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Thread: Information on Running a Frost Free Water Line from building to building

  1. #1

    Default Information on Running a Frost Free Water Line from building to building

    Hi Was wondering if anyone could give me some information on running a frost free waterline from one building to another. The frost line is 42". It is going from the house existing water lines, copper pipes, to a 100' greenhouse I just put up, 200 feet away. A frost free hydrant will be installed in the greenhouse, with a one way check valve. What is the best material to use for the line itself? Copper? PVC?

    Thank you for any assistance.

  2. #2
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Yakima WA


    I'd use PVC, at least 1" and maybe even 1-1/2" to avoid flow loss due to friction. You must remember that there is no way to positively guarantee the pipe will not freeze even if it is buried below the frost line. Therefore, I'd suggest you put a shut off valve were the line branches from the main supply and install a drain valve at the lowest point. If you have an air compressor, you can blow the line in the fall much like we blow out irrigation lines. You might go forever and not freeze up, but on the other hand, this could be the 100 year winter, and if you design it to be drained, you won't have to go so deep.

  3. #3


    Thank you so much for the reply. I was not sure which way to go with the copper or pvc. I will be using the water over the winter in the greenhouse. We plant in January. We are putting a shut off value. Thanks for the tip on the drain valve. In case we sell and the new owners don't want to operate the greenhouse it will come in handy Thanks again.

  4. #4
    Master Plumber Dunbar Plumbing's Avatar
    Join Date
    Apr 2005
    Northern Kentucky/Greater Cincinnati Area


    Bury the pipe at least 8 feet deep.
    Read what the end of this sentence means.

  5. #5


    Quote Originally Posted by RUGGED View Post
    Bury the pipe at least 8 feet deep.

    Where and why???????????????????


  6. #6
    That's all folks! Gary Slusser's Avatar
    Join Date
    Aug 2004
    Wherever I park the motorhome.


    A much better and less expensive choice that takes much less time to install and has the lowest friction loss of any water line material is a roll of PE (polyethylene) pipe. You unroll it right into the trench and there are only two fittings, one on each end. You can get various length rolls at any pump or plumbing supply house. I'd use 160 psi rated 1"-1.25" and if any fitting is buried, SS or red brass fittings. For above ground sch 80 PVC fittings. And double oppose clamp all buried fittings.

    It's the same stuff water companies and many well water systems use and it's been used for 50 years. It is much more forgiving if frozen and contraction/expansion is taken care of by letting it zig zag from side to side in the trench. Just keep it off sharp edged rocks and don't bury it with them against it.
    Gary Slusser Retired (= out of business)
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