Lowering a Kitchen Sink Drain Line

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by morpheusmurals, Aug 5, 2012.

  1. morpheusmurals

    morpheusmurals New Member

    Aug 5, 2012
    Chicago, IL

    I just installed a 10" undermount sink- used to have a 8" above. Nice surprise when I figured out the drain line was too high.

    I am planning on cutting open the wall to lower the drain in the main line.

    Couple questions:
    Currently the main drain travels 24" horizontally connected with a Tee at the 2" main line. That 2" pipe is vented to the roof. Is that vented correctly?

    Can I just open that line and do the same thing lowering it to the appropriate height? Is the Tee creating a vent? Can I use a Fernco Quick Tee to make the new connection? The line is galvanized pipe.

    Do I need to slop the horizontal line downward toward the main line?

    I attached a photo when the wall was open. Of course now it is all drywalled and has a nice cabinet in front.


    Attached Files:

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Cut the T out with enough pipe beneath and above to allow for a stub to be glued into a pvc (or abs, whatever is generally used in your area) to a sanitary T (I can never remember if that must be a sanitary T or a wye - since above is a vent, I think a sanitary T is okay), not a t like is there now, and a stub above then use nohub connectors to reattach that new assembly that you cut out. The pipe coming up from below is likely a revent from something below (maybe the laundry or a sink in the basement?). Note that, depending on what's above, once you cut the pipe, it might move. To ensure that doesn't happen, you might want to install a hanger brace.
    Last edited: Aug 5, 2012
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