I am planning the DMV system for a new second floor bathroom. The bathroom is directly above a first floor bathroom (the house is a 50's Cape).
There is an existing 3" drain/vent stack to which I will be draining the vanity and toilet into (they are on the same wall as each other and the main stack).
The tub is on the other side of the bathroom. Currently, the vent pipes from the first floor bathtub and kitchen sink run just above the second floor. I will be reventing these.
My question is:
Can I drain the tub into the existing vent from the kitchen sink below instead of draining it into the main drain/vent stack?
Thank you for your reply.
I don't get the whole picture, but you cannot drain a second floor bathroom into a pipe which is serving as the vent for the lower floor. To drain into that pipe, you must revent all the lower floor fixtures, including the toilet.