Most slab leaks are found on the water bill before they are found on the floor. The meter test takes two hours and costs nothing, and it is the one every plumber will ask about.
A slab leak almost never introduces itself as water on the floor. It shows up as a water bill that stepped up for no reason, a meter that keeps moving after you have closed everything, or a patch of floor that is warm when nothing should be warming it. The useful part is that you can check the most reliable sign yourself, in two hours, for nothing.
The meter test is the one piece of evidence every plumber will ask you for, so run it first. The U.S. Environmental Protection Agency's method is to check your water meter before and after a two-hour period when no water is being used, and if the meter does not read exactly the same, there is probably a leak.
Gwinnett County's leak detection guidance fills in the parts people get wrong. Turn off the water-using appliances as well as the taps, including the washing machine, dishwasher and ice maker, and make sure nobody uses a sink, shower or toilet for the whole two hours. Write down the reading or photograph it. Watch the small leak detection wheel on the face of the meter too: nothing on the meter should be moving when no water is being used inside or outside the home.
A meter that moves with everything closed is telling you water is leaving the system between the meter and the fixtures. That is the whole finding. Where it is leaving is the next question, and that one usually needs equipment.
A running toilet is the most common cause of a moving meter and the cheapest thing on this page to fix, so eliminate it first. The EPA's test is to place a drop of food colouring in the tank at the back of the toilet, and if colour shows in the bowl within 5 to 10 minutes, there is a leak. Flush afterwards so the tank does not stain.
Do that for every toilet in the house. If one of them is the culprit, your meter test will come back clean once the flapper is replaced, and you have saved yourself a leak detection call.
Usage is the earliest signal most households get, because a slab leak runs continuously and does it out of sight. The EPA puts the scale of ordinary household leaks at nearly 10,000 gallons wasted a year for an average home, enough to add as much as 10 percent to a water bill, and nationally household leaks waste nearly 1 trillion gallons annually.
For a rough benchmark on a winter bill, the EPA notes that a family of four using more than 12,000 gallons of water per month could have a leak. Read your own history rather than a national average though: the step change in your usage, at a time when nothing about your household changed, is the signal.
| What you notice | What it can mean | What to do first |
|---|---|---|
| Bill stepped up, habits unchanged | Continuous loss somewhere | Run the meter test |
| Meter moves with everything off | Water leaving the pressurised system | Dye-test the toilets, then call |
| Warm patch on the floor | Possibly a hot line under the slab | Run the meter test before concluding |
| Running water sound, nothing open | Pressurised line losing water | Run the meter test |
| Soggy patch of yard in dry weather | Possibly the service line outside | Note where, then call |
| Flooring lifting or staining in one area | Moisture from below | Do not lift it. Get it located first |
The ground under the slab moves, and it moves a lot. A Texas Highway Department research report held in the Center for Transportation Research library at the University of Texas at Austin states the problem directly: the distortion and cracking of buildings caused by the swelling or shrinking of expansive clay foundation soils creates major engineering problems in Texas. The same report records that layers of montmorillonite expansive clay sit under wide areas of the state, in a climate whose conditions are conducive to those clays alternately shrinking and swelling.
How much movement is involved is the part that makes it real. In a ponding study described in that research, dry expansive clay areas that were ponded for six months swelled as much as 5 to 6 inches, with soil moisture content rising from an average of about 13 percent to an average of 19 percent in the top 7 to 8 feet of soil. That is the scale of movement available under a Central Texas slab between a drought summer and a wet spring.
A water line cast into or running beneath a slab that is being lifted and set back down is a line under repeated stress at its joints and bends. That is why slab leaks here are a maintenance reality rather than a freak event, and why a house that has had one is worth watching.
This cuts both ways on a leak you already have. Water escaping under a slab changes the moisture content of exactly the soil that moves with moisture, which is why a slab leak left alone stops being only a plumbing problem.
Before you need them, find them. The 2021 International Plumbing Code, adopted by Leander with local amendments by Ordinance No. 25-034-00 and adopted by Cedar Park as its plumbing code, requires a full-open valve on the building water service pipe from the public water supply near the curb, and another on the water distribution supply pipe where it enters the structure. Those two are your house shutoffs, and one of them is usually in a box near the street.
