A warm spot on the floor that wasn't there before
If the leaking line carries hot water, the floor above it often warms up noticeably — sometimes enough that you'll notice it through socks before you notice anything else. It's one of the most reliable early signs of a slab leak specifically.
A water bill that jumped with no change in habits
A slab leak can run for weeks before any visible sign appears, and your meter is tracking every gallon of it the whole time. If your bill climbed sharply and nothing about your household's water use changed, that's worth investigating.
The sound of running water with everything turned off
Go around the house and shut off every faucet and appliance that uses water. If you can still hear water moving — a hiss or trickle you can't place — there's a leak somewhere in the system, and a slab leak is one of the more common hidden culprits.
Cracks in flooring or baseboards pulling away from the wall
Water escaping under a slab can erode the soil beneath it over time, letting the slab shift slightly. Cracked tile, buckling laminate, or baseboards separating from the wall are later-stage signs that the leak has been active for a while.
Mold or a musty smell with no obvious source
Moisture seeping up through a slab can feed mold growth in carpet padding or along baseboards long before it's visible on the surface. A persistent musty smell with no obvious wet spot is worth a closer look.
A slab leak is serious, but it rarely means you need to tear up your whole floor. We use acoustic leak detection equipment to narrow down the exact location before any flooring is opened, so the repair touches as little of your home as possible.