Dishwasher drain into Y pipe

Found this today. Dishwasher draining into a Y fitting with lower part of Y open. Pretty sure I should call it out but not sure how to write it. Suggestions would be great!

Improper dishwasher drain connection.


Yup write it up. Must make a direct connection to the drainage system.


Improper Air-Gap



I don’t know, Jeffery.

Need a image further back to see the stand pipe.
I will say the washer discharge hose in this image is not secured to the DWV.

Home Inspector Terry Love has a blog on this very question. Stand Alone Dishwasher Drain

I will try to come back with the rules.

What he ^^^^^^^^^^ said.


easy to write …the dishwasher drain is improperly terminated. I recommend repairs by a qualified plumber…


Thank you Gentlemen, I saved this for last on the report. I found so much other crap to write up on this 11th month inspection, but this one kinda threw me a little, probably because most of the other plumbing in the house was actually installed well…

I have built several commercial applications where it is required to have an air gap for drainage systems for the dishwasher, you will find also that it is always acceptable for the washing machine. This is commonly done where the drains will have an excessive flow… is the kitchen sink oversized? I would check your local building codes, here the standpipe has to be 15" above the trap

Commercial dishwashers discharge through an air gap or an air break into a floor sink or floor receptor. Residential plumbing codes for dishwashers are very very different.

802.1.6 Commercial Dishwashing Machines

The discharge from a commercial dishwashing machine shall be through an air gap or air break into a waste receptor in accordance with Section 802.3.

This is from the OP state plumbing code book. As you can see codes vary and an air break to a stand pipe is legal. Now we would need to know more about the standpipe. Like I always recommend contact a LOCAL plumber for verification. I was blown away a standpipe under a kitchen sink is legal. The drain line does need to be mounted higher according to code.

409.4 Residential Dishwasher Waste Connection

The waste connection of a residential dishwasher shall connect directly to a wye branch fitting on the tailpiece of the kitchen sink, directly to the dishwasher connection of a food waste disposer, or through an air break to a standpipe. The waste line of a residential dishwasher shall rise and be securely fastened to the underside of the sink rim or counter top.

This standpipe was installed in such a way that it went through the bottom of the cabinet and there was no visible connection to the drainage system. The dishwasher drain hose was zip tied to the stand pipe and terminated above the open Y section of the fitting at the top. It was tucked in the back of the cabinet and hard to even get a picture of.

Michael according to your state code this is legal. Do you yourself a favor and just double check with a local licensed plumbing contractor.

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This thread is pretty entertaining, indeed! :slight_smile:

no visible connection upstream the plumbing trap under the sink or to the DWV.
At times stand alone dishwashers have a separate standpipe. In that case a standpipe is capped with a receptor. In this case they installed a wye and DWV riser. I see nothing wrong but that’s just me.
I would mention the drainage setup and refer to a plumbing contractor.

Thanks again gentlemen. I just basically wrote it up as needing further evaluation by a licensed plumber and repaired as needed. This was the first time I saw one set up this way, just didn’t seem right.