The seven signs
One of these alone can have an innocent explanation. Two or more together means treat it as real.
A warm spot on the floor
A hot-water line leaking under the slab warms the concrete above it. If one patch of tile always feels warmer than the rest, that’s the single most telling sign.
The meter moves with everything off
Turn off every faucet, appliance, and irrigation zone, then watch the water meter. If the leak indicator keeps creeping, water is escaping somewhere.
A water bill that jumped
Compare against the same month last year. A slab leak runs 24 hours a day, and the bill shows it.
The sound of running water
A faint hiss or rush in a quiet house, with every fixture off, is water moving where it shouldn’t be.
Damp or lifting flooring
Moisture wicking up through the slab shows up as damp carpet, cupping wood, or tile grout that darkens in one area.
Lower water pressure
A significant leak steals pressure from the rest of the house, especially noticeable on the hot side.
Cracks and mildew that keep coming back
New cracks in flooring or baseboards, or a musty smell in one room, can sit on top of a long-running leak.
The hot-side test you can run right now
Turn off all fixtures and check the meter. If it still moves, shut off the cold-water valve feeding your water heater and look again. If the meter stops, the leak is on the hot side, which fits the warm-floor symptom and narrows the search dramatically before anyone touches concrete.
Why you never guess with a slab
Breaking concrete in the wrong spot is the most expensive mistake in plumbing. Professional detection uses acoustic sensors, thermal imaging, and line tracing to pinpoint the leak first, so the repair is one small opening, or a reroute that avoids the slab entirely, instead of exploratory demolition.
Depending on pipe condition, the right fix might be a spot repair, rerouting the line overhead, or repiping if the same era of pipe is failing everywhere. A located leak gives you those options; a guessed one doesn’t.
“With slab leaks, the detection visit is the repair, everything after that is just execution.”
The bottom line
If two or more of the signs above sound familiar, run the meter test today and get the leak professionally located. A slab leak never gets cheaper by waiting, the water has nowhere to go but into your foundation and floors.