Empty and rinse the tank daily, deep clean the tank and base on a schedule of roughly every few days, and let every part dry fully when the unit is not in use. The cleaning sequence, the schedule for each part, the water in the tank, and the cleaners to avoid all follow below.
The Environmental Protection Agency (EPA) advises changing the water often and cleaning the unit regularly, following the manufacturer's instructions. Standing water and damp surfaces allow microbial growth, and drying parts fully reduces that growth. For the wider question of whether a humidifier can add to mold in a home, see whether a humidifier can cause mold.
How to Clean a Humidifier Starts With a Daily Rinse
Empty and rinse the tank every day the unit runs. A deep clean of the tank and base follows on a longer schedule, and many manufacturers specify about every three days during use.
The EPA advises changing the water often and cleaning the unit regularly, following the manufacturer's instructions. The manual for a given unit sets the exact interval, and it governs whenever that interval differs from three days.
Drying is the second half of the routine. Standing water and damp surfaces allow microbial growth, and drying parts fully reduces that growth, according to the EPA.
Eight Steps From Unplugging to Drying
Work through these steps in order each time you deep clean the tank and base.
- Unplug the unit before you touch the tank, the base, or any electrical part.
- Empty all remaining water from the tank and the base.
- Disassemble the parts the manual shows you how to remove, and lay them out where they can dry.
- Scrub visible residue from each part.
- Descale mineral deposits with white vinegar, which is commonly used to dissolve mineral scale.
- Rinse every part thoroughly with clean water to clear the vinegar, then disinfect only if the manual allows it. Some makers use a dilute household bleach rinse, so use the dilution the manual specifies.
- Rinse every part thoroughly with clean water until the smell of vinegar or cleaner is gone.
- Dry every part fully before you reassemble the unit or store it.
Cleaning Frequency by Part Under Common Guidance
The table below lists common guidance from the EPA and manufacturers. At The Indoor Report, we compile and explain published guidance, so the table is not a result from our own testing. Where the manual for a unit gives a different interval or method, the manual governs.
| Part | Task | Frequency | Basis |
|---|---|---|---|
| Tank | Empty and rinse, then refill with fresh water | Daily while the unit runs | EPA: change the water often |
| Tank and base | Deep clean: scrub, descale, rinse, dry | About every three days during use | Many manufacturers specify this interval |
| Evaporative wick or filter | Replace | On the maker's replacement schedule | Maker schedule; evaporative units use a wick or filter that collects minerals |
| Ultrasonic unit | Deep clean and rinse | As the manual directs | Maker instructions; no fixed interval is published. |
| Any part | Disinfect | Only where the manual allows it | Some makers use a dilute household bleach rinse |
| Whole unit | Empty and dry | Whenever the unit is stored | Many manufacturers specify emptying and drying for storage |
Standing Water and Damp Surfaces Feed Microbial Growth
Standing water and damp surfaces allow microbial growth, according to the EPA, and drying parts fully reduces it. A tank that holds water between uses, or a base that stays wet, gives microbes the conditions the EPA describes.
Room humidity is a separate control. The EPA advises keeping indoor relative humidity between 30 and 50 percent, and below 60 percent at all times, to limit mold growth, according to its guide titled A Brief Guide to Mold, Moisture and Your Home. Cleaning addresses the water and surfaces inside the unit. The humidity band addresses the air in the room.
For a fuller look at the mold question, read whether a humidifier can cause mold.
Mineral Dust Starts With the Water in the Tank
Distilled or demineralized water reduces mineral dust where the maker recommends it, according to the EPA. The manual's water recommendation governs. If the manual names distilled or demineralized water, that is the water to put in the tank.
Tap water carries minerals. Ultrasonic units can disperse those minerals as fine white dust, and evaporative units collect them in the wick or filter.
For the water question in more detail, see distilled water for a humidifier.
Evaporative and Ultrasonic Units Need Different Attention
Evaporative humidifiers use a wick or filter that collects minerals, and the maker's schedule governs when to replace it. Ultrasonic units can disperse minerals from tap water as fine white dust, according to general description consistent with EPA guidance.
The unit's design sets which of these issues applies. For the general differences between design types, see types of humidifiers and warm-mist versus cool-mist humidifiers.
Never Mix Bleach With Vinegar, Ammonia, or Other Cleaners
The Centers for Disease Control and Prevention (CDC) warns never to mix bleach with vinegar, ammonia, or other cleaners, because the mix can release toxic gases.
The routine above uses vinegar to descale and, on some units, bleach to disinfect. Rinse every part thoroughly between one cleaner and the next, and use only the cleaner the manual allows for each step.
Keep each cleaner in its own step. Do not add one cleaner to a tank that still holds another.
Target Humidity Band and a Hygrometer Reading
Keep indoor relative humidity between 30 and 50 percent, and below 60 percent at all times, according to the EPA's mold and moisture guidance.
Read the room with a hygrometer and compare the reading with the 30 to 50 percent band. For the target band in more detail, see ideal humidity in a house.
The cleaning routine covers the unit itself, and the humidity reading covers the room.
Replacement Timing and the Gaps in Published Guidance
Replace evaporative wicks and filters on the maker's schedule. If a part will not come clean as the manual describes, the manual's replacement guidance governs.
No service life for a humidifier, cleaning time in minutes, product model, or price is published.
Your next step is to empty the tank tonight, then set a reminder for the first deep clean three days out.
Common questions
How often should I clean a humidifier?
Empty and rinse the tank daily, and deep clean the tank and base about every three days during use. Many manufacturers specify that interval. The EPA advises changing the water often and cleaning the unit regularly, following the manufacturer's instructions, so the manual for the unit governs when it gives a different interval.
Can you clean a humidifier with vinegar?
White vinegar is commonly used to dissolve mineral scale, so it is the usual descaling step in the routine. Rinse the parts thoroughly afterward. The Centers for Disease Control and Prevention (CDC) warns never to mix vinegar with bleach, ammonia, or other cleaners because the mix can release toxic gases.
Is bleach safe to use in a humidifier?
Bleach is an option only where the manual allows it. Some makers use a dilute household bleach rinse to disinfect, according to general guidance. The CDC warns never to mix bleach with vinegar, ammonia, or other cleaners, because the mix can release toxic gases.
Why does a humidifier leave white dust?
Ultrasonic units can disperse minerals from tap water as fine white dust, according to general description consistent with EPA guidance. Distilled or demineralized water reduces mineral dust where the maker recommends it, according to the EPA.
Can a dirty humidifier grow mold?
Standing water and damp surfaces allow microbial growth, according to the EPA, and drying parts fully reduces that growth. For whether a humidifier can add to mold in a home, see whether a humidifier can cause mold.