No way!!!! Every plumber I ever spoke with advised not to use it ifyou haveplastic piping. That's what they use in RW's. The tanks and tank valves would seem to be even more susceptible to damage than plastic piping. I'd try one of those "snakes" that rotate or baking soda and boiling water. If neither of those works I would think the next step would be to take the trap apart. Just my opinion.