Some basement laundry room layouts include an adjoining bathroom. Because these are seldom used, some homeowners report a bad odour coming from the laundry room, which is sometimes blamed on the laundry itself, the laundry room floor drain, or another source.

Before you call a plumber, try a simple experiment by pouring water into the toilet, sinks and shower stall in the adjoining bathroom. Flush the toilet, let the water drain in the sinks and the bath and check back in a day to see if you still detect a bad smell. The water in your “u-bend pipe” or sink trap will evaporate over time if the plumbing isn’t used regularly, allowing odours to seep into the laundry room. Running water in the adjoining bathroom should cure your laundry room odour problem if dry pipes are to blame.