So I have what is a sewer type smell from the Laundry room (basement level of a 3 level TH). I've had this once or twice before and it lasted a couple of days and went away, but I'm concerned it keeps happening. Last night moved both the Washer and Dryer to see if there was any mold or leaks or dead rodents or anything on the floor, but they were fine (I cleaned the floor anyways). Today I flushed the Washing machine with Baking Soda and Vinegar. I've attached a photo of how the water line/drain valve is. There is hot/cold, a drain line and a studor vent. Is it possible the vent is bad? Could anything else be causing this?