The translucent water tank is easy to fill and monitor and outputs about 1.2 gallons of moist air into the room--enough for 18 hours of continuous use on one filling. Impurities or minerals in the water are trapped in an antibacterial wicking filter so vapor is pure and is emitted without any white dust. When the tank is empty, it totally drains without leaving any potentially bacteria-laden standing water in the bottom. Two settings--high and low--let you adjust the humidity level to the appropriate room size or moisture level and Vicks’s special "evaporative technology" also kicks in to ensure that rooms maintain the proper moisture level and are not overly humid. This humidifier has a dishwasher-safe tray for hygienic cleaning and is covered by a three-year warranty. --Cristina Vaamonde