25 year old house, Washroom waste pipe (copper) is first ,(or last) connection on the waste line before the exit main (cast) to my septic system outside.

I can smell that sewage smell in the room, and in the washer tub. I just had the cesspool drained/cleaned/inspected/ in August.

What does this mean? Can I add Rid-ex to the system? Does that help?

I don't have that smell at any of the sinks, or in the basement.

Thanks, and Hello to all, looking forward to participating on these boards.