Many people try to wash or vacuum their furnace filters to extend the life. Washing your furnace filter is generally a bad idea. Many filtering materials do not hold up well when wet. Washing your furnace filter significantly increases the risk for mold or microbiological growth on the filter itself (which will release those mold spores into the air that is circulating throughout your home). Â Also, you can never get the filter clean enough, which puts a strain on your unit and restricts your air flow so your furnace has to run a lot longer to reach the desired temperature.
Vacuuming your furnace filter is a healthier alternative to washing your furnace filter, but is still not recommended. Although you may slightly prolong the life of your furnace filter, you will probably make a mess doing it, and a vacuumed filter will release a lot of
dust and particles into the duct work when you first re-install it. Additionally, most furnace filters are made from a delicate filtering material and are prone to ripping or tearing, which will render the filter useless.