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Plumbing in the Home/How to find a water leak with the water off?



Thanks for being on here.  We have a HUD property in contract and the went to de-winterize it yesterday and the plumbing did not hold pressure.  Therefore, they would not allow the water to be turned on for inspection.  Is there a way to find a water leak WITHOUT actually turning on the water?  They don't want us to turn the water on at all until the leak is repaired and passes an air test.  Thank you.

Yes there is.  An air compressor with a valve and gage will have to be attached to the piping system. The gage must be on the line after the valve in order to monitor the pressure loss. Start pumping air in and listen for obvious leaks. Once those are repaired recharge with air, lock the air in using the valve and watch the gage. The air test will (at least where I am) need to be on for at least an hour and be at twice the working pressure of your area. In most cases 100 psi is sufficient to properly test and satisfy your inspectors.
Be sure all faucets are closed tightly, I also shut any valves under the fixtures as well as the faucets.
If there were breaks caused by freezing, this  more than likely will have ruined the faucets too. Listen for leaks at the faucets if pressure will not hold
Don't forget outside hose faucets.
Find where lines go to second floor(if applicable) and listen  close to the wall for leaks. Also under bathroom floors
If the house was winterized properly, chances are this will be an easy test.
The best way to attach air line to water line is to cut a tee into the main line so both hot and cold can be tested.
Do the cold first by isolating the hot side at the water heater. Just shut the cold feed to the tank

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Jay Nicholas


Plumbing & Heating (warm air, hot water & steam heat)


40 years in the business, 40 years as a lic. master plumber in NY State. Retired

Graduated Magna cum laude at the School of Hard Knocks

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Commercial, residential and light industrial. You name it ...I have probably worked on it

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