: What a treat to ask a question of a plumber that may answer the "call"! For years now- when we do laundry - especially in the winter- there is a terrible odor coming from the sewer drain just as the washer finishes filling and goes into it's first wash cycle- the smell is intense then subsides within 5-10 minutes- any thoughts?
Make sure that there aren't any open sewer lines or clean-out fittings that could let gases escape. Also, if you have any infrequently used plumbing fixtures make sure the trap seals haven't dried up, including floor drains.
Good Luck. e-plumber