
• Construction or landscaping damage

Who’s responsible for the leak?

In most areas, the homeowner owns the line from the meter to the house, and the utility owns the meter and the line up to it. If the leak seems to be at or near the meter, contact your water utility first. Rules vary, so confirm with your provider.

Get the leak marked

If the shutoff test points to your service line in Bargersville or elsewhere in Johnson County, our underground water leak detection service traces the line and marks the leak on your lawn, so your plumber digs once, in the right place.