Can You Wash a HEPA Filter? Benefits and Drawbacks

HEPA (High-Efficiency Particulate Air) filters trap particles and allergens that you otherwise wouldn’t be able to see or smell such as pollen, dust mites, pet dander, and mold spores. They work by forcing the air through a layer of material with an extremely high level of filtration (over 99% efficient). You can wash a HEPA filter but only if it’s labeled as ‘washable.’ 

A washable HEPA filter is cleaned by rinsing under cold water while a permanent HEPA filter is cleaned with a vacuum cleaner. Don’t use water on permanent HEPA filters. A disposable HEPA filter isn’t cleaned by water or vacuum cleaner but only replaced when dirty. Don’t brush or wipe the filter.

An important point is the difference between HEPA and true HEPA. A HEPA filter in your vacuum cleaner is likely washable or at least cleanable by vacuuming. HEPA filters in air purifiers are true HEPA and better off just replaced when dirty. Carbon filters should only be put in the sun for 3 hours and they’re good for reuse. 

How Often To Wash a HEPA Filter? 

You can wash HEPA filters, but that reduces the effectiveness of the filter. You can wash a HEPA filter with water or vacuum it to remove dirt and debris. Only wash a HEPA filter that’s labeled as ‘washable’ or ‘permanent.’ The third type is ‘disposable’ which should be replaced once it’s too dirty to clean the air. 

You should also only use cold water when you clean them because hot water could damage the filtration system on your air purifier. If there’s mold on your HEPAs, then replace them right away as they won’t get rid of any harmful chemicals like some other types of filters might.

How to Clean a HEPA Filter

Before you clean any air filter, always have a mask on to prevent the inhalation of pollutants caught by the filter. There are two ways to wash a HEPA filter as follows:

How to wash a HEPA filter

Only wash HEPA filters labeled ‘washable’ and with cold water as follows:

1. Remove the HEPA filter from the air purifier, HVAC system, vacuum cleaner or car.
2. Fill a large container with cold water. Wash WITHOUT A DETERGENT since detergents destroy the filters. 
3. Place the HEPA filter in the water, ensuring it is fully submerged for at least 30 minutes. Washing under pressure damages the air filter. 
4. Rinse multiple times using fresh clean water until all traces of soap and dirt are gone from the filter. Shake off any excess water then place on an absorbent towel to dry overnight or use a fan if available to speed up drying time. 
5. Place the filter back into machine once thoroughly dried.

Note that washing will reduce the level of filtration. As such, avoid washing when possible as you may need to change filters earlier than expected due to restricted air flow which needs more energy consumption levels than normal. 

Washable HEPA filter air purifiers include brands such as Levoit, Dyson, Winix, Coway, Honeywell and many others. Always check for the ‘washable’ label before washing the filter or prefilter since you can wash vacuum filters but some can only be washed on the outside. 

How to vacuum a HEPA filter

A non-washable HEPA filter is often labeled as ‘permanent’ and should thus be cleaned by vacuuming only.

Vacuum a HEPA filter as follows:

1. Remove the filter from the car, vacuum cleaner, HVAC system or air purifier.
2. Vacuum the filter gently to remove loose dust, dirt and debris. Do not press too hard or you will damage it. A gentle vacuuming should suffice for most filters.
3. When done, refit the HEPA filter back into car, HVAC system or purifier unit before use immediately after vacuuming to avoid contamination by dirt, dust and debris. Most filters such as those in the Germgurdian air filter are quite easy to fit.

You should replace filters at least once per year in order to maintain cleanliness of the breathable air. Even with regular vacuuming, maintenance should be performed throughout the year. Clean air purifier filters at least once every 6 months or as indicated by the air purifier.

In both types of cleaning, never touch the filter’s folded and delicate parts since you’ll damage them and reduce its effectiveness in cleaning the air. 

What HEPA filters are made of

As per the EPA, HEPA filters are made of various materials including coated animal hair, synthetic fibers, metallic wool, glass fibers, vegetable fibers, synthetic foams and even expanded foils and metals. 

These materials are then designed into sheets to increase the surface area of the filter. This way, the HEPA filter is able to catch up to 99.97% of particles at least 0.3 microns in size. Mold spores, mites, allergens and others are caught by the filter. Anything smaller than 0.3 microns such as some smoke and airborne chemicals can still pass through the filter. 

To further increase the effectiveness of HEPA filters, they’re chemically treated to make particles stick to them, added with activated carbon to remove odors, and pre-filters to screen out the larger particles (larger than 0.3 microns). 

Washing the HEPA filter will mess up the structure of the materials used to make the filter sheets thus allowing more of them to pass through. If you clean or wash it, do as little damage as possible. Even then, replacing your HEPA filters (and filters in general) should be your first choice and not cleaning them. 

If the filter is washable, you can wash it once every 6 months and there is no limit to the number of times you can wash it. However, each time you wash it, it’ll reduce in effectiveness. I would thus advice that you wash it a maximum of 3 times before replacing it. 

Drawbacks of Cleaning HEPA air filters

While the aim of cleaning a HEPA filter is to make it more effective at cleaning the air, the drawbacks include the following:

1. Reduces the filter’s effectiveness

When you wash the HEPA filter, you reduce its effectiveness. This is because the ability to capture the dirt in the air is reduced by up to 40%. Therefore, dust particles and allergens stay in your home instead of being sucked out with the rest of the clean air. In fact, most filters should last about 50% longer if not cleaned on a regular basis.

2. Releases some of the filtered particles 

The filter is designed to capture particles, so when you clean it and release those particles back into the air, they can be inhaled. This is especially problematic for individuals who have asthma or some other respiratory issues. 

Besides that, you need a vacuum cleaner with a HEPA filter to clean a HEPA filter from another appliance. If not, you will only be dispersing the captured particles to the air. 

3. Can introduce mold into the filter

If you wash your HEPA filter, it can introduce mold into the filter. If you notice dark spots, use a brush to scrub them out and then allow your vacuum to dry completely before putting it back together again. You can as well just replace the filter if it has mold. 

You should also allow a HEPA filter to air dry for at least 24 hours before putting it back into the air purifier. Otherwise, it’ll develop mold which will then spread around the house when the purifier is working. 

You can have clean air without necessarily cleaning your HEPA filter. Consider removing pollutants in your house, regular house-cleaning and opening windows each day unless you have a major source of pollution around.

Felix Newton