I have a question about the water for the humidfier box (not sure what it is called). Does anyone know why it has to be distilled? And how often do you change the water? My respiratory therapist said to do so every day, but I saw a post a month ago or so in which someone asked if the distilled water should be refrigerated since it lasts a month. My gallon bottle lasts less than a week. I do live in a hot climate (Arizona) so maybe that's why, but I'd like to know other people's experiences.

