Does Reverse Osmosis Remove PFAS, PFOA & PFOS from Water?

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PFOA and PFOS are two types of PFAS. Both have been found in water sources across the United States and around the world.

PFAS are also collectively referred to as “forever chemicals”. That’s because they are very stable and persist in the environment for decades.

Many people facing PFAS in their water supply are trying to filter them out using reverse osmosis. But does reverse osmosis remove PFAS, PFOA, and/or PFOS from water at all? Let’s find out!

Key Takeaways

  • Reverse osmosis can be very effective as a means of removing PFAS, including PFOA and PFOS, from water.
  • The reverse osmosis membrane in an RO system removes up to 99% of PFAS.
  • Carbon pre and post-filter stages are also effective at PFAS removal. Under the right conditions, activated carbon can remove up to 100% PFAS.

Does Reverse Osmosis Remove PFAS, PFOA, and PFOS from Water?

Polyfluoroalkyl substances, or PFAS, are a group of man-made chemicals used in a variety of products, including non-stick cookware, food packaging, and firefighting foams.

PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate) are two types of PFAS that have been found in many US water supplies.

Because of their chemical structure, PFAS are very difficult to remove from water sources without specialized filtration systems. Reverse osmosis is one such technology that is often used for drinking water treatment and as part of a home water purification system.

Because the reverse osmosis process effectively removes PFAS, equipping your home with an RO system is a wise decision if you’re worried about their presence.

So yes, reverse osmosis does remove PFAS, PFOA, and PFOS!

Perfluorooctanoic acid (PFAS), Skeletal formula

Does Reverse Osmosis Remove PFOA?

Yes, reverse osmosis does remove PFOA. As mentioned above, PFOA belongs to the group of PFAS chemicals.

By the way, PFOA is also known as “C8”. So if you ever wonder, yes, reverse osmosis removes C8!

Does Reverse Osmosis Remove PFOS?

Yes, reverse osmosis removes PFOS. Just like PFOA, PFOS is one type of PFAS.

How Does Reverse Osmosis Filter Out PFAS?

Reverse osmosis systems remove PFAS (including PFOA and PFOS) from water by using a membrane with extremely small pores that allow pretty much only water molecules to pass through. The PFAS are trapped on the other side of the membrane and flushed out with waste water.

Aside from the semipermeable RO membrane, carbon pre and post-filters found in all residential reverse osmosis filtration systems are also highly effective at adsorbing PFAS.

How Many “Forever Chemicals” Does RO Remove?

The percentage of forever chemicals or PFAS that reverse osmosis removes is typically in the range of 90-99%, depending on the type of reverse osmosis system used.

For example, a standard residential reverse osmosis system may only remove about 95% of PFAS, but an industrial grade unit could be as effective as 99%.

Do All Reverse Osmosis Systems Remove PFAS?

It’s important to note that the reverse osmosis treatment process merely refers to the process by which specialized RO membranes remove PFAS and other contaminants from water.

Filtration and purification via a full reverse osmosis treatment system, however, typically involves additional steps. This is because any reverse osmosis system for home use also features pre-treatment and post-treatment stages.

Pre-treatment can involve the removal of contaminants and substances that could potentially damage a system’s membrane. Post-treatment involves addressing residual taste issues and sometimes even the low pH and lack of mineral content in water after it’s gone through the reverse osmosis process.

That said, all reverse osmosis systems remove PFAS to some degree. The extent to which they do so can vary from one model to another.

Again, a typical home reverse osmosis system will usually remove at least 90% of PFAS (including PFOA and PFOS), while a system for industrial use may have a reduction rate of 99%.

What Else Does a Reverse Osmosis Water Filter Remove?

PFAS aren’t the only types of contaminants a reverse osmosis water filter can remove:

  • Bacteria and other microbes
  • Viruses
  • Heavy metals (including lead, arsenic, mercury, etc.)
  • Water disinfectants (such as chlorine and chloramine, and their byproducts)
  • Fluoride
  • Pesticides and herbicides
  • Salts and minerals
  • Volatile organic compounds (VOCs)
  • Sediments
  • Chemicals/pharmaceuticals

What Are PFAS, PFOA, and PFOS Exactly?

PFAS, PFOA, and PFOS are all synthetic chemical compounds known as “forever chemicals” because they don’t easily break down in the environment.

