A humidifier's demineralization cartridge works by filtering excess minerals from the water. Granules in the cartridge must soak for at least 24 hours prior to first use. This allows the granules to expand and more efficiently remove minerals from the water.
Using a demineralization cartridge in a humidifier helps increase the lifespan and function of the unit. It also helps prevent white dust, which occurs when the humidifier expels excess minerals found in water. As of 2015, the United States Environmental Protection Agency has found no known health risks to white dust, but using distilled water or a demineralization cartridge in humidifiers is still recommended.
Demineralization cartridges typically last about two to three months, depending on the water hardness and the frequency of humidifier use. To determine if the demineralization cartridge needs replacement, look for the presence of white dust or decreased mist output from the humidifier.
Some demineralization cartridges allow users to replace the granules when the cartridge becomes ineffective. When replacing the granules, do not allow them to escape the cartridge and enter the base or water tank of the humidifier. If this occurs, turn off the unit, empty the water and remove all of the granules. Dispose of used granules in a trash can.