Plumbers find hidden leaks with a short list of proven methods: a pressure-gauge drop test to confirm a leak exists, acoustic listening gear that hears escaping water through concrete, thermal imaging that shows hot spots on a slab, tracer gas for pinhole leaks, and meter behavior checks. Each method narrows the search so digging happens in one spot, not five.
Step 1: Confirm there is actually a leak
Before any fancy gear comes out, a pro confirms the leak is real with a pressure-gauge drop test. A gauge goes on the hose bib to read city water pressure. Usually around 70 psi in this area. Then the water is shut off at the meter, the gauge reading is photographed, and everyone waits 15 minutes. If the pressure dropped, the system is losing water somewhere. No drop, no leak, and no need to tear anything open.
Step 2: Acoustic listening. Hearing the leak
Pressurized water escaping through a pinhole makes a distinct hissing sound, even through concrete. An acoustic listening device. Basically a highly sensitive ground microphone. Picks it up. The technician moves along the suspected pipe path and compares volume and pitch at each point; the leak is where the sound is loudest. Different frequencies even hint at the type of break. This is how a leak under six inches of slab gets narrowed to a dinner-plate-sized area.
Step 3: Thermal imaging. Seeing heat through the floor
A thermal camera reads surface temperature. On a hot-water line leak, the slab above the break shows up as a warm patch. The hot spot homeowners sometimes feel with bare feet. The camera verifies what the acoustic gear heard: when the loudest sound and the warmest patch are in the same place, the location is confirmed twice over.
Step 4: Tracer gas. For the stubborn ones
When a leak is too small to hear clearly, a safe mix of hydrogen and nitrogen gas is pushed into the drained line. The gas escapes at the break and rises through soil or concrete, where a sensitive sniffer detects it at the surface. Down to parts per million. It pinpoints pinholes that acoustic gear can only get close to.
Step 5: Line locating. Knowing where the pipes run
You cannot find a leak in a pipe you cannot find. A line locator sends a signal through the pipe that a receiver picks up above ground, showing exactly where the line runs and how deep it is. In Citrus Heights, where many 1970s homes have copper lines buried under slab additions and patios, this step prevents a lot of wrong guesses.
Why this beats guessing
Every method above answers a different question. Is there a leak, which line, exactly where. Stacked together, they shrink a whole-house mystery to one small dig site. That is the entire point of professional detection: minimum damage, minimum cost, one repair instead of exploratory demolition. See how our detection process works.
Frequently asked questions
Can I rent this equipment and do it myself?
Some acoustic gear rents by the day, but reading it takes trained ears. Background noise, pipe material, and depth all change what a leak sounds like. Most homeowners spend the rental fee and still call a pro. The meter test in our meter guide is the DIY part; pinpointing is the pro part.
How accurate is leak detection equipment?
With stacked methods. Pressure test, acoustic, thermal. A good technician narrows a slab leak to within a foot or two. No method is perfect through every material, which is why pros cross-check with at least two methods before anyone cuts concrete.
Will detection damage my floors or walls?
No. Detection itself is non-invasive: listening, imaging, and pressure readings. Only the repair requires opening anything, and precise detection is what keeps that opening small.
How long does professional leak detection take?
Most residential jobs take one to three hours on site, depending on how many lines need testing and how the house is laid out. You get a written location report, not just a verbal guess.
What is the difference between a leak test and a hydrostatic test?
A leak test uses normal city water pressure and watches for a drop. It answers whether a leak exists. A hydrostatic test pumps the system above normal pressure, which is a different procedure used for sewers and new installations. For finding a suspected house leak, the simple drop test comes first.
Related
Think you have a leak?
Call AquaTrace Leak Detection to describe what you are seeing in Citrus Heights and get a plan to find it.
Call (123) 456-7890Last updated: October 25, 2026.