Why slab leaks happen

In a slab-on-grade house, some water lines run beneath or within the concrete floor. Over decades, pipe can wear where it rubs against concrete or gravel, corrode from the outside, or develop pinholes at bends. Because the leak is out of sight, water can run for a long time before anyone notices.

A hot water line leaking under the slab often shows up first as a warm patch on the floor, while a cold line leak may only show as a moving meter and a rising bill.

Clues worth taking seriously

  • A warm or damp spot on tile, wood or carpet with no obvious cause.
  • The sound of water running when every fixture is off.
  • The water meter moving with everything closed.
  • Cracks or lifting in flooring that were not there before.
  • The water heater running more often than usual.
  • Mildew smell or damp baseboards along an interior wall.

What to do if you suspect one

  1. Run the meter test.Turn everything off and watch the meter. Rule out toilets and irrigation first.
  2. Feel the floor.Walk barefoot and note any warm spots, especially between the water heater and fixtures.
  3. Limit the loss.If the leak seems to be on the hot side, a plumber may suggest closing the cold supply to the water heater until repair. Ask before doing this.
  4. Call for leak location.A licensed plumber can use pressure tests and listening or thermal equipment to pinpoint the leak before cutting anything.

Repair approaches

The right choice depends on where the leak is, the pipe's overall condition, and how many leaks the house has had.

Direct spot repair through the slab

  • Opens the floor at the leak and repairs that section.
  • Can make sense for a single leak in otherwise sound pipe.
  • Involves flooring removal and concrete patching.
  • Leaves the rest of the under-slab pipe in place.

Reroute above the slab

  • Abandons the leaking line and runs new pipe through walls or attic.
  • Avoids breaking the floor at the leak.
  • Often considered after repeat leaks.
  • Involves wall openings and patching instead.

What usually drives the cost

Leak location
How deep and how far under finished flooring
Flooring type
Tile and hardwood take more care to open and restore
Repair approach
Spot repair versus rerouting through walls
Permits
Some reroutes may need one; check with the city

Common questions

Can a slab leak damage the foundation?

Water running under a slab for a long time is never good for the soil or the floor. That is why prompt leak location matters.

Will insurance pay for a slab leak?

Coverage varies widely, especially between access, repair and resulting damage. Ask your insurer before work starts and keep photos and invoices.

How is the leak found without breaking the floor?

Plumbers typically isolate lines with pressure tests and then use listening or thermal equipment to narrow the location before any cutting.

General information for Sunny Hills, not a quote or professional advice. In an emergency, call 911.