Your Question– “What is the best chemical to use down the outside waste pipe? This pipe accepts waste from the bathroom sink, bath and shower. No matter what I try, I can’t get rid of the bad odor in pipes. It is strongest outside, but pretty bad in the bathroom as well. What can you suggest?”
Our Answer– In our opinion, you may have a broken vent line or a leaky wax ring at the base of the toilet causing the bad odor in pipes. We recommend calling a local plumber to come out and determine the cause of the smell.