Devil's advocate: the back of those drain cleaner solutions make a point that the solution should never sit or pool in any surface or pipe. You have to run wate

Devil's advocate: the back of those drain cleaner solutions make a point that the solution should never sit or pool in any surface or pipe. You have to run water and chase it down so it doesn't corrode the pipes. I know where I live some of the pipes have "flow issues" because of bad design, and if there was already a partial blockage I can see drain cleaner corroding the pipes... We just mechanically clean them out ourselves, anyway.