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    ozad7880's Avatar
    ozad7880 Posts: 2, Reputation: 1
    New Member
    		  
    #1

    Feb 11, 2010, 12:00 PM
    How to stop back flow from garbage disposal to dishwasher
    Waste water from the garbage disposal when filled with water, will flow back from the disposal through the dishwasher waste hose and back into the dishwasher. Is there some sort of one-way valve that will prevent this?
    afaroo's Avatar
    afaroo Posts: 4,006, Reputation: 251
    Ultra Member
    		  
    #2

    Feb 11, 2010, 01:45 PM

    You have a partial blockage in the horizontal drain line in the wall, the solution would be to dip the water out of the sink and remove the "J" bend from the trap and send a snake up into the wall, (see image) You will hit a bend about 8 inches in but once around that you only have to put out 5 feet more. After, flush with a tub of hot water.
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    massplumber2008's Avatar
    massplumber2008 Posts: 12,832, Reputation: 1212
    Senior Plumbing Expert
    		  
    #3

    Feb 11, 2010, 04:52 PM
    Hi Ozad...

    Could be that you have a blockage as Afaroo has suggested... could be.

    I'm also thinking that it could be simpler than that... maybe? I'm wondering if the dishwasher hose connects directly to the disposal without having a high loop in place. Here, if the dishwasher hose doesn't loop up high under the sink, higher than the disposal, then water can simply drain back toward the dishwasher via gravity every time you use your sink or disposal... can be kind of yucky if you have clean dishes in there... ;)

    Anyway, check the hose under the counter... see if it loops up high. Let us know... O.K?

    MARK
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    ozad7880's Avatar
    ozad7880 Posts: 2, Reputation: 1
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    #4

    Feb 11, 2010, 08:16 PM
    Quote Originally Posted by massplumber2008 View Post
    Hi Ozad...

    Could be that you have a blockage as Afaroo has suggested...could be.

    I'm also thinking that it could be simpler than that...maybe? I'm wondering if the dishwasher hose connects directly to the disposal without having a high loop in place. Here, if the dishwasher hose doesn't loop up high under the sink, higher than the disposal, then water can simply drain back toward the dishwasher via gravity every time you use your sink or disposal....can be kinda yucky if you have clean dishes in there...;)

    Anyway, check the hose under the counter...see if it loops up high. Let us know...O.K?

    MARK
    That was exactly the fix that was needed. Thank you
    Milo Dolezal's Avatar
    Milo Dolezal Posts: 7,192, Reputation: 523
    Plumbing Expert
    		  
    #5

    Feb 12, 2010, 01:55 AM

    This is exactly what Air Gaps are for...
    Widdershins's Avatar
    Widdershins Posts: 87, Reputation: 5
    Junior Member
    		  
    #6

    Feb 12, 2010, 06:43 AM
    Quote Originally Posted by Milo Dolezal View Post
    This is exactly what Air Gaps are for.....
    Yes, Milo, it sure is. :)
    speedball1's Avatar
    speedball1 Posts: 29,301, Reputation: 1939
    Eternal Plumber
    		  
    #7

    Feb 12, 2010, 08:22 AM

    Yeah! A high loop is the way to go.
    Good luck, Tom
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