How Water Filters Remove GenX – A Short Chain PFAS


Reverse Osmosis and water filters that use anion exchange resins can effectively remove >99% of GenX from water. Activated carbon filters can only remove ~30% of GenX. Most (but not all) water filter pitchers and bottle filters are ineffective at removing Genx.

GenX is a man-made chemical that is used in manufacturing many everyday objects, including non-stick cookware, food packaging, cleaning supplies, and components of cell phones and electronics. GenX was first introduced in 2009 as a healthier alternative to PFAS compounds that are linked to cancer.

This article will trace the roots of GenX, including how we are exposed to it and what we currently know it does to the human body. We’ll also explain the different methods you can use to remove GenX from your water.

  • Ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoate (known under the trade name GenX) is a short chain PFAS linked with liver damage in rats and humans.
  • Reverse osmosis systems and anion exchange resins can remove >99% of GenX from water.
  • GenX is used to make food wrappers, outdoor clothing and electronics.
  • Boiling water will not remove GenX as it is a solid until 406°F and dissolves in water.

The Story of GenX

GenX is the name of a synthetic chemical compound that is a member of per- and polyfluoroalkyl substances, which are more commonly known as “PFAS“.

PFAS has become notoriously famous, thanks to its contamination at air fields and military bases across the country (and around the world) from its use in fire-fighting foam.

GenX is just one of more than 9,000 PFAS chemicals, and was created to replace “forever chemicals”, such as PFOA (perfluorooctanoic acid).

It was originally thought that GenX would be able to safely replace PFOA, and not cause the same environmental and health problems.

The structure of PFOA and GenX is quite similar, but instead of carbon, there is an ether oxygen group in the GenX chemicals. This small switch was supposed to make GenX less stable and less likely to stick around in the environment.

It’s also a smaller chain compound, with just 6 carbons (PFOA has 8) – this was also supposed to make it more unstable, and lower its persistence in the environment, and our bodies (if we became exposed).

Chemical structure of GenX (ammonia 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoate), also known as HFPO.
Chemical structure of GenX. Image created for Waterpurificationguide.com.

Unfortunately, GenX has now been found in our drinking water, and the Environmental Health Perspective has shown us that it is as bad as PFOA.

(GenX is) a “regrettable substitute,” whose effects may be as bad as or even worse than the chemical it replaced.

A Regrettable Substitute: The Story of GenX

How GenX Enters Our Water Supply

GenX contamination in the United States was first recorded in North Carolina in 2016.

Location of GenX environmental contamination in North Carolina.
Location of GenX environmental contamination in North Carolina on the Cape Fear River. Image created for waterpurificationguide.com.

It was detected in the Cape Fear River. The Cape Fear River supplies water to around 250,000 people. The Fayetteville plant, 80 miles upstream from Wilmington, is where DuPont and Chemours manufacture GenX.

It’s important to note that GenX is a trade name used by Chemours to describe the chemical compound used to make high-performance fluoropolymers without the use of PFOA.

Company officials revealed that PFAS chemicals had been released into the river for nearly four decades.

In fact, research into the water of the Cape Fear River found 17 different PFAS compounds, including GenX.

A study by North Carolina University confirmed an elevated presence of GenX in Wilmington’s tap water.

The strong carbon-fluorine bond makes most standard water treatment methods ineffective, and GenX (and other PFAS) were detected in the tap water even after treatment at the local facility.

When production of GenX started, the company didn’t know if this material would become toxic to the environment. And because of the lack of awareness, no one focused on a safe disposal system and waste was allowed to be discharged into the river.

The NC Department of Environmental Quality has since directed Chemours to sample and test the water in four counties (Bladen, Cumberland, Robeson and Sampson) for possible GenX contamination, and the company is no longer allowed to discharge into the river.

Unfortunately, PFAS (and related by-products) have been found in the blood and urine of people living in Wilmington. While the people of Wilmington have higher levels of PFAS compared to the U.S. population, we can still be exposed to these forever chemicals in our every day lives.

