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How to Clean a HEPA Filter

Last updated January 21, 2023

Daniel is our resident house gadget geek. He is our man in the frontline, following consumer trends to help him identify the best up and coming tech to review for HouseFresh. When he’s not tinkering with new gadgets, he composes and records his own music at home.

Our verdict:

Unless specified, the general recommendation is that HEPA filters should not be cleaned and reused. Trust me; I’ve tried it. 

HEPA filters are made from a tightly woven maze of materials that make them so effective at trapping the tiny particles from the air in your home which are harmful to your and your family’s health.

When you wash/clean a HEPA filter, you can compromise the integrity of these fibers, making them less effective at their job, which is why we always recommend replacing the filter when needed.

HEPA filters are used in most air purifiers as they are highly effective at clearing harmful particles from the air. Here at HouseFresh, we’ve researched the science behind different filters and have concluded that HEPA technology is the most efficient way of removing tiny particles from your home.

If you have an air purifier with a HEPA filter in your home, you should already be aware that these filters need replacing periodically and doing this will come at a cost. Different brands use filters specifically made for their units, so you must buy a particular replacement each time. 

But why do we have to fork out whenever a filter needs replacing? Can’t we save money by cleaning them when they’re dirty? This is what we’re going to look into.

How Do HEPA Filters Work?

HEPA stands for High-Efficiency Particulate Air [filter] (also known as a fibrous media filter) and was developed during WWII to filter out radioactive particles from the air. They are now used worldwide in vacuum cleaners, HVAC systems, cars and air purifiers.

HEPA filters work by trapping at least 99.97% of harmful particles down to 0.1 microns in size through a maze of woven fibers that act like a spider web, removing them from the air that passes through it. 

These fibers can be made from various materials, including coarse glass fibers, coated animal hair, vegetable fibers, synthetic fibers (such as polyester or nylon), synthetic foams, metallic wools, or expanded metals and foils.

The maze is made by randomly tangling all the fibers and compressing them into sheets to ensure they are tightly compact. These sheets are then pleated, increasing their surface area so air can pass through them. They are then mounted onto a frame to be installed into your air purifier.

One negative about using HEPA technology is that once particles become trapped, they stay in the filter. This means that HEPA filters become less effective over time as they fill up with contaminants. Because of this, it’s recommended that you replace the filters periodically so your air purifier can remain effective.

Can I Clean My HEPA Filter?

Replacing your HEPA periodically does come at an expense; if you’re changing it more often, this expense can increase over the years. But can we avoid buying new filters by simply cleaning and re-using them?

Some HEPA filters are labeled as “washable” or “permanent,” meaning they can be re-used. But you should always check the washing instructions before attempting this and follow them precisely to lower the risk of damaging the filter. 

Although this would be more environmentally sound, most HEPA filters should not be washed; even vacuuming them can cause damage that will affect the filter’s efficiency. 

As I mentioned, HEPA filters are made from a compact weave of tightly packed fibers that microscopic particles cannot pass through. By cleaning/washing/vacuuming them, you could damage the mesh of fibers by breaking and/or stretching them. If this happens, the weave will be left with holes that harmful contaminants can pass through to be re-circulated back into the air in your home.

As with the actual filter, the frame can damage when cleaned. When installing a HEPA filter into your air purifier, it should form a tight seal so contaminants cannot pass around the edges. If you remove the filter and tamper with it, you can damage the frame, which will alter the fibers’ pattern and compromise the seal’s integrity.

Before You Attempt to Clean Your HEPA Filter

If you still want to have a go at cleaning your HEPA filter instead of replacing it, there are a few precautions we would recommend taking before setting out. 

