How to clean a humidifier: descale, disinfect and keep it clean

Step by step: how to clean a humidifier

Safety first. Unplug the humidifier before you empty or clean it. Never use vinegar and bleach together or one right after the other without rinsing; the mix releases chlorine gas. Rinse out any cleaner thoroughly, because whatever stays in the tank gets misted into the room.

1. 1

   Unplug and take it apart

   Unplug the humidifier, carry it to the sink, and pour out any standing water. Separate the tank, base, cap and any filter, wick or float, following your manual. Set aside the motor housing or top, which should never be submerged.

2. 2

   Soak the scale off with vinegar

   Pour 2 to 3 cups of undiluted white vinegar into the tank and the base reservoir so the crusty white areas are covered. Swish it around and leave it for 15 to 20 minutes. You should see the scale soften and start to flake.

3. 3

   Scrub the tank, base and small parts

   Scrub the inside of the tank, the base, the cap and the float with a soft brush. On ultrasonic models, clean the small metal disc (the transducer) only as gently as your manual allows, with a soft brush and no hard tools. Pour out the vinegar.

4. 4

   Rinse out the vinegar

   Rinse every part with clean tap water two or three times until the vinegar smell is gone. This matters before the next step, because vinegar and bleach must never meet.

5. 5

   Disinfect the parts that hold water

   Use the disinfectant your manual specifies. If it does not name one, the EPA suggests wiping or filling all surfaces that touch water with 3% hydrogen peroxide. Leave it for the contact time on your manual or the product label, then pour it out.

6. 6

   Rinse several times

   Rinse the tank and base with several changes of tap water until no smell of the disinfectant remains. Anything left behind will be misted into the air the next time the unit runs.

7. 7

   Check the wick or filter

   Evaporative wicks and filters wear out. If yours is hard, crusty or no longer soaks up water, replace it. Only rinse or soak a filter if the manual says that is allowed; some makers say to replace, never wash.

8. 8

   Dry, reassemble and refill with distilled water

   Wipe every part dry and let the pieces air dry for 15 minutes. Reassemble, fill the tank with distilled water, and plug it back in.

How often should you clean a humidifier?

Empty and refill a portable humidifier every day, and clean it every third day. That is the EPA’s schedule, and it is stricter than many people expect because standing water grows bacteria and mold quickly.

The EPA’s humidifier guide gives the daily and every-third-day schedule, recommends 3% hydrogen peroxide when the manufacturer does not name a cleaner, and says to rinse the tank with several changes of water after any cleaning agent. It also says to clean the unit again after storage before using it.

Cleaning ultrasonic, evaporative and warm mist humidifiers

All humidifiers need the tank and base cleaned, but each type has its own weak spot. Ultrasonic models spread minerals as white dust, evaporative models clog their wicks, and warm mist models build scale on the heating element.

• Ultrasonic and impeller (cool mist): the EPA says these disperse the most microorganisms and minerals into the air, so distilled water and strict cleaning matter most. White dust on furniture is a sign of minerals in the water.
• Evaporative: Vornado says to wash the base with warm water and mild detergent and, to disinfect, fill it with 1 teaspoon of chlorine bleach per gallon of water for 20 minutes, then rinse until the bleach smell is gone. Its wicks are disposable and typically last 4 to 8 weeks.
• Warm mist and steam: scale forms on the heating element. Descale it with vinegar as the manual describes, let the unit cool fully first, and keep it out of children’s reach because steam and hot water can burn.
• Tabletop and travel units: Levoit suggests weekly emptying and wiping, and an occasional soak with about 3 cups of white vinegar for 15 to 20 minutes, then a soft brush, a rinse and complete drying.

How do you clean a Vicks humidifier? First work out which kind you have. Vicks’ support pages list filter-free and filtered cool mist humidifiers, warm mist humidifiers and steam vaporizers, each with its own FAQ. Use the matching method above, and follow your model’s manual for the cleaning solution and soak time, since they vary by model.

Keep humidity below 50 percent

Run the humidifier only enough to keep indoor humidity at or below 50%. Higher humidity encourages dust mites and mold, which is the opposite of what a humidifier is for.

The EPA recommends a hygrometer to check levels, and says to turn the output down or relocate the unit if water condenses on windows, walls or pictures. Keep carpets, curtains and bedding near it from getting damp. If you notice musty odors or black spots on nearby surfaces, see our guides to musty smells and dust mites. Stop using a humidifier and talk to a doctor if you have breathing symptoms that seem linked to it.

Mistakes to avoid

• Leaving water in the tank for days between uses.
• Disinfecting with bleach right after a vinegar soak without rinsing in between.
• Not rinsing the disinfectant out, so it gets misted into the room.
• Using hard tap water in an ultrasonic humidifier, which leaves white dust and scale.
• Washing a filter or wick that the manual says to replace.
• Putting parts in the dishwasher when the manual says they are not dishwasher safe.