First, my calculations. Let's assume a sealed 5x3x2 meters room and ambient temperature of 20 C. Volume is 30 cubic meters. According to this table, at 100% relative humidity there would be 17 g of water vapor per cubic meter or 510 g in the whole room. Henceforth a 10% drop in relative humidity should require about 50 g of water to be removed from the air.
The problem is that I'm getting about 100 g of water from my dehumidifier every day and (according to the psychrometer I have) the room is still at 70-80% relative humidity like it was before I installed the dehumidifier. Psychrometer works well outdoors and there's no reason to suspect it. The room has no sources of water vapor, save for myself and a cup of cold water. The door is closed most of the time.
Am I wrong at math? Missing some other important aspect? Any ideas how to help the situation in general?