Humidifiers help restore moisture to dry indoor air, but without proper care and maintenance they can pose a potentially serious risk to health. Wet and dirty humidifiers easily become contaminated with mold, bacteria and other allergens and respiratory irritants, according to the Mayo Clinic, and they may worsen asthma and allergies in vulnerable people. Moldy humidifiers may also cause or contribute to respiratory infections and cause flu-like symptoms, even in healthy adults. Preventing and eliminating mold from humidifiers requires daily cleaning and frequent sanitizing.
Empty the water reservoir and wash it with soap and hot water every day. Remove any scale or mold using a scrub brush and soap. If the water tank is not detachable from the humidifier base, be careful not to get any water inside the motor.
Rinse the tank very well with clean water, then wipe down the inside of the base with peroxide. A 3 percent hydrogen peroxide solution is effective at removing mold from the water tank of your humidifier, according to the U.S. Environmental Protection Agency.
Refill the water tank with distilled water. In some areas, tap water may be suitable for use in humidifiers. Most tap water, however, contains minerals that accumulate inside the unit. This mineral buildup provides a breeding ground for microorganisms and can be dispersed into the environment with the humidifier mist.
Add about 2 cups of white vinegar to the water tank once each week. Fill the rest of the tank with water, then run the machine for at least 30 minutes. Do this outside or in a well-ventilated area. After 30 minutes, rinse the tank and refill with plain water. Allow the unit to run for several minutes to flush out any remaining vinegar.
Clean heavy mold out of your humidifier by mixing equal parts water and bleach in the tank and running the unit outside for 30 minutes. Rinse very well with clean water to ensure no bleach is left inside the unit, and let the unit run for several minutes to flush the filter. If any bleach remains, it may be dispersed when you run the unit indoors, where it may be inhaled.
Throw away used filters, cartridges and cassettes before storing your humidifier. The Mayo Clinic suggests buying new ones the next season.
Replace your humidifier if you cannot eliminate all mold from the unit. Portable units are affordable and widely available.