The code also requires a full-open valve on the water supply pipe to every water heater, and shutoff valves on the supply to each fixture other than tubs and showers in a one or two-family home, on each sillcock, and on each appliance. Those smaller valves are how a plumber isolates one run to narrow down where the loss is, and how you stop a specific fixture without losing the house.
Locating comes before deciding, always. A leak is found by pressure-testing the system to establish which side is losing water, hot or cold, and then narrowing the position with acoustic equipment rather than by opening the floor to look. Nothing good comes of breaking concrete to find out.
Once located, there are broadly two routes. The leak can be accessed and repaired at the point of failure, or the run can be abandoned and rerouted, usually overhead, so nothing load-bearing is disturbed and the old line under the slab is simply left in place. Which is appropriate depends on where the leak sits, what the pipe is made of, whether it is the first failure on that run, and what the floor above it is. It is a judgement made after the leak is found, not before.
Leaks inside and outside the home are the property owner's responsibility to repair, as Gwinnett County puts it, so this is your call to make rather than the utility's. What a plumber owes you is a located leak and the honest version of both options.
Texas Occupations Code Chapter 1301 governs plumbers and defines the responsible master plumber: the licence holder authorized to obtain plumbing permits who assumes responsibility for the plumbing work performed under that licence. You can check anyone before they start, because the Texas State Board of Plumbing Examiners publishes a free public licence search showing a licence type, its status and any disciplinary history.
Nothing on this page is an instruction to open a slab, cut into a wall, or work on a gas line. Vaquero Plumbing is family-owned, works under licence RMP 15304 and backs its work with a two-year warranty. We locate and repair slab leaks and handle leak detection across Leander, Liberty Hill, Cedar Park, Round Rock, Georgetown and Austin. The office is open Monday to Friday 8:00 to 5:30 and Saturday by appointment, and the number is 512-893-8705.
Run the meter test, which costs nothing and is what any plumber will ask whether you did. The U.S. Environmental Protection Agency's method is to check the water meter before and after a two-hour period when no water is being used, and if the meter does not read exactly the same, there is probably a leak. Gwinnett County's version adds the detail that matters: turn off the washing machine, dishwasher and ice maker as well, have nobody use a sink, shower or toilet for those two hours, and watch the small leak detection wheel on the meter face, because nothing on the meter should be moving when no water is being used.
Usually a number rather than a puddle. A water bill that steps up without a change in habits is the common first sign, and the EPA notes that the average household's leaks can account for nearly 10,000 gallons wasted a year and could add as much as 10 percent to a water bill. After that come the physical signs: a patch of floor that is warm underfoot, the sound of running water with every fixture off, a section of flooring that lifts or stains, or an area of the yard that stays soggy.
No, and it is worth being careful about this one. A warm patch of floor is a reason to run the meter test, not a diagnosis on its own. Hot water lines in a slab can produce it, but so can a duct run, a heating system, or sun through a window on a tile floor. The meter is the check that separates a leak from everything else, because a meter that moves with every fixture closed is reporting water leaving the system somewhere.
The soil moves. A Texas Highway Department research report held at the University of Texas at Austin describes the problem plainly: the distortion and cracking of buildings caused by the swelling or shrinking of expansive clay foundation soils creates major engineering problems in Texas, and layers of montmorillonite expansive clay sit under wide areas of the state where the climate drives repeated shrinking and swelling. The same research measured dry clay areas swelling as much as 5 to 6 inches once ponded. A pipe cast into or running beneath a slab that is being lifted and dropped is a pipe under stress.
Yes. Vaquero Plumbing works in Leander, Liberty Hill, Cedar Park, Round Rock, Georgetown and Austin, and slab leak work runs from locating the leak through repair or rerouting under licence RMP 15304. The office is open Monday to Friday 8:00 to 5:30 and Saturday by appointment, and the number is 512-893-8705.
From leaks and clogs to water heaters and repipes, our family-owned crew is ready with same-day service and honest pricing.