How Slab Leaks Are Located Without Tearing Up Your Home

The old way to find a slab leak was to guess, cut concrete, guess again. The modern way is a sequence of non-invasive tests, each narrowing the search, until three independent methods agree on one spot. Here's exactly how it works.

Step 1: Prove it with pressure

The supply system is divided into zones — hot vs. cold, branch by branch — and each is pressure-tested. A dropping gauge proves which line is leaking. This step alone eliminates most of the house from suspicion and tells us whether we're hunting a hot line (thermal-friendly) or a cold line (acoustic-dependent).

Step 2: Hear it with acoustic equipment

Electronic ground microphones and listening discs trace the confirmed line's path, listening for the high-frequency sound of pressurized water escaping. The sound peaks directly above the leak. Correlators — two sensors at known points — can calculate the position from the sound's arrival-time difference.

Step 3: See it with thermal imaging

For hot-water leaks, an infrared camera shows the heat plume spreading through the slab — a visual confirmation that converges with the acoustic peak. Cold-water leaks get verified with moisture meters and, when needed, tracer gas.

Step 4: Mark it, document it

Where the methods converge, the location is marked on the floor and photographed, with a written report: which line, where, how confident. Your plumber gets everything needed for a targeted repair — typically a small opening or a reroute, not a trench through your living room.

Frequently asked questions