Can HEPA Filters Be Washed And Reused? (YES & NO)

Here's a question with indefinite answers. Can you wash a HEPA filter without damaging it or diminishing its efficiency? While the answer is NO with a big but, many types of HEPA filters have different usability and washability. As a layman, how can you tell which is which? Can you even tell the difference if the HEPA filter is clean or dirty? More importantly, how do you clean a HEPA filter and a non-washable one properly? Find out all the answers below.


Can a HEPA filter Be Washed And Reused?

A permanent or washable HEPA filter can be cleaned and reused multiple times as long as it is done properly without damaging the filter. Most permanent HEPA filters can be cleaned gently with a vacuum cleaner, while a washable HEPA filter can be cleaned by rinsing it in cold water. Note that there are no standards or terms defined officially on which type is considered permanent or washable. If you are unsure if the HEPA filter is cleanable, look for the label “washable” or “permanent” on the air purifier’s packaging box or website.

How To Clean a HEPA filter Without Ruining It

The most common method of cleaning a HEPA filter is using a vacuum cleaner with a brush attachment. Set the speed to the lowest, gently vacuum the surface dust, hair, and mites away without applying pressure on the filter material. Another method is to rinse it with cold water to loosen up all the trapped particulates. Let the HEPA filter air dry completely (usually the whole day) before inserting it back into the device. You can also shake off the excess water to reduce the drying time. Ultimately, follow whichever method the manufacturer recommends, including any special instructions on how to clean the HEPA filter. If there is none, the general guideline is a True HEPA filter should be disposed and replaced rather than clean.

While you’re at it, remember to:

  • Wear a face mask to decrease the risk of you inhaling the escaped pollutants.
  • Take the filter outside for cleaning to prevent the airborne pollutants from being introduced back into your home.

The Risk Of Cleaning a HEPA Air Filter

There are many reasons why most HEPA filters are non-washable, as improper cleaning can be a bad idea. To help you understand the risk, there are things you need to look into before you get started.

  • Washing it routinely will damage the filter’s fiber density, thus reducing its efficiency in capturing microscopic particles. Even if you clean it with extra care, there is no guarantee that the HEPA filter will perform the same prior to cleaning as the quality could have been compromised.
  • Cleaning a HEPA filter is a dirty job that some dust and pollutants will inevitably escape. Not only it is troublesome and potentially dangerous, but you will also have to do it every couple of weeks to prevent the filter from being clogged with particles. A big hassle compared to a disposable HEPA filter that you will only have to replace every year or so.
  • A damp HEPA filter will promote the growth and spread of microorganisms on the filter. If you are rinsing it with water, the HEPA filter must be completely dry to prevent mold and bacteria growth. Most HEPA filters will take roughly 24 hours to dry, and you cannot use a hairdryer to speed things up as the heat will damage the fiber. As a result, indoor air will be left unfiltered for the entire drying duration.
  • You will be exposed to the pollutants like pet dander, dust mites, mold, and pollen, during the HEPA filter cleaning process. Inhaling to the allergens could trigger allergic reactions like cough, sinus, headache, eczema, sore throat, and red eyes. In the long run, it could lead to respiratory issues such as asthma attacks, COPD, and bronchitis.
  • You are essentially transferring the dirty particles from one filter to another. For example, vacuuming the HEPA filter will move and trap the particulates in the canister vacuum cleaner’s filter instead. At the end of the day, you will still need to dispose of the filter when it is worn out.

Are Washable HEPA Filters As Effective?

Washable HEPA filters are effective that can reduce up to 99.97% of airborne particles in the air. However, the efficiency will drop after washing and reusing multiple times. If you notice your indoor air is not as clean as it used to, check if the filter is damaged/ torn. Replace it when necessary.

How Do I Know If My HEPA Filter Is Dirty?

You can tell if the HEPA filter is dirty when an air purifier struggles to capture air pollutants in the air. A dirty HEPA filter will have debris, hair, or dust clogged and is apparent just by looking at it. At this stage, you could either replace or clean it if is washable. Keep in mind that a yellowish filter is a sign of oxidation or aging, not dirty.

Alternatively, you can avoid the hassle of maintenance by going with the best filter-free air purifier. Click here to learn how does filterless technology works in an air cleaner.

What Is a HEPA Filter Made Of?

HEPA filters are made from a variety of materials such as plastic polypropylene (PP), polyethylene terephthalate (PET), nylon, wools, metals, foils, vegetable fibers, or fine glass fibers. The fibrous filter glass threads are tangled and compressed in myriad directions to form a filter mat with less than 1-micron diameter. Multiple folded sheets of fibrous material are pleased to increase the surface area and efficiency of the filter. A normal HEPA filter will have around 2,500 layers of interlaced glass threads allowing the capturing of microscopic particles like mold, pollen, PM2.5, viruses, and bacteria.

How Does a HEPA Filter Work?

HEPA filter works by forcing air into its filtration, capturing passing airborne particles such as mold, pollen, pet dander, dust mites, bacteria, viruses, and releasing purified air out. Because the HEPA filter has a very narrow opening, contaminants that pass through will be stuck on the fiber in either Direct Impaction, Diffusion, Sieving, and Interception. Direct Impaction happens when particles travel straight, collide, and are stuck on a fiber. Diffusion happens when ultrafine particles move volatilely, collide with fiber, and are stuck to it. Sieving happens when the particles are too large to pass through the gaps and get ensnared by surrounding fibers. Interception happens when Airflow is rerouting the particles around the fibers, but will eventually stick to the sides of fibers.

A HEPA filter is often accompanied by a pre-filter that traps large particles like dust and an activated carbon filter that removes smoke, odors, and chemical gases.

What Is a HEPA Filter?

HEPA stands for high-efficiency particulate air and is a type of mechanical filter that traps 99.97% of harmful airborne particles as small as 0.3 microns (0.00001 in, 0.0003 mm). All HEPA filters are officially labeled and must be produced and tested for quality assurance. The filter performance is guaranteed and certified by DOE, IEST, and UL in the United States. European standard has a lower filtration efficiency standard at 99.95%. There are many types of HEPA filters in the market with different MERV ratings based on their air filter efficiency. You can compare and learn more about HEPA VS MERV ratings here.

HEPA filters are commonly used in hospitals, research, industrial facilities, and now residential properties due to the increased awareness of good air quality. You can also find HEPA filters in many household appliances, including air purifiers, vacuum cleaners, HVAC systems, and cars.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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