Offset Sink Drains Slow

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by k-auss, Jul 24, 2012.

  1. k-auss

    k-auss New Member

    Messages:
    3
    Location:
    Salem, OR
    Hello,

    I've just replaced a kitchen sink but it seems to be draining very slow now. Also, after reading some threads I think I might need to re-do the offset trap. The old setup was a two bowl sink plus disposal. My questions are;

    1 - Could this setup be the reason for a slow drain? All parts are new or have been cleaned, and it seemed to be fine before. This is also a new strainer basket, but with the strainer removed it is still pretty slow to drain.

    2 - Should I re-do the offset, so that it is tail-with-dishwasher/p-trap/horizontal/long bend/wye?

    Thanks for reading!

    P-trap screenshot.jpg
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,680
    Location:
    Bothell, Washington
    What you have looks fine.
    It may be that the second sink allowed more air, but there are plenty of singles plumbed that way.
    Normally you would have the p-trap under the basket, but in a two bowl sink, it looks more like how yours is.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,161
    Location:
    Cave Creek, Arizona
    One possibility, unless the drain is actually partially plugged, is that that long pipe has a lot of trapped air that cannot escape if water covers the bottom of the drain fitting too quickly. It is exactly the same as a vessel sink without an overflow. With two sinks the second one acts as vent to evacuate the air.
  4. bluebinky

    bluebinky Member

    Messages:
    381
    Location:
    Santa Clara, CA
    Did you leave a rag inside the drain stub-out when you hooked everything back up?
  5. k-auss

    k-auss New Member

    Messages:
    3
    Location:
    Salem, OR
    no I did not.. wait a minute, where's my other sock?
  6. k-auss

    k-auss New Member

    Messages:
    3
    Location:
    Salem, OR
    Ok, so based on your and Terry's response at least I don't have anything major to worry about like an S-trap situation. I guess if the drain-speed continues to bother after a while it isn't that difficult to try it as tail/trap/horizontal/bend.

    Thanks!
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,161
    Location:
    Cave Creek, Arizona
    Stick a straw down the drain before you put water in the sink. if it still drains slow it is a clog problem, if it drains good it is a trapped air problem.l
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,769
    Location:
    New England
    Can't tell from the photo...does that horizontal trap arm slope down some?
  9. Hairyhosebib

    Hairyhosebib New Member

    Messages:
    173
    Location:
    Arizona
    I agree with this question. Perhaps if the pipe had a bit more fall it might drain better.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,161
    Location:
    Cave Creek, Arizona
    That would have absolutely NO EFFECT on the drainage, unless it had so much back pitch that it created a double trap, which is not the case here.
  11. Hairyhosebib

    Hairyhosebib New Member

    Messages:
    173
    Location:
    Arizona
    You already pointed out an obvious problem!! "THAT LONG PIPE HAS A LOT OF TRAPPED AIR" Flat pipes don't drain well. On the other hand I have seen some severely back pitched drains drain pretty good too. They just get plugged by all the stuff that gets put in the sink to drain out with the water. I have seen drains that seem mostly plugged do to the fact the water streaming out of the aerator on the spout was dead center to the center of the strainer basket. Once the spout was moved off center of the drain, the water could form that swirl and the water would then sound like it was getting sucked out of the sink. The guy might have a vent problem too. I personally think it will drain better if the trap is hooked up to a longer tailpiece and ran with a bit of fall to the wall connection.
    Last edited: Jul 30, 2012
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