Due to a structural complication in an old stone house I would like to use a slightly flexible pipe for the inital (20 feet) run of waste outlet for a Saniflo macerator toilet. I can't get 22mm copper and certainly not 32mm plastic waste routed to the unit but 22mm hep20 will go. Does anybody know how Hep20 stands up to general purpose detergents,disinfectants etc or if some other product has both the durabilityand flexibility required in this particular situation??