I would like to add a sink in the garage, the house already has a rough in for it but it was never added. When I started looking at it I realized that it not properly vented. The question I have is what is the proper way to vent a garage sink and standpipe? I am very, very far from being a plumber; I would not even consider myself a rookie so I am looking to others for help. I think that the right answer is that I need a vent for both the washer drain and the garage sink independently but I don’t know how to do that with the setup that I have since they are so close together. I am hoping that I can just add a Y at the sink rough out and run it up through the roof but I am not sure. Can someone that knows what they are doing take a look at the image below and tell me what they would do?

[s1164.photobucket.com]


If I screwed something up with this post I am sorry, I am new to plbg.com

thanks in advance for any insight.

My code would permit the installation of a sanitary tee in the washer standpipe and the installation of the laundry sink drain. Not sure about your code.

you will need one 1 1/2 vent

you need to remove the upsidedown trap and replace it with a sanitary tee. the top of that tee will be the washer vent.
next, you need to cut a "Y" into the horizontal drain for the sink. that too will need a vent. both vents can be tied together and run thru the roof with one 2 inch vent termination.

Since the whole drain line is INCORRECT, adding a sink to the riser could not make it any less "correct". THe first step would be to cut the horizontal pipe to the left of the second tee and cut the riser above the trap. Throw those pars away and start over, but HOW you start over would depend on a lot of things that we do not know and would have to be there to lay it out.

Depending on which supply is hot, it's either on the wrong side at the washer or in the garage....not specifically to the OP's question but indicative of the level of workmanship here.

I would use a combination + cleanout at the base of the stack, a tee and trap for the washer in the vertical pipe, and a tee and trap for the laundry sink also in the vertical pipe, then the vent will extend up thru the roof.
Here in NC that horizontal pipe would have to be 3", but you can use 2" where you are.

quote; indicative of the level of workmanship here.

you mean there WAS "workmanship" there? Since the lower line continues on, I assume it is the cold, which means whoever install the sink openings, (and probably the washer too), did not know any more about water lines than he did about drains.

Thanks for the replies, you basically told me what I thought but didn’t want to hear. I will cut it out and redo all of it.
For the standpipe I will add a new trap with (at least a 4inch) horizontal run to a vertical sanitary tee, the top of the tee will be the vent. The lower part of the tee will tie into the horizontal drain line using a wye and a 45 elbow.
As for the sink drain I will move it over to give me a little room, have another trap with vertical sanitary tee tie into the horizontal drain pipe below (more or less the same as the standpipe).

The two vents will get combined into one with a vent tee and a clean out above the level of the standpipe.


Nice catch Don411, I didn’t realize until now that the hot supply in the garage is on the wrong side. hj is correct, the water line that runs off the left side of the image supplies my refrigerator with water, I need to rerun that line as it is rather inconveniently located. I will switch the hot and cold at that time.

Electrically this house was a mess, not surprised that the plumbing has its issues as well. I wonder what other Easter eggs I will find later.

Thanks again for your help



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how far over is the refrigerator located?
if not too far, you can have a shut off for the icemaker line behind the washer/dryer. use a 1/4 x 15 foot braided supply to feed thru the wall leaving slack to slide the refrigerator in and out. you can even mount a filter for the ice maker behing the washer/dryer if you want.
i would not change the hot/cold for the laundry sink. just criss cross the flexable supplies. (it will be our little secret)

HE is moving the sink so the cold might be able to stay where it is and just move the hot about 16" to the left, and many, if not most, refrigerators already have filters in them



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most of my customers opt for an external filter that can be had for 10-15 dollars at a home center rather than the 45-50 dollars for an OEM replacement. they simply leave the bypass tube plugged into the internal filter socket.
of course if there is no practical way of installing a filter then they are stuck. remember, we have open basements under first floor ice boxes around here.