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Thread: Three Sinks, One Drain?

  1. #1
    DIY Member thegallery's Avatar
    Join Date
    Oct 2006
    Philly, Europe

    Default Three Sinks, One Drain?

    I'm way ahead of myself, but I'm just buying a place that has a finished basement with a separate entrance. So I'm considering putting in a mini kitchen and bathroom as an 'in-law' suite. I'll have plenty of questions in this regard down the line...

    But right now I'm wondering if I can drain three sinks into one drain hole? There is only one drain for the laundry deep sink in the basement now. But the way I'm seeing the layout I could actually have the kitchen sink, the bathroom sink, and the deep sink all adjacent to each other (in the corners of their respective rooms). Center line to the drains would all be within 30" of each other. Could I utilize the one deep sink drain line to drain them all? Even perhaps a dishwasher too?

    I plan to use an up-flush system for the toilet and shower, though everything will be very close the the main drain of the house. I don't know how deep it goes but I know the deep sink drain ties into it below ground. If I find out I can dig out a trench and hook it up, to code, relatively easily I will, but my guess the the up-flush will be best.... ahead of myself again...

  2. #2
    Homeowner geniescience's Avatar
    Join Date
    Nov 2005
    humid summers hot, humid winters cold

    Default DFU's, and venting

    Check out Drain Fixture Units (DFU). This will answer your question. You have to measure the inside diameter of the drain pipe, easy to do if you measure the circumference of the pipe and post that information here.

    The bigger question, after you get your "Yes" answer, is how you will bring sufficient venting to the drains. More drains, more vents needed, to prevent having one draining fixture suck water out of the adjacent P traps and therby allow sewer gases to come back up the drain and into the house.


  3. #3
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default drains

    There is no correct answer to your question until you show us how you plan to make the connects, otherwise the answers will be YES, NO, or MAYBE, it all depends on how you finish the job.


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