Underground leak detector.

[Dave Shepard]

Anyone tried finding underground water leaks with an ultrasonic detector, homemade or otherwise? I've got a small leak I've been chasing, and I don't really want to dig up 150' of lawn looking for it. I'm going to try the DIY method next (as seen on YouTube):

[MikeON]

Could we have the YouTube link?  This sounds interesting.
My brother-in-law found a leak by waiting until very wet weather, then putting compressed air in the water line.  The bubbles appeared on the ground surface above the leak.

[Dave Shepard]

I don't have a YT link, but it was just a 38 second clip of a guy finding a leak in his yard. The original concept, as far as I can, tell came from a Farm Show article. 

[LAZERDAN]

Is it copper or plastic ?  Steel ?  How deep is it. got the right tools. Can you do a pressure test ?

[Dave Shepard]

1" plastic, should be 4'+ deep. The leak is fairly slow. With the pressure tank shut off it takes about 20 seconds to leak down enough to trip the pressure switch, which then cycles very rapidly. That is almost nothing to worry about. Almost.  :D

[jason.weir]

Good luck Dave,

I've got a 25 unit mobile home park with 30-40 year old black poly water lines with those white nylon unions & tees.  It was all buried without any sand around the pipe, just thrown in the hole and backfilled with whatever was dug out of the hole.  As you can imagine I deal with leaks constantly. 

We've tried everything from the high end ultrasonic detectors, to that Farm Show article, to dowsing, nothing works.  Most of the time we end up waiting until it bubbles up to the top and then start digging and follow the water.

My leaks are usually in the 1-2 gallons per minute range - you'd think those would be easy to find but water takes a funny path to the surface.  Had one a year or so back that was 8' in the ground and water bubbled up 150 feet away...

Your leak is so small you are unlikely to hear it without some really sensitive equipment.

Sorry I'm no help,
Jason