One Slab Leak Turned Out to Be Two: A Real Case From Plano, TX

Real case from FPP Plumbing, your plumber in Plano, TX. It started the way most slab leaks start: quietly. The homeowners noticed their water bill climbing month after month with no change in how they used water. If that sounds familiar, we wrote a full guide on what a rising water bill and wet spots in the yard usually mean.

Then the leak stopped being quiet. Water started pooling near the water heater in the garage. At the same time, water was building up clear across the property: in the backyard, along the side yard, even creeping toward the neighbor’s lot. A leaking water heater does not water your lawn from fifty feet away. Something bigger was going on under the house.

The Diagnosis: Pressure Test, Air, and Bubbles Through the Floor

We did a full inspection and found a small crack in the garage concrete floor. Then we isolated the system and ran a pressure test, pushing air into the line and watching the gauge. The pressure would not hold, and water with air bubbles started pushing right up through that crack in the floor. That confirmed it: a slab leak on the hot water line under the foundation.

But here is the real kicker. We kept testing the line instead of stopping at the first hit, and we found two separate leaks on the exact same hot water line under the slab. Because the line sits under constant pressure beneath the foundation, water from the second leak traveled under the concrete and found another way out into the yard. The “water heater leak” and the backyard flooding were the same problem the whole time.

What Failed: 3/4″ Copper and a Pinhole That Grew

The line was a 3/4 inch copper hot water line running under the slab. It started as a pinhole leak, the kind that drips a little and shows up as nothing but a higher water bill. Over time the water eroded the copper around the hole, the pinhole became a real opening, and the drip became an active leak flooding the soil under and around the house.

This is a common story in our area. Homes that are 20 to 30 years old have copper lines that have spent decades in North Texas soil, with our water chemistry working on the metal from the inside and the clay shifting under the foundation with every wet and dry season. When one spot on a line pinholes, the rest of that line has been living the same life. Finding the second leak was not luck. It is why we always test the entire line instead of patching the first hit and driving away. A patched line with a second active leak means the homeowner pays twice: second visit, second access, second repair.

The Repair: A Tunnel Under the House, Floors Untouched

Homes in Plano and Frisco sit on post-tension slabs with steel cables running through the concrete. Cutting that slab from above is a risk we do not take. So we repaired this one through tunnel access. That’s how we handle every slab leak repair in Plano and Frisco.

The excavation crew dug a tunnel from outside the foundation, under the slab, to reach the failed line. We replaced the hot water line all the way to the manifold at the water heater, so there is no old, thinning copper left waiting to pinhole next year. Then we pressure-tested the new line before anything was closed up, and the tunnel was backfilled and compacted in stages to keep the ground under the slab stable. The homeowner’s tile and floors stayed exactly where they were.

The Water Damage Part: Why We Called In Restoration

Here is the honest part of this story. The leak had been running long enough that everything under the floor was soaked. Wet soil and moisture under a slab do not just dry out on their own in a closed, air-conditioned house. Left alone, that moisture keeps wicking up, damages flooring from below, and creates exactly the conditions mold needs.

So we brought in our water restoration partner to handle the drying and moisture control. They extracted the water, set up structural drying, and monitored moisture levels until everything under the floor was actually dry, not just dry-looking. That stopped further floor damage and shut the door on mold before it started. Plumbing fixes the source. Restoration fixes what the water already touched. A complete job needs both.

Think You Might Have a Slab Leak?

The signs rarely look like a flood at first. Watch for a water bill that keeps climbing, a warm spot on the floor, the sound of running water when everything is off, low water pressure, or wet spots showing up in places that make no sense, like a backyard with no sprinkler running. Our water leak detection finds the source before anyone opens concrete or digs a tunnel. Detection first, then repair. Never the other way around.

And if your water pressure has been acting strange along with a high bill, check your pressure reducing valve too. A failing pressure reducing valve (PRV) puts extra stress on every line in the house, including the ones under the slab.