7 Signs You Have a Slab Leak (and What to Do Next)

A slab leak is a break in a water line that runs beneath or inside the concrete foundation of your home. Because the pipe is hidden, these leaks can run for weeks before you notice, and by then they may have damaged flooring, soil and the slab itself. Knowing the early signs can save thousands of dollars.

The first and most common sign is a water bill that climbs without any change in how you live. If your usage jumps by 20 percent or more for no clear reason, something is leaking. Second, listen: with every faucet and appliance off, you may hear a faint hiss or the sound of running water coming from the floor or walls. Check your water meter too. If the dial or low-flow indicator keeps moving when everything is off, water is escaping somewhere.

Third, look for warm spots on the floor. A leaking hot line heats the concrete above it, and you may feel it through tile or bare feet. Fourth, watch for damp carpet, curling laminate, buckled hardwood or cracked tile with no visible source. Fifth, a musty smell or new mold along baseboards suggests moisture is rising from below. Sixth, low water pressure throughout the house can mean a main line is losing water before it reaches your fixtures. Seventh, cracks in walls or a shifting foundation can follow when leaking water erodes the soil under the slab.

If you suspect a slab leak, shut off the main water valve to limit damage and call a licensed plumber. Do not break up the floor to look for it yourself. Professionals use electronic listening equipment and thermal imaging to pinpoint the leak within inches, which means a small access hole instead of a torn-up room.

Repair options depend on the pipe's condition. A single failure can often be spot-repaired. If your copper is thin and failing in several places, rerouting lines through the attic or walls, or repiping the whole house, usually costs less over time than chasing one pinhole after another. A good plumber will explain the options and give you a firm price before starting.

Coastal Orange County homes built between the 1960s and 1980s are especially prone to this, because original copper pipe was installed in slab foundations and has now aged. If you notice any of the signs above, call ABC Plumbing for fast leak detection. Early action keeps a small repair from becoming a major remodel.