Please give another look to my planned new-construction under-the-basement-slab DWV arrangement.
The main sewer line has a few branches coming in from above. An upper bathroom has its lav and WC coming down then into the sewer with a wye. A little up from that a 1.5″ waste stack brings in the shower from the upper floor, and way down, the kitchen sink comes in using a combo for the transition.
The basement fixtures are called out in the picture, and venting is shown.
I’ll want a backwater valve, right? I can place one in the 3″ sewer line where shown, and it can be the type with an integral stack for inspection and cleaning. That wall is in a mechanical room, so it is open so the valve port can be seen and accessed.
