Adding laundry sink next to washer, can I share the drain and vent?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by DIYdidyoudothat, Aug 17, 2021.

  1. DIYdidyoudothat

    DIYdidyoudothat New Member

    Joined:
    Aug 17, 2021
    Location:
    Olympia, WA
    Hello, i want to install a vanity sink unit from Costco to the left of our washer and dryer. These photos were taken pre-drywall but the home is finished and inhabited now so the less cutting into drywall the better.

    Can I tap the utility sink's drain into the vertical pipe, either below or above the washer horizontal pipe? And then, can I just feed the sink with a couple Y connectors off the washer hot/cold spigots? Any tips about ensuring proper venting, draining, etc is much appreciated. Thank you!

    IMG_2729 copy.jpg IMG_7106 copy.jpg
     
  2. DIYdidyoudothat

    DIYdidyoudothat New Member

    Joined:
    Aug 17, 2021
    Location:
    Olympia, WA
    Here's exactly what I need help figuring out:

    1. Should I feed the sink drain ABOVE or BELOW the horizontal washer drain?
    2. Do I need to cut into the horizontal pipe and add a cheater vent parallel to the main vent so both the washer and sink can vent independent of each other?
    3. Do I need to worry about distances/heights/slopes with something this close together?

    IMG_2729.jpg
     
  3. Sponsor

    Sponsor Paid Advertisement

     
  4. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    You can add a tee above the santee and remembering to add the vent for the washer arm too.
    Normally the lower santee would be 2" and the upper one 2x1.5x1.5" to pass the inspection.

    [​IMG]
     
  5. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    If you want to have two san-tees on your stack, they can be in either order if each san-tee is vented separately (which means a horizontal vent takeoff on the lower trap arm; the upper trap arm is vented by its san-tee). But the pipe between the san-tees needs to be 2", because a laundry sink needs a 2" drain under the UPC, even though it is allowed a 1.5" trap arm.

    So for that arrangement, you'll need to replace the current san-tee with a 2" san-tee, extend the 2" pipe up to a 2x1.5x1.5 san-tee for the laundry sink, and add the yellow vent connection shown in the OP on the existing trap arm (which connects back to the existing vent at a height at least 6" above the standpipe and the laundry sink flood rim).

    If you want to disturb less of what's existing, you could cut a 2" wye in below the existing san-tee, where the red arrow points. Then the yellow vent is not required. But a wye like that is not suitable for venting a trap arm, plus it's too low for a sink. So you'd have a new separate parallel vertical pipe with a 2x1.5x1.5 san-tee for the laundry sink, and its vent would tie back into the existing vent (see above for height requirement), with its drain going to the wye. I don't think that's actually any easier to do, though.

    Cheers, Wayne
     
Similar Threads: Adding laundry
Forum Title Date
Plumbing Forum, Professional & DIY Advice Adding Laundry Sink Sep 27, 2021
Plumbing Forum, Professional & DIY Advice Adding half bath to laundry room help Sep 9, 2021
Plumbing Forum, Professional & DIY Advice Adding Laundry Sink with Washer/Dryer between it and the drain Aug 24, 2021
Plumbing Forum, Professional & DIY Advice Need help adding Sink to laundry room May 9, 2021
Plumbing Forum, Professional & DIY Advice Adding laundry sink to laundry room with existing washer Mar 11, 2021

Share This Page