I am renting an apartment in the Midwest United States and I have noticed that during a change in the seasons that a rotten smell seems to be coming from the two bathrooms in my 2nd story apartment.
It really perplexed me for a while and made me OCD about cleaning them but I just can't get rid of the smell, though it does come and go, but it does not coincide with the cleaning. I have gone so far as to clean the drain traps for the sinks.
The only thing that seems to help is closing the drains, also the bathroom that I use much more frequently seems to smell better. The only thing that exacerbates the problem is turning on the bathroom fans.
These "facts" lead me to believe that the smell is coming from the drains. As a result I have tried pouring bleach down the drains and letting it sit overnight, and it doesn't seemed to have helped.
Is there anything I can do to confirm it is the drains? Is this a known issue in older (built ~15 years ago) apartments? Is bleach my best bet to kill the seemingly probable bacterial buildup?