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  1. #1
    Join Date
    Aug 2008
    Posts
    1

    Default Dishwasher drain to Disposer connection

    I am installing a dishwasher and garbage disposal in a kitchen where there were none before. Standard instructions say to create a high loop with dishwasher drain hose and connect it to the dishwasher drain port on the disposal (after removing knock out). A plumber I spoke to said to bi-pass the disposal port an attach the dishwasher drain hose behind (downstream of) the disposer to avoid noise and potential clogs. I've heard that if a disposer is present, you must by code, attach DW drain to it. Is this true? Is there a good reason to drain the DW into the disposal, or can I by-pass the disposer input with no issues?
    Additionally, the disposer drain fitting is a pvc elbow which requires a loop or small "trap" be created before horizontally teeing into the vertical drain in front of the main trap. I was told I can remove this elbow and go straight to the tee. Is this true?
    Last edited by Foster; 08-23-2008 at 09:41 AM.

  2. #2
    Join Date
    Aug 2008
    Posts
    109

    Default Re: Dishwasher drain to Disposer connection

    There aren't any circumstances where a dishwasher drain should be attached to the same drain line downstream of a garbage disposal. Your dishwasher drain hose should be looped up to the top of the underside of the counter then to an airgap before dropping to drain. Do you have a multi-bowl sink?
    Last edited by Gray Watson; 08-23-2008 at 10:15 AM.

  3. #3
    Join Date
    Dec 2007
    Location
    MN
    Posts
    455

    Default Re: Dishwasher drain to Disposer connection

    Quote Originally Posted by Foster View Post
    I am installing a dishwasher and garbage disposal in a kitchen where there were none before. Standard instructions say to create a high loop with dishwasher drain hose and connect it to the dishwasher drain port on the disposal (after removing knock out). A plumber I spoke to said to bi-pass the disposal port an attach the dishwasher drain hose behind (downstream of) the disposer to avoid noise and potential clogs. I've heard that if a disposer is present, you must by code, attach DW drain to it. Is this true? Is there a good reason to drain the DW into the disposal, or can I by-pass the disposer input with no issues?
    Additionally, the disposer drain fitting is a pvc elbow which requires a loop or small "trap" be created before horizontally teeing into the vertical drain in front of the main trap. I was told I can remove this elbow and go straight to the tee. Is this true?
    I will share what we had done when remodling our kitchen.
    In our case we have a double sink and installed the disposer into the right side sink. Our dishwasher is located to the left of the left side sink. The hose needs to be installed high up attached to the underside of the counter. In this case the plumber highly recommended not to tie the dishwasher hose into the disposal because of many problems he has seen with blockages. Instead the dishwasher hose was tied into the drain pipe that connects the two sinks before the disposal.
    That was 3 1/2 years ago with a blessing from the inspector and no prblems with backups, touch wood.

  4. #4
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,560

    Default Re: Dishwasher drain to Disposer connection

    One thing, if you are on a septic system it is advisable not to install a garbage grinder.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

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