How to Clean a Portable Humidifier

White portable humidifier releasing steam next to plant

The Spruce / Sarah Lee

  • Total Time: 45 mins
  • Skill Level: Beginner
  • Estimated Cost: $5 or less

Dry winter air can lead to a broad range of health issues from nosebleeds to dehydration, from dry skin and cracked lips to bronchitis. Dry air can even cause pneumonia to be more severe should you get infected with a disease-causing bacteria or virus.

The standard preventive measure for these dry-air health problems is to use a portable humidifier, which helps avoid these health problems by putting much-needed moisture back into the air you breathe. All too often, though, a humidifier can cause other health problems. Symptoms that are sometimes caused by humidifiers include:

  • Allergies
  • Asthma flair-ups
  • Coughs
  • Flu-like symptoms
  • Lung and sinus infections

A Clean Humidifier Is a Safe Humidifier

When a humidifier causes health problems, it is almost always because it contains bacteria and molds that can trigger allergy and asthma symptoms or even lung infections. It is easy to understand how this can happen because the nature of a humidifier is to hold standing water so it can evaporate it through one or more damp wicks, and to blow that moistened (and possibly infected) air out into the room to raise the ambient humidity levels in the room.

That is all well and good if the water being evaporated is perfectly sterile. But the standing water reservoir is a natural place where molds and bacteria can multiply, and the moment the reservoir or saturated wick in your humidifier becomes infected, your appliance has just become a distribution system for germs and molds. As germs and mold spores are blown into the air, they are on the hunt for new moist, warm places to take up residence—often your lungs or sinus cavities.

This may sound so scary that you wonder why anyone would ever use a humidifier. Fortunately, it's fairly easy to prevent your humidifier from becoming a petri dish for bacteria: Just clean it regularly. If using a humidifier daily, a cleaning routine repeated every three days should keep your air perfectly healthy.

What You'll Need

Equipment / Tools

  • Clean toothbrush


  • Hydrogen peroxide or white distilled vinegar
  • New humidifier wick (if needed)


Brown bottle of hydrogen peroxide, glass container of distilled white vinegar and a toothbrush to clean portable humidifier

The Spruce / Sarah Lee

  1. Clean the Base

    To deep clean your machine, begin by disinfecting its base using 3 percent hydrogen peroxide or white distilled vinegar. Start by unplugging the humidifier unit from the wall outlet, then remove the unit's water tank and filter.

    Pour a generous amount of hydrogen peroxide or white distilled vinegar into the base of the humidifier. Use a clean toothbrush to scrub away film and mineral build-up from the base of the unit.

    Allow the liquid to sit in the humidifier’s base for at least 10 to 30 minutes, then pour the liquid out. Rinse by adding and swishing fresh water to the base. If any mineral residue is left, repeat the entire process. When the base is clean, let it air dry.

    Base of portable humidifier scrubbed by toothbrush to remove film and mineral build up

    The Spruce / Sarah Lee

  2. Clean the Wick

    Ultrasonic humidifiers don't have an evaporative wick, but many evaporative humidifiers have a wick pad that soaks up water to facilitate its evaporation. This wick can either be a flat pad or a cylindrical pad that fits around a rotating drum.

    Whatever type of wick you have, remove it from the humidifier each time you clean it and thoroughly rinse it in clear water. Don't use any cleaning solutions on the wick. If the wick has become caked with white mineral deposits, replace it with a fresh wick pad.

    Humidifier wick pad rinsed under running water in sink

    The Spruce / Sarah Lee

  3. Clean the Tank

    A humidifier's water tank is also a haven for bacteria and mold. Mix a solution of four parts water to one part hydrogen peroxide (3 percent) in the tank. Allow the solution to remain in the tank for at least 30 minutes. Empty the solution, then rinse thoroughly with clean water and let the tank air dry.

    Hydrogen peroxide and water mixture poured into humidifier tank for cleaning
    The Spruce / Sarah Lee

Is Your Humidifier Still Making You Sick?

If your humidifier is still aggravating your sinuses and throat even though you are cleaning it thoroughly and regularly, it's time to stop using tap water and switch to distilled water. Tap water contains minerals and contaminants that encourage bacteria growth. These minerals are especially prevalent if you have hard water; it's these minerals that cause the white dust that's left behind in the tank and on the evaporative wick after the water evaporates away.

Distilled water is produced by an evaporation process that captures only the water molecules and leaves behind the mineral deposits. Combined with regular cleaning of the humidifier, tank, and evaporative wick, using distilled water should eliminate any health problems you experience from using a portable humidifier.

Consider a New Humidifier

Over time, there can be such a build-up of mineral deposits that a portable humidifier can no longer work efficiently. When this happens, it's time to buy a new humidifier. Where there is a noticeable build-up of mineral deposits, a build-up of bacterial is almost certainly present, as well.

Now is the time to switch to an antimicrobial humidifier. These units are able to purify stored water, so they produce a cleaner and healthier mist. To keep your machine in tip-top-shade, follow instructions for cleaning. Consult consumer advocacy sources, such as Consumer Reports, for advice on the best portable humidifiers.


If your main forced-air HVAC system has a built-in humidifier feature, its components need to be cleaned and maintained regularly, just as with a portable humidifier. Whole-house units can be even more prone to health problems than portable units. Consult the instructions for your furnace/air conditioner system for directions on how to clean and maintain a whole-house humidifier unit.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Davis, Robert E et al. The impact of weather on influenza and pneumonia mortality in New York City, 1975-2002: a retrospective study. PloS one, vol. 7,3 2012, e34091. doi:10.1371/journal.pone.0034091

  2. Svendsen ER, Gonzales M, Commodore A. The role of the indoor environment: Residential determinants of allergy, asthma and pulmonary function in children from a US-Mexico border community. Science of the Total Environment, 616-617:1513-1523, 2017. doi:10.1016/j.scitotenv.2017.10.162

  3. Dirty Humidifiers May Cause Health Problems. U.S. Consumer Product Safety Commission.

  4. Central Humidifiers. International Association of Certified Home Inspectors.