New kitchen sink is deeper - how to hookup to drain (pics)

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by wxtornado, Mar 14, 2007.

  1. wxtornado

    wxtornado New Member

    Mar 14, 2007
    Thank you very much in advance for all your knowledge. I have a new kitchen sink - it one of those double-bowls that's part of my new Corian countertops - all one piece. The sink on the right is deeper than the one that was previously there. You can see the two drains in this pic:


    My problem is getting from the right sink drain to the P-trap, as the P-trap is only about an inch or so lower, and very close. Also, if I hook up this gizmo, you can see that the dishwasher connection is now lower than the drain pipe going out of the house:


    Here's another view:


    Will this cause water to drain into the dishwasher?

    Can someone offer a way to get this connected - I'm hoping someone will come back and say "oh this is easy!" I want to avoid having to lower the drain pipe going out of the house, as I have no idea of even how to begin to do that.

    Thanks much!
  2. Verdeboy

    Verdeboy In the Trades

    Jun 12, 2006
    Problem 1. Lowering the trap: Get a 1 1/2" slip-joint extension piece with nut and plastic ferrule. Use a hacksaw to cut it to the right length.

    Problem 2. Hooking up the dishwasher: You can either high-loop the DW drain or install a plastic air-gap. Doing the latter requires that there be a separate hole made in the new sink if there isn't already a hole with a plug in it.
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  4. wxtornado

    wxtornado New Member

    Mar 14, 2007
    Thanks Verdeboy. A few more questions:

    1. Is there a limit on how low I can make the P-trap? Will I have any drainage problems if I make the p-trap too low?

    2. On the dishwasher drain hose, does "high loop" mean to make sure part of the hose is very high inside the cabinet? If I go the air-gap route, is there any reason this air gap has to be on the sink? Can it be installed somehow under the sink?
  5. Verdeboy

    Verdeboy In the Trades

    Jun 12, 2006
    I don't know what the code is on how low you can make the trap, but you're only lowering it a few inches.

    High loop means to raise a portion of the drain line as high as you can under the sink, usually with a piece of bailing wire. This will prevent contaminated water from backing into your dishwasher, unless the backup goes right up to the rim of your sink, in which case, an above-sink air-gap is the only thing that will prevent cross-contamination.

    Here's a good link for you:
    Last edited: Mar 14, 2007
  6. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    I would use two traps and connect the dishwasher to the drain in the higher sink. There is no way to connect the dishwasher the way you have it without having problems, even with a high loop or air gap fitting. Even with a high loop, the DW can/will siphon the water out of the trap down to the level where the connection is made into the vertical pipe. With an air gap, the water standing in the trap will create a restriction and the air gap will overflow.
  7. Master Plumber Mark

    Master Plumber Mark Master Plumber

    Feb 6, 2005
    Sensitivity trainer.. plumber of mens souls
    indianapolis indiana - land of the free, home of
    the biggest problems I see

    Why dont you flip that whole configuration
    and try it with the dishwasher tee connect to the
    left hand drain ????

    all you would need on the right hand side is just a
    street ell type tailpiece....
    But you could fix everything verily easily....another way..

    your biggest problem are those crappy plastic
    basket strainers you are useing....

    those are probably one of the worst types becasue they
    usually come loose after a while and they also put you down
    so low into the cabinet, like you got now..

    Unless they are some "sissey white or biskit " color that
    your wife must have, might I suggest you go to the store
    and get some "spin and grin" chrome real brass metal basket strainers .....

    they will raise the whole mess up about 3 inches and it would probably work....

    just take them back and spend 20 bucks and get youself out of this mess the easy way...

    but some good pipe dope too
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