I'm trying to add a sink next to an existing bathroom. Sink will be probably 3 feet from shower vent pipe. Floor is a concrete slab so all existing drains are underneath. I'd like to minimize busting thru concrete. The picture below is a pretty good representation of the existing piping, except for the pipe below grade that are probably running horizontally.

Can a sink drain/vent into a nearby shower vent pipe (e.g. connection in red on the picture)?

If this is not allowed, what's the best solution here?

New sink drainage

2 Answers 2


I wanted a utility sink installed on the common wall of our garage and house. There was a vertical vent inside the wall near a bathroom and near the washer/dryer alcove. The plumber plumbed the drain into that vent saying that this was allowed by code if done in the right way. I didn't understand what would make it code compliant and would make it work properly, but he put it in and it has worked for 20 years.


Make sure you have enough slope. Also I would rather use a Y instead of a Tee. If I am not mistaken, if the distance from the Sink trap to the drain (Vent) pipe is under four feet, you should be ok.

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