What Are the Signs of a Slab Leak?
A closer look at the clues that typically show up before a slab leak becomes obvious.
Slab leaks are hard to catch early because the pipe causing the problem is buried under concrete. By the time water is visible on the surface, the leak has usually been active for a while. Here's what tends to show up first, and why.
A Rising Water Bill
This is often the very first sign, and the easiest one to overlook. If your household's water usage hasn't meaningfully changed but your bill has climbed, it's worth comparing a few months of bills side by side before assuming it's a rate change.
A Warm Patch on the Floor
If the leak is on the hot water line, the escaping water can warm the surrounding concrete and flooring. This shows up as a patch of floor that's noticeably warmer than the rest of the room, sometimes only in bare feet.
Sound of Running Water
With every fixture in the house off, a hissing or trickling sound near the floor is one of the more reliable indirect signs, since there's no other obvious source for it.
Cracks and Flooring Changes
As water saturates the soil beneath a slab, minor foundation movement can cause new cracks in tile grout, flooring, or nearby drywall — usually a later-stage sign than the ones above.
When to Get It Checked
One sign on its own is a reason to pay attention. Two or more together — especially a rising bill plus a warm spot or sound — is a good reason to have detection equipment confirm what's actually happening before assuming the worst or ignoring it.