What is a Slab Leak and How Do You Spot One?

“Slab Leak” is what plumbers call a leak in the copper water pipes under your home’s concrete slab. Both the hot and cold water lines can spring a slab leak, though the hot water line gets them more often. The leak can be any size from a small hole in the side of a pipe to a large crack. The released water then soaks into the surrounding soil under your home.

You should always fix a slab leak as soon as possible. Leaving it alone can let mold and fungus grow under your flooring and cause a variety of health problems. On top of that, the increase in your water bill can cost more than the repairs over time. A severe slab leak can even lead to your foundation collapsing.

One of the most common causes of a slab leak is movement in the ground. That can come from the soil settling over time, earthquakes, or weather changes. That movement can stress the pipes until they fail. Or the same movement can scratch the side of a pipe against a rock or other abrasive material to cause a leak.

Slab leaks can also come from the copper pipes corroding or poor water quality. Hard water can be as abrasive as minerals in the soil, causing them to wear from the inside. Or your home might be standing on a poor foundation and stressing your water lines. Older homes might have several of these causes combined.

An obvious sign of a slab leak is water coming up from under the floor. For example, it could be soaking through your carpets or pooling out from under your cabinets. Another indicator is finding a hot spot on your floor. If there’s a leak in your hot water line, it could be warming that spot up.

Other than that, you might realize your water heater never shuts down. Or you could see a random increase in your water bill. Or you might turn off all the faucets and still hear running water. You might even notice mold already growing under your carpets. Any of these could mean a leak under your foundation.

A skilled plumber you trust is your best bet for a slab leak. They should be able to locate the leak and let you know what it would take to access and fix it. Often that means cutting into the foundation and removing the dirt around your pipes. That way they can remove and replace the leaking section. Sometimes the pipe isn’t as easy to access, and they might need to dig a larger access tunnel to get to it.