A couple weeks ago we looked at one reason why a bathroom might stink - there could be a whole bunch of smelly hair in the drain:
This week let's look at another leading cause of smelly bathrooms. I was invited over to a friend's house this weekend. Married couple, kids, nice folks. But they asked me to help with a problem - Their bathroom stinks. You walk into the bathroom and it smells. Bad. They had been closing the door and running the fan, which isn't optimal because it wastes a lot of energy by sucking air conditioned air out of the house. They had looked for everything - dead animals, standing water causing mold, leaking toilet, etc.
So here was the problem. They had one of these bathrooms with a separate tub and shower. No one ever used the tub. So the P-trap for the tub had dried out. When that happens, air from the sewer system has easy access to the room, and the room starts to stink. This video offers a nice explanation of how a P-trap works:
The solution is easy. Just run the water in the tub to refill the P-trap.
This problem can also arise in the sink, shower or tub of a guest bathroom that is rarely used.
This problem can also arise in a utility room that has a place to hook up a washing machine, but you don't have a washing machine. The washing machine drain has a p-trap that can dry out. Or if you have a big utility sink in your utility room, and you use that sink to hold laundry instead of using it as a sink, its P-trap can dry out.
See also: How to Repair a Garbage Disposal
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