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Whether you're sick with chest congestion or just suffering from the effects of the dry air caused by your heating system, a humidifier can be your best friend. "Research shows that keeping your home's relative humidity level between 40 and 60 percent can decrease influenza survival in the air and on countertops, doorknobs, faucets, etc., by up to 30 percent," says Lynne Hammell, director of marketing for Vicks.

But putting a humidifier to work also means that it's going to need routine cleaning. "Remember that whatever is in your water is going directly in your air," says Sarah Drake, humidifier brand manager for Honeywell. With that in mind, here are the details for keeping your air—and humidifier—cleaner.

How to Choose a Humidifier

Before we tackle cleaning, finding the perfect humidifier for you—or deciding that your current model is a bad fit—is essential. Each of the three main types of humidifier—evaporative, ultrasonic, and warm-mist—use different methods to put moisture into the air. Which one you choose really comes down to personal preference and reason for use.

Types of humidifiers

  • Evaporative models contain wicking filters, which absorb minerals so that the mist emitted is clean. Some of these humidifiers have an antimicrobial-treated filter, which can inhibit mold growth on the filter itself.
  • Ultrasonic models contain an ultrasonic nebulizer that vibrates and breaks apart particles and emits a cool mist that you can see.
  • Warm-mist models boil water and emit steam for purified, bacteria-free moisture.

If you're looking for a short-term solution for relieving cold-like symptoms, look for a model you can add inhalant or scent pads to, like the Vicks Mini Filter Free Cool Mist Humidifier, (about $43; Relief from general dry-air discomforts—and the lack of sleep they may cause—can be gained through humidifier models with longer run times and quiet operating systems.

Warm- and cool-mist humidifiers offer the same benefits, so narrow your choice based on personal preference. Warm mist increases the temperature of a room, while cool mist—which is recommended by the American Academy of Pediatrics—helps maintain a room's existing temperature. The size of the room where your humidifier will go should also figure into your buying decision. Check product details for small-, medium-, and large-room classifications.

Ease of use is an important factor as well. For example, is refilling the tank a breeze—and how often will you have to refill it because of the unit's size? You can also get a humidifier that you can program to run for a specified amount of time. And some allow you to manually set levels of humidity, while others can program levels automatically.

Bacteria-eliminating technology can also help you breathe more easily about your home's air. Models like the new Dyson Humidifier, (available September 2015), and the Vick’s Germ Free Humidifier use ultraviolet light to rid the water in your humidifier of 99.9 percent of bacteria, the companies say.

Accreditation for different features is a final assurance that your humidifier purchase will meet your needs. For example, Dyson's humidifier is certified by the Skin Health Alliance and the Asthma & Allergy Foundation of America, and it has the Quiet Mark seal.

Shop based on cleaning ease

"Cleaning is often one of consumers' pet peeves with humidifiers," says Hammell. Make your investment well worth the cost by choosing a model in keeping with the effort you're willing to put in to keep it clean. Look for models with a large opening and filter, or dishwasher-safe components, for easier cleaning.

Slime and Minerals

Dyson engineers point out that many companies whose humidifiers use UV-light technology claim it kills 99.9 percent of bacteria—but look closely, they say, and there's often a caveat stating that the claim is only true after several hours. Manufacturers agree that you must give a humidifier a weekly—and, at the least, light—cleaning to keep it running efficiently. The care instructions for many models recommend a deeper, monthly cleaning, as well.

Cleaning steps will vary, depending on the size and type of your humidifier, but the two cleaning processes—bacterial removal and descaling—entail disinfecting for algae, bacteria, and slime, and the removal of mineral buildup caused by hard water.

If your humidifier smells, looks slimy, or is turning a color, it's time to disinfect it. Many manufacturers recommend using soapy water or a mixture of bleach and water; Honeywell's Sara Drake suggests 1 teaspoon of bleach per gallon of water. "If you're using your humidifier every day, you're changing the water, cycling it through, and that's a good thing to do," says Drake, who recommends emptying your humidifier when it's not in use. If you have an evaporative humidifier with a wick, take out the wick and let it dry.

For descaling, many manufacturers recommend using distilled white vinegar; the amount and process depend on what's specified in the model's owner's manual. The cleaning methods you use should be specific to the type of humidifier you have.

Person setting up air purifier iStock

How To Clean Different Types of Air Humidifiers

The three main types of humidifiers use different methods to put moisture in the air. Which method you prefer really comes down to personal preference and reason for use.


Though the filter on some models can inhibit mold growth on the filter itself, keep in mind that if you have hard water, the filter needs to be changed more frequently, to prevent mineral buildup.


The nebulizer may absorb minerals from hard water, which can interfere with operating efficiency. Soaking it in white distilled vinegar will break up the minerals and make them easy to wipe away.


Minerals and other substances in your water have to go somewhere, which means they're going to settle and build up on the heating element. Tackle mineral buildup by soaking the heating element in white distilled vinegar.

Maintaining Air Humidifiers

Preventing mineral buildup

If you have hard water and find the buildup requires that you clean more often than you'd prefer, Dyson engineers recommend using distilled water or filtered tap water to help alleviate the buildup. If you live in an area that has hard water, using distilled water can minimize the production of "white dust"—a mineral residue that can accumulate and settle on the surfaces in a room—which is a problem unique to ultrasonic humidifiers.

Additionally, you can use a demineralization cartridge, like the Protect Demineralization Cartridge, (about $12; Amazon) to help reduce the white dust produced by an ultrasonic humidifier.

However, not all ultrasonic models will accept these cartridges. If you live in an area with hard water, Vicks experts recommend using distilled water in a warm-mist humidifier because the minerals in hard water can build up on the humidifier's heating element. Alternatively, consider switching to an evaporative model if you have hard water. But before filling the unit with distilled water or filtered tap water, check the owner's manual for recommendations.

Preventing slime buildup

Bacteria are the culprits for nonmineral residue on humidifiers. Aside from routine cleaning, dropping an antimicrobial cleaning cartridge, like the Protec Antimicrobial Cleaning Cartridge (about $12 for two cartridges, Amazon), in your humidifier's tank can kill the bacteria that cause odors and inhibit the growth of bacteria and mold, which cause slime buildup in the water.