Does Reverse Osmosis Remove PFAS?

Yes, reverse osmosis can effectively remove PFAS from water. Reverse osmosis is a filtering process where dissolved materials are taken out of the water by passing it through a membrane that is permeable only to certain molecules. This means that while some particles, such as minerals and salts, can pass through the membrane, others, such as nitrates and PFAS, are blocked and retained. Reverse osmosis systems typically remove up to 99% of contaminants from water, making it an effective means for removing PFAS and other pollutants.

What Are PFAS, And Why Are They Dangerous?

What Are PFAS, And Why Are They Dangerous
PFAS Sources

PFAS (per- and polyfluoroalkyl substances) are synthetic chemicals created in the 1940s and widely used since then in products such as food packaging, waterproofing materials, stain repellants, firefighting foams, and other products. PFAS are very difficult to break down once they enter the environment, which means they can stay there for a very long time.

These chemicals have been linked to health problems in animals and humans, including cancer, thyroid disease, weakened immune systems, fertility issues, and hormone disruption. Because of their environmental persistence, PFAS can contaminate drinking water sources such as rivers, lakes, and groundwater.

Does Reverse Osmosis Remove PFAS?

Does Reverse Osmosis Remove PFAS
Reverse Osmosis Remove PFAS

Yes, Reverse osmosis (RO) filtration systems are effective at removing PFAS from water supplies because the contaminants are removed via a physical process that involves forcing water through a semi-permeable membrane. This membrane traps pollutants, including PFAS, within its structure, and as a result, clean drinking water exits the other side.

How Does Reverse Osmosis Filter Out PFAS?

How Does Reverse Osmosis Filter Out PFAS
Semi-permeable membrane Filter PFAS

Reverse osmosis systems work by using a semi-permeable membrane to filter out contaminants. This is the same technology used in home and commercial water filtration systems, although these are typically more effective than standard activated carbon filters. In reverse osmosis, water is forced through the membrane while PFAS molecules remain behind.

Additionally, reverse osmosis systems can be combined with other filtration methods further to reduce the amount of PFAS in the water supply. For example, adding an activated carbon filter after an RO system can help capture any remaining contaminants that were not removed by the membrane.

How Much Will PFAS Reverse Osmosis Remove?

How Much Will PFAS Reverse Osmosis Remove
PFAS Reverse Osmosis Remove

It depends on the type of reverse osmosis system you have installed. Generally, reverse osmosis systems effectively remove most PFAS (per and polyfluoroalkyl substances) from drinking water. However, not all types of PFAS are removed by reverse osmosis systems.

Generally, reverse osmosis systems can remove up to 99 percent of PFAS from drinking water. Still, it depends on the type of reverse osmosis system and the size of each PFAS molecule. The larger molecules are more difficult for some reverse osmosis systems to filter out, so there may be variations in what each system can remove. Additionally, the type of pre-filtration used before the reverse osmosis system can also affect the effectiveness of removing PFAS from drinking water.

How Do You Know Your Water Has PFAS?

How Do You Know Your Water Has PFAS
Water Has PFAS

If you are concerned about PFAS in your water, there are several ways to test for them. The most accurate method is to have a laboratory test your water sample. This testing can be done by a certified lab or through a home-testing kit. Home-testing kits typically include strips that react with the presence of PFAS and indicate the level of contamination.

What Level Of PFAS Is Safe In Drinking Water?

What Level Of PFAS Is Safe In Drinking Water
PFAS Is Safe In Drinking Water

The U.S. Environmental Protection Agency (EPA) has established a Lifetime Health Advisory (LHA) of 70 parts per trillion (ppt) for PFAS in drinking water. This means that levels exceeding this threshold may harm human health over the long term. However, it is important to note that this level only serves as a guideline, and individual states may have different PFAS drinking water standards.

The Health Effects of PFAS

  • Increased cholesterol levels:  PFAS have been linked to increased cholesterol levels, which can lead to a higher risk of heart disease and stroke.
  • Changes in hormone levels: Studies suggest that PFAS may interfere with the body’s natural hormones, leading to health problems such as infertility, cancer, and thyroid disruption.
  • Suppressed immune system: PFAS exposure has been linked to a suppressed immune system, leading to an increased risk of infection and illness.
  • Thyroid hormone disruption: Studies have shown that PFAS can disrupt the thyroid hormones in humans, leading to various health issues.
  • Liver and kidney damage: PFAS chemicals have been linked to liver and kidney damage. In some cases, high concentrations of PFAS may cause an increased risk for cancer, reproductive and developmental issues, and anemia.

