I cannot for the life of me figure out where this excess moisture is coming from. My bathroom has humidity about 10% higher then the rest of the apartment. The living area is fine. I check the humidity on a Humidity monitor and it is always very high in the bathroom, around 68% The thing is its only 30% humidity outside so its not coming from outside. I have a fan that I use every shower and leave the door open. If I open the window it drops to about 58% (that is with the outside being 30%) It won't get lower then 58. As soon as I shut the window it goes back to 68 or so. I see no leaks under sink, no condensation on toilet. I don't know where this is coming from. I live on the 2nd floor of a 3 floor apartment complex that is only 2 years old. I have lived on the 2nd floor of a 3 floor complex before and never had this problem. And that bathroom didn't even have a window. This one does. I don't get it. Can someone tell my why it is so humid? What gives?
Definitely get the Landlord involved. Unless there's a standing pool of water, much bigger than the toilet, there's no apparent nor logical reason for any room to stay so noticeably different.
I'd say maybe a backdraft through the exhaust fan from a faulty damper, but you've disproven that. In the meantime, check with the neighbors & see if either are doing anything strange or noticed the same thing.
I'd suspect the 1st floor got a Hot Tub or started Indoor Gardening. A Room Humidifier or Air Conditioning System's Humidifier wouldn't even do anything like your saying.
Firstly, when your fan is running DO NOT open your bathroom window. Open one elsewhere and have your door ajar of if there is a good gap at the botton close it. Why? What you are looking to do is draw air ACROSS the bathroom space so the warm moist air is picked up and drawn out. By having the window open you have what's effectively a short circuit so air flows in through the window and immediately out of the fan picking up almost no moisture laden air on its journey.
It's important to keep the fan blades and duct clean as that encourages best flow rates.
Try this test. Put a candle night light on the floor by the door withh the door closed and the fan on. Watch the flame dance. Then open the window and watch the flame sit bolt upright. That tells you there is no through draught.
Make sure your fan runs for a good while post showering.