Add laundry sink to washer drain?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by djbabyk, Jul 24, 2008.

  1. djbabyk

    djbabyk New Member

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    Jul 24, 2008
    Hi. I'm adding a laundry sink next to my washer and was thinking I could just cut off the top of the standpipe where my washer now drains, then plumb in a tee to come out of the wall in order to put in my sink drain and ptrap. I would then just have the washer drain into the sink. The only problem (is it a problem?) it that there is a ptrap in the wall a the bottom of the washer stand pipe and the sink would now have two ptraps. issue or nonissue?

    Thanks
     
  2. Redwood

    Redwood Master Plumber

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    A double trapped sink woud be a problem that could create a flood.
     
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  4. Redwood

    Redwood Master Plumber

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    You actually need to configure the drain pipe inside the wall something like this to do what you want to do. This would ensure proper drainage and venting.

    [​IMG]
     
  5. hj

    hj Moderator & Master Plumber Staff Member

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    drain

    Cut the trap off and install an elbow facing out of the wall. Then connect the sink's P trap to that, if you are not going to use the pipe in the wall for the washer drain. If you do plan to keep the current connection and add a sink, (by connecting it to the washer's standpipe), then you will not really have the classic two trap situation, nor will you even need a P trap on the sink.
     
  6. djbabyk

    djbabyk New Member

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    Jul 24, 2008
    OK. So it sounds like I can use a properly vented and trapped washer standpipe (correct term?) to drain both the washer and a laundry sink and they will both share the ptrap at the bottom of the standpipe? Perhaps some water will come up into the sink when washer is draining? This sounds like the same as a dishwasher draining into the kitchen sink's ptrap.
     
  7. Redwood

    Redwood Master Plumber

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    No!
    You can have both plumbed in per the picture I posted above.

    or,

    You can eliminate the washing machine standpipe and elbow out to a sink drain & P-Trap and then drain the washing machine into the sink.

    You cannot have the washer and the sink share a trap!
     
  8. hj

    hj Moderator & Master Plumber Staff Member

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    sink

    You CAN connect the sink to the standpipe, but it would not pass an inspection. You CAN use the washer p trap connection, after you cut off the P trap, for the washer and then drain the washer into the sink. This is an approved method.
     
  9. Wayne in Gville

    Wayne in Gville New Member

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    Redwood, can you explain the function of the part I circled in red?

    washer_rough_b question.jpg
     
    Last edited by a moderator: Feb 13, 2017
  10. Terry

    Terry Administrator Staff Member

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    That is the vent. The UPC code require that the washer p-trap and standpipe gets vented before dropping below the laundry sink plumbing.
    UPC doesn't allow wet venting of laundry trays and washers.
    All of this is to prevent the traps from siphoning during use. It adds a few dollars and keeps the home from stinking. It's worth it.
     
  11. BYUFan

    BYUFan New Member

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    Denver, CO
    I have a similar project coming up, except I'd like to avoid draining the washer into the sink. Forgive the shoddy sketch, but the pencil is the existing washer system and the red is the proposed plumbing for the new sink. I THINK this method is legal, but can anyone recommend a better or easier solution?

    Thanks in advance!
     

    Attached Files:

  12. Reach4

    Reach4 Well-Known Member

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    In my marked up version, the pencil and red both are there. I think your way is probably legal, but the washer may blow some water into the laundry sink. That is not so bad, but this would avoid that.
    C needs to be a long sweep, and B can be a combo or wye and 45. I think the drain for the laundry sink can be 1.5, but the drain for the standpipe would be 2 inch if new stuff. If preexisting 1.5, it is probably OK. I am not a plumber.
    img_3.jpg
     
  13. Williamrobert

    Williamrobert New Member

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    Sc
    Would an aav work for the sink in this appli action?
     
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