How Do I Know If My HEPA Filter Is Washable?

HEPA (High-Efficiency Particulate) filters are some of the most efficient filters known to the modern air cleaning community. However, regular usage of the devices in which these filters are installed can cause them to get dirty. Thus, people who understand the inefficiency that a dirty filter can bring usually wonder if these filters are washable?

Well, your HEPA filters are washable if the manufacturer of your device indicates that the filter is washable or permanent. Of course, the professional consensus around the air cleaning industry is to replace a dirty HEPA filter. Nonetheless, if you have to wash the old one, these labels could help.

Well, we have already established that your HEPA filters could be washable, but how do you go about it? If you have no idea how to go about it, you can read through this article to find out how. 

Are All Hepa Filters Washable?

The short answer is no; not all HEPA filters are washable. However, if you were to inquire from an industry professional, they would declare that no HEPA filters are washable.

The reason is that HEPA filters are very delicate items, and washing them could easily cause damage to their fibers. If you want to understand why they are so delicate, a crash course on their history and purpose is pertinent. 

What Are HEPA Filters? 

HEPA filters can also be referred to as high-efficiency particulate arrestance filters or high-efficiency particulate absorbing filters. These filters are designed to remove at least 99.97% of pollen, bacteria, dust, or mold. Generally, they are believed to remove all particles that are 0.3 microns in size. 

This means all particles that are 0.3 microns in size or higher would be caught on the filter. Conversely, this means that any particles lower than 0.3 microns would pass through it. 

The 99.7% rating denotes the worst-case efficiency for this filter. This means that its efficiency at removing particles that are 0.3 microns in size is 99.7% at worst. Of course, this would mean a higher efficiency for particles larger than 0.3 microns. 

HEPA filters are usually used in vacuum cleaners and air purifiers to trap particles in the air. In addition, some HEPA filters are utilized in HVAC (Heating, Ventilation, and Air Conditioning) systems and cars. 

How Are HEPA Filters Made?

Modern HEPA filters could be made from various materials such as vegetable fibers, coated animal hair, and metallic wools. Some can also be made from coarse glass fibers, synthetic foams, and synthetic materials such as nylon and polyester. 

Before HEPA filters are compressed into their common paper-like consistency, these fibers are tangled together in a pre-defined manner. After which, the paper-like sheets are doubled and folded on themselves to provide an increased surface area for air. Finally, they are mounted onto their commonly seen metal, plastic, cardboard, or wood frames when done. 

Of course, each manufacturer possesses its secret recipe. Some manufacturers pair this common arrangement with other elements such as activated carbon for odor removal. Others include a chemical treatment to get all particles stuck on the filter’s fibers or a pre-filter. 

How Do HEPA Filters Work?

The principle of operation for most HEPA filters can be classified as direct impaction, sieving, interception, and diffusion. These processes direct how the particles in the air get taken out when they pass through a HEPA filter.

Direct Impaction

This part entails how very large particles hit a HEPA filter and get stuck to its fibers. These particles could be anything like dust, pollen, or mold. 


As the air stream goes into the filter, it gets to certain points where the filter’s fibers are close together. As a result, particles larger than these gaps get left behind when they reach these points.


This process is based on the nimbleness of air particles. Air is free-flowing, and it is known to find a way out of tight spaces. That is the property that is brought to bear here.

Due to the wild or random manner in which the filter’s fibers are tangled, the air stream is often rerouted. While the air stream would eventually find a way across, some particles are slaves to their inertia. This acts against them by getting them stuck in-between the fibers while the airstream moves ahead.


This process works against ultrafine particles, which may be finer than air particles. Thus, as the air particles move through the HEPA filter, those ultrafine particles are bound to move more erratically.

This could, in turn, make them collide with the fiber particles and get them stuck there. So after going through all these processes, there’s a very low chance of any particles remaining in the air stream.

How Do I Know If My HEPA Filter Is Washable?

Although HEPA filters are essential components of vacuum cleaners, air purifiers, and air conditioners, they are not cheap. While some individuals can afford to replace their HEPA filters when they get dirty, many more cannot.

Some manufacturers have made it possible for their customers to reuse their HEPA filters. However, this is a welcome development; not all air cleaning products employ such filters. Some manufacturers believe that a disposable HEPA filter is best since washing it would never compromise its integrity.

Thus, you are probably wondering how you as a consumer know which is which? Do you want to know if there are any tells or marks on the filter indicating that it is possible? Or if there’s a theory that could help you determine a washable air filter?

The answer is simple, you can’t tell. The only party that can determine these things is the manufacturers themselves.

Thus, the only way to tell if a HEPA filter is washable is to look for the manufacturer’s declaration. This could be written on the filter, amongst the operational manual of that device, or on the device. 

