I am having two problems that I think are related. Backstory, just moved into a 2010 built home. Replaced the contractor grade dishwasher with a new one. Kitchen has two sinks. When the disposal is used, the water shoots up in the opposite sink. Additionally, the dishwasher is leaving food, sediment on the dishes. Took the trap apart and no clog was present. Hoping to find a solution before calling a plumber. enter image description here

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    I think the hamster got stuck in there. The piping is all wrong. the waste out of the disposal only has a short distance to go before going into the other sink and three times the distance to go out the drain... I'd be looking at adding a tee before the air vent and giving each sink it's own trap. I can't really tell where your dishwasher drain is routed so don't know if waste from the disposal is backfeeding into the washer or it's not draining properly.
    – JACK
    Apr 14 '20 at 12:58
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    I think the dishwasher is the flex that is going high, that may be the issue there but I agree that habitrail or hamster living quarters nave have a body stuck.
    – Ed Beal
    Apr 14 '20 at 14:12
  • For the dishwasher, it looks like the 7/8" hose is coming down from an air-gap unit. Check the air-gap unit by pulling the cap off from above and make sure there is no blockage. Also, disconnect both the 5/8" & 7/8" lines from the dishwasher to confirm no blockage, if necessary. Check the 7/8" drain port where the dishwasher dumps into the disposer and make sure that is not plugged with food/gunk. There are several things that can cause the dishwasher issue you describe. Apr 14 '20 at 14:40

You should be using a baffle tee to connect the disposer drain to the other sink outlet, prior to the trap.

This will require significant alteration of the existing setup, but will fix your problem.

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  • I think a baffle would help with the shooting water but the dish washer drain routing may need to be modified. No problem dumping in the disposal but the DW may not be able to pump up and over causing solids to be trapped.
    – Ed Beal
    Apr 14 '20 at 14:17
  • If the dishwasher can't pump up and over then it is FUBARed. They are designed to pump up to an air-gap or over a raised loop to prevent siphoning. Apr 14 '20 at 14:42
  • But the loop only needs to be high enough to break any possible syphon it looks like goes to the top of the sink did the flex pipe get crimped with the new unit causing a blockage?
    – Ed Beal
    Apr 14 '20 at 16:11
  • Won't a check valve installed on the other basin do the same thing?homedepot.com/p/…
    – user68386
    Apr 14 '20 at 22:08
  • @user68386 No. These are not used in sink waste lines because they need too much pressure to open and the mechanism gets gunked up with debris and goo. Won't work here but work well in clean pressurized water systems... Apr 14 '20 at 23:03

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