Because I know a dummy who needs one for bad sinuses. The humidifier has to be foolproof and turn itself off when the water runs low. Easy to clean with bleach would be good. Is it OK to use tap water, or would the mineralization build up so much that distilled water would have to be provided, too? I look and look and look, everywhere, at all of them, and just can’t make a decision, there are so many. Thnx.