How can I tell if I have a slab leak?

Common signs are a hot spot on the floor, a spike in your water bill with no other explanation, or the water meter still moving when every fixture is off.

Do they have to break my floor to find the leak?

Not to find it. Detection uses listening and imaging equipment first. Breaking concrete only happens once the leak is pinpointed, and only if repair (not rerouting) is chosen.

Is rerouting better than repairing under the slab?

Rerouting avoids cutting concrete and is often preferred for older slabs, but it means running new pipe through walls or the attic, which has its own cost tradeoffs.

Slab leak detection under concrete floors

A slab leak, water running under a concrete foundation, shows up as warm spots on the floor, unexplained water bills, or the sound of running water when everything is off. It needs specialized detection equipment (acoustic listening devices, thermal imaging, or tracer gas) before any concrete gets cut, since guessing at the location means unnecessary demolition.

This is distinct from a general leak check because of the equipment and the decision point it forces: repair the section under the slab, or reroute the line through walls or overhead to avoid breaking concrete at all.

Locating the leak without blind demolition
Comparing spot-repair (breaking concrete) versus rerouting the line
Coordinating any flooring or foundation patch work after the repair
Checking water pressure and pipe condition to catch related risk spots

What it costs

Detection cost depends on the equipment needed and how large an area has to be scanned. Repair cost varies a lot depending on whether the fix requires breaking and patching concrete or rerouting the pipe instead, which avoids the slab entirely but adds pipe and labor length.

Top 3 by our score

Ranked from our published scoring of public Google reviews for leak detection & repair.

1. CPS Drain & Plumbing
5.0★ · 400 reviews

94
2. Cottrell & Co., Inc Plumbing Heating And Air
4.9★ · 621 reviews

93
3. On Call Plumbing, Heating & Air
4.9★ · 251 reviews

93

FAQ

How can I tell if I have a slab leak?: Common signs are a hot spot on the floor, a spike in your water bill with no other explanation, or the water meter still moving when every fixture is off.
Do they have to break my floor to find the leak?: Not to find it. Detection uses listening and imaging equipment first. Breaking concrete only happens once the leak is pinpointed, and only if repair (not rerouting) is chosen.
Is rerouting better than repairing under the slab?: Rerouting avoids cutting concrete and is often preferred for older slabs, but it means running new pipe through walls or the attic, which has its own cost tradeoffs.