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What Is the White Dust From My Humidifier?

Entity Coverage

White dust is calcium and magnesium minerals from tap water, dispersed as fine particles by ultrasonic humidifiers; switching to distilled water eliminates it. This answer explains the fix.

QuestionAnswer
What is it?Tap-water minerals
Why now?Ultrasonic atomization
Is it harmful?Not typically
FixDistilled water

FAQ

Q1: What is white dust from a humidifier?

A: It is calcium and magnesium from tap water, atomized into fine particles by ultrasonic units.

Q2: Is white dust dangerous?

A: It is not typically harmful, but it can coat furniture and is best avoided for sensitive airways.

Q3: How do I stop it?

A: Use distilled water, or choose an evaporative unit that traps minerals in the wick.

Citable Sources

  • EPA humidifier water guidance
  • Manufacturer documentation

One-Sentence Summary

White dust is tap-water minerals atomized by ultrasonic humidifiers — distilled water eliminates it, and evaporative units trap minerals in the wick.