Dishwasher Drain

I’ve never seen this configuration. Dishwasher drain connected just above the trap rather than the disposal. What are your thoughts on this setup?

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I have no problem with where it is connected, but wish it was bracketed to the underside of the counter,for a reverse trap.

I see this set-up quite a bit.

Not a big deal.

I’ve noted the lack of a high loop.

Thanks for the help guys.

The high loop should only be called out if it’s connected to the disposal.

The p-trap will take care of the waste connection.

Wouldn’t water or food being washed down the sink still have the possibility of entering the dishwasher drain particularly in the case of a clogged drain?

Yes, I’d call it out with no high loop.

David , always call it out , unless you know that particular model has it built into itself.

Water always seeks its own level.

Thats why some of the guys call out for the airgap devise.


I prefer your arrangement to mine…

Vince …that particular fitting is called a dishwasher tailpiece and was designed to be used just as shown…whether they are legal everywhere or not anymore is something i can’t tell you…jim

Looks like the bottom of an old cast iron sink.

How was the porcelain holding up?

Who needs shut offs ,eh

Whats up with the black PVC though…is that a new fashion trend?

Marcel hope that DW has a check valve. Did they have a plunger nearby?

Correct. It doesn’t matter whether it’s connected to a disposal or not, it should have a high-loop or air gap fitting.


The sink bottom was holding up OK and shut offs are not required on sinks in my area. They are required at toilet’s and exterior hose bib’s though.

That black drain pipe is referred to as Acrylonitrile Butadiene Styrene ABS for short and is very common in my area; PVC is not.

What I wanted to bring forward in my pic is that the dishwasher drain pipe is not trapped.


I would comment on the lack of a high loop, and that the DW drain line installed on the garbage disposal, helps keep it clean.


Hopefully the Illinois HI’s know that it is illegal in this state to hook up your dishwasher discharge to the disposal. See it all the time, but do you report it?


High loops are common, but if an air-gap is an anti-bacterial device as well as an anti-siphon device then I guess it’s essential. It’s been my impression that they are recommended by manufacturers, but does anyone know for sure?

Although they defer to the manufacturers installation requirments, CA code specifically prohibits direct connection of the dishwasher-drain line to a drainage system without a listed air-gap device.

Jeff: Yes, that’s my understanding, but I’ve also been told about some fancy dishwashers in high-end residences that the air-gap is “built-in” or “not required,” etc. I recommend them anyway, and defer to the manufacturer’s specs. It seems to me that bacteria can migrated through a dark tube and on into the “clean” dishes if an air-gap is not present. Having said that, I’ve become woefully aware of my own ignorance on many occassions.

Is this ever allowed…connection to the waste line in the crawl space? Obviously no high loop.

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