10 Slab Leak Signs & Symptoms

A nasty slab leak

On a scale of one to ten, a slab leak is the Chernobyl of plumbing disasters.

Not at first, but undetected, the leak grows and spreads, sometimes slowly and at other times in a burst. Untold damage ensues.

That biblical flood in your living room? It points to a slab leak.

The runaway mold growth in the den? A slab leak is suspect #1.

What Is a Slab Leak?

A slab leak is a water pipe leak occurring in or under the concrete foundation of your home. It can be a pinhole leak in an old copper pipe or a full-on break due to shifting foundations.

What all slab leaks have in common is:

  • Their location in or under a concrete foundation.
  • Their difficulty to detect.
  • Their destructiveness. Left unchecked, they always lead to costly repairs.

So the trick is to catch a slab leak early before it undermines your foundation and turns your home into a petri dish for mold.

In this blog, we’ll list some telltale signs of a slab leak that should put you on high alert. Call your plumber immediately for tests if you notice one or more of these things.

1. Damp Spots Around Your Foundation

Sometimes water in a slab leak finds its way outside and leaves damp spots that look like rain runoff, even when it hasn’t rained.

This sign usually indicates a sizable slab leak. If water’s noticeable on the ground, and the soil around your foundation is saturated, you have a significant problem. The more water you see outside, the larger the leak.

2. Buckling or Warped Floorboards & Walls

Your floorboards may warp or buckle; drywall near the affected area may also buckle.

Bad news! This means a slow slab leak has been at work for some time. It has saturated the drywall so a mold colony can plant its flag. Get help fast! You have an extensive and expensive repair on your hands!

3. Damp Carpet & Floor

A slow, persistent slab leak can lead to damp carpet and flooring. The dampness will be consistent over time.

The worst-case scenario? You may have a flooding incident on your hands anywhere from a few days to weeks after you first notice the slab leak symptoms. That’s why it’s crucial to spot these signs early and call for help as soon as possible!

4. Warm Areas on the Floor

You may have a hot water slab leak if you detect one or more spots consistently warmer than the rest of the room.

5. Inexplicably High Water Bills

Unexpectedly high water bills suggest a slab leak (or another leak in your water system). You may see an increase in your bills without any corresponding increase in usage.

6. Low Water Pressure

A sudden drop in water pressure signals a slab leak somewhere nearby, but it may not be under the house. It might also be a pipe inside a wall or even below the yard.

7. Constant Sound of Running Water

You may hear running water even when all faucets are off, and no one is using water anywhere in the house. This sound comes from a leak in the system pumping out gallons of H2O!

It may not be a slab leak, but it bears investigation — even if it turns out to be the aquarium.

8. Foundation Cracks

It takes a lot of pressure to move a slab and create cracks in the foundation or walls. That pressure comes from water buildup finding its way through those tiny crevices.

Water carved the Grand Canyon. It should have no trouble at all putting a crack or two in your foundation.

9. Foul Odors

A pungent smell indicates mold growth, so it’s time for an inspection! Mold colonies love moist environments created by slab leaks and spread fast. Mold repairs are time-consuming, invasive, and expensive.

10. Visible Water Spraying

In extreme cases, you may see water spraying up from the foundation or yard due to a major pipe break. Get help fast! The dog may love it, but the longer you wait, the more damage will occur.

What to Do If You Suspect A Slab Leak

Plumbers can pinpoint a slab leak with specialized diagnostic equipment, including pressure sensors, acoustic listening devices, and video inspections.

Also, have your plumber check for other plumbing problems that can cause the same slab leak symptoms. A water heater leak or clogged sewer line can mimic a slab leak in some ways.

The earlier you catch and fix a slab leak, the less costly it will be! Don’t wait if something seems wrong. Call your plumber today to find out for sure!



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