In your first post you state: "Why does my township require that I use ABS and not PVC?" Now you state: "I cannot cite the code, but I have been told by a local plumber that PVC must be used for new work in this area (Bucks County, southeastern PA). I informally confirmed this with a different plumber at my place of employment. So I think it is likely correct." Bucks County does not enforce building codes - it's the responsibility of the individual local municipalities (towns & townships). I don't know of a single township in Bucks County that requires "PVC must be used for new work". In fact, ABS, copper, galvanized steel, polyolefin and cast-iron are permitted by code. Add to that list brass and stainless steel. The only restriction is that you can't install galvanized wrought-iron or galvanized steel pipe below grade anymore. Please ask your plumbers which municipalities only allow PVC.