Under ground water line.

[Stephen Newell]

youtube video shows using compressed air after capping the pipe and watching for the dirt to move. I question what it would do to the pipe that isn't leaking/broken. I've been lucky in one way that I've always found a pool of water where the pipe broke. We did have to try and isolate one time, pick a spot and dig and cap the pipe after cutting. Turn water back on if no leak you now have half as much line to look at.

Unless you put 175 psi air in the pipe it wouldn't hurt it. I've been using PVC pipe for compressed air for more than 50 years without any issues. I regulate the air down to 120 psi or lower before it goes to PVC. If the pipe is very deep in the ground I don't think you would ever find the leak pressurizing the water. It's already pressurized in the 40 to 80 psi range.

 

[Frank(Mi.)]

Unless you put 175 psi air in the pipe it wouldn't hurt it. I've been using PVC pipe for compressed air for more than 50 years without any issues. I regulate the air down to 120 psi or lower before it goes to PVC. If the pipe is very deep in the ground I don't think you would ever find the leak pressurizing the water. It's already pressurized in the 40 to 80 psi range.

Too true, ten years ago I had this very experience when our water line from well to house broke. I spent a day trying to find the leak using air at 120 psi. I gave up and called our plumbing contractor and he got a directional boring contractor and we got a new line installed. All it took was many $$...

 

[Eman85]

Unless you put 175 psi air in the pipe it wouldn't hurt it. I've been using PVC pipe for compressed air for more than 50 years without any issues. I regulate the air down to 120 psi or lower before it goes to PVC. If the pipe is very deep in the ground I don't think you would ever find the leak pressurizing the water. It's already pressurized in the 40 to 80 psi range.

I don't assume what type of pipe the OP has, plenty of piping done underground with the black rolls and hose clamps on plastic fittings.

 

[a49deere]

OP stated he had it fixed three days ago!! FYI