Finding and Fixing Slab Leaks

What Is a Slab Leak?

A slab leak is a water leak in the pipes that run beneath or within your home's concrete slab foundation. These leaks are caused by pipe corrosion, ground shifting, poor installation, or chemical reactions between the pipe material and soil. Slab leaks are particularly dangerous because they can go undetected for months while undermining your foundation, promoting mold growth, and wasting enormous amounts of water.

Warning Signs

Common indicators of a slab leak include unexpectained spikes in your water bill, the sound of running water when all fixtures are off, warm spots on the floor (indicating a hot water line leak), damp or dark spots on floors, cracks in walls or flooring, mildew or excessive moisture under carpets, and a noticeable drop in water pressure. If you suspect a slab leak, perform the water meter test: shut off all water usage and check whether the meter continues to register flow.

Professional Detection Methods

Locating a slab leak requires professional equipment. Plumbers use electronic amplification equipment to listen for the sound of water escaping from pipes through the concrete. Electromagnetic pipe locators trace the path of pipes beneath the slab. Thermal imaging cameras can detect temperature anomalies caused by leaking water. These methods allow precise location of the leak without unnecessary demolition of your concrete floor.

Repair Options

Once located, slab leaks can be repaired several ways. Spot repair involves jackhammering a section of slab to access and fix the specific leak — this is the least expensive option for a single leak. Pipe rerouting involves abandoning the leaking section and running a new pipe through the walls or ceiling. Epoxy pipe lining coats the inside of existing pipes with a durable epoxy that seals leaks and prevents future corrosion. For homes with multiple or recurring slab leaks, whole-house repiping through the attic or walls may be the most cost-effective long-term solution.