How to Clean Mold Out of Your Humidifier in 3 Steps

Humidifier in a kitchen ready for cleaning

Regular humidifier cleaning is necessary to prevent visible mold growth and keep ever-present mold spores in check. But what happens if you miss a cleaning or two?

When you fearfully glance down into the water tanks, you’ll notice a slimy film on the surface, black specks on the inner walls, or unidentified green mounds nestled in the deepest corners. Yikes!

In this post, you’ll learn an easy 3-step solution for cleaning mold from your humidifier naturally and discover tips for keeping it out from the start.

Why You Should Clean Your Humidifier

A moldy humidifier will release mold to drift in the air when it makes mist. This could lead to you inhaling mold spores, which can lead to severe airborne disease and poor respiratory health.

Cleaning the humidifier regularly and effectively will help reduce the risk of ill health.

How to Clean a Humidifier With Mold in 3 Simple Steps

Cleaning mold out of your humidifier can be painless when you follow the simple 3-step method below. It will take approximately 30 minutes, but it can take longer if the mold growth is widespread.

Once your humidifier is clean, a short, daily drying out period with a wipe down using our recommended sanitizer is sufficient to prevent mold buildup. We recommend daily distilled water changes to keep microbes under control, limiting the need for scrubbing to remove mold.

Essential items to clean mold out of your humidifier

What You Need to Remove Mold From a Humidifier

Here’s a list of the basics and why you need them.

  • Hydrogen peroxide (3% solution): To kill mold
  • Clean toothbrush: To get mold out of the deepest corners
  • Baking soda: Added abrasion for tough spots
  • Dishcloth: To wipe down humidifier parts and base
  • Spray bottle: For general sanitizing or mold spot cleaning
  • Waterproof gloves: To protect your hands
  • Goggles: To shield your eyes from mold spores
  • N-95 mask: To guard against inhaling airborne mold spores
  • Distilled water: For final rinsing and to fill up your humidifier after cleaning
  • (Optional) Distilled white vinegar (4-6% solution): May be used in place of hydrogen peroxide (Optional)
  • (Optional) Dish soap: May be used in place of baking soda (Optional)

Note: Never mix hydrogen peroxide with vinegar. The chemical reaction produces toxic vapors.

Humidifier Mold Cleaning Process

If you’re short on time and money but need a functioning, mold-free humidifier, try the following simple 3-step process. Depending on your mold problem, this procedure could take up to an hour. If it’s not too severe, it may take only 20 minutes. (Air drying may take an additional 2-3 hours of drying time unless you use a hair dryer.)

Before beginning, unplug the humidifier, drain the water, and put on protective gear. Open windows and run exhaust fans for improved ventilation or work outside.

1. Sanitize

Cleaning a humidifier tank with hydrogen peroxide

When there is extensive mold, fill the reservoir with hydrogen peroxide (3% solution) straight from the bottle until all mold is submerged. Do the same for other removable plastic parts. (Ensure you don’t soak parts with electrical components or the filter.) You may notice fizzling and bubbles as the chemical works.

If there are only 1-2 small, isolated mold patches in the water tank and on other plastic parts of the humidifier, apply hydrogen peroxide via a spray bottle.

If there’s no visible mold, thoroughly wipe down the insides and other removable plastic parts with hydrogen peroxide to eliminate microscopic mold spores. Wait 10 minutes.

Note: Do not use harsh chemical disinfectants. They may cause serious health problems, including lung injury disease.

2. Scrub

Scrubbing humidifier parts

Using a clean toothbrush, scrub away mold. For added abrasion, combine baking soda with a small amount of hydrogen peroxide separately in a small bowl until it forms a paste. Dab the brush in the paste and scrub until the mold disappears.

For tough mold stains that won’t budge, remove hydrogen peroxide from the water reservoir and put the baking soda-hydrogen peroxide paste you prepared earlier directly on the mold stains. Wipe away the paste after 10 minutes.

Note: Some discoloration from mold may be permanent.

3. Rinse and Dry

Humidifier parts drying after being cleaned

Flush the moldy, cloudy water down the toilet. Then rinse the reservoir twice with tap water. For the final rinse, use distilled water. Then drain and air dry before refilling the reservoir with fresh water.

How Often Should You Clean Your Humidifier?

Daily distilled water changes after a drying-out period should be enough to prevent visible mold growth in your humidifier. Add fresh water each time instead of just topping up the water tanks.

