Have you ever considered what goes down your drain in terms of temperature and chemical composition? There is hot and cols / soaps / bleaches / hair products / beauty products / fats and oils etc. Because a trap stores same contents of whatever goes down the drain, it is exposed to all these chemicals for a longer period of time. It is for this reason that EPDM is chosen as a material that will last as it is extremely stable and resistant. EDPM is used in the motor industry for items such as radiator, hoses and door seals. If you see a trap that has gone hard / perished it is not EPDM.
SABS Accredited Material