What is a slab leak and how do I know I have one?

What a slab leak actually is, in plain English

Your house sits on a poured concrete foundation called a slab. In slab-on-grade construction, which is the norm across the Las Vegas valley, the water supply lines and sometimes the drain lines run either through that slab or in the soil directly beneath it. A slab leak is simply a failure in one of those buried lines: a pinhole, a crack, or a full break that lets pressurized water escape into the ground and concrete under your floor.

There are two broad types. A pressure-side leak comes from a supply line carrying clean water under pressure, so it leaks continuously, day and night, whether or not anyone is using water. A drain-side leak comes from a waste line and only releases water when something upstream is draining, so it tends to be sneakier. Pressure-side leaks usually show up on your water bill first, while drain-side leaks often announce themselves with odor or soft, settling soil.

Why do they happen so often here? Three desert-specific reasons stack up. First, our soil expands and contracts with moisture and heat, and that constant ground movement stresses rigid pipe. Second, Las Vegas tap water is famously hard, and years of mineral scale plus abrasion wear thin copper from the inside out. Third, slab homes from the building booms of the 1990s and 2000s are now reaching the age where original plumbing simply fails. None of that is alarming on its own. It is just the normal arithmetic of pipes, water, and time.

What to do next if you suspect a slab leak

Take it in order. The plumbing comes first, then the structure. Rushing past either step is how a fixable leak quietly becomes a mold problem.

1. Confirm the leak with a plumber. A licensed plumber locates and repairs the failed line under the slab. That stops the water at its source. This is the plumbing half of the job and it has to happen first.
2. Stop assuming the area dried on its own. Water trapped under and beside a slab does not air-dry the way a surface spill does. Concrete holds moisture for weeks, and the desert heat above can actually drive that moisture deeper into cool wall cavities through condensation. Looking dry and being dry are not the same thing.
3. Get the affected materials properly dried. If the leak soaked subfloor, drywall, baseboards, or insulation, those materials need controlled structural drying to a measured, documented standard, not just a fan and time. This is the step that decides whether the water problem ends or becomes a mold problem.
4. Have the moisture and mold risk assessed. Because the water sat hidden, the only way to know your structure is sound is to measure it. We offer a free inspection for homeowners and property owners, an on-site visit where we read moisture levels and look for any growth the leak may have started. If lab analysis is warranted, samples go to an independent third-party lab and are billed at cost. The inspection is free; the lab work is the only paid add-on, and only if it is actually needed.

If the leak was a sudden, larger event rather than a slow weep, the cleanup overlaps with full water damage restoration, and if ground water or a drain line was involved it can edge into flood restoration territory. Whatever the scale, the principle is the same: fix the pipe, dry the structure to a verified standard, and confirm with data that nothing was left behind. We are anti-upsell by design, so if your structure is genuinely dry, we will tell you that and you will owe us nothing.