Signs You May Have a Slab Leak

A slab leak is a leak in one of the water lines that runs beneath your home's concrete foundation. Because the pipe is hidden under the slab, these leaks can go unnoticed for a long time while quietly causing damage to your foundation, your flooring, and the structure around them. Recognizing the warning signs early can make the difference between a contained, manageable repair and a much larger and more disruptive problem, so it pays to know exactly what to watch for and what to do if you suspect one.

Common Warning Signs

Slab leaks tend to reveal themselves through subtle clues, often well before any water becomes visible on the surface. Because the leak is sealed under concrete, you are usually noticing its side effects rather than the water itself. If you notice several of the signs below occurring together, a slab leak becomes considerably more likely and is worth investigating with professional help.

• A warm or hot spot on the floor, which can signal a hot water line leaking below.
• The sound of running water when every fixture in the home is turned off.
• An unexplained and sustained spike in your monthly water bill.
• New cracks appearing in floors or walls, or floors that feel uneven underfoot.
• Damp, warped, buckled, or discolored flooring with no visible surface source.
• A persistent musty odor or mold developing near floor level.

A Safe Check You Can Do

You can confirm whether water is escaping somewhere with the same simple meter test used for other hidden leaks. Turn off all water inside and outside the home, locate your water meter, and note the reading or the position of the leak indicator dial. After an hour or two with absolutely no water use, check the meter again. If it has moved, water is leaking somewhere in the system, which may be a slab leak or another concealed leak elsewhere. This test will not pinpoint the location for you, but it reliably tells you a problem exists and that a professional diagnosis is warranted.

When to Call a Professional

Slab leaks are not a do-it-yourself repair under any circumstances. If the signs above and a meter test point to a leak under your foundation, leak detection services can pinpoint the exact location using specialized tools and without unnecessary demolition. From there, slab leak repair can resolve the problem while protecting the integrity of your foundation. Addressing a slab leak early keeps a contained pipe issue from turning into costly foundation and flooring damage that is far harder to put right. For a broader look at catching concealed leaks elsewhere in the home, see our guide on how to find a hidden plumbing leak, which covers the warning signs and the meter test in more detail.