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.

I would think it should be fine... but I don't understand your original problem.

Tom

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 commiting to it.

Thanks.
A 3" toilet drain is acceptable on all 2nd. story baths and 1st. floor baths where there is a basement. However, county codes differ on slab installations under cement. In my area Manatee county allows 3" toilet drains under the slab while Sarasota County holds you to 4". I would be comfortable using 3" drains myself. Good luck, Tom