Quick answer: The leak detection process is how a pro locates a confirmed leak before any concrete is opened — locate the lines, isolate the leak to one section of the system, listen for it with a ground microphone, and amplify the sound with air until it can be pinpointed.
Confirming that a home has a leak is the easy part, a simple water leak test will tell you the system is losing pressure. The hard part, and the part that separates a professional from a guesser, is locating exactly where that leak is before anyone breaks concrete. That’s what the leak detection process is for. And, knowing where all the lines are is the first step so you aren’t listening to every square inch of the house. You will use the same underground/under-slab line locating equipment that you use now.
At LeakPro®, the process is built on location, isolation and acoustics: narrow down where the leak can be, then listen for it with the right equipment and amplify the sound until it’s unmistakable. Here’s how it works for the three kinds of leaks we teach — under-slab water lines, underground (yard) water lines, and sewer lines.
Every job starts at the street meter. Watch the leak indicator: if the flow reading is strong, water is moving somewhere. If the sound of water at the meter is loud, there’s a good chance the leak is right there, so work the ground around the meter first with your LeakPro® Probe.
Next, isolate the house from the meter. If there’s a shut-off valve at the house, an isolation valve, close it and go back to the meter (be careful here, if it is an old valve, explain to the customer that you are not responsible if it breaks and may need to be replaced). If the indicator is still turning with the house valve shut, the leak is in the yard, the underground service line between the meter and the house. If it stops, the leak is inside the building envelope, most likely under the slab. This one step tells you which of the next two paths to follow.
With the leak isolated to the house, isolate the hot and cold lines just like you did the house and the yard service, then walk the interior listening at hose bibs and at the valves under sinks and toilets. Shut each toilet valve (very carefully) as you go and listen again, if the sound stops at a fixture, the leak was that fixture, not the slab. Eventually one valve will be noticeably louder; locate exactly where the lines go from that manifold, then start listening to the floor on either side of that wall with the Sidekick and pinpoint the loudest point. Normally you will hear two valves that are louder than the others. Figure out how these valves are connected.
Because water leaking into an open pocket under a slab is sometimes nearly silent, the pros amplify it with air. Get the water heater out of the loop, introduce air into the line, and the escaping air creates a strong, high-frequency noise under the slab that’s far easier to trace. Most under-slab leaks sit within two or three feet of the wall where the plumber made the bend in the tubing.
If the isolation test pointed to the yard, leave the house valve off, locate the yard service, and walk the property with the Probe, touching the point to anything coming out of the ground — hose bibs, irrigation risers, service fittings. Do this with all irrigation shut off, as an isolation. Then introduce air through a hose bib or the laundry valve box and listen at the meter and any other hose bibs. Air moving through the buried service line makes the leak louder than just the running water.
Sewer lines don’t hold pressure the way water lines do, so they’re located differently. Run a camera or take a sewer machine and bend the end of the cable just a little, so it knocks against the inside of the pipe as it travels underground. Then follow that knocking sound with the Probe, setting the point on solid objects on the ground above the line. It’s remarkable how far that sound carries, this is how you trace and isolate a sewer line’s path without a schematic. When you are trying to find sewer leaks under the slab, you can isolate different branch lines to determine exactly where the leak is at.
None of this works without the right ears. The LeakPro® Probe is an in ground probe/microphone tuned for the high-frequency noise a pressurized leak makes, and the LeakPro® Sidekick is the acoustic amplifier that makes faint sounds hearable. Most pros carry both — the Complete Kit pairs them with two headphones and adapters so one technician can isolate, amplify, and pinpoint on a single call, or two technicians can work inside and outside if needed. If you’re weighing your options, here’s an honest look at how our equipment compares.
Reading the steps is one thing; finding a real leak under a real slab is another. Our 2-day leak detection training in Wylie, Texas takes you through under-slab water lines, an underground water line, on live leaks, and sewer line isolation testing, so you leave able to run this process on your own jobs with confidence.
It’s the professional method for locating a leak once you know one exists: locating the lines, isolating the leak to a section of the system (yard vs. under-slab, hot vs. cold), listening for it acoustically with an in ground microphone, and amplifying the sound with air until you can pinpoint it, all before any concrete is opened.
Isolate the house from the meter. With the house shut-off closed, if the meter’s leak indicator is still moving, the leak is in the underground line between the meter and the house. If it stops, the leak is inside the building, most likely under the slab.
Water leaking into an open space under a slab can be almost silent. Introducing air into the line creates a strong high-frequency noise at the leak that a LeakPro® Probe or Sidekick can trace far more easily than with just water.
Not quite, sewer lines aren’t pressurized. Instead, a camera with a locator is used to locate the lines, and sewer isolation techniques show you which lines are leaking and which lines are holding tight.
A ground probe/microphone like the LeakPro® Probe, an acoustic amplifier like the Sidekick, and a way to introduce air into the line. The LeakPro® Complete Kit lets you hear what others can’t.
