What causes white dust to appear on cool mist humidifiers? What causes white dust to appear on cool mist humidifiers?

With certain types of ultrasonic cool mist humidifiers, white dust may appear on or around the unit after use. While nothing to be alarmed about, it's important to know what it is.

  • White dust is the residue from minerals in water
  • As water is vaporized and turned into mist, mineral residue is released at a molecular level
  • Depending on the kinds of minerals in the drinking water, the makeup of this white dust will differ

Keeping the humidifier clean is a daily ritual. This helps prevent the growth of bacteria and/or mold. Use distilled water in the humidifier or install a sink water filter to remove minerals from tap water to minimize mineral residue.

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