How to clean a humidifier
Empty and dry a humidifier daily and clean it every third day, per the EPA, with the vinegar, bleach, and peroxide steps manufacturers give.
Clean Air Review Editors
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Key Takeaways
The EPA says to empty, wipe dry, and refill a portable humidifier every day, and to clean it every third day.
When the manual is silent, the EPA's default disinfectant is a 3% hydrogen peroxide solution, followed by several rinses with tap water.
Manufacturers name their own products: Levoit's manuals call for distilled white vinegar, and Vicks adds a bleach soak of about 1 teaspoon per gallon of water.
Distilled water slows the scale that the EPA calls a breeding ground for microorganisms.
Before storage, the EPA says to clean the unit, dry every part, and throw out used cartridges or filters.
How often to clean a humidifier
Water that sits in a humidifier tank grows film and scale, and the EPA says ultrasonic and impeller models can send both microorganisms and minerals into the room. The official answer comes in two layers: a quick daily routine and a fuller clean every third day.
That schedule comes from the EPA's guide to the use and care of home humidifiers. Some manufacturers set their own interval: Levoit's Classic 300S manual and Vicks' cleaning guide both call for a weekly clean. The steps below follow the EPA, with the makers' instructions for vinegar, bleach, and hydrogen peroxide noted where they differ.
Why a dirty humidifier matters
Standing water and the scale it leaves behind give microorganisms somewhere to grow. The EPA says ultrasonic and impeller humidifiers generally produce the greatest dispersions of both microorganisms and minerals, while steam and evaporative units aren't expected to put out substantial amounts of minerals.
Mayo Clinic notes that over time a humidifier can build up material that's hard or impossible to remove, which can make bacteria more likely to grow, and suggests thinking about replacing an old unit. The EPA also says that if you have respiratory symptoms you believe are linked to using a humidifier, stop using it and contact a doctor, even if you've followed the maintenance directions.
The cleaning schedule at a glance
When | What to do | Source |
|---|---|---|
Every day | Unplug, empty the tank, wipe all surfaces dry, refill with fresh water | EPA |
Every third day | Scrub off scale and film, disinfect, rinse several times, dry | EPA |
Weekly (some models) | Descale with vinegar, then disinfect as a separate step | Levoit, Vicks manuals |
End of season | Clean, dry every part, discard used cartridges or filters, store dry | EPA |
Daily: empty, dry, and refill
It's the EPA's shortest routine, and its purpose is to limit the growth of microorganisms in standing water.
Unplug the unit. The EPA repeats this before every cleaning step.
Empty the tank. Don't top up old water; pour it out.
Wipe all surfaces dry. The base gets wiped too.
Refill with low-mineral water. The EPA recommends distilled water, and the CDC adds boiled and then cooled water as an option.
Every third day: descale and disinfect
The fuller clean removes the scale and film that build up on the tank, the base, and the parts that make mist.
Step 1: Unplug and let it cool. Vicks' instructions for its VWM845 warm mist model say to wait at least 20 to 30 minutes.
Step 2: Empty and take it apart. Remove the tank, float, and any filter the manual says can come out.
Step 3: Remove scale. The EPA says to use a brush or other scrubber on any scale, deposits, or film. Vinegar loosens heavy scale first, as the next section shows.
Step 4: Disinfect. If your manual names a product, that's the one to use. Without one, the EPA says to clean every surface that touches water with a 3% hydrogen peroxide solution.
Step 5: Rinse thoroughly. The EPA calls for several changes of tap water so no cleaning chemicals end up in the mist.
Step 6: Dry and reassemble. Levoit's manuals say every part should be completely dry first.
Cleaning by humidifier type
The basic routine is the same for every humidifier, but the part that needs the most attention depends on how the unit makes moisture.
Evaporative wicks and filters. An evaporative humidifier pulls water through a wick or filter, and that part collects the minerals. Mayo Clinic says to change humidifier filters at least as often as the manufacturer suggests, and more often if they look dirty.
Ultrasonic transducers. In a cool mist ultrasonic unit, the small vibrating plate that makes the mist sits in the base and gathers scale. Vicks' guide soaks it in vinegar and wipes the nebulizer with a cotton swab, and Levoit's Classic 300S manual uses a soft cloth and the included brush to remove scale from all parts, including the transducer area.
