# 2 dishwasher hookup, one drain



## CGallagher (Apr 20, 2010)

Had a new home we did about 4 years ago where there was a single drain sink with a dishwasher on each side. The plumber hooked one up to the disposal and one to the branch tail piece. The dishwasher which is drained to the disposal never has problems, but the other sometimes gets water coming back into it. 

I want to get this fixed and I'm looking for thoughts on how this should have been hooked up. I thought maybe a "Y" fitting to the disposal with both hooked up should take care of it. Or does anyone have a better solution.

Apparently, this has always been a problem for the homeowner. She just never told me about it.


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## goneelkn (Jan 9, 2010)

With no air gap, try a vertical loop along the back wall. Have you tried switching lines to be sure it's not the dishwasher??


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## The Coastal Craftsman (Jun 29, 2009)

The last time I see 2 dishwashers on one waste disposal it had a y adaptor fitted. Seems to have worked ok has they looked like they had been in there for years. Make sure you also lift the waste pipes from the dishwasher up high to stop the waste back filling into the dishwashers.


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## aptpupil (Jun 12, 2010)

agree with goneelkn. with all that tubing that is wrapped around the disposal i would guess that there isn't much left to be go up high behind the sink in the absence of an air gap.
since it's always been a problem i wouldn't expect it to be the check valve in the dishwasher or anything like that.


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## CGallagher (Apr 20, 2010)

The hose does go high up behind the sink, but there is no verticle loop. I imagine when that large sink gets full, and someone runs the disposal, the force of the water is getting sent back up the drain tube of the dishwasher. I'll try the verticle loop first, and if it doesn't work, I'll engineer the Y fitting. Thanks for the input.


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## Smatt (Feb 22, 2011)

What a cluster @@@@. You a $1500-$2000 set up. That disposal cost maybe $75 at the most that set up is illegal where I am from that would never pass inspection. 




Was it inspected? I'll bet not. Had it been you would not be in the predicament that you are in.


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## CGallagher (Apr 20, 2010)

Smatt said:


> What a cluster @@@@. You a $1500-$2000 set up. That disposal cost maybe $75 at the most that set up is illegal where I am from that would never pass inspection.
> 
> 
> Was it inspected? I'll bet not. Had it been you would not be in the predicament that you are in.


 
It passed inspection by the city, but it obviously shouldn't have. Not a big deal, there really isn't any damage. Just the occaisional back discharge into the dishwasher that's hooked up at the lower location. 

What would be the way that you hook it up?


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## Smatt (Feb 22, 2011)

CGallagher said:


> It passed inspection by the city, but it obviously shouldn't have. Not a big deal, there really isn't any damage. Just the occaisional back discharge into the dishwasher that's hooked up at the lower location.
> 
> What would be the way that you hook it up?


I would use a "y" fitting at the garbage disposal. You can make one out of copper with a tee and a street 45 an a DZ 100. 

You never want a branch tailpiece below garbage disposal. I am hope no one got sick. 

The d/w discharge lines should be drilled at the bottom of the cabinet and looped up in the corner and "j" hooked in place.


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