We bought our house a year ago. The basement was already finshed. In the basement bathroom there is a drain in the floor that would give off a sulphur smell. We would dump water down the drain every other day but the smell really never went completely away. About a month ago I noticed a sewage smell coming from underneith the wall of the laundry room that is shared with the bathroom wall. Around this time I noticed the drain in the bathroom did not smell as strong. The smell is very strong at times in our laundry room. It is there everyday. It sometimes can even be faintly smelled in the stairway above the laundry room. About a week ago my brother in law capped up the drain in the bathroom, hoping that it would take care of the smell. The bathrom no longer smells, but the laundry room smells where the floor of the bathroom meets it. I called rotorooter, but they seemed to think that just flushing our system would not solve an odor problem when we have no clogged drains or apparent leaks. We use all of our sinks washer, toilet and shower in the basement, so nothing is just sitting unused. Any suggestions?