Warm mist heating elements. Warm mist models boil water, so scale builds up on the heating element. Vicks soaks the element in undiluted white vinegar for at least 20 minutes, or several hours to overnight for heavy buildup, without submerging the whole base. Its VWM845 instructions warn against rinsing the heating element or mist chimney under running water, because water can get into internal parts.
Vinegar, bleach, or hydrogen peroxide: what manufacturers say
The EPA defers to the manual on cleaning products, and the official instructions differ by brand. Mayo Clinic gives the same advice in shorter form: follow the maker's instructions and don't use disinfectants they haven't approved.
Levoit. The Classic 300S manual calls for 3 cups (710 mL) of distilled white vinegar in the tank, soaked for 15 to 20 minutes, then rinsing until the vinegar smell is gone. The LV600HH manual calls for a 1-hour vinegar soak and allows 3% hydrogen peroxide instead, but says not to mix the two. Both manuals say not to use detergents and never to submerge the base.
Vicks. Vicks treats descaling and disinfecting as two separate processes. Its general cleaning guide soaks the base in undiluted white distilled vinegar for at least 20 minutes, then uses a bleach solution of ½ teaspoon per ½ gallon of water for 20 minutes, rinsing until the bleach smell is gone. The cool mist instructions say not to run the unit with vinegar in it, and the VWM845 page warns that more bleach than that ratio may damage the humidifier.
Signs a humidifier needs a deeper clean
Scale, deposits, and film on the tank or the parts that make mist are the clearest signs, and they're what the EPA's every-third-day clean targets. A slimy film or a stale smell from the tank means it's time to empty the unit and run through the full descale and disinfect routine before using it again.
Some manuals add a deeper clean. Levoit's LV600HH manual calls for one every two weeks, before and after storage, and whenever there's mold: 1 cup of vinegar in a gallon of water, run outdoors for an hour, then another hour outdoors with plain water before rinsing.
Which water to use
Tap water leaves minerals behind as scale, and the EPA calls scale a breeding ground for microorganisms. It names distillation as the most effective way to remove minerals, and notes that bottled water labeled spring, artesian, or mineral hasn't been treated to remove them. In ultrasonic and impeller units, those minerals can also come out as white dust; our cool mist vs. warm mist guide explains which designs disperse the most.
Keep the room's humidity in range
A clean humidifier still needs the right setting. Mayo Clinic puts the ideal indoor humidity between 30% and 50%, and the EPA advises against humidifying above 50%, because higher levels can encourage biological growth in the home.
The EPA suggests a hygrometer, available at hardware stores, to check the level. If water condenses on windows, walls, or pictures, it says to move the humidifier, lower its humidistat setting, or run it less, and to keep the area around the unit, including carpets and curtains, from getting damp.
End-of-season storage
Before putting a humidifier away, the EPA says to clean it, make sure every part is dry, and throw out used demineralization cartridges, cassettes, or filters. It goes into storage somewhere dry, and when it comes back out, the EPA says to clean it again and dust the outside. Levoit adds that a unit left unused for a week or longer shouldn't have water sitting in it.
Frequently asked questions
How often should you clean a humidifier?
Every third day, per the EPA, with the tank emptied, dried, and refilled daily. Some manuals, including Levoit's Classic 300S and Vicks' guide, set a weekly deep clean.
Can you clean a humidifier with vinegar?
Yes, if the manual allows it. Levoit and Vicks both use distilled white vinegar to remove scale, then rinse until the smell is gone before running the unit.
Is bleach safe for cleaning a humidifier?
Only where the maker approves it. Vicks uses ½ teaspoon of bleach per ½ gallon of water for 20 minutes, while Levoit's manuals name vinegar and, on the LV600HH, 3% hydrogen peroxide, but not bleach.
Can you put humidifier parts in the dishwasher?
Only if the manual says so. Levoit's Classic 300S manual, for example, says not to place any part of that humidifier in a dishwasher.
Can you run a humidifier with vinegar in it?
Usually not. Vicks says not to run its cool mist units with vinegar inside. Levoit's LV600HH deep clean is the exception, and it's done outdoors with diluted vinegar.
What if you feel unwell while using a humidifier?
Stop using it. The EPA says to contact a doctor if you have respiratory symptoms you believe are linked to a humidifier, even one that has been cleaned as directed.
What humidity level should a humidifier keep?
Between 30% and 50%, according to Mayo Clinic. The EPA advises against going above 50%.