Most manufacturers indicate this by the words ‘washable’ or ‘permanent’ for that filter. If this isn’t written on that filter, the cleaning device, or its manual, then that filter is not washable.

What Happens If You Wash A HEPA Filter?

HEPA filters meet their requirement of possessing a 99.7% efficiency due to the consistency of their fibers. Therefore, any situation that could cause these fibers to stretch or tear would tamper with that integrity.

Unfortunately, washing could do just that. Of course, this only occurs if you don’t wash the reusable filter well. If adequately washed, your filter’s integrity efficiency won’t be affected. 

How To Wash A HEPA Filter

Although some manufacturers have termed their filters to be washable ones, that doesn’t change the fact that they are delicate. Thus, anyone washing these filters must do so with care. 

If this is your first time cleaning a HEPA filter, you can follow these steps to do so. If you are a veteran, you could also find out if there is anything that you have been doing wrong.

  • First and foremost, you have to remove the HEPA filter from the air cleaning device. You could do this by referring to the manufacturer’s manual. If you can’t do it yourself, you could get a qualified technician to help you out.
  • You also need to outfit yourself with a nose mask if you have any air-related illnesses like asthma. People with a clean bill of health can also wear the nose mask, as the filter would be very dusty.
  • It would help if you considered taking the filter outside. Every filter that has been used for a while is usually dusty. As such, there’s every chance that you could reintroduce the dust particles back into the air.

So, it would be best to clean your filter outdoors, not inside your home. Some of the particles reintroduced into the air could contain microbial growth.

  • After which, you can clean the filter by running it under cold water. This means you could just put on your kitchen tap (at very low pressure) and run your filter under it. 

It would be best if you take heed that nothing comes into contact with the filter fibers, not even your hands. The only thing allowed to touch the filter is cold water.

  • After which, you can dry the filters in a well-aerated area before replacing them in the device.

Once done, your filter would be clean and ready to work again. However, some manufacturers usually outline certain steps for cleaning their filters. So, you can check that first.

You should also make sure to wash your filters at least once in six months. Of course, you are also free to wash them earlier than that.

Precautions To Take When Washing A HEPA Filter

Many people have ruined their HEPA filters by making costly mistakes while cleaning them. Outlined below are some things to avoid when cleaning your HEPA filters:

  • Do not use hot water for cleaning the filter. The only water allowed is a cold one, as hot water could damage the HEPA filter.
  • You should avoid using any detergents or soaps while cleaning. Some of the HEPA filters are made with special materials, and the chemicals from these cleaning agents could damage them.
  • Make sure the washed filter is completely dry before replacing it. Filters with any moisture on them could support mould growth on their surface.

A HEPA filter is made up of a mesh of fibers that are tangled up pretty well. As such, at least a day or 24 hours of drying time is recommended. This gives the filter enough time to remove all the water and moisture from within its fibers. 

How Do You Clean A Non-Washable HEPA Filter?

While it’s always advisable to replace a non-washable or disposable filter, that doesn’t mean you can clean them somewhat. 

Unlike permanent or washable filters, disposable filters are even more delicate. Nevertheless, these are the available methods for cleaning non-washable HEPA filters:

Use A Damp Cloth

HEPA filters are delicate, so you can’t use water on them. If you have to clean such filters, run a damp cloth over its fibers to remove any dirt. The cloth should have no water on it, only moisture.

So, you dip a clean cloth in cold water and wring out all the water from the cloth. After which you can run the cloth over the fibers of the filter. 

You should also ensure that your fingers do not come into contact with the filter. When you have done this, you can dry the filter before replacing it. 

Using A Vacuum Cleaner

You could also try using a vacuum cleaner to suck out all the dirt on the filter. First, however, you have to ensure that the vacuum cleaner is also fitted with a HEPA filter. 

Using a vacuum cleaner that doesn’t possess a HEPA filter could lead to some filtered particles escaping. A HEPA filter would not allow any particle 0.3 microns or greater to pass through it. However, if you use a generic filter, those fine particles would escape through the filter of that vacuum cleaner.

When using the vacuum cleaner, you are also advised to ensure that it isn’t on a very high setting. Vacuums that are set to high vacuum speeds could potentially lower the integrity of the HEPA filter. It could cause rips or tears to form in the fibers due to its immense force. 

Although using a vacuum is an option for cleaning disposable HEPA filters, some experts advise against it. This is because the dirt particles are trapped on the surface of the filter and within it. Vacuums would, therefore, only be able to take care of the surface dirt particles. 

Some experts also believe that vacuuming could pull out pieces of the HEPA filter’s fibers together with the dirt particles. 

In addition, they believe that vacuuming the filter reduces its integrity with each session. As such, the most advised method of cleaning disposable HEPA filters is using a damp cloth.