What is a slab leak?
It's one of the most common plumbing terms homeowners hear and rarely have explained clearly. Here's the plain-language version.
The basic definition
A slab leak is a leak in one of the water lines that run underneath a home's concrete foundation (the 'slab'). Because the pipe is buried in or under concrete, the leak isn't visible the way a leak under a sink would be.
Why the location matters so much
Because the pipe is inaccessible, a slab leak can run for weeks or months before it's noticed — often first showing up as a rising water bill, a warm floor spot, or a sound of running water, rather than a visible puddle.
Why it's treated differently from other leaks
Repairing a slab leak may involve accessing concrete, which is why accurate detection — confirming the exact spot before any concrete is opened — matters so much more here than with an exposed pipe leak.
You might also be wondering
It depends on severity, but it's generally something to address promptly rather than ignore, since it can worsen and cause additional damage the longer it continues.
Any home with water lines running through or under its foundation can develop a slab leak, though age and pipe material affect the likelihood.
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