How and when to clean your humidifier

A humidifier prevents dryness of your nose, throat, lips and skin. The air it dampens will also alleviate static electricity, peeling wallpaper, and cracks in paint and furniture. However, humidifiers can encourage the growth of organisms such as dust mites and mould, so proper care and cleaning are essential.

How and when to clean your humidifier

1. Regular maintenance pays

To reduce growth, plan a daily cleaning, with a more thorough cleaning every three days, and a regular disinfect.

2. To clean a portable humidifier

  • First turn the unit off.
  • Empty the reservoir (the tank where the water sits) every day and wash it out with hot, soapy water, using a brush or other scrubber to remove mineral deposits or film.
  • Rinse well under running water, taking care that no water gets into the motor.
  • Wipe all surfaces dry with a clean cloth, and fill the reservoir.
  • The use of distilled water is preferable because you'll avoid the build up of mineral deposits, but tap water will suffice.

3. Every three days

  • You need to clean your humidifier more thoroughly. Begin as you would the daily cleaning. After rinsing, wipe the reservoir with white vinegar (diluted with water, if you wish) to break up mineral deposits.
  • Wipe off the mineral deposits, rinse again, wipe dry and refill the reservoir.

4. Disinfecting your humidifier

  • Disinfecting will reduce spore growth. Mix a solution of 125 ml (1/2 cup) of household bleach with 4 litres (4 quarts) of water and add it to the humidifier's reservoir.
  • Run the humidifier until it starts to mist or steam. Make sure you do this outside or in a well-ventilated area and don't stand near the steamed bleach — it can injure your lungs.
  • Turn off the humidifier and let the bleach sit for a couple of minutes.
  • Empty the reservoir into a sink and rinse the reservoir with running water.
  • Fill it again with fresh water, run the system for 2–3 minutes, and then turn it off.
  • Empty the reservoir and rinse again.
  • Repeat the cycle until you no longer smell the bleach.
  • If the manufacturer's instructions don't recommend bleach, don't use it. They may recommend instead a 3 per cent solution of hydrogen peroxide, which is fine but does not work as well as bleach.

5. If your humidifier has a filter

  • Check it every third day.
  • If it's grey, replace it. The filter can't be cleaned.

6. At the end of the humidifying season

  • Clean the humidifier following the bleach method described previously.
  • Make sure all parts are dry, and store the unit in a dry location.
  • When it's time to use the humidifier again, clean the unit again and wipe up any dust on the outside with a damp cloth.

7. Humidifiers that are part of a central heating system

  • These humidifiers need to be cleaned regularly. Otherwise, they may become breeding grounds for mould.
  • The designs of such units vary widely, but typically a tube carries water from the water heater to a rectangular box mounted on the air-supply duct that goes from the heating unit to the rest of the house. The water flows across a disposable water panel or, in the case of older models, a rotating drum. The water evaporates into the air being fed throughout the house, thus raising the humidity. A drain removes the excess water.

8. If you have a newer system

    • If your system is no older than mid-1990s, replace the water panel every year. Do it more often if you have hard water, which builds up on the panel and makes it less effective.
    • Clean the water distribution tray at the same time. To do this, open the access panel on the box and unsnap and discard the water panel.
    • Unsnap the water distribution tray, take it to a sink, and give it a quick cleaning in warm water and dishwashing liquid.
    • Wipe the drain (it's not removable) with a soapy rag and rinse with a wet rag.
    • Reassemble the unit with a new water panel.

9. Cleaning the inner workings of an older system

  • Once a year, open the unit and replace the filter that wraps around the rotating drum.
  • Remove the water tray and wash it in the sink.
  • Two or three times a year, check the filter for mould or mineral deposits. If it needs cleaning, soak it for several hours in a solution of 1 part vinegar to 2 parts water.
  • Rinse the filter thoroughly with fresh water and return it to the drum.
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