Just started a basement renovation project and part of that project is updating the original 1940s bathroom layout. I've broken up the concrete and exposed the cast iron drain lines. The first picture shows the trench as is currently stands. Side question: I have absolutely no idea what the 2" cast iron pipe is to the right of the main sewer line. It's not a black iron gas line (that's the vertical black pipe on the far left of the picture that starts about half way up) All other drains in the house have been accounted for and it's definitely 2" cast iron. Ok, back on topic - the second picture outlines the cast iron pipe since it's hard to see among the dirt. The original basement bathroom had a lav and a toilet. The vertical cast iron pipe on the right was the original lav drain, the one on the left is a vent pipe that connects above the drains on the floor above it. They both tie into the 3" toilet line, which ties into the main line. The new bathroom layout consists of a lav, toilet and bathtub. Two questions: Is the proposed setup in the third & fourth picture accurate? The third picture was a drawing of what I am proposing - the fourth picture is a quick mockup in PVC. Can the bathtub wet vent the toilet this way? The second question is about the vents. In my PVC mockup the wye for the vent on the tub line is rolled to 45. Is that the proper way to attach that vent pipe or is that a better way? For the tub and lav vent the idea is to tie it into the original cast iron vent. The vertical cast iron pipe on the left of the first picture is a vent that connects above all other drains on the floor above. Can the lav and toilet vent run horizontally (with proper pitch) along the ceiling (or at least above ~42") to tie into that vent line? The basement bathroom is directly below a bedroom so I can't go straight up with my vents without going through the middle of the room above.