Signs of a Hidden Water Leak

Run a meter test

Turn off every fixture and appliance that uses water, including ice makers and irrigation. Look at the meter's leak indicator — a small triangle or dial. If it moves at all over 20 minutes, water is going somewhere.

What the symptoms usually mean

A warm spot on a slab floor points toward a hot-water line under the concrete. Sounds of running water with everything off suggest a pressurized line. Musty smells and buckling flooring point to a leak that has been going for a while.

Stains that grow across a ceiling or wall are usually a supply or drain line above; a stain that stays the same size after weeks may be old damage that has already dried out.

What not to do

Avoid cutting open drywall or breaking concrete to hunt for the source. Leak detection equipment locates the line far more precisely, and the smaller the opening, the smaller the repair.