garbage disposal overflow to other sink

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by boDoanh, Jun 9, 2009.

  1. boDoanh

    boDoanh New Member

    Messages:
    2
    I replaced a garbage disposal 1/2 hp, Insinkerator Badger 5) under a double-sink. I would like some help determining how to prevent water backed up over other sink when in use.

    With the stronger disposal (1/2hp vs. old 1/3hp), the water could not drain to the main pipe (through P-trap) and some popped up other sink. When I removed the Air Admittance Valve, problem went away.

    How can I fix this problem? Your assistance is greatly appreciated.
  2. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    The problem is the lack of a proper vent. The unit is causing a positive pressure in the drainage line which is the issue.
  3. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    You didn't happen to put the tailpiece in upside down....don't know if it's possible but if it worked before and doesn't work now.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,242
    Location:
    Cave Creek, Arizona
    drain

    There are many possible causes an obstructed drain being the first option, especially since removing the AAV eliminates the problem. Or there might be a missing baffle tee, or.................
  5. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    I skimmed over and missed the AAV part. OP - your AAV may be bad, try to replace it.
  6. boDoanh

    boDoanh New Member

    Messages:
    2
    Yes, I think lack of proper vent is the problem. When I remove the AAV, problem goes away.

    The pipe goes from the disposal into side of a T (other sink goes straight down into top of the T), other end of the T goes to a P-trap and out to the main pipe which an AAV is installed.

    I didn't have this problem with a weaker 1/3hp waste disposal.

    Attached Files:

    Last edited by a moderator: Jun 10, 2009
  7. Terry

    Terry Administrator Staff Member

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    [​IMG]

    Most plumbers would have used a disposer kit, straight from the disposer into a baffle tee.
  8. Herk

    Herk Plumber

    Messages:
    547
    Location:
    S.E. Idaho
    Is the drain partially plugged? A Badger V isn't a particularly powerful disposer - it should handle a 3/4 horse disposer just as easily. And I have no idea why removing the AAV would make any difference. If the drain can handle the discharge, even a complete absence of a vent shouldn't make a difference.

    Does the kitchen drain connect to a larger pipe under the floor, or does it go out to a drywell? If there is pressure resistance in the pipe there is bound to be a problem somewhere in the line. For example, it might have a swale in the pipe that is full of water. Or it may be that it's mostly plugged and the water goes through very slowly.

    I'd fill both sinks to the top without running the disposer and see if they drain quickly.
  9. kingsotall

    kingsotall Plunger/TurdPuncher

    Not only that but all that tubular 1 1/4" pipe will be holding water to the level of the dirty arm.
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