How to Repair a Slab Leak

by Edmund Celis, December 2, 2016.
Water piping
Photo by Edmund Celis

Disclaimer: I am not a plumbing professional. Please use the advice at your own risk. I am not responsible for any damages that might occur.

It began with a noise coming from some piping where a sink used to be. Tightening the valve to the hot line seemed to do the trick but there was still an occasional noise that seemed to be just air. Several weeks later however, the noise seemed to get worse but the valve was not leaking.

Then, upon showering, I noticed the tiling floor to be unusually hot. It then occurred to me that there might be a leak from the hot water supply line.

Turning off the water heater both mitigated the noise of the leak as well as the heat from under the shower floor.

I also checked the water meter while the boiler was on to find that the low flow indicator (red triangle) was spinning, further suggesting a leak.

After doing a lot of research (YouTube videos, reading forums, posting in forums--plbg.com, diy.stackexchange.com and plumbingforums.com are all great for asking questions-- calling plumbing companies), I found that it is typically called a slab leak. The plumbing professionals that I called were all suggesting that I repipe the whole water system since the house is fairly old and a leak in one area may suggest that other pipes may falter soon as well.

They were quoting me about $10,000 up to $20,000!

Going straight to the leak and fixing the piping there would cost me around $2500 they said.

After watching several videos on YouTube however, I decided to tackle this problem myself. Most videos offered the most direct solution of jackhammering the floor to get to the broken pipe, as shown in this video. However, after cutting through the wall on the other side of the shower where the noise of the leak was prominent, I discovered three pipes and the middle one was vibrating much more than the other ones and thought that there must be a better way.

(Caution: wear appropriate personal protective equipment such as long sleeves, hair tie, mask, goggles and gloves when working on plumbing type of work, especially when exposed to the asbestos in some walls, which is the pink fluffy stuff used for pipe and wall insulation).
I did more research and then discovered this video showing a smarter way to do it without jackhammering into the concrete slab, which is basically cutting off the pipe that supplies the leak and applying a stop valve.

After studying the house’s water system layout with the help of some diagrams, like this one, and using a metal detector (which I downloaded as a free app on my iPhone), I did more testing with turning on and off the water heater’s cold supply valve, and finally discovered that there was moisture near the bottom of the middle pipe!

Thus, the plan was now clear. Cut the middle pipe and install a stop valve.

After doing a lot of measurements, I then went to Home Depot and bought a Sharkbite End Stop for about $7.

I went with this type of push-to-connect solution, rather than a more stable compression (screw-on) or sweat (soldering) valve because of the close quarters, and simply, I just wanted to test my theory.

I then went to my Dad’s toolboxes and got a hacksaw, a steel wool brush, some sandpaper, a filer, a headlamp, a sharpie, a measuring tape, and of course, a good ol’ rag.

I knew the top must be the feeder line, in which hot water comes from the water heater, because the three lines going down into the cement must be going to some source, such as a sink or shower valve. I marked my cuts with a sharpie and then sawed away for a good hour with a hacksaw because the close quarters limited my ability to use a simple pipe cutter. I also sawed away at the top half first and then realized that the bottom was now flimsy due to no anchoring force from above, so I had to use a clamp to stabilize the bottom half.

Nevertheless, I eventually got the section of copper pipe off and then cleaned the edges of the top remaining pipe with the sandpaper, file and steel wool brush and wiped away the debris with the rag.

Finally, I simply pushed in the Sharkbite stop and then turned on the water heater’s cold supply valve and…drum roll...no more noise!! Then, to make sure, I checked the water meter outside, and the flow indicator was not moving at all!!

After rejoicing for several minutes and laughing at how I spent $7 to do this repair (of course, I spent several weeks researching but it was worth it to learn so much!), I then tested some of the faucets and showers to see which line was affected and it seems to be the sink, but the sink’s hot line is off for now since it’s tubing and faucet handle are not working.

I still can’t believe how well the repair went. It goes to show that you can do anything with the help of the internet! Go internet!

(Thank you to the many great people who offer free advice online. It is really inspiring to see how helpful people are all over the world. Much love!).
Water piping with Sharkbite end stop
Photo by Edmund Celis


Please check out my article "Tunnel to the Ocean". It gives some advice on how to care for the environment!

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