Leak under slab???

What kind of equipment do prfessionals use to detect under slab leaks?

Is it a listening device of some sort?

I have a good sized under slab hot water leak under in a rental condo of mine. The noise is very apparent in the back to back bathroom walls. It is as loud as say, when the toilet is refilling, but since there is no water showing, it's obviously going out under the slab.

My plan is to remove the 30" wide vanity cabinet and jackhammer the floor to access the leak but I want to be more certain that the leak is close by.

Should I spend the $150 for a leak locator service of just proceed? I can easily do he repairs but if the leak is 10 feet away under the carpeted living room floor, I don't want to mess with removing/replacing the vanity.

It sounds awfully close to the bathroom but?????

Crap. I suppose I just need to cough up the $150. In the old days ( a couple years ago) I wouldn't think twice about it, but work (electrical) is still slow as hell and $150 is more important than it used to be.


Any input will be apreciated. I have to decide tonight and call a locator tomorrow.

Electronic leak detectier is the only accurate way to locate a leak under the slab.

An IR thermometer might help you to locate it, but someone who knows how to run the leak detector properly is possibly more reliable. My sister works for a municipal water company. For a time, she ran the leak detector. She got a reputation of being spot on, and when they dug up the road, they found the leak. The majority of the others got close, but the holes in the road were often much larger. The skill level of the operator and the equipment used can vary a lot along with the accuracy of the results.

If there is not an obvious hot section on the floor, then a professional leak locator, not a plumber with a stethescope, is the only way to pinpoint it. A professional locator has many more options to find it than just a thermometer or a sound detector.

I had a plumber come out with a stethescope. They call them geophones.... I'm not sure he used it correctly, and I'd imagine they're tough to use. They hooked up an air compressor to my hose bib outside, which makes a gurgling noise in the pipes. The theory is that as you place the two geophones on the floor, you'll know you're over the leak when you hear the sound equally in both ears.

If I could do it over, I would consider using electronic leak detection if it allowed them to trace the pipe. It's a little pricey but you save money in terms of the time spent digging.

Edit - BTW, we just started digging since we knew where it sounded the loudest - before the geophone - and it's probably six feet from where we started. Live and learn.

This is a good lesson for people reading this post after it has been written. Slab leaks may not be wher ethe noise is, and you can save time and money in the long run by using a leak detection company. Perhaps you would not have needed to remove the cabinet/vanity if the leak detection company had told you right where the leak was located. United Leak Detection

Why not try these one it might help you solve your problem.


1.Identify the location of the leak. If this is a hot water leak, walking around with bare feet will probably lead you right to the area. Mark the area with masking tape.

2.Remove the flooring from the area. Try to remove as little flooring as possible--a square-foot piece--to prevent extensive damage and replacement.

3.Using a concrete drill bit, begin to drill through the concrete. Since the slab is about 4 inches thick, this will take some time. Make an opening big enough for your hand to fit in so that you can reach down to feel the leak. Once you have located the leak, make the opening bigger to repair the pipe.

4.Shut the water at the main and, using a pipe cutter, cut off the piece of pipe that is leaking. Replace the type of pipe you removed with an identical piece, whether copper or PVC. If PVC, cut a new piece to length and replace it the same way you would for any other PVC pipe repair. If it is copper, you will need to weld the piece into place. Leave this hole open for a day or two to make sure that the leak is properly sealed.

5.Mix a bag of concrete and fill the hole to the top, sealing it with the surrounding slab. Leave to dry and cure for several days.

6.Once the concrete is cured, use construction adhesive to secure a new piece of flooring in place.

I had occasion to use an infrared camera (by a company called FLIR) inside a building to assess heat leaks. As I was moving from one area to another I noticed a very dark line across a carpet-covered concrete floor. It turned out that the dark (cooler place) was where the municipal water supply (not leaking) passed under the floor.

If you can borrow one of those infrared cameras you should be able to find the leak. You might find one at a rental company, or some company that is selling windows or insulation systems who will come and show you where you are losing heat. If you are present during the inspection you might incidentally find the warm spot where the leak is.

I'm sure the problem the original poster had back in March has probably been found by now.
United Leak just dropped a spam link awakening this old dead thread.
He's been booted off a couple of other forums so far...

Buyer Beware! http://www.bbb.org/indianapolis/bus.../united-leak-detection-in-carmel-in-90003573/