Have a 3 story colonial built in '84. The septic tank out take pipe is located ceiling level of the basement boiler room. I had a blockage in the septic pipe with a bad back up a month ago, sewer water all over boiler rm, garage, & basement, after clean up including having tank pumped, I'm still getting sewer gas smells in boiler room.
Prior to back up a plumber advised we attach water softener discharge hose to a vented trap going into septic outtake pipe but I did not have an issue with smells until after the back up.
I've disinfected area and pipes, refilled trap, cleaned out sump pump (also in boiler rm) Had plumber check for cracks, none. Odor seems to be around large rubber gasket surrounding out take pipe.
Also would it be a good idea to re-route water softener discharge to sump pump drain pipe?