Slab Leaks in North Texas Homes: Signs, Damage and Who Fixes What

What is a slab leak, and how do you know you have one?

A slab leak is a leak in a pressurized water line (or sometimes a drain line) that runs through or under a concrete slab. Clues include a warm spot on the floor, a water meter that moves with every fixture off, the sound of running water in a quiet house, an unexplained bill increase, or damp flooring and baseboards.

Most North Texas homes are built slab-on-grade, which means the house sits on a concrete pad poured at ground level instead of over a basement or a crawl space. In a slab house, some water lines run in the attic and the walls, and others run through or under the slab itself. When one of the buried lines leaks, nothing drips from a ceiling and nothing pools in a basement. The water goes into the ground and the concrete, and it shows itself sideways.

That is why the signs are indirect, and why people talk themselves out of them. A hot-water line leaking under the slab can warm a patch of floor you notice with bare feet. Water that finds a seam in laminate or a gap at a baseboard shows up as swelling, cupping or a musty smell. If you hear a faint hiss or running sound with every tap closed, that is worth taking seriously.

The cleanest test you can do yourself costs nothing. Turn off every fixture, the ice maker and the irrigation system, then look at your water meter. If the dial or the small leak indicator is still moving, water is going somewhere. Take a photo of the reading, wait an hour without using water, and look again. Your meter is usually in a box near the street, and you should know where your main shut-off valve is before you ever need it.

• A warm or hot area on a floor that is not over a vent or a heater
• A water meter that keeps moving with every fixture off
• The sound of running or hissing water when the house is quiet
• A water bill that rises with no change in how you use water
• Damp, buckled or discolored flooring, or wet baseboards
• A musty smell that returns after cleaning

Why do slab leaks happen in North Texas?

Lines under a slab can fail from age, corrosion, poor installation, or rubbing against concrete and gravel, and North Texas soil can add stress. Much of the region sits on expansive clay that swells when wet and shrinks in drought, so slabs can move and strain lines. Movement is only one possible cause.

Plumbers describe several ordinary causes: a pipe that has corroded from the inside or outside, a joint that was never seated well, a line rubbing against rock or the edge of a slab, or water pressure that is higher than the system likes. These happen in every part of the country. They are not specific to Texas.

What is more specific to this region is the ground. The Blackland Prairie, a belt of heavily clay soil that crosses much of North Texas, is described by geologists as holding some of the most expansive clays in North America, and these clays take on water between their mineral layers and change volume as moisture shifts. A slab sits in the zone where that movement is greatest. In a dry summer the soil shrinks and the slab can settle unevenly. After heavy rain, the soil swells again.

Who fixes what: the plumber, the foundation contractor and the drying crew

A licensed plumber locates and repairs the leaking line, whether by spot repair, re-routing or re-piping. A foundation contractor or structural engineer evaluates slab movement or settlement. A restoration crew extracts water, removes wet materials and dries the house. This site covers only the drying and cleanup, not the plumbing or foundation work.

Homeowners are often pitched all three jobs by one company, and it helps to know the lines between them. In Texas, plumbers are licensed by the Texas State Board of Plumbing Examiners, and you can ask any plumber for a license number and look it up. Locating a slab leak (with acoustic or thermal methods), repairing it through the slab, tunneling beneath the house, or abandoning the line and re-routing it through the attic are plumbing decisions.

The crew's part starts where the water has already gone. It shuts off water where that is safe to do, extracts standing water, uses moisture meters and thermal tools to find hidden moisture, removes flooring and baseboards that cannot be saved, sets air movers and dehumidifiers, and keeps checking until the materials read dry. It can give you photos and moisture readings to share with your insurer. Our emergency-stage price is explained and approved before drying starts, and repairs after drying are quoted separately.

Sequence matters. The plumber usually stops the leak first, because drying a floor while a pipe is still feeding it is wasted effort. If you can reach the main valve and shut it, do so right away. The slab leak water damage service page covers the drying side, and the burst pipe water damage page covers leaks in walls and attics.

What does a slab leak do to flooring, walls and the house?

Water from a slab leak travels up through flooring seams, wicks into the bottom of drywall and baseboards, soaks carpet pad and swells wood or laminate. Tile may survive with the water cleaned out from under it. If materials stay damp, mold can begin, so drying and moisture checks matter even when the stain looks small.

In a slab house the concrete is the lowest surface, and the water has to go somewhere once the soil beneath is saturated. It rises along expansion joints, plumbing penetrations and the edges where the slab meets the walls. From there it moves into whatever is sitting on the slab: flooring, tack strips, baseboards and the bottom few inches of drywall.

How each material responds is predictable. Carpet and pad hold water, and pad is usually removed because it is not worth drying. Laminate and engineered wood swell at the seams and often cannot be saved. Solid hardwood can cup. Tile and the concrete usually come through, though water can sit under the tile and in the grout lines. Drywall wicks upward, which is why crews cut it away a couple of feet up the wall to let the cavity dry.

Then there is mold. The EPA's advice is to dry water-damaged areas within 24 to 48 hours, which is a guideline and not a deadline. A slab leak is hard to meet it, because the leak may have been running for days or weeks before anyone noticed. Mold may already have grown behind baseboards or under flooring even if the materials can still be dried. In Texas, mold assessors and remediators are licensed separately by TDLR, and larger jobs generally need a licensed assessor and a different licensed remediator. See the mold after water damage guide for the rules.

What does the water-damage side of a slab leak cost?

Our working estimate for slab leak water damage mitigation, covering extraction, drying, and removal of flooring and baseboard, is $1,500 to $6,000. The plumber's leak repair is not included, and rebuilding after drying is quoted separately. The number is an estimate that is confirmed on site, after a technician reads the moisture.

Your plumber's bill is the other half of the problem and is separate, from a separate trade. The same is true of any foundation work. The water damage restoration cost guide lays out the whole line-item table, including repairs after drying.

Because insurance may be involved, document before you change anything. Photograph the meter reading, the wet areas and any damage before materials are removed, and keep your plumber's report. Your insurer decides coverage, and a policy may treat a leak under the slab, and any foundation damage, differently from a burst pipe in a wall.

What should you do in the first hour?

Shut off the water at the main valve, stay off wet floors near outlets and appliances, and turn off power to the area only if you can reach the panel safely. Photograph the meter and any damage, call a plumber to locate the leak, and call your insurer early. Then call for water removal.

Start with the main shut-off. It is usually where the water line enters the house, often near the water heater, in a garage or at an exterior wall, and many homes also have a shut-off at the street meter. A slab leak is pressurized, so shutting the water off stops it feeding the ground. A meter that stops moving after you close the valve tells you the leak is somewhere downstream of it.

Keep safety in mind. Do not walk through standing water near outlets, power strips or appliances. If water is near the electrical panel or you are unsure, stay out and call for help. A warm floor spot can mean a hot-water line, so avoid kneeling on it for long.

Next, collect information a plumber and an insurer will both want: a photo of the meter before and after you shut off the water, photos of every wet area, and notes on when you first noticed a sign. Do not start pulling up flooring before photographs. Then call a licensed plumber to locate and repair the leak.

When you want a crew to handle the water, call (833) 490-5225. A crew is dispatched as fast as one is available, and the emergency-stage price is explained to you and approved before drying starts.

• Close the main water valve and confirm the meter stops
• Keep off wet floors near outlets and appliances
• Photograph the meter, the wet areas and the damage before anything is moved
• Call a licensed plumber to find and repair the line
• Call your insurer or agent early, and ask how your policy treats a leak under the slab
• Call for water extraction and drying