Double Basin Sink - Backup

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by jaspol, Sep 17, 2011.

  1. jaspol

    jaspol New Member

    Messages:
    2
    Location:
    Connecticut
    Hoping someone can offer some help...

    I just undid the plumbing under the kitchen sink - 2 basin sink (the alignment is such the basin on the left hangs lower and further back than the basin on the right), no garbage disposal. It was draining slowly, but draining. So I cleaned all the pipes, put a fernco adapter on the pvc line out where it meets the old metal pipe in the wall (when I undid the pipes and put things back together the 1st time it was leaking at this spot), fixed the p-trap (it was actually installed backwards or in reverese so the high end was closest to the line out) and even snaked a bit of the pipes behind the wall.

    Things work fine now when I run the water at a trickle or at medium speed. When I dump a lot of water down the sink, or run the water quickly, it quickly stops draining and water comes in through the other sink basin. The two basins connect at a T in the middle of the assembly and I even ran the water without one of the T's being closed off to watch the water. The faster the water (or more water), that is when it wanted to come out the other end of the T (and if it was connected, up through the other sink).

    All the other drains in the house are working fine.

    I've attached a picture (assuming I can get the attachment feature to work). Does the height here of the line out and the trap and the sinks basins matter / is it an issue? Before I redid this, the other thing different was the lines from the sink basins were longer (because the p-trap was reversed and therefore hung lower). If the picture doesn't work, both basins feed directly to a T. The other part of the T goes to the P-trap, and then out.



    I'm stuck as to what to do now - other than not run a lot of water. I know the moment I turn on the dishwasher though, it'll backup.

    Thoughts? Thanks in advance!
    Last edited: Sep 17, 2011
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,303
    Location:
    Cave Creek, Arizona
    Snaking a "little ways" is NOT the solution. You have to snake the line ALL the way to clear it.
  3. jaspol

    jaspol New Member

    Messages:
    2
    Location:
    Connecticut
    Under Sink.jpg

    Thanks appreciate it. The initial snaking got in about 5 feet before I couldn't get it further - not sure what it got caught up on. I'll continue to try

    My real question...the drop from the sink basin to where it eventually meets the T piece is only about an 1 inch or two. Does it need more vertical drop or as long as it's a little lower, gravity does the rest?
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,303
    Location:
    Cave Creek, Arizona
    The HEIGHT of the drain is okay. HOW it is put together makes it a "nightmare", but not for drainage reasons. It would have been difficult to assemble it using MORE slipnut joints than they did.
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