Leaks under the house: crawl spaces and slabs

Crawl space homes

The good news: the pipes are reachable. Twice a year, and after any hard freeze, take a flashlight under the house or look through the access door. Look for:

• Puddles or damp soil under bathrooms, the kitchen or the water heater.
• Wet or sagging insulation, or insulation that has fallen off pipes.
• Drips at fittings, especially old galvanized joints and the joints between different pipe types.
• Musty smell or mold on joists, which can mean a long-running leak or poor ventilation.

A leaking drain line under a tub or shower is common and easy to miss because it only drips when the fixture is used.

Slab homes: signs of a slab leak

• The meter moves with everything off. The meter test.
• A warm spot on the floor (a hot water line leaking).
• Sound of running water when nothing is on.
• Cracked or lifting flooring, or damp carpet away from any fixture.

How plumbers find them

A plumber will isolate hot and cold, then pinpoint the leak with acoustic listening equipment, thermal imaging or line tracing, so only a small section of floor is opened.

Repair, reroute or repipe

• Spot repair: open the floor at the leak and fix it. Good for a single leak in otherwise sound pipe.
• Reroute: abandon the line under the slab and run a new one through walls or the attic.
• Repipe: if the pipe is failing in several places. Repiping.

Insurance and drying

Policies often cover water damage from a sudden leak but not the repair of the pipe itself, and may exclude long-running leaks. Dry wet crawl spaces and floors quickly; the EPA says to dry water-damaged areas within 24 to 48 hours to prevent mold. Drying and mold.