A homeowner guide from Drain Edge Rooter, a licensed plumbing company in Rialto, CA (C-36 #1078977). Open 24/7, call anytime: (909) 927-3194.
A slab leak is a leak in a water line that runs under or inside a home's concrete foundation. Many homes across the Inland Empire are built on slabs, and many tract homes from the 1970s through the 1990s have copper supply lines under the concrete. As that copper ages, pinhole leaks can develop where you cannot see them. Catching a slab leak early limits water waste and damage to floors and walls.
Common signs of a slab leak
- A water bill that rises without any change in how you use water.
- The sound of running water when every fixture is off.
- A warm or hot spot on the floor, often from a leaking hot water line.
- Damp carpet, warped wood floors, loose or cracked tile, or mildew smells near the floor.
- Lower water pressure, or a water heater that seems to run constantly.
- Water pooling near the foundation outside.
How to check for a hidden leak with your water meter
- Turn off every faucet, appliance, irrigation timer and the ice maker.
- Find your water meter, usually in a box near the street. Look for the small leak indicator, often a triangle or dial.
- If the indicator is moving with everything off, water is flowing somewhere.
- Write down the meter reading, wait an hour without using water, and check again. A change confirms a leak.
- Check the obvious places first: toilets (put a few drops of food coloring in the tank and see if color shows in the bowl without flushing), outdoor hose bibs and the irrigation system.
If toilets and irrigation are fine and the meter still moves, the leak may be in a supply line under the slab or in a wall.
Hot or cold?
Turn off the cold water supply valve on top of the water heater. If the meter stops moving, the leak is likely on the hot side. A hot-side slab leak often shows up as a warm spot on the floor.
What to do right away
If you see active water damage, shut off the main water valve. Move belongings away from wet areas and take photos for your insurance company. Do not start breaking concrete to find the leak; guessing usually means more damage and more cost.
How a plumber finds a slab leak
Professional leak detection uses pressure testing to confirm which line is leaking and acoustic equipment to listen for the sound of escaping water through the concrete. This narrows the spot before anything is opened.
Repair options
Depending on the pipe, location and condition, a slab leak can be repaired by opening the slab at the leak, rerouting the line through walls or the attic, or repiping the house if the copper is failing in many places. A plumber should explain the options and the trade-offs before work starts.
Slab leak checklist
- Compare your water bills month to month.
- Walk the floors barefoot and feel for warm spots.
- Listen for running water at night when everything is off.
- Run the meter test with every fixture and irrigation off.
- Rule out toilets, hose bibs and sprinklers.
- Shut off the cold supply to the water heater to check the hot side.
- Shut off the main valve if you see active water damage.
Keep notes, photos and copies of your water bills. They are useful for your plumber and, if you file a claim, for your insurance company. If your home has already had one slab leak, ask your plumber whether rerouting or repiping makes more sense than repeated spot repairs.
When to call a pro
Call a plumber if your meter test shows a leak you cannot find, if you notice a warm spot on the floor, or if water is appearing on floors or walls. Drain Edge Rooter is open 24/7, so call anytime at (909) 927-3194.
Related services and areas
Related services: Slab Leak Detection, Leak Detection, Repiping. We serve the whole Inland Empire, including plumber in Rialto, plumber in Rancho Cucamonga, plumber in Grand Terrace, plumber in Loma Linda. See all homeowner plumbing guides.
Signs of a Slab Leak and What to Do: FAQ
Does homeowners insurance cover slab leaks?
It depends on your policy. Some policies cover water damage and access to the leak but not the pipe repair itself. Check with your insurance company.
Can a slab leak fix itself?
No. A pressurized line that is leaking will keep leaking and usually gets worse.
Is rerouting better than breaking the slab?
Often, especially if the pipe is old or there have been multiple leaks. The right choice depends on the pipe, location and condition.
How do I know if the leak is hot or cold?
Shut off the cold supply to the water heater. If your meter stops moving, the leak is likely on the hot side.
Need help?
Drain Edge Rooter is open 24/7, so call anytime at (909) 927-3194. We will talk through the problem and give you a straight answer on timing.