They are commonly used in industrial and consumer products, such as non-stick cookware, food packaging, and firefighting foams.

As a result, these compounds have made their way into our water bodies: Lakes, rivers, creeks, and oceans.

The Health Effects of PFAS

PFAS are considered a health hazard due to the potential long-term effects they can have on humans. Studies suggest that PFAS exposure can contribute to cancer, hormone disruption, liver and kidney damage, increased cholesterol levels, thyroid issues, and even weakened immune systems.

It’s therefore important to take steps to protect yourself from PFAS exposure, and having a reverse osmosis filtration system installed in your home is one way to do that.

While this may not completely eliminate PFAS from your drinking water, it will significantly reduce the amount of exposure you and your family receive on a daily basis. This will reduce your chances of experiencing health problems.

How PFAS End Up in Our Water Supply

PFAS can enter our water supply when they’re released into the environment from manufacturing processes or landfills.

When they enter our water supply, they don’t bind to soil particles or break down like other contaminants, meaning they can remain in the environment for a long time, ultimately making their way into our drinking water.

How to Test Your Water for PFAS

The only way to know for sure if your water contains PFAS is to have it tested by a certified lab. It’s recommended that you test your water once per year, or more often if you live in an area known to be affected by PFAS contamination.

If you are on tap water, you can also check your latest Consumer Confidence Report. It should list PFAS, PFOS, and PFOA levels found in recent years.

What Is Reverse Osmosis?

Reverse osmosis is a water purification process that works by pushing water through a semipermeable membrane. This membrane filters out impurities, allowing only purified water to pass through.

It’s an effective way to remove PFAS and other contaminants from water sources in both residential and commercial settings.

Under Sink Reverse Osmosis System

Things to Consider When Buying a Reverse Osmosis System

Water Demand

Ensure a reverse osmosis system’s storage tank or flow rate can meet your water demand.


Some systems are easier to install than others. Although you should always hire a professional to install a system if you’re not confident in your own ability to do so, depending on which type of system you buy, it may be necessary to make certain changes to your kitchen countertop or sink.

Water Pressure

If your home’s feed water pressure isn’t optimal, a reverse osmosis system can waste more water than is necessary. Luckily, electric pressure pumps can reduce wastage.


You always need to account for your budget when making this type of purchase. Just be aware that purchasing a low-quality system to save money in the short term can actually be a poor financial decision in the long term if the unit fails to deliver results or breaks down earlier than expected.

You also want to check the costs for replacement filters.

Cons of Removing PFAS Using Reverse Osmosis

Although reverse osmosis can remove PFAS reliably, it’s important to understand the potential drawbacks of these systems:


Reverse osmosis systems produce wastewater as a by-product. This water contains the contaminants that were removed from your drinking water.

Depending on parameters like feed water pressure, a standard RO system wastes between 3 and 5 gallons for every gallon of purified water. A system using a pressure pump may waste as little as 20% of the water.

Minerals Loss

Reverse osmosis is effective at removing contaminants from water, but it also strips the water of beneficial minerals like calcium and magnesium. However, the right post-treatment element of a system can address this.

Alternative Treatment Technologies

Activated Carbon

Activated carbon filters are another method effective at reducing PFAS from drinking water.

The highly porous filter media adsorbs up to 100% of PFAS, depending on the type of PFAS in question, the type of carbon used, contact time between water and filter media, temperature, and the type and amount of other contaminants in the water.

Ion Exchange

Ion exchange is a water treatment method that works by replacing harmful ions with harmless ones. It’s an effective way to reduce or eliminate PFAS from drinking water, but it can be expensive and requires periodic maintenance.


Nanofiltration is a water filtration process that uses membranes with tiny pores to filter out contaminants. It’s effective at reducing PFAS and other contaminants from drinking water, but it can be expensive and time-consuming.

If you have any thoughts about the question, does reverse osmosis remove PFAS from water, please don’t hesitate to leave a comment below!

About the Author Gene Fitzgerald

Gene Fitzgerald is one of the founders of BOS and currently head of content creation. She has 8+ years of experience as a water treatment specialist under her belt making her our senior scientist. Outside of BOS, Gene loves reading books on philosophy & social issues, making music, and hiking.
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