There's Water Under My Slab. What Do I Do Right Now?

Water under your slab? Here's what to do right now, before it undermines your foundation or lets mold take hold beneath the flooring. A warm spot on the tile, a running-water sound when every faucet in the house is off, or a water bill that jumped for no reason are all signs the leak is already underway. Waiting to see if it goes away is how a plumbing problem turns into a foundation problem.

We've walked into more than a few homes in Tarrant County and across North Texas where a slab leak had been quietly running for days before anyone called. Here is what to do right now, and why the timeline matters more than it seems.

What to Do Right Now If You Suspect a Slab Leak

Start by checking your water meter. Turn off every faucet and water-using appliance in the house, then watch the meter for a few minutes. If it is still moving with nothing running, water is escaping somewhere between the meter and your fixtures, and a slab leak is a real possibility.

Do not cut into the slab or start pulling up flooring on your own. Slab leaks run beneath concrete and often under plumbing lines that require a trained technician to locate safely. If you're not sure what separates a technician who guesses from one who tests, here's how to choose a restoration company in North Texas before you make that call.

If you can locate your main water shutoff valve and the leak seems severe, such as visible water pooling on the floor, shutting off the water supply to the house limits how much more gets into the slab and subfloor. Leave the water off until a professional arrives to assess the source.

Photograph any warm spots, damp flooring, baseboards, or visible water before you touch anything. This documentation matters if you end up filing an insurance claim, even though slab leaks are not always covered the same way as other water damage.

How Do I Know If This Is a Slab Leak?

A slab leak is not always obvious. A warm or damp spot on tile or laminate flooring, especially over what should be a cold water line, is one of the clearest signs. A sound of running water when nothing in the house is on is another. Water can also move under a slab from a source that never looks obvious from inside the house, the way it did for one North Texas homeowner whose water came in during a storm without an obvious cause.

An unexplained jump in your water bill, sometimes doubling or tripling with no change in usage, often shows up before any visible sign inside the home. Mildew smell, mold near baseboards, or a section of carpet that stays damp for no reason can also point to water moving under the slab.

Why North Texas Homes Are Especially at Risk

North Texas homes sit on clay-heavy soil that expands and contracts with the season, and that movement puts extra stress on the pipes running beneath the foundation. This is one reason slab leaks show up more often here than in many other parts of the country. General prevention steps for protecting a North Texas home from water damage apply here too, even though a slab leak itself usually can't be prevented from the outside.

When to Call a Professional

Call a restoration professional immediately if the water meter confirms a leak, if you see standing water on the floor, or if a warm spot and a rising water bill show up together. Like a burst water heater, a slab leak often starts as a straightforward Category 1 loss but doesn't stay that way if it sits. A slab leak that sits for more than a day or two starts to soften the soil beneath the foundation and creates the conditions for mold to grow in the subfloor. This is not a wait-and-see problem, and it is not one to diagnose by guessing.

Key Takeaways

• Turn off every faucet and appliance, then check whether the water meter is still moving.
• Do not cut into the slab or pull up flooring without a professional.
• Shut off the main water supply if you see standing water on the floor.
• Photograph warm spots, damp flooring, baseboards, or standing water before cleanup for insurance documentation.
• Call a restoration professional immediately if the meter confirms a leak or a warm spot and a rising water bill show up together.

Does homeowners insurance cover a slab leak?
Most homeowners policies cover the water damage caused by a slab leak, such as damaged flooring, drywall, insulation, and personal property, but many exclude the cost of locating and repairing the leak itself. Coverage often depends on whether the pipe failure was sudden and accidental or the result of long-term wear. A restoration company can document the damage in a way that supports the claim. Check the policy's water damage and foundation exclusions before assuming what is and is not covered.

How long can a slab leak go undetected?
A slab leak can run for days or even weeks before it becomes obvious, especially if the leak is small or in a rarely used part of the house. By the time a warm spot or a water bill spike shows up, water has often already been moving under the foundation for a while. That is why an unexplained increase in the water bill deserves attention right away. Waiting to investigate gives the moisture more time to affect the soil beneath the slab.

Can a slab leak be repaired without cutting into the foundation?
In some cases, yes. A plumber can reroute the damaged line above the slab instead of tunneling through the concrete, depending on the location and severity of the leak. Other times, accessing the pipe requires cutting into the slab itself. A licensed plumber needs to locate the leak first before anyone can say which repair method applies.
Sources and References

ANSI/IICRC S500 (5th ed., 2021) — Standard for Professional Water Damage Restoration
Texas Department of Insurance — homeowner policy guidance

For more on how water damage develops and what the restoration process looks like from start to finish, visit NTX Risk Preparedness for North Texas homeowner guides and resources.