Contamination of our drinking water can happen from the many products made with GenX chemicals. Non-stick cookware, outdoor clothing and even food wrappers from fast food chains contain GenX.

Sources of GenX contamination, including hydraulic fluids, electronics, outdoor clothing, personal care items, food packaging, fuel lines in cars, non-stick cookware, paint, fire fighting foam, pesticides and cell phones.
Products that contain GenX and act as a contamination source. Image created for waterpurificationguide.com.

Although, larger scale contamination is usually through waste, spills, and disposals.

GenX can be transferred from trash in the ground to the river by rainwater, and can continue to spread in our rivers and lakes, and enter our groundwater.

Once in our water it dissolves easily and remains in the environment

GenX is persistent in the environment and has been shown to cause adverse effects in animal models

Roberts et al., 2022

Once GenX is in our river water it spreads through our environment quickly, just like other PFAS chemicals.

PFAS contamination sites across the United States. PFAS contamination of military sites is country-wide. Detection of PFAS in hydrological units is concentrated in the east and south west, with limited detection in central U.S.
PFAS contamination sites and locations of PFAS detection in water supplies, across the United States. Data sourced from Harvard University, Northeastern University, the U.S. Environmental Protection Agency (EPA), the Department of Defense (DoD) and the Environmental Working Group (EWG). Map created for waterpurificationguide.com.

Known Health Effects of GenX

What GenX does to the human body is still largely unknown. Most research takes many years to conduct, especially when we want to learn the longterm effects of GenX.

GenX is thought to be less bioaccumulative than longer chain PFAS. This means it should be less likely to become concentrated in the bodies of animals (including humans).

However, GenX is still mobile and persistent in the environment enough to enter humans, usually through consumption of contaminated water. Researchers have finally begun to discover that it may be as harmful as the PFAS it replaced, if not worse.

Even though GenX was only discovered in the environment in 2016, as early as 2015 we had evidence of just how damaging it can be to the health of mammals.

A toxicity study linked GenX to benign tumors of the liver, pancreas and testes in rats.

Changes in the kidney, tongue, and stomach were also observed when they were exposed to high amounts of GenX.

Caverly Rae et al., 2015. Toxicology Reports

Interestingly, males were more likely to experience negative effects after being exposed to GenX, compared to females – even at lower doses. This is currently thought to be the result of menstruation allowing women to rid their bodies of some of this toxic chemical.

We know that GenX is quickly and completely absorbed by the body and is not metabolized, this means that our organs, such as the liver or kidneys, can not process it and remove it naturally.

Another study published in the Environmental Health Perspective discovered that ingesting (swallowing) GenX increased liver weights, lowered thyroid hormones and even negatively impacted the reproductivity tissues of rats.

In 2020, a study published in a special edition of Science, Environment and Technology demonstrated that exposure to GenX caused the livers of rats to become enlarged and triggered bile acid metabolism disorder – a type of liver disease.

All of these assessments help us understand how harmful GenX can be to the human body, even though these tests were conducted on other mammals.

It is clear that GenX can harm the body, and the liver especially.

Finally, in July of 2022 the first study was published into the effects of GenX on humans. The research looked at the effects of GenX on human hepatocyte cells, which are cells in the liver.

Their results showed that even at low doses GenX can interfere with metabolic pathways. The results were even worse at higher doses, with exposure to GenX causing fibroinflammatory changes in the human liver cells.

Fibroinflammation can lead to lesions, growths or even cancers.

Even though research into the health effects of GenX is only beginning, we can already see the damage it can cause.

Removing GenX From Water

GenX is difficult to detect and can remain in water for a long time. The genetic structure of this chemical makes it ridiculously resistant to most water treatment processes.

It’s important to understand that while GenX is a type of PFAS, water filters that claim to remove PFAS are only effective at removing some types – not all types. Every single one of the more than 9,000 PFAS has a different chemical structure, which makes them respond differently to the various water purification methods.

In fact, because GenX is a short chain PFAS it is even harder to remove than longer chain compounds.

