Slab Leaks in San Fernando Valley Homes

Why are slab leaks common in Valley homes?

Slab leaks happen wherever water lines run beneath or through a concrete floor, and many Valley houses are built on slabs rather than over a crawl space. Once a pipe sits in gravel under concrete, a small hole can run for weeks before anything shows indoors.

Why the pipe fails is a harder question. For copper, the causes of pinholes are debated; water chemistry, flow velocity and installation are all studied, and the pinhole leak page covers what is known. Pressure is one factor you can measure yourself: the 2025 California Plumbing Code (§608.2) requires a regulator where street pressure exceeds 80 psi, and the pressure regulator page shows the hose-bibb test.

What are the signs of a slab leak?

The most reliable sign of a slab leak is a water meter that moves when nothing in the house is running. Other clues are indirect, and none proves a slab leak alone:

• a damp or warm patch on the floor, or carpet that stays wet near an interior wall;
• the sound of running water when every tap is closed;
• a water bill that climbs while your habits have not changed;
• a water heater that seems to run more often, which can point to a hot-side leak.

EPA offers a seasonal yardstick: in January or February, a family of four using more than 12,000 gallons a month "could" have serious leaks. Compare your winter bill with that before you call anyone.

How do you confirm a slab leak with the meter?

You confirm a slab leak by proving water is moving with every fixture off, then narrowing down where it goes. LADWP's meter sits in a concrete box near the curb, and the line from it to the house is yours (LADWP water service guide).

1. Turn off every faucet, the irrigation controller, the ice maker and the washer.
2. Read the meter and note the low-flow indicator, if it has one.
3. Wait 15 minutes (City of San Fernando) or two hours (EPA WaterSense) and read it again.
4. If it moved, close the house shutoff valve and watch the meter. If it stops, the leak is inside the house; if it keeps turning, look at the yard line between meter and house.
5. Rule out toilets with a dye test before blaming the slab.

The hidden leaks page walks through toilet, irrigation and fixture checks in more detail, and the main water shutoff page shows where the house valve usually sits.

How are slab leaks found?

Slab leaks are usually located by a leak detection specialist or plumber after the meter test shows a loss. No government agency publishes a slab-leak detection method, so treat any description as general practice rather than a rule. The usual sequence is to separate the hot and cold sides, see which one loses pressure, then listen for the leak through the floor or use other equipment to pin down a spot before cutting concrete.

Ask the person doing the work which tests they will run, what each costs, and how precise a location they expect to give you. A written report with the suspected spot marked on a floor plan helps you compare repair quotes and talk to your insurer.

Should you repair the spot or reroute the line?

Repair the spot when there is one leak in otherwise sound pipe; consider rerouting when the same line has leaked more than once. A spot repair means opening the floor at the leak and patching the pipe. Rerouting abandons the line under the slab and runs new pipe through the attic or walls, which the repiping page describes.

The code shapes both choices. Copper water pipe must be at least Type L, and PEX buried in soil for drinking water must be sleeved in a material that resists solvents and petroleum (2025 CPC §604.3 and Table 604.1, IAPMO). Hot-water piping must be insulated (§609.12), which matters for lines moved into a hot attic. The copper vs PEX page compares the materials.

Paperwork depends on the job. Los Angeles exempts "repairing of leaks" from permits when no fixture or drain section has to be removed (LAMC 94.103.1.2.3), but replacing piping needs a permit (94.103.1.1, amlegal). On a detached house, a certified licensed contractor may replace defective water piping of equal size and file a Certificate of Compliance instead. A C-36 plumbing contractor's license can be checked at cslb.ca.gov.

Does insurance cover slab leaks?

Insurance may cover water damage from a slab leak, but the wording of your policy decides, and long, slow leaks are where claims usually fail. The California Department of Insurance's residential insurance page lists "sudden & accidental water damage" among perils typically covered, and lists "water damage cause by seepage or leaks," "wear and tear or maintenance," mold and neglect among perils generally not covered.

The department's claims guide says homeowners should "immediately attempt to find and stop leaks at the source" and report water damage to their agent right away. Policies often separate the cost of reaching and fixing the pipe from the damage the water caused, so ask your insurer how your policy treats each. Keep the meter readings, photos and the detection report.