What you can establish before anyone arrives
Turn off every fixture and appliance that uses water, including the ice maker and the irrigation timer. Read the meter, including the small leak indicator dial if it has one. Wait an hour with nothing running and read it again. If it moved, water is escaping somewhere between the street and the last fixture in the house.
Then shut the valve where the supply enters the house and repeat. If the meter keeps moving with the house isolated, the leak is on the service line in the yard. If it stops, it is inside, which on a slab-on-grade Florida house usually means under the concrete.
That one hour does something no instrument can do for us: it proves the leak is real and tells us which half of the property to work in. Plenty of callouts for a high bill turn out to be a running toilet flapper or a pool autofill, and the meter finds those too.
What the meter cannot do is tell you where. It measures flow at one point. Everything after this is about location.
Acoustic listening: what it hears and what stops it
Pressurized water escaping through a small opening makes noise. It is a hiss at the break and a low rumble carried along the pipe, and most of it sits outside what an ear on the floor can pick up. Ground microphones and a listening disc amplify it and filter out the frequencies that are not it.
The technician works a grid, listening at points across the slab or along the line, and compares amplitude. The sound is loudest directly over the escape. Moving in from the loud readings toward the loudest one is how a spot gets marked rather than a room.
Acoustics work best on metal pipe under pressure with a decent-sized escape. They get difficult on a slow weep that barely makes a sound, on plastic lines that damp the noise instead of carrying it, and on a drain leak, which is not pressurized and so makes almost nothing to hear. Traffic, a running air handler and a neighbor's pool pump all go into the microphone too, which is why this often gets done with the house quiet.
When acoustics are inconclusive, that is information. It usually means the leak is not where we were listening, or it is not a pressurized supply leak at all.
Acoustic listening does not find water. It finds the sound water makes getting out, which is why a slow weep is harder to locate than a bad break.
Pressure testing: proving which system is leaking
A pressure test isolates a section of pipe, brings it up to pressure with water or air, shuts it off from the supply and watches the gauge. A gauge that holds says that section is sound. A gauge that falls says it is not, and how fast it falls says something about the size of the opening.
This is how the problem gets divided. Hot side or cold side. Supply or drain. The line to the house or the line inside it. Testing the hot and cold separately is often the first useful split, because it immediately halves the amount of floor anyone is thinking about.
Drains are tested differently, by isolating and filling or by camera, because there is no working pressure in them. A sewer line is inspected with a camera that records distance along the run, so a defect comes back as a depth and a direction rather than a sound.
Pressure testing on its own almost never gives a spot. It gives a certainty — this pipe, not that one — and it is what tells the acoustic and thermal work where to look.
Thermal imaging and tracer gas
A hot-water line leaking under a slab heats the concrete around it. A thermal camera reads surface temperature and shows that plume as a shape on the floor, usually wider and vaguer than the pipe itself but centered near the escape. On a hot line in a tiled or vinyl room it can be the fastest answer in the kit.
It has clear limits. A cold-water leak leaves little or no thermal signature, carpet and thick flooring hide what is underneath, and afternoon sun through a window will put a bright patch on a floor that has nothing wrong with it. Thermal is a confirming instrument more often than a finding one.
Tracer gas is the fallback when the others do not resolve it. The line is drained and charged with an inert gas blend that is lighter than air and harmless, and a sensitive detector finds where it surfaces through the slab, the grout or the soil. It works on slow weeps and on plastic pipe, the two cases acoustics struggle with most.
No single method covers every leak. Which combination gets used depends on what the pipe is, whether it is hot or cold, pressurized or not, and what is on top of it.
Why locating properly means opening the floor once
Water under a slab runs along the path of least resistance — down the pipe trench, along the fill, out to wherever the fill ends. The damp spot inside the house is frequently a long way from the break. Cutting where the floor is wet is the most common way a one-opening repair becomes three.
Every opening in a slab is saw cutting, dust, excavation, a repair, new concrete and then flooring over the top. The concrete and finish work is the expensive, slow, disruptive part of a slab leak, not the fitting that goes on the pipe. Locating accurately is what keeps that to one hole.
Good location also changes the conversation about what to do. A single pinhole in otherwise sound copper is a repair. A located break in a run that has already failed twice is an argument for rerouting the line overhead instead of going back under the slab a third time. You cannot make that call without knowing where it is and what it looks like.
Keep the record while this is happening. The meter readings, the dated photographs of the wet area, the location that was marked and what was found when it was opened. If a claim follows, that is the documentation an adjuster wants to see. Whether your policy covers any of it is between you and your carrier, and we will not predict what they decide.
Pipe Perfect LLC is a Florida Certified Plumbing Contractor, licence CFC1431903. We locate and repair plumbing, and that is all — we do not perform or sign home inspections, four-point inspections, or anything else requiring a licence we do not hold.