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Slab Leak Glossary: Plumbing Terms Explained

Plumbers use a lot of shorthand. Here is what the common terms mean, with links to the pages that cover each in detail.

By Pomona Slab Leak Pros · Updated November 2026

The basics

Slab: The concrete foundation floor poured at ground level. Pipes may run beneath or through it.
Slab leak: A leak in a water line under or within the slab. See how to tell if you have a slab leak.
Pinhole leak: A tiny hole in a pipe, often copper. See copper pinhole leaks.
Leak indicator: The small dial or triangle on a water meter that moves when water flows.
Main shutoff: The valve that stops water to the whole house.

Pressure isolation test: Testing sections of the plumbing to narrow down which pipe is leaking.
Acoustic detection: Listening equipment that picks up the sound of escaping water.
Thermal imaging: A camera that shows temperature differences, such as a hot water leak.
Line tracing: Mapping the path of a pipe so marks are accurate.

Spot repair: Opening the slab over the break and repairing that section. See spot repair.
Reroute: Abandoning the leaking line and running a new one elsewhere. See reroute.
Epoxy lining: Coating the inside of an existing pipe. See epoxy lining.
Repipe: Replacing the supply system. See repipe.
PEX: Cross-linked polyethylene, a flexible plumbing tube. See PEX vs copper.

CSLB: The California Contractors State License Board.
CC&Rs: Covenants, conditions and restrictions that govern an HOA community. See slab leaks in HOAs and condos.
Transfer Disclosure Statement: A form California sellers commonly use to disclose known property conditions.

What is a slab leak?

A leak in a water supply pipe under or within a concrete slab foundation.

What is the difference between a reroute and a repipe?

A reroute replaces the leaking line. A repipe replaces the whole system.

What does a leak indicator do?

It moves when water flows through the meter, so it can show a leak when everything is off.

Where do I start?

Shut off the main if water is visible, then call. A Pomona plumber will tell you what to do next.