  1. Take the filter outside to clean it – You’re cleaning your HEPA because it’s full of harmful contaminants collected over time. If you attempt to clean your filter indoors, you risk releasing all of those trapped particles back into the air in your home, plus any microbial growth that may have occurred on the filter.
  1. Wear a respirator – When dealing with harmful contaminants, it’s always best practice to wear respiratory protection so that non of those particles are breathed in. Once you clean your HEPA, you will disrupt the contaminants captured by the filter, which may release them back into the air. You don’t want to inhale them as you’ve done all that work removing them from your environment in the first place.
  1. You will need a filter for your filter cleaner – There is no point in cleaning your HEPA filter if you simply transfer the particles somewhere else. For example, if you decide to vacuum your HEPA, ensure your vacuum cleaner also contains a HEPA filter. Those harmful contaminants may be released into the air if it doesn’t.
  1. Make time for the filter to dry – Re-installing a wet HEPA filter will lead to one thing…mold, further damaging the filter and making it less efficient. HEPA filters take time to dry (manufacturers recommend at least 24 hours) and your air isn’t being filtered every second it’s drying. Ensure you’ve left enough time for the HEPA to dry completely before using it again.

How To Clean a HEPA Filter (If You Have To)

We will always recommend that you do not clean your HEPA filter but replace it when it becomes ineffective. If you decide that you still want to clean it and have taken all the precautions mentioned above, here are a few tips on cleaning your HEPA filter, causing as little damage as possible.

📖 Always read the manual first

If your filter is classed as “washable” or “permanent,” the manual for your air purifier will provide you with strict instructions on how to clean the filter.

🧽 Do not scrub the filter material with a sponge or cloth

Try not to touch your HEPA filter with anything at all if you can help it. When you rub against the filter, you are damaging it. You may not be able to see any damage, but trust me, doing so will move, break, or stretch the fibers that make your HEPA filter so efficient.

🚿 If you’re using water, ensure it’s cold and low pressure

As I’ve already mentioned, anything that comes in contact with the filter material may damage the integrity of the fibers, even water. It’s important to minimize any damage to the filter by using cold water on low pressure, more of a rinse than a wash, if you know what I mean.

🧹 If you’re using a vacuum cleaner, be gentle

A vacuum cleaner can be an excellent method to suck away the dust and debris from your HEPA but use it with caution. If you start rubbing the vacuum over the filter’s fabric, you will cause damage. It’s best to hold the vacuum at least a millimeter away from the surface of the filter without making contact.

TIP 💡 Make sure your filter is completely dry before installing it back into your air purifier. Following our precautionary instructions, you will have set aside enough time for the filter to dry out. It’s recommended that you leave it for at least 24 hours before checking it is fully dry. Take this time to relax, put your feet up and maybe treat yourself to a dry martini with three olives.

When Should I Replace My HEPA Filter?

Now that we know that HEPA should be replaced when full, the question is, how often do you need to do this?

Unfortunately, the answer isn’t straightforward. Each purifier manufacturer produces their own filters with different gradients of efficiency. Luckily, the shelf life of a filter is usually displayed somewhere on the packaging of the unit, in the manual, on the brands’ website or shown in product reviews.

The life of a HEPA filter can last anywhere between three months to four years depending on several factors, including;

  • The grade of the HEPA filter (H10, H11, Medical grade H13 etc.)
  • How often you use your air purifier
  • The quality of the air in your room
  • The size of the filter

Apart from the information on the box, there are some telltale signs that your HEPA filter needs to be replaced for a new one.

🔺 Is the filter visibly dirty?

HEPA filters may capture microscopic particles but trap larger particles like dust, hair and mold. These particles can be visibly seen when you remove the filter from your air purifier. Some of the things you need to look out for are a build-up of dust/dirt, black spots and patches of mold. These are all indicators that your filter(s) needs replacing.  

🔺 The air isn’t getting any cleaner?

If you’ve operated an air purifier for a while, you will notice the change it makes to the air in your home and you will probably notice when your unit is not performing to its full capability. Maybe your room is dustier than usual, your allergies have returned, or you’ve noticed odors lingering longer than usual; these can all indicate that your filter may need replacing.

🔺 Your purifier is telling you

Nowadays, many air purifiers include a filter change indicator that lights up or flashes when the unit senses that the filter is full and needs replacing. Each unit has different indicators, so consult the manual to find where yours is located.

Final Thoughts 

So, we don’t recommend you attempt to clean your HEPA filter, no matter how tempting it is. Cleaning your filter may end up damaging the fibers that make your filter so effective at clearing harmful pollutants from the air in your home.

The tightly compact fibers in a HEPA filter are engineered to trap microscopic contaminants that can harm your health; if you compromise their integrity, your air purifier won’t work as efficiently as it should.