Probably not. In most homes we test, warm spots in several rooms trace back to one leak on a hot water line under the slab. Hot water that escapes under a foundation does not stay in one place. It runs through the sand bed under the concrete, follows pipe trenches, and collects in low spots, warming the floor everywhere it goes. The warm spots tell you hot water is leaking. They do not tell you where the pipe is broken. Finding the break takes pressure isolation and acoustic listening, done in order, before anyone cuts concrete.
As a basic first check, the U.S. EPA WaterSense home-maintenance guidance recommends reading the water meter during a period when no water is being used and checking it again later. Professional isolation and acoustic testing are needed to move from “water is leaving the system” to a defensible location under the slab.
Why Frisco homes see this in the fall
Frisco is built on expansive clay. Over a hot, dry summer that clay shrinks and pulls away from the slab, and the foundation shifts with it. The copper and PEX lines in and under the slab shift too. After a summer of that movement, a lot of those lines give out in late summer and early fall.
The first thing most homeowners notice is a warm patch on tile or wood flooring. A week later there is another one in a different room, and then a third. It is natural to assume each one is its own leak. Usually it is the same water showing up in different places.
What warm spots in several rooms are telling you
A hot water leak under a slab can move a lot of water, and your water heater reheats every gallon of it. That heat moves through the concrete wherever the water travels. A thermal camera can show a hallway, a bathroom and a living room all glowing, and only one of those spots sits over the actual break.
These signs together point to a hot-side slab leak:
- Warm spots on tile, wood or laminate that do not line up with an air duct, a sunny window or an appliance
- A water heater that seems to run all the time, or a gas bill that climbs along with the water bill
- The water meter moving when every faucet, toilet and sprinkler is off
- The sound of running water near a wall or floor when nothing is on
- A water bill that jumped without any change in how your family uses water
Treat the warm spots as a map of where the water went. The break could be under any one of them, or somewhere between them.
How a Master Plumber tests for it
Here is how we work a home with warm spots in several rooms.
1. Confirm water is leaving the system
With every fixture, the ice maker, the irrigation and any pool autofill turned off, we watch the leak indicator on the water meter. If it moves, water is escaping somewhere past the meter.
2. Split hot from cold
We close the cold water supply valve into the water heater. If the meter stops, the leak is on the hot side. In homes with two water heaters, we shut them off one at a time. Each heater usually feeds a different part of the house, so whichever one stops the meter tells us which hot water branch to chase.
3. Map the heat with a thermal camera
We scan floors and walls in every room and mark each warm area. This gives us a list of places to listen. It does not pinpoint the leak by itself.
4. Pressure-isolate the line
We isolate the hot line that failed and hold it under steady test pressure. A line that will not hold pressure is confirmed leaking. Keeping it under pressure also makes the escaping water louder, which helps the next step.
5. Listen with a geophone
A geophone is a sensitive ground microphone. We set it on the floor over each warm spot and along the pipe route between them. Water escaping a pressurized line makes a hiss or gurgle that is loudest right at the break and fades with distance. A warm spot with no sound is a place the water traveled to. The spot with the loud, steady sound is the leak.
We will ask everyone in the house to stay still and we turn the air conditioning off for this step. Footsteps, fans and refrigerators can all sound like water through a geophone.
6. Trace the pipe and confirm
Electronic line tracing confirms the pipe actually runs under the spot we hear.
Then we mark the spot and put everything in your written Certified Master Plumber Report: what we tested, what held, what failed, and where the leak is.
A Real Job in Windhaven, West Plano: One Leak, About 15 Warm Spots
In September we tested a home in the Windhaven neighborhood of West Plano, near Legacy and the Tollway. The homeowner never noticed a warm floor. What he noticed was the water bill. The house had lost about 40,000 gallons in roughly a week, close to a swimming pool’s worth of water under one slab. Water was even wicking up through the garage floor, so we knew there was a lot of it under the slab.
The home has two water heaters. With everything off, the meter kept moving. We shut off the left-hand water heater and the meter kept moving. We shut off the right-hand water heater and the meter stopped, so the leak was on the hot water branch fed by that heater.
A walk-through with the thermal camera found about 15 warm spots across the house. It looked like leaks everywhere. We put the line under about 30 psi and listened with the geophone at each spot. Most were quiet. In the half bath, right in front of the toilet, we heard a loud gurgle. That was the leak. Every other warm spot was water from that one break spreading under the slab.
The line was losing about half a pound of pressure per minute, which is a substantial leak. The break was 18 to 24 inches deep. The repair was a spot repair, reached by tunneling about 5 feet from under the pool deck to below the slab, so the floors inside stayed intact. When we retested after the repair, the meter did not move.
What it costs
Leak detection starts at $339, which covers the first two hours on site. Additional time is $175 per hour. Every visit includes a written Certified Master Plumber Report.
A home with many warm spots or two water heaters can take longer than two hours, because each warm area gets listened to and ruled in or out. For example, a visit that runs three hours would be $339 plus $175, or $514. Ask us at the start how long your home is likely to take.
The repair is a separate cost. It depends on where the leak is and whether the best fix is a spot repair through the slab or a reroute of the line above it. Your report explains the options so you can make that decision with the facts in hand.
What not to do
Do not let anyone break concrete at the warmest spot just because it is the warmest. The hottest area is often just where the water collected. Before any floor is opened, ask for the pressure test results and the acoustic confirmation in writing.
When to call
- Your meter moves with everything off
- A warm spot is spreading, or new ones are showing up in other rooms
- Your water heater runs far more than it used to
- Your water or gas bill jumped and you can’t explain it
While you wait for us, you can slow the water loss by closing the cold water valve on top of the water heater that feeds the leak. Set a gas water heater to “vacation” or pilot, or turn off the breaker for an electric one. If you are not sure which heater it is, closing the main water shutoff stops the loss until we arrive.
Call or text 972-333-5448 to schedule slab leak detection in Frisco.
Frequently asked questions
Can one slab leak really cause warm spots in different rooms?
Yes. Water under a slab follows the sand bed and pipe trenches toward low areas, and hot water carries its heat everywhere it goes. One break can warm floors several rooms away.
Is a warm spot on the floor always a slab leak?
No. Ducts in the slab, sunlight through a window, appliances and radiant floor heat can all warm a floor. A meter test and a hot and cold isolation test sort that out quickly.
Can you find the leak without breaking the floor?
Yes. Meter testing, thermal imaging, pressure isolation and acoustic listening are all done from the surface. Concrete only gets opened for the repair, at the spot we mark.
How long does testing take?
Many homes fit within the first two hours. Homes with a lot of warm spots or two water heaters can take longer, since every area gets checked before we mark the leak.