Slab Leak Detection
A slab leak is a water line failure beneath your home's concrete foundation. Pros locate it with acoustic listening devices, thermal imaging, and pressure tests — pinpointing the break without tearing up floors. FlowFast connects you with an independent local plumber who can detect a suspected slab leak and explain your repair options.
- Connected with an independent local pro — never a call center queue.
- Part of our Leak Detection & Repair services — explained up front.
Parent service
Leak Detection & RepairHigh water bill or mystery damp spot? How pros find hidden leaks with acoustic and thermal tools, and how to get connected with an independent local plumber.
View all Leak Repair servicesSlab leaks happen when copper or plastic water lines buried in or under a concrete foundation corrode, crack, or rub against the slab until they fail. Because the pipes are encased in concrete, the leak often announces itself indirectly: a hot spot on the floor, an unexplained jump in the water bill, the sound of running water when every fixture is off, or damp baseboards with no visible source. Left alone, escaping water erodes soil under the slab, which can cause settling and cracking in the foundation itself.
Detection is a diagnostic service, separate from repair. A plumber isolates sections of your system with pressure tests to confirm which line is losing water, then narrows the location with acoustic equipment that hears the leak's vibration through concrete or thermal cameras that spot the temperature change from escaping water. The goal is to mark one small target area so any later repair breaks the least concrete possible. FlowFast Plumbing is a referral service — we connect you with an independent local plumber who performs slab leak detection and walks you through what comes next.
Warning signs
Signs you need this service
- A patch of flooring that feels warm to the touch, usually above a hot water line leaking beneath the slab. The warmth often spreads slowly.
- A water bill that climbs sharply with no change in household habits. Slab leaks run constantly, so the meter keeps turning even overnight.
- The sound of running or hissing water when every faucet, toilet, and appliance is off. Press your ear to a ground-floor wall to check.
- Damp carpet, warped baseboards, or a musty smell near floor level with no visible drip. Water wicks up through the slab and into finishes.
What to expect
The process, step by step
The pro shuts off fixtures and pressure-tests hot and cold lines separately to confirm a leak and identify which line is losing pressure.
Using acoustic listening equipment, the plumber scans the slab for the vibration a pressurized leak makes, narrowing the break to a small area.
Thermal imaging may follow, showing the temperature signature of escaping hot water through the floor so the location can be confirmed visually.
You get a marked location, photos or notes of the findings, and a plain-language explanation of repair paths before any concrete is broken.
Prevention
How to avoid this problem
- Keep water pressure at a moderate level, since excessive pressure strains pipe joints and fittings over time, especially under a slab.
- Have a plumber check pressure and inspect visible plumbing during routine visits so small issues are caught before they become slab failures.
- In homes with older copper lines, periodic water testing for corrosive chemistry can flag conditions that eat pipes from the inside.
Frequently asked questions
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