: help!!!! we have three bathrooms – two upatairs and one downstairs. two of them have sever like smells— i believe due to their proximity they share sewer lines– i have tried everything snaking, bleach, new wax seals, rinsing the vent pipes from the roofs etc. the funny thing is that they dont smell all the time but when they do they come in waves. any help?John, 95% of the time two wax rings are needed. It is very important that the seal from floor to toilet is gas tight. Regards, Terry Love