You probably won’t have visible mold if you keep up with regular maintenance, but invisible mold spores might be present. So, you must stay on top of the game with regular deep cleaning.

The U.S. EPA recommends a deep cleaning every three days. The previous section describes the 3-step process for disinfecting your humidifier.

The EPA does not recommend chlorine bleach as the sanitizer. Use hydrogen peroxide instead. Alternatively, substitute household vinegar (4-6% solution) straight from the bottle if that’s what you have on hand.

Note: Vinegar coming in contact with baking soda will yield a non-toxic but overflowing explosion of foamy bubbles. Their cleaning action could eliminate stubborn mold stains. But if you’re not feeling adventurous, substitute dish soap in place of baking soda when using vinegar to sanitize.

Do not mix vinegar with hydrogen peroxide! It creates toxic peracetic acid and toxic fumes.

If you have no visible mold, wipe down the water tanks, the base, and all removable humidifier parts (except the filter) with hydrogen peroxide or distilled white vinegar every three days. Rinse twice with tap water, then finally once with distilled water.

Follow the 3-step process given above only if you see or smell mold.

Should you see mold in the humidifier, complete the 3-step method described above. Additionally, for super cleaning, you may run the humidifier outside by using hydrogen peroxide instead of water to flush out all tubes where mold could hide. 

Let it run, so one gallon is vaporized OR for one hour of continuous use at a moderate or high mist mode. Ensure that you perform this clean outside and don’t breathe in the mist.

To support this recommendation, a 2017 EPA study on bioremediation using low-concentration hydrogen peroxide running through commercial off-the-shelf humidifiers showed it effectively killed mold spores.

A Note on Humidifier Filters and Mold Cleaning

Your humidifier’s filter is a delicate but vital component of its effective operation. Do not expose it to any cleaning products. They could destroy the anti-microbial coatings on it.

Inspect it thoroughly for mold growth. If you find mold, you’re better off buying a replacement filter than cleaning it. Humidifier filters are relatively inexpensive.

During routine cleaning of your humidifier, lay the filter flat in a shallow pan to soak in plain water and swish around. Then thoroughly rinse it with water, preferably distilled. Replace filters following the manufacturer’s recommendation. 

Filters should usually be replaced at least every three months, preferably between one and two months, depending on how often you use your humidifier and your water’s hardness.

Bonus Tips Tips For Cleaning Mold and Proper Use of Your Humidifier

Humidifier operating on a desk

Here are nine bonus tips for maintaining and operating your humidifier correctly to help keep mold spores in check.

  1. Monitor conditions with a portable hygrometer to confirm the humidifier’s built-in humidistat. Ensure the indoor relative humidity is at the EPA’s recommended 30-50%. Turn off the humidifier temporarily if it’s higher than 50%. Overusing your humidifier can cause mold to grow.
  2. Keep the area around the humidifier dry. Lower the output setting if you see moisture building up around the humidifier, and direct the mist to the center of the room.
  3. Ensure that your humidifier is in the correct position to prevent mist puddling on the floor. Place it three feet away from your bed and at least two feet off the ground on a desktop, bench, or nightstand with a water-resistant tray underneath.
  4. Distilled or demineralized water will prevent scale buildup inside the humidifier and eliminate “white dust” on furniture.
  5. Perform a deep clean before storing your humidifier for the season. When it’s time to crank it back up, dust it off and re-sanitize the machine before use.
  6. Tightly close hydrogen peroxide bottles after pouring and store them in the refrigerator to slow down this chemical’s natural degradation into inactive water and oxygen.
  7. A drop or two of 100% USDA organic tea tree essential oil in the water tank during regular operation provides anti-microbial protection and a pleasant odor.
  8. Keep all-natural EC3 Mold Solution Concentrate on hand when nothing else will work to clean mold out of your humidifier.
  9. Investing in a countertop water distiller will save money over time. It works as a source for drinking water, too.

Final Thoughts

Emptying the tank, air drying, and refilling with distilled water daily, followed by a deep clean every three days, will prevent mold from being an issue in your humidifier.

However, it’s time for mold cleaning when you notice a slimy film, black spots, or green growths on the interior water tank walls.

Fortunately, our simple 3-step process to disinfect and clean mold out of your humidifier will have your humidifier sanitized and operating effectively again to create a healthy environment for your home in no time.

Remember, preventing mold is easier than removing it. So ensure that you perform routine maintenance to keep mold growth out of your humidifier.

Published: December 4, 2022

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  1. Avatar Barbara Rodriguez June 10, 2024
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