Home Safety
A slab leak is a pressurized water line failing beneath your concrete foundation — and because you can't see it, it announces itself sideways: a warm patch of floor, a water meter that moves with every fixture off, a bill that crept up for no reason, the faint sound of running water in a quiet house. Caught early, it's a targeted repair. Ignored, it's flooring, foundation, and mold.
EPA WaterSense's leak check uses your water meter: read it, use no water for two hours, and read it again. If the reading changed, you probably have a leak.
Post-war and tract-era SoCal homes commonly ran soft copper supply lines under the slab. Decades of contact with soil, minor slab movement from our seismic reality, water chemistry, and simple age produce pinholes — most often on the hot line, which is why a warm floor spot is such a reliable early signal. Homes that have had one slab leak often see more: the conditions that caused the first apply to every foot of the same-era pipe.
The old way to find a slab leak was educated guessing with a jackhammer. Electronic detection changed that: acoustic listening equipment, line tracing, and pressure isolation locate the failure within a small area before anything is opened. The confirmation and repair happen in one targeted spot — or the line is simply abandoned and rerouted overhead through walls and the attic, which avoids opening the slab entirely.
A single pinhole in otherwise-sound pipe justifies a spot repair. A second leak in the same era of pipe starts the reroute conversation: abandoning the under-slab run and routing new line overhead is often barely more than a second spot repair and removes the whole failure mode. A home collecting leaks across multiple lines is a repipe candidate — we'll show you the pipe condition and let the evidence make the case, not the sales pitch.
Maybe not — a hot-water line that runs under that spot warms the floor slightly during normal use, and radiant heat from long hot showers can linger. But a persistently warm spot deserves a check: a slow hot-line leak can be small enough to hide in normal meter noise. A plumber can isolate the hot side and test it specifically.
Policies commonly cover the water damage a slab leak causes and the access work (opening and closing the slab), while the pipe repair itself is often the homeowner's. Every policy differs — document the signals early, because 'sudden and accidental' language favors leaks you caught promptly over ones that ran for months.
It's a this-week problem, not a this-minute one — unless you see active flooding, foundation movement, or your water bill has doubled. Water running under a slab erodes soil and feeds mold with every day it runs, so the cost curve slopes up steadily. The meter test above tells you which side of urgent you're on.
Last reviewed: 2026-07-22
Book Service
Real people answer around the clock. Tell us what's going on and we'll dispatch a licensed pro from the office nearest you.