Different Types Of RO Systems To Remove PFAS

  • Point-of-use reverse osmosis systems: Point-of-use reverse osmosis systems are typically used for drinking water and other household uses. These systems are designed to remove contaminants from small volumes of water. Point-of-use systems have filters specifically designed to remove PFAS from the water, making them an effective solution for removing PFAS in your home.
  • Whole-house reverse osmosis systems: Whole-house reverse osmosis systems are designed to treat all the water entering a home, providing PFAS-free water for drinking and household use. These systems can be more expensive than point-of-use systems, but they provide a higher level of protection from PFAS contamination.

Disadvantages Of Removing PFAS Using Reverse Osmosis

  • Wastewater: Reverse osmosis technology produces a large amount of wastewater by removing dissolved solids from water. As PFAS are not completely removed, the wastewater can contain high levels of these compounds, which must be disposed of safely or treated to reduce their concentration.
  • Cost: The cost associated with purchasing and installing reverse osmosis systems can be significant, as these systems require periodic maintenance and replacement of filters. The cost of disposing of wastewater generated by reverse osmosis must also be considered.
  • Limitations: Reverse osmosis cannot remove some types of PFAS, such as short-chain compounds that can pass through membranes. Furthermore, the technology has a limited capacity for removing PFAS from water in large quantities.

Alternative Treatment Technologies

  • Activated Carbon: Activated Carbon is a popular technology for treating PFAS. However, it has not been proven effective in removing shorter-chain compounds.
    Activated Carbon
    Activated Carbon
  • Ion Exchange: Ion Exchange is a water treatment that removes charged particles from water. It can be used for the removal of PFAS. Still, it was found to be ineffective in removing short-chain compounds such as those found in perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA).
    Ion Exchange
    Ion Exchange
  • Nanofiltration:  Nanofiltration is a process that uses small particles to remove contaminants from water. It effectively removes PFAS, including shorter-chain compounds such as PFOS and PFOA.


Do All Reverse Osmosis Systems Remove PFAS?

Yes, reverse osmosis systems are highly effective at removing PFAS from water. Most reverse osmosis systems can reduce the amount of PFAS in your drinking water by up to 99%.

How do I know if the filter I’m purchasing works on PFAS?

When purchasing a filter for your drinking water, it is important to consider what contaminants the filter can remove. Reverse osmosis filtration systems are effective in removing PFAS from water. To ensure that your reverse osmosis system will effectively reduce PFAS levels, check the product specifications and certifications of the filter you buy.

Does Bottled Water Contain PFAS?

Does Bottled Water Contain PFAS
Bottled Water Contain PFAS

PFAS has been found in some bottled water products. Not all bottles water and not all brands contain PFAS, but based on testing by the Environmental Working Group (EWG) and other organizations, it has been found in some products.

Does my Brita filter treat PFAS?

No, Brita filters do not treat PFAS. While some Brita models may reduce chlorine and other contaminants from the water, they are not designed to remove PFAS.

Can bacteria grow in reverse osmosis water?

Yes, Reverse osmosis (RO) water is purified through filtration. However, it does not remove all bacteria and contaminants from the water. In some cases, bacteria can grow in RO systems due to inadequate maintenance and filter changes, incorrect storage, or contamination of the storage tank. Regular maintenance of your system and changing filters when needed are necessary to prevent bacterial growth in RO water.


Reverse osmosis is an effective method for removing PFAS from water. Because of its ability to remove particles as small as 0.001 microns, reverse osmosis can effectively filter out PFAS before they enter the water supply. Reverse osmosis is also an efficient process that can be used over a large area, making it well-suited for treating contaminated water sources. While reverse osmosis does not completely remove PFAS from water, it can reduce their concentration to safe levels. It is important to remember that to eliminate PFAS from the water supply, more comprehensive methods may be necessary. Combining reverse osmosis with other treatment systems is also recommended for the best results.

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