Slab leak signs: how to tell if water is leaking under your floor

Common signs

• A warm or hot spot on tile or flooring
• Hissing or running-water sounds when nothing is on
• Water bill rising without changes in use
• Damp carpet, loose or cracked tile, or swelling baseboards away from bathrooms and the kitchen
• The water heater running more than usual
• Low water pressure

The meter test

Turn off every faucet, appliance, irrigation system and the ice maker. Find your water meter (usually in a box near the street) and watch the small leak indicator (often a triangle or dial). If it's moving, water is going somewhere.

Then close the house shutoff valve. If the meter stops, the leak is inside the house (possibly the slab). If it keeps moving, the leak may be in the line between the meter and the house.

Why Arizona homes get slab leaks

Many homes built from the 1960s to the 1990s run copper lines in or under the slab. Hard water, soil movement in expansive clay and caliche, and pipes rubbing against concrete or gravel wear through over time. Hot-water lines tend to fail first.

What happens next

• A plumber locates the leak with acoustic and thermal equipment.
• The line is repaired through the slab or rerouted through walls or the attic.
• A restoration company maps moisture, removes damaged flooring or baseboards, and dries the slab and walls.
• Your insurer is notified; many policies treat access and resulting damage differently from the pipe itself.