I have dirty laundry smell in the laundry room upstairs in my house, and also in the room of my finished basement where the floor drain is located. The vent pipe is clear, and I have run water through all fixtures to insure none of the traps are dried out. The smell goes away when I pour bleach into the wash machine discharge pipe, but returns in a week or so. I'm thinking bacteria (?). How might I treat this to make the smell go away for good?
