Why slab leaks are different

In a lot of 1950s to 1970s slab-on-grade homes, the main water line comes up at an outside wall near a front hose bib, and branches run from there. In some homes, though, part of the supply runs beneath the concrete slab before it surfaces inside. A leak in that section is hidden under the floor.

Instead of a wet lawn, you may notice a warm patch on the floor, damp carpet or flooring, cracked tile, or the sound of running water inside a wall. Repairing in place means opening the slab. Rerouting means abandoning the buried section and running a new line through the walls, attic or along the exterior.

Signs the leak may be under the slab

Repair under the slab or reroute

Open the slab and repair

  • Fixes the leak where it is
  • Requires breaking and patching concrete
  • Flooring above must be removed and replaced
  • The rest of the under-slab pipe stays in place

Reroute

  • Abandons the under-slab section
  • New line runs through walls, attic or outside
  • Avoids future leaks in that buried section
  • Requires wall openings and patching instead

What a reroute often involves

  1. Confirm the leak is under the slab.Isolation tests and leak location narrow it to the buried section.
  2. Plan the new path.The plumber maps a route through walls, attic or the exterior to the fixtures served.
  3. Install and connect.New pipe is run, connected, and the old buried section is capped off.
  4. Test and patch.The new line is pressure tested and wall or ceiling openings are closed.

Questions to ask

  1. Is the leak on the main service line or an interior branch under the slab?
  2. What would a reroute path look like in my house?
  3. How many wall or ceiling openings will be needed?
  4. Does it make sense to reroute other under-slab lines at the same time?
  5. Will any permit or inspection be needed?

Common questions

Is a slab leak part of the main water service line?

Sometimes it is the incoming supply; often it is an interior hot or cold branch. Either way, a plumber can isolate which section is leaking.

Will my insurance cover a slab leak?

Policies vary widely. Call your insurer, describe the situation and keep photos and invoices.

Is rerouting always better than repairing?

Not always. If the under-slab pipe is newer and the leak is isolated, a spot repair may be reasonable. Older pipe with one leak often has others coming.

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