Slab leak signs in Orange County homes: spot one early

What to look for

A slab leak is a leak in a water line running underneath your home's concrete foundation. Because the pipe is hidden, the signs tend to show up somewhere else first: a spot on the floor that's noticeably warm (usually a hot water line), a water bill that climbs without a clear explanation, or the sound of running water when every faucet, toilet, and appliance in the house is off. As a leak progresses, you may also notice damp or discolored carpet and flooring, a musty smell in one area, low water pressure, or cracks in the flooring or slab.

In Orange County

Age is why this guide exists. The Census Bureau's 2024 American Community Survey puts about 12 percent of Orange County's homes in the 1950s, 19 percent in the 1960s and 22 percent in the 1970s. Our guide to Orange County home age by city gives each city's median year built. In the tract homes of those decades, from Fountain Valley and Huntington Beach to Garden Grove, Anaheim and Santa Ana, copper water lines were commonly run under or through the concrete slab rather than through walls or an attic.

InterNACHI, a home inspectors' association, gives copper water lines 70 years, so original pipe from the 1960s is now inside that window. Decades of contact with concrete and soil, along with the normal expansion and contraction of a hot water line, make pinhole leaks more likely than in homes with more accessible plumbing.

Our city pages are a starting point: Fountain Valley, Huntington Beach, Garden Grove, Westminster, Cypress, or all Orange County cities.

Check your water meter

You can test for a hidden leak before calling anyone. The EPA's WaterSense program suggests reading your water meter, using no water at all for two hours, and reading it again. If the number changed, you probably have a leak somewhere. Turn off the ice maker and irrigation timer first so they do not fool you. WaterSense also says that if a family of four uses more than 12,000 gallons in a winter month, there could be a serious leak. The test does not tell you where the leak is. How a plumber finds it is under slab leak detection in our repair guide.

What are the repair options?

The three options are a spot repair, a reroute through the attic or walls, or a whole-house repipe. Our guide to slab leak repair in Orange County compares the three and covers permits, and the repipe guide covers copper versus PEX.

When it's an emergency

Active water pooling, water coming up through the flooring, or a leak you can't stop by closing the main shutoff valve are all reasons to call a plumber right away. A slow leak, where the only signs are a warm spot and a rising water bill, is worth fixing soon, since it can damage flooring and drive up water costs, but it usually doesn't need a same-hour response.

How much does a slab leak repair cost?

It depends on where the leak is, how it has to be reached and whether you choose a spot repair, a reroute or a repipe. We found no reliable published price for Orange County, so we don't quote one: a licensed plumber can once the leak is located.