How appropriate and adequate is 3" PVC drain for a toilet? It would solve the current issue I have with a ridge from trying to mate 4" PVC to cast iron. I could slip the 3" pvc right into the main stack and avoid the butting of PVC and cast iron.
I do see that most PVC toilet goods come in both 3" and 4" but I need to be comfortable that 3" is acceptable in performance before committing to it.
Thanks.