Slab Leak Signs in a Torrance Tract House
Updated 2026-10 · Torrance, CA
Why this is a Torrance question
Torrance built houses faster than almost anywhere in the county after 1949, in tracts where hundreds of homes went up on concrete slabs with the water lines poured under or into the floor. In the copper era those lines were often laid straight on gravel or tight against footings. Sixty to seventy years of hot water expanding and contracting against concrete is the most common way a Torrance copper line fails.
The fifteen-minute meter test
Find your meter: usually in a box near the curb, under a concrete or plastic lid. Most modern meters have a small triangle or star-shaped dial, the low-flow indicator, that turns with even a trickle.
- Turn off every tap, the dishwasher, the washing machine and the irrigation controller
- Make sure nothing is refilling: no toilet hissing, no ice maker cycling
- Note the meter reading and watch the low-flow indicator for a few minutes
- Wait fifteen minutes without using any water and read it again
If the indicator moves or the number changes, water is leaving the system. Next, close the cold inlet valve on top of the water heater and repeat. If the meter stops now, the leak is on the hot side, which in a slab house very often means under the floor.
Signs inside the house
A warm patch on the floor
The most specific sign of a hot-line slab leak. Walk the floor barefoot: hallways, the kitchen and the bathroom run are the usual places, because that is where the hot line travels.
Sound with nothing running
A faint hiss or rushing in a wall or under the floor at night, when the house is quiet.
The water heater never rests
A gas heater that seems to fire constantly may be reheating water that is running out of a leak.
Damp or smell without a source
Carpet damp at the edge, a musty smell, or a wood floor starting to cup, with no plumbing fixture nearby.
Meter moving, and it stops when you close the water heater inlet? That is a hot-side leak. Call and say so; it saves time on the visit.
Signs outside and on the bill
Water pooling against the foundation with no sprinkler on, new cracks in tile or concrete alongside other signs, and a bill well above the same month last year. Compare like with like: a South Bay bill in August, with irrigation running, is not the same as one in February.
What it is not
A running toilet will move a meter and fail this test; so will a leaking irrigation valve. Check both first. A warm floor near a south window or over a radiant-heat zone is sun or design, not a leak. The meter test settles most of these before anyone visits.
What happens next
If the test points to a leak, the next step is location, not repair. A technician isolates the systems, pressure-tests them and finds the spot with listening gear. Only then is there a sensible conversation about whether to open the floor, reroute, or repipe.
Where to go next
Common questions
Can a slab leak fix itself?
No. A pinhole only grows, and the water undermines the soil under the slab as it goes.
How fast should I act?
A hot-side leak, the same day: close the heater inlet and call. A slow cold-side leak within days rather than weeks.
Are slab leaks more common in older Torrance neighbourhoods?
They are most common in the 1950s and 60s copper-plumbed slab tracts. Older galvanised houses tend to fail by clogging rather than leaking.