I am trying to figure out how to lay out my basement plumbing, and I wanted to use a double wye to connect my shower, toilet, and sink to the existing waste system in the house.
My question is, am I allowed to have the vent plumbing be behind a double wye since all 3 fixtures combine at this one point? Or am I required to have each fixture individually vented and then join the vents later into one common vent?
All of this work will be under the concrete slab. I am connecting to the existing waste system that runs under the concrete slab.
The existing waste system is connected to all the fixtures on the 1st floor (toilet, tub, sink, kitchen sink) of the house and then travels down into the basement, under the slab, and out to the road. This system is vented through the ceiling.
I should probably also ask if I even need to vent this new basement bathroom separately, or if the current venting system would be sufficient.