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Thread: Underground Leak

  1. #1
    Rancher
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    Default Underground Leak

    How do you locate an underground leak.

    Leaking 2 GPM somewhere between the pressure tank and the house, 2" PVC, 3' underground.

    No apparent wet spots.

    Rancher

  2. #2

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    I'm curious to see the answer to this one.

    Tom

  3. #3
    Geologist sjsmithjr's Avatar
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    In the absence of a wet spot at the surface, find someone with the specialized equipment to locate the leak using listening devices, maybe use a fiber optic camera, or start digging.

    -Sam

  4. #4
    DIY Senior Member Mike Swearingen's Avatar
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    Rancher,
    Sam has the easiest way, but if your want to DIY...
    It is most very likely leaking at a joint or other connection. No need to dig up the whole line. Hopefully, the PVC line is in 20' joints, and you can start at one end until you find it. You shouldn't have to dig all the way down to the 3' depth at each joint. You should hit wet ground before that. In lieu of hand digging, if you really want to find it quickly yourself, you can get a helper and rent one of those gasoline-powered posthole augers to drill down next to the joint areas. Either one will be work, but the auger will be faster. It won't get any less with time. (Another reason to move to NC...LOL).
    Good Luck!
    Mike
    Last edited by Mike Swearingen; 12-20-2007 at 09:08 AM.

  5. #5
    Geologist sjsmithjr's Avatar
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    Truth be told Mike, I'd probably wind up digging too as they tend to frown on my requests to borrow high dollar equipment from work. I did get to thinking, however. If Rancher knows where the line is and the soil isn't too rocky or saturated at 3', then he might be able to run a probe rod along the line watch for it to come back wet.

  6. #6
    Rancher
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    Thanks for the rapid response, I do own a backhoe, so the digging part is not that hard, I was thinking maybe one of those automotive stethoscopes might hear the hiss of the leak, anybody try that?

    And I do own a Fsher cable locator, and since the electric is also in that joint trench, I can locate the general location of the line.

    Rancher

  7. #7
    Geologist sjsmithjr's Avatar
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    Wouldn't hurt to try. I'd think you'd have to drive a rod into the ground and touch the stethoscope to that to pick it up. You could start by touching the stethosope to the exposed pipe on either end to see if you can hear it. PVC doesn't transmit sound well, but the folks here say that a 2 gpm leak in a 2 inch pipe buried 3 feet should be audible over the length of the pipe. The tough part will be how easily you can discern the differences in audible intensity.

    The listening equipment we have measures changes in audible frequency, not intensity, to pinpoint the leak.

    I'm curious to hear how this works out for you.

    -Sam

  8. #8
    Rancher
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    Just did the stethoscope trick on the copper pipe going to the water softner, and it appears that the leak is either in the 20' run from the outside valve (which I haven't vacuumed all the crud out of yet to turn off) to the water softener/heater closet, or in one of the runs to the front and back doors, which also feed from that closet. I had turned off the water at the softener thinking that would isolate the house, but forgot about the unsoftened runs to the front and back.

    How do you repair an underslab leak? Can you use it as a sleeve to run pex thru? It's 3/4" copper.

    Rancher

  9. #9
    Master Plumber Redwood's Avatar
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    There are companies that specialize in leak detection and locating. I would recommend you use their services.

  10. #10
    DIY Senior Member Marlin336's Avatar
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    3/4 pex will not fit inside 3/4 copper.
    You fix an under slab leak by abandoning the line and re-pipeing above the slab or by chopping the slab.

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