Why Do Humidifiers Need Filters?

Humidifiers use filters for a number of purposes.

Wicking

Humidifiers that use some form of heat to produce moisture through evaporation need filters for other reasons, but cool evaporation humidifiers use their filters as a wick. Moisture is drawn up into the filter material and a fan causes the necessary evaporation. These filters are usually treated with some form of anti-microbial coating to prevent bacteria and virus growth. Humidifiers that use heat tend to kill viruses and bacteria by heating the water and do not need extra additives.

Mineral Absorption

Many humidifier filters and cartridges are designed specifically to trap minerals in the water you add to the unit. When mist is created by a humidifier, any minerals that evaporate with the water enter the air and create a fine white dust. Its unknown if this dust can cause lung problems. Change your humidifier's filter frequently if your water contains high amounts of dissolved minerals, or try bottled distilled water.

Clean the Air

Particles of all kinds, including dust, pollen and cigarette smoke settles in the water contained in your humidifier. Filters installed in each unit help trap these particles before they can rise with the evaporating water. While humidifier filters do have some limited particle filtering abilities, a humidifier can't replace an air purifier. If you are having problems with the air quality in your home, try using a purifier and humidifier in conjunction with each other.

Filterless Models

While most humidifiers feature some kind of filter, one type does not. Cool evaporation, warm evaporation and hot steam humidifiers all need filters. Ultrasonic humidifiers, which create mist through sound vibrations without any heat, use no filters. Some larger evaporation and steam humidifiers offer permanent filtration trays that can be cleaned. Disposable filters must be replaced between twice a week and once a month, so a permanent filter may save you money in the long run.