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Slab leak warning signs

Warm floor spots, a meter that spins with every tap closed and the sound of running water are classic slab leak clues.

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Mon–Sat · north and south of Las Tunas Drive

Updated · 3 min read

The quick version

A slab leak is a break in a water line under a concrete floor. Shut every fixture, watch the meter's leak dial, and look for warm or damp floor spots. If the dial moves, the next step is pinpointing the leak before anyone breaks concrete.

Sections
  1. Which San Gabriel houses have slabs
  2. Signs to watch for
  3. Confirm it with your meter
  4. What happens next
  5. Questions we hear

Which San Gabriel houses have slabs

The city's Historic Resources Survey describes 1920s and 1930s neighborhoods north of Las Tunas Drive. Houses of that age usually sit on raised foundations, with pipes in a crawlspace.

Postwar tract homes and many newer builds farther south tend to sit on concrete slabs, with copper lines buried below the floor. Those are the houses where slab leaks happen.

Raised foundation: Crawlspace under floor; Pipes visible from below; Leaks drip onto soil. Slab foundation: Concrete floor on grade; Pipes buried in or under slab; Leaks hide under flooringRaised foundation• Crawlspace under floor• Pipes visible from below• Leaks drip onto soilSlab foundation• Concrete floor on grade• Pipes buried in or under slab• Leaks hide under flooring
Two foundation types found across San Gabriel.

Signs to watch for

Confirm it with your meter

Turn off every faucet, the ice maker and irrigation. Then open the meter box and watch the small triangle or star dial.

Close all fixtures then Open meter box then Watch the leak dial then Close house shutoff then Recheck the dial1Close all fixtures2Open meter box3Watch the leak dial4Close house shutoff5Recheck the dial
A five-minute meter test for hidden leaks.

If the dial spins with the house shutoff closed, the leak is between meter and house. If it stops, the leak is inside the house, possibly under the slab.

What happens next

Leak locating uses acoustic listening, pressure tests on hot and cold separately, and sometimes thermal imaging. The goal is to mark the leak within a small area before any concrete is cut.

Then you decide between opening the floor at that spot or rerouting the line overhead. Our guide on choosing between those depends on how old the rest of the pipe is.

Questions we hear

Which water company should I call about a high bill in San Gabriel?

The city's water company FAQ explains that more than one supplier serves San Gabriel, so check the name on your bill.

Is a slab leak an emergency?

A large leak can undermine flooring and soak walls. Close the main shutoff if water is surfacing and call for a repair.

Can homeowners insurance cover a slab leak?

Policies vary. Many cover resulting damage but not the pipe repair itself, so read your policy.

References