A couple of months ago we started noticing a sweet/musky smell in our powder room. It is worse on warm/sunny days. The entire room is filled with this smell. It is hard to locate it's origins. Called the plumber and he suggested pouring bleach down the sink drain thinking bacteria. (We do not see any leaking around the toilet). That worked temporarily or it masked the problem as the bathroom smelled like bleach for quite a while. A week or so after pouring the bleach, the smell started to come back. We are also noticing it in our other bathroom on the opposite side of the house. Both of these bathrooms are on the main floor. We do not notice the smell upstairs or in the basement bathrooms. The plumber is coming on Monday and I want to be prepared to ask the right questions.