We have a leak somewhere, maybe under bathroom faucets or tub spouts as we hear noise there. Is there any harm done by trying to locate it by adding compressed air to the water line? What are steps to check for the leak that way and not cause any other problem? Are these the correct steps?


1. Leaving main water on, attach Schrader valve to hose bib, ours is NOT vacuum type.
2. Apply 90 psi compressed air to hose bib as our water pressure is 85 psi.
3. Turn off water supply to house.
4. Listen for any bubbling noises in the house to identify location of leak

That would be a first step, although it may NOT be successful if there is not a pond of water around the leak.

3. I always leave the water on, if you turn the water off the noise will not be near as easy to detect. You want water to mix with the air to increase the noise level.

Thank you for clarification about leaving water on. How much total psi should be read on the Schrafer valve with the water on?

If there's no PRV, how do you increase the pressure by admitting air? Any air pressure greater than incoming water pressure will just push incoming water back into the street piping, just like thermal expansion.

I would turn the water off at the ball valve where the Pressure Regulator should be installed. If you don't have a ball valve but instead have a gate valve then turn off the cock (valve) at the meter to isolate your entire water system. Fill the line with 90 PSI as you indicated and watch to see how fast the gauge goes down. Then listen in each bath and kitchen, laundry, etc. If you can't hear any sound then you should call a professional plumber because you will need special equipment to locate a leak under a slab. I will add that a great majority of leaks under a slab are hot water lines that have pin holes or other cracks from improperly rolling the copper up into the slab. It seems that heating water changes the chemical make up of the water causing it to be more corrosive.

After you resolve this problem, if you don't already have one, install a pressure regulator on your system just outside the house just below your hose bib. Set your pressure to somewhere between 50 and 65 PSI for less wear and tear on your water system. You can purchase a gauge at Homedepot or your favorite Hardware store.

steve, you don't need a lot of air pressure. the idea behind using air with the water is the air will make the water around the pipe at the leak bubble so it gives off a sound at the leak site because the water flowing sound travels through the pipe making it almost impossible to pinpoint

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exactly.. the main valve needs to be shut.

Thank you for replies. So 90 psi should be put into hose bib via air compressor with Schrafer valve with main water being turned off right before inserting the compressed air. Then we listen for any different bubbling noise under the sinks in question. Is this correct?



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make sure the hose valve does not have a backflow device on it. if it does you can not get anything to go backwards into the valve. don't be afraid to put 100 PSi nto the system. when we have to test piping for an inspection we are required to put at least 100 (and sometimes more) into a system.

Thanks for replies. Our hose bibs don't have vacuum seal. Still have not actually tried doing the compressed air. If leak still not found, what are best methods to find the leak? Is there state of the art technology that works better? What are reputable?
Thanks in advance for opinion.