Two waste pipes under kitchen sink/air gap question

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by marie, Jun 27, 2005.

  1. marie

    marie New Member

    Messages:
    6
    I am installing a new sink in my top floor (converted from an apartment) condo and need to disconnect and then reconnect all of my plumbing for the faucet, garbage disposal and dishwasher. I am confused regarding the current connection of the air gap. It looks like there are two waste pipes under my sink. I have a double sink, so one waste pipe is connected to the disposal (with dishwasher drain tube attached) and sink drain, the other waste pipe is only connected to the air gap that is installed into one of the sink holes on top of my sink (the air gap is not connected to the dishwasher). Prior to purchasing my condo, I was told that the owner of the adjoining condo had a backup in his garbage disposal sink bowl and that it also backed up into my unit through the air gap. When I had the condo inspected, the inspector told me that the second waste pipe is connected to the adjoining condo unit’s waste and that I should have it capped off so that no more backups occur.

    My question is: Can anyone see a good reason why the air gap would be installed this way and therefore be left alone? Or why there would be two waste pipes? I would like to connect the air gap the traditional way (to the dishwasher and disposal) and cap off the second waste pipe, but fear that I may be doing some harm by doing this (such as blocking off a vent). Any advice would be much appreciated.
    Last edited: Jun 27, 2005
  2. Go ahead and set it up the normal way.

    Sounds crazy having two drain lines.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,614
    Location:
    Cave Creek, Arizona
    gap

    Unless it is connected to a trap it is not legal and is unhealthy.
  4. marie

    marie New Member

    Messages:
    6
    Air gap

    Thank you for the two replies!

    I think I will go the normal route and connect the dishwasher to the air gap and the air gap to the disposal, and only use the one waste pipe.

    The second waste pipe is connected to a trap and the trap is connected to a hose that goes up to the air gap. If I remove the hose going up to the air gap, do you think it would be okay to put some sort of plug/cap at the open end of the P-trap, which will close off this waste pipe to my unit?
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,614
    Location:
    Cave Creek, Arizona
    cap

    It is not a question of whether you can put a cap on it, but rather you MUST seal the opening. When you connect to the disposer, be sure the hose is as direct as possible with no "sags".
  6. marie

    marie New Member

    Messages:
    6
    Seal

    Hi,

    I'll seal it off completely and make sure there are no sags in the hose to the disposer. Thanks so much, again!
  7. bjc612

    bjc612 New Member

    Messages:
    1
    2 drain pipes

    there is a good chance that one pie is there for a product called a ventamatic it is a small plastic piece made to go onto drin line for the purpose of a vent instead of a outside pipe vent it goes onto a line cnected together with drai pipe to let air in but will not let air out .:)
  8. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    We would like a picture of what you have.

    If you are in a multi-story condo or apartment, there is always a risk on the first floor. If a main line is blocked, then wastes from the upper floors will by action of gravity find an outlet in the fixtures of the first floor apartments.
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