Yard Line Leak or Slab Leak? Testing the Line From the Meter

When a water meter keeps moving with every fixture turned off, the water is escaping somewhere between the meter and the faucets. In most Texas homes that leaves two main suspects: the service line that runs underground from the meter to the house (often called the yard line) and the water lines inside or beneath the slab. These are different problems, handled in different ways, and one simple valve tells you which you have. This guide explains how.

Who owns which pipe

The water utility usually owns the meter and the pipe on the street side of it. The homeowner usually owns everything on the house side: the service line through the yard, the main shut-off valve, and all the plumbing inside and under the house. If the meter itself or the connection at the meter box is leaking, that's typically the utility's job to fix, so call them. Anything past the meter is generally yours.

Service lines in Texas homes may be copper, PVC, polyethylene, or in very old homes galvanized steel. They're often 30 to 100 feet long, and on rural or lake properties they can run hundreds of feet. Long lines have more places to fail, and clay soil movement, tree roots and construction work in the yard can all damage them.

The house shut-off test

Most homes have a main shut-off valve where the water line enters the house. In Texas it's often outside near a hose bib on the front or side of the house, sometimes in the garage, and in some newer homes in a small box near the foundation. Our guide on how to shut off your water main shows where to look.

1. Turn off every faucet, appliance and the irrigation system.
2. Confirm the meter's leak indicator is moving, so you know there is a leak to find.
3. Close the main shut-off at the house.
4. Watch the meter for 15 to 30 minutes.

If the meter keeps moving with the house shut off, water is escaping between the meter and the house. The yard line, or the house shut-off valve itself, is leaking.

If the meter stops, the yard line is holding water and the leak is inside the house. If no toilet is running and no fixture is dripping, a pipe under the slab or inside a wall is likely.

One caveat: old gate valves sometimes don't close completely. If the meter slows but doesn't stop, the valve may be passing a little water. A plumber can confirm with a pressure test.

Signs of a yard line leak

• A patch of grass that stays green or soggy, especially in a straight line between the meter and the house
• Water bubbling up near the meter box or along the driveway
• A sunken area or sinkhole in the yard
• Low water pressure throughout the house
• A wet meter box when it hasn't rained

Yard line leaks don't always surface. In sandy soil, water can drain away without ever reaching the surface. In clay, it may take weeks to appear.

Signs of a slab leak

• A warm or hot spot on the floor, usually from a hot-water line
• The sound of running water inside the house when nothing is on
• The water heater running more than usual
• Damp carpet, cupped wood flooring or a musty smell near an interior wall
• New cracks in tile or flooring along with a rising bill

How a yard line leak is found

When the shut-off test points to the yard line, a plumber will often check the main shut-off valve first, then trace the line's route with an electronic locator if the pipe is metal or has a tracer wire. Acoustic listening on the ground surface along the route finds the loudest point, which marks the leak. On plastic lines without a tracer wire, the route may be found by other means or by watching where the ground is wettest. Tracer gas also works well on yard lines because the gas rises through soil easily.

Because a yard line is under soil rather than concrete, reaching it is usually simpler and cheaper than reaching a pipe under a slab. But pinpointing still matters, especially under driveways, sidewalks and landscaping.

How a slab leak is found

When the shut-off test points inside the house, slab leak detection takes over. The plumber confirms the leak with a pressure test, closes the cold inlet at the water heater to tell whether the leak is on the hot or cold side, isolates individual lines where possible, traces the route of the leaking line, and pinpoints the leak through the concrete with acoustic listening, thermal imaging or tracer gas. The exact spot is marked on your floor and documented in a written report. Our process page walks through every step.

What if both are leaking?

It happens, especially in older homes on expansive clay, where soil movement stresses both the yard line and the lines under the slab. If you repair a yard line leak and the meter still moves with everything off, repeat the house shut-off test. A meter that stops with the house shut-off closed but moves when it's open means a second leak inside.

Long service lines on rural and lake properties

Properties around Texas lakes and in rural areas often have long service lines, sometimes several hundred feet. Some are on private wells instead of a city meter. On a well system, there's no meter to watch, so the plumber uses the pressure tank and pump instead: a pump that turns on when no water is being used, or pressure that drops with everything off, means a leak. Isolating the house from the well line works the same way as closing the house shut-off on a city system.

Common causes of yard line leaks in Texas

Several things damage service lines across the state:

• Clay soil movement. In North and Central Texas, expansive clay swells after rain and shrinks in drought, bending and pulling at buried pipe, especially where it connects to the meter or turns up into the house.
• Tree roots. Roots don't usually break into pressurized water lines, but they can lift, shift and crush them as they grow.
• Construction and digging. New fences, landscaping, sprinkler installation and utility work are common culprits. A fence post driven through a line can leak slowly for months.
• Aging pipe. Galvanized steel corrodes from the inside, and older polyethylene and polybutylene can crack at fittings.
• Freezes. Lines that run shallow, or come up above ground at the house, can split in a hard freeze.

Knowing whether any of these happened recently helps the plumber focus the search.

Water bill credits for yard line leaks

Many Texas utilities treat a leak in the customer's service line as a hidden leak that may qualify for a partial credit once it's repaired. Others limit credits to leaks inside the home or under the slab. Keep your invoices and ask your utility about its policy and deadline soon after the repair.

Questions to ask

Before booking any leak detection, it helps to know:

• Do you test the yard line and the house separately?
• What methods do you use to pinpoint the leak?
• Will I get a written report with the location marked?
• What's the price range before you arrive?

Our FAQs answer these and other common questions about detection visits.

Long yard lines are common on lake lots near Conroe, on larger properties in Rockwall and on the bigger lots around Katy.

The bottom line

The main shut-off valve at the house is the dividing line. With everything off, close it and watch the meter. If the meter keeps moving, the leak is in the yard line between the meter and the house. If it stops, the leak is inside, and when nothing above ground is leaking, it's time to test the lines under your slab. Knowing which side of that valve the leak is on tells you who to call and keeps anyone from digging in the wrong place.