For example, granular activated carbon is particularly effective at removing the long chain PFAS compounds Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS), but is mostly ineffective against GenX.

Research into both powdered and granular activated carbon (PAC and GAC) demonstrated it can only remove ~30% of GenX in water.

Fortunately, recent research found that anion exchange resins can remove 99% of GenX and other perfluorinated ether acids from recycled and drinking waters. Making anion-exchange resins far more successful in eliminating GenX than activated carbon.

Reverse osmosis systems can also effectively remove both long and short chain PFAS. We have known for quite some time that reverse osmosis could remove other PFAS, but studies have now shown that it is equally effective at removing GenX (>99%).

  • In a reverse osmosis process, dissolved and particulate contaminants are removed by the semi-permeable membrane.

Through this intense water filtration process, we would like to expect that 100% of the GenX would be removed, and it’s close, with reverse osmosis able to remove >99% of all PFAS (long and short chain) from water.

We have only just begun to analyse and treat water with GenX contamination, and the EPA and researchers are still determining the best way to remove it from water, but for now we know the following:

  • Anion exchange resins remove >99% of GenX
  • Reverse osmosis systems remove >99% of GenX
  • Activated carbon can remove ~30% of GenX

Types Of Water Filters That Can Remove GenX

Let’s examine some of the most typical water filtration systems and see which ones can remove GenX from water. 

Water Filter Pitchers

Water filter pitchers are a very convenient way of filtering water because of their size, shape, and filtering system. Many filter pitchers are available, but very few can remove PFAS.

This type of filtration process might not look very effective, but some brands use advanced technology that can remove a large number of contaminants.

Water filter pitchers that use anion exchange resins (or a combination of anion exchange resins and activated carbon) should theoretically be able to remove GenX from water.

Of all the water filter pitchers available, we could find only one (the Clearly Filtered water filter pitcher) that has been tested against GenX.

Clearly Filtered Water Filter Pitcher

The Clearly Filtered water pitcher with Affinity Filtration Technology removes a range of PFAS from water using granular activated carbon and proprietary technology that recognizes the ionic structure of contaminants.

The Clearly Filtered water filter pitcher has been tested to remove >99.4% of GenX from water.

This is the only filter pitcher that we recommend for removing GenX from water. In fact, it is the only water filtration system of any kind that we could find that has been tested against GenX.

This filter pitcher has been tested to remove 9 different PFAS contaminants (not just PFOA and PFOS like most other pitchers). These include:

  • EPFB: >95.0 % removal
  • GenX: >99.4 % removal
  • NFBS: >95.0 % removal
  • PFBS: >95.0 % removal
  • PFBA: >95.0 % removal
  • PFNA: >95.0 % removal
  • PFOS: >99.5 % removal
  • PFOA: >99.0 % removal
  • PFHA: >95.0 % removal

It also removes up to 99.9% of more than 365 tap water pollutants, including heavy metals, pesticides and microplastics.

This pitcher by Clearly Filtered has been independently tested to meet NSF 42, 53, 244, 401, and 473 criteria.

Pros:

  • Removes a range of PFAS.
  • BPA and BPS-free.
  • Lifetime guarantee warranty.

Cons:

  • No filter change indicator.

Note: There are also cation exchange resins available for water filtration, but these are ineffective against GenX.

Water Purification Guide has a complete breakdown of all the water filter pitchers that can remove other PFAS, including PFOA and PFOS, available here.

Water Filter Bottles

Water bottle filters are a great travel partner when you are unsure of the safety of the water sources. But the question is, do they remove GenX? Currently the answer is “no.”

The Epic Nalgene OG by Epic Water Filters has been tested to remove PFOA (>98%) and PFOS (>99%), but at this stage it has not been tested for GenX. Because the chemical structure of these PFAS are so different it is not clear whether this filter bottle could remove GenX, but it is certainly effective against these long chain PFAS.

These portable water filters have easy-to-install filters that you can install and remove easily. Most bottle filters recommend using tap water only for safety issues. And discourages