How can I locate a small leak in my concrete slab floor. Copper supply line is buried in the slab. Leak can be heard but water not evident... the water must be absorbed through to the earth below.

Well the cheapest way we did it in the old days since you can hear the leak is take a long screw driver and hold it tight to your ear and the concrete floor at the same time. The loudest spot in sound should be where the leak is. Hopefully the copper is not IN the concrete floor itself copper and concrete don't MIX and corrode copper lines. The other way is to call a plumber and he should have a tool to locate the line its self but not the spot that actually leaks. It detects pipes and not water in that sense. So try the ear tight to screwdriver handle and touching the floor at he same time A kitchen implement can work also a wooden dowl rod and see how close that gets you if finding the hhhsss

Signed 21 Boat

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Call Slab Leak Detection Service. They'll locate leak within +/- 24" of the actual leak. Repair it ASAP so it won't cause hollow spot under your house and potential foundation sinking. Then, repairs would be very expensive...

themipper
Sorry you disagree but just on a factual note On a job site I had a customer that called me to help solve why they were still getting water in their basement after they had someone else dig up there whole outside yard and had drain tile put in and stone and more pitch and it stilled leaked at the concrete floor by the block inside the house. I came out during a heavy rain and put My ear to the wall and the customer thought I was nuts. I then said I found the leak and had them listen to the plink plink of the water dripping Inside the wall block core and falling and hitting drop by drop in the bottom of the Inside block core wall where just a couple of inches of inches of water in it. They were amazed. They were even more amazed when I told them that the company that did the outside sealing job did it right assuming the water was getting in through the foundation form the outside dirt at bottom of block wall. I told them there brick was sucking in the water and it was dripping inside the block wall. I broke out the cement brick beside the I beam pocket and it was leaking thorough the brick wall. It was above ground where the leak started through the brick that was only 15 years old. This without a screwdriver. On the plumbing re-hap jobs we do we bang/tap a pipe in the basement and one of us uses a screw driver on the 3rd floor to check which line is the hot or cold. As a shop mechanic this screw driver method is also used to see which valve cover has a valve tap inside it and which side which is very hard to tell when the motor belts and fan is making noise. This same method is used to tell if a train is may a mile or so away by putting your Ear to the steel track.
Before you disagree ask an old plummer if there is a small leak on a water line in the house and he will tell you if his well experienced that you can put an ear to the pipes and find which one is sshh. I do the same thing on a zone valve on a boiler system to test to see of that valve opens. I personally have found Many of leaks and bad bearings on small motors before. So as far fetched as it may seem this is why was done only 30 years ago before the tech toys came out or was affordable for the tradesmen jobber

Well the cheapest way we did it in the old days since you can hear the leak is take a long screw driver and hold it tight to your ear and the concrete floor at the same time. The loudest spot in sound should be where the leak is. Hopefully the copper is not IN the concrete floor itself copper and concrete don't MIX and corrode copper lines. The other way is to call a plumber and he should have a tool to locate the line its self but not the spot that actually leaks. It detects pipes and not water in that sense. So try the ear tight to screwdriver handle and touching the floor at he same time A kitchen implement can work also a wooden dowl rod and see how close that gets you if finding the hhhsss

Signed 21 Boat

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I find the rating for "Answers" to be very difficult in this program. My REAL reply is that your suggestions are very plausible and I thank you. I will be trying your methods. themipper

themipper I didn't personal insult on your disagree. I could see from your position reading My post could sound borderline nuts of what I suggested to find the leak. I only suggested this approach because you stated that you could "Hear" the shhhh already in the water line and the screwdriver method could get as close or closer than a tech device. It hears sounds but not if it a hollow sound as opposed to just the sound itself. I have blown away some townships when we called them to find a water line and couldn't but I found it with metal bent coat hangers 'dowsing" Believe it or not our City of 50,000 uses dowsing rods as a backup to find a water line. So don't worry about the rating system here I'm an old seasoned tradesmen 50+ and the main objective here is to offer help and or an opinion to help and there are many ways to approach and solve things.
So don't feel bad and keep on using this site and don't worry about the rating system. Its just to help us answer web volunteers keep us on our toes and remind us not to get sloppy. Its a good check and balance for the site and the people on it. Once in a while I could have given a reddie to a regular answer person but I don't. I just post behind there post to remind them they are not quite correct just as i have been in that same position where I got hammered on a repost of my suggestion. When that is done in the TRUE spirit of trying to help out the "question" person then its all good. Never take it two serious.
Iv screwed up a couple on times hear where i should have gotten a reddie and didn't. oooppss on me!!! Themipper Iv seen quite a few "Disagree" that happened because the question person is not very descriptive on there question and we try to answer the best we can on the information we receive and that can get sometimes Wacky.

So good day my friend.
Mark 21 boat

How can I locate a small leak in my concrete slab floor. Copper supply line is buried in the slab. Leak can be heard but water not evident...the water must be absorbed through to the earth below.

You may try Boats method of location first but be advised that the surest way to pinpoint a slab leak is through a leak detection service such as Sleuth. They will come in, locate the leak, break up the cement , dig down to it, bag the dirt and expose the leak so the plumber can repair it. Good luck in whatever you decide. Tom