Is It Possible to Clean a HEPA Filter? Here's What Experts Recommend

When an item in your home appears dirty, your immediate response is likely to be to clean it. However, with air filters, soap and water might not do the job. HEPA filters, which are commonly used in portable air purifiers, are one such item that experts suggest replacing instead of attempting to clean. Discover more about these effective filters and how to properly replace them when the time comes.

What Exactly is a HEPA Filter?

HEPA, short for high-efficiency particulate air, refers to a type of air filter that resembles folded paper. If you own a high-quality portable air purifier, it likely contains a HEPA filter, made up of a dense web of fibers that allow air to pass through—top pet-friendly air purifiers all feature HEPA filters. The fibers are tightly packed, forming a tiny path for air to travel through.

According to George Negron, Vice President of Operations at EnviroKlenz, a company specializing in air quality, this fiber mesh effectively traps tiny particles and filters them out of the air, ultimately enhancing indoor air quality. HEPA filters are also commonly found in home air handling systems, as well as in some vacuum cleaners and top-rated shop vacs.

What Is the Function of HEPA Filters?

Filters are characterized by how efficiently they capture particulates from the air. HEPA filters excel at trapping particles of various sizes, and in theory, they eliminate at least 99.97% of particles as small as 0.3 microns. This feature is particularly crucial in pet-friendly vacuum cleaners, like the Shark Wandvac, which prevent allergens from being released back into the air. According to John Bloemer, an engineering fellow at Aprilaire with over 20 years of experience in the air quality field, these are some of the most challenging particles to capture.

HEPA filters are designed to capture harmful microscopic particles.

These tiny 0.3-micron particles originate from sources like combustion smoke, smog, and diesel exhaust. Due to their size, they can penetrate deep into your lungs when inhaled, explains Bloemer. In contrast, larger particles such as pollen, which triggers allergy symptoms in the spring, are typically 10 microns in size. These are usually filtered out by your body's natural defenses (such as your nose and throat), rather than reaching your lungs. This is why HEPA filters are essential for trapping those harmful 0.3-micron particles.

Is It Possible to Clean a HEPA Filter?

If you notice visible dust or particles on your HEPA filter (it may appear gray or dirty) or experience reduced airflow through your air purifier, you might think it needs cleaning. However, experts advise that HEPA filters should always be replaced, not cleaned.

Cleaning Ruins the Filter.

"You can't clean a HEPA filter with a vacuum because particles are trapped not just on the surface but also deep inside the filter material," says Bloemer. He also warns against rinsing it under water, as liquids like water and soap will damage the filter's fibers.

A bit of accumulated dirt is perfectly fine.

When you notice buildup on a HEPA filter, it’s simply the particles it has trapped, ranging from those produced by combustion (like car exhaust, gas stoves, and candles) to mold spores and pet dander, explains Ted Myatt, ScD, senior scientist at Environmental Health & Engineering. These particles may come from both indoor and outdoor sources and can travel inside through open windows, wall joints, or cracks. While it may seem unusual, a HEPA filter can actually work more effectively with a thin layer of collected particles. However, once the filter becomes too clogged, airflow becomes restricted, signaling that it needs to be replaced, Myatt adds.

Pre-filters can be cleaned.

If your air system includes a pre-filter before the HEPA filter, it’s the one exception to replacing a HEPA filter when dirty, says Negron. The pre-filter captures larger particles, and some of these pre-filters are washable, allowing you to clean the dust and debris they collect. However, keep in mind that this is not the actual HEPA filter. Experts agree that HEPA filters should always be replaced, never cleaned, when they get dirty.

How Do You Replace a HEPA Filter?

If you notice visible buildup on your HEPA filter, the best approach is to simply replace it. To do so, turn off the unit, open the access door, remove the old filter, and install the new one, advises Bloemer.

You don’t have to rely solely on your own observations. Many manufacturers provide a recommended replacement schedule (typically around six to 12 months), and some portable air purifiers even have an indicator light that signals when it's time to replace the HEPA filter.

However, relying solely on time may not be the best gauge, says Negron, as the true need to replace a HEPA filter is determined by how much particulate matter it has captured, which can differ significantly depending on your environment. If your air purifier runs constantly or if your area is particularly smoky or filled with pollen, you should plan on replacing your HEPA filter more frequently.