7 Signs You Have a Slab Leak (and What to Do First)

Same house, same habits, bigger bill. A pressurized line leaking under the slab runs 24 hours a day, and it shows up on the meter long before it shows up on your floor. Leaks are not a small problem nationally: the EPA estimates household leaks waste nearly 1 trillion gallons of water annually nationwide, and fixing easily corrected leaks saves homeowners about 10 percent on their water bills.

Stand in a quiet room with every faucet, appliance, and sprinkler off. A faint hiss or rush coming from the floor or a wall is water moving somewhere it should not be. Under-slab leaks often telegraph through the pipe itself, so the sound can seem to come from a bathroom wall even when the break is under the hallway.

This is the classic hot-side slab leak tell. If a patch of tile or wood floor feels warm underfoot, and it is not sitting in a sunbeam, hot water may be escaping under the slab there. Pets are good detectors: if the dog suddenly has a favorite new spot on a hard floor, pay attention. Hot-side leaks also make your water heater run more than usual.

Water under the slab eventually finds its way up through cracks and joints. Damp carpet with no spill to explain it, wood planks cupping or buckling, grout lines darkening, or a musty smell that will not leave a room are all signs moisture is coming up from below, not down from above.

A break in a supply line under the slab bleeds off pressure before the water reaches your fixtures. If the shower went weak in the whole house, not just one bathroom, and your city is not doing line work, a leak on your side of the meter is a prime suspect.

North Texas clay soil moves with moisture. A slab leak feeds that movement by soaking the soil under one part of your foundation, and the house can shift with it. Hairline cracks in tile, drywall cracks over doorways, and doors that suddenly stick can all follow. Cracks alone do not prove a leak, but cracks plus any other sign on this list mean it is time to test.

This is the one you can run yourself today, and it is the same method the EPA recommends for finding leaks: check your water meter before and after a two-hour window when no water is being used. If the reading changed, water went somewhere. If you also shut off the valves at your toilets and water heater first and the meter still moves, the leak is likely in a supply line, and under-slab lines are on the short list.

First, shut off water at the house shutoff valve or at the meter. That stops the leak from feeding the soil under your foundation while you line up a plumber. Second, take photos of any visible damage and note the meter readings from your test. Your insurance company will want documentation, and so will your plumber.

Do not wait it out. Water damage is one of the most common and expensive claims in the country: the Insurance Information Institute reports the average water damage and freezing claim paid out $13,954 between 2018 and 2022, and about 1 in 60 insured homes files a water damage or freezing claim every year. The longer a slab leak runs, the more of that damage is soil movement and foundation trouble instead of just a plumbing repair.

We use electronic leak detection to pinpoint the break before anyone touches concrete, so you are opening one small spot instead of trenching the whole floor. Depending on the pipe and its condition, the fix is a spot repair on the pinhole or a re-route of the line through the wall or attic, and we will lay out both options with a written estimate before work starts. We also document everything for your insurance claim.

Think you have a slab leak in the DFW Metroplex? Call (682) 540-5053. Owner answers, emergencies jump the line, and we serve Fort Worth, Dallas, Arlington, and the surrounding cities. Financing is available through Service Finance and Hearth Financial for bigger repairs.