As discussed, cleaning a HEPA filter almost certainly will cause damage to the extremely fine mesh of fibers that allow the filter to do its job. But even if you could be 100 percent sure the filter would not be damaged by cleaning, there are other reasons that cleaning a HEPA filter is not a great idea.

Cleaning a filter is a dirty job. Unless you take the filter outside to clean it, there is a good chance that the act of cleaning it will introduce some airborne pollutants to your house. Getting rid of those pollutants is the reason you may want to use a HEPA filter in the first place. The pollutants introduced back into the air may include any microbial growth that has taken place on the filter.

You may inhale some of the pollutants from the filter. Even if you can clean your HEPA filter outdoors, some of the particles from the filter will be in the air while you clean it. Unless you wear some type of respirator, you can inhale those pollutants, which could trigger an allergic reaction.

You will need a filter for your filter cleaner. If you use a vacuum to clean out a HEPA filter, the vacuum will also need to have a HEPA filter, or it will not be able to keep the particles from the dirty filter in the canister. It will disperse all those particles into the air. And if the vacuum does have a HEPA filter, what will you use when it is time to clean that one?

The filter must be completely dry before using. A wet HEPA filter could further allow mold to form on the filter surface. Because of the fine mesh of fibers in a HEPA filter, they take a long time to dry (manufacturers recommend at least 24 hours). The whole time the filter is drying, you are not filtering air.