Dishwasher connection in Illinois

Discussion in 'Plumbing Code Questions' started by Pdeclerck, Dec 20, 2019.

  1. Pdeclerck

    Pdeclerck New Member

    Joined:
    Dec 20, 2019
    Location:
    Palatine, IL
    After a new sink install (sink has one drain) , my plumber told me he couldn't connect my dishwasher drain hose to my disposal because of a change in code. So he added a second trap and connected the dishwasher drain to it. But now I have dirty water filling my dishwasher. Over a couple days after running my dishwasher I remove 8 quarts of smelly water from the bottom of my dishwasher. The dishwasher drains completely, after finishing, but slowly fills over days of inactivity. I closed the supply valve to make sure it wasn't a leaking supply. There is high loop but I believe there is insufficient column of air above dishwasher trap to break the siphon activity. Or there is sufficient air but the air slowly is replaced by water after several dishwashing runs. I am about to connect the dishwasher drain to the disposal again to fix this problem but I won't pass an inspection in Illinois. I could add an air gap but my wife is not keen on that idea. What other changes would fix my problem?
     

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  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    You have a good analysis I think.
    Check valve.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    The disposer provides an air break that normally will prevent siphoning, but not necessarily under all conditions. There's a reason why restaurants are required to have theirs drained via an air gap, and some codes are now being updated to bring that into homes. A check valve would be suspect, as the dirty water from the DW can have lots of food particles, etc., in it, that could accumulate and prevent it from working reliably long-term. You can't fool gravity...the air gap is the safest way.

    How tall was the riser coming out of the trap? If you just put the hose into the trap, that's the problem. You could fashion an air gap beneath the counter and fashion something to hold the discharge hose above, but centered on the riser out of the trap. Might not pass code, but could be safer that what you have now.

    Post a picture of what you did...
     
  5. Pdeclerck

    Pdeclerck New Member

    Joined:
    Dec 20, 2019
    Location:
    Palatine, IL
    I have a picture posted in my first comments. The riser is 8 inches above the trap but capped off at the top. I could install a taller riser , that extends to the nearly the top of the sink with a small opening for air (a psuedo air gap). There is a non-return valve ( a steel ball) in my Miele dishwasher which I have cleaned many times. I don't think this valve is intended to stop all water from backing up. Should I just install a check valve in the dishwasher drain line?
     
  6. Pdeclerck

    Pdeclerck New Member

    Joined:
    Dec 20, 2019
    Location:
    Palatine, IL
    I have some advice from my daughter and son in law, the chemical engineer, to add a vacuum relief valve to the top of my capped off riser. It allows air to fill the riser to allow air to break the siphon activity. What do you think?
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    That should work, but it would have to open with a small vacuum. An AAV (air admittance valve) would probably work for this.
     
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