Water leak detection? Acoustical, electrical, and such? The real thing?

[e9999]

been chasing a water leak outside. Been digging up for a while now and still not found the leak. Looks like the water may be travelling some distance underground and I fear the leak may even be under concrete.
Anybody knows about those companies that claim they can find leaks using acoustics, magnetometers or some such thing? Any truth to that? Even under concrete?

 

[jynx]

Not sure about under concrete, but in the utility business a good leak detection guy can be worth his weight. The acoustic listening devices do work. No experience with magnetic devices for leak detection.

Typically the acoustic ones basically listen for the water leaving the pipe. On the utility side they "listen" for leaks a lot. Closing valves down or "squealing" them to listen for water moving past. Ive seen them find them under asphalt so concrete wouldn't be a stretch. May not be as dead on as in earth, but should be able to narrow it down.

I have seen a good leak guy stop and say dig here and the leaks be within a foot or so of where he is at.

 

[e9999]

this is a comparatively small leak. I can see water pooling in a deep hole I dug something like a gallon in 2 or 3 hours. More like the equivalent of an aboveground drip, probably. It seems unlikely that a simple listening acoustic device might hear anything I would guess. What do you think?
Is there any other technology? Something that measures humidity or density variations maybe electromagnetically or using a sonar of some sort?

 

[ferg]

Are you sure it's your water and not some other source? Tried turning off your source and checking the pooling after a few hours?

 

[e9999]

yes. I have turned the main valve at the street on and off many times and there is perfect correlation with the flooding I see in the hole I dug.

 

[e9999]

well, I did talk to a recommended leak detection outfit in town, and they can't do too much it turns out.
Basically, to find a leak, what they will do is pressurize the line with air and attempt to listen to noises the air makes when leaking. I had actually already done that, and interestingly, that actually allowed me to identify which pipes were water. Could not hear the leak itself but could hear noises in the pipes. (Amazingly, I also tried to spray soapy water on the dirt and I think it did show some bubbling on the leak side, but not a clear thing.)
They can also insert a camera/transponder in the line and find out where the (first) connection is, which is not necessarily where the leak is unfortunately.
I was hoping they could trace a bare (no marker wire) water pipe underground but apparently the only way they can do that is thumping the pipe with water hammer and then listen for the noise it makes (the tech guy said he did not recommend that for fragile systems). I suppose that ground penetrating radar is a possibility but they did not do that.
And their accuracy is typically something like 2 or 3' it seems so not much better than what I can do by digging.

So, no miracle solution yet.