Originally Posted by BigTJohn
Could be from water sitting in the washer lines. If you don't have a washer but have the hookup, water just sits in the lines and usually smells really bad at the nearest faucet. Flushing out the lines is really easy. Jose attached to the valve and the other end in the drain. Run the water a minute or so, flushed.
If Jose won't do it, you can go ahead and hook up a hose to the washer valves yourself!
l had this problem earlier this season and rinsed the washer lines out--no smell. Ours was just at bathroom sink.