How to Tell If You Have a Hidden Water Leak

The meter is the witness. Turn off every fixture and appliance in the house, then look at the meter's low-flow indicator: a small triangle, star or dial that moves at flows too low to turn the main register. If it is moving with nothing running, water is escaping somewhere.

Do it properly

Nothing running means nothing: no ice maker, no irrigation timer, no water softener regenerating, no toilet with a passing flapper. A leaking toilet flapper is silent and is the single most common false positive in this test. Put food colouring in the tank and check the bowl an hour later to rule it out first.

Isolate house from yard

If there is a shutoff between the meter and the house, close it. If the indicator stops, the leak is in the irrigation or the service line outside; if it keeps moving, it is inside. That single step halves the search area and it takes a minute.

Signs that arrive before the meter test

A bill that climbed with no change in use. Warm patches on a slab floor, which mean a hot-water slab leak. The sound of running water with everything off. Musty smell in one room. Paint or skirting lifting on a wall with no fixture on it. Any of those is worth the meter test the same day.

Slab leaks in Orange County

A great many homes here are slab-on-grade with supply lines run in or under the concrete. When copper fails in a slab it usually shows as a warm floor, an unexplained bill, or the sound of water with nothing on. It is not a plumbing inconvenience: it is water under a foundation, and it does not improve with time.

How the leak is actually located

Pressure testing isolates which line is losing. Acoustic equipment listens for the escape through the slab. Thermal imaging finds the warm path of a hot line. The point of all three is to open one small area rather than exploratory demolition, and any approach that starts with breaking concrete has skipped a step.

Repair, reroute, or repipe

A single failure in otherwise sound copper can be spot-repaired or the line re-routed above the slab. Repeated failures in the same slab usually mean the whole run is at the end of its life, and re-routing or repiping costs less than opening the floor twice.

What to do tonight

If the meter is moving with everything off, note the reading, shut the main, and read it again in an hour. A reading that has not moved confirms the leak is downstream of the main and that you have stopped it. That is useful evidence and it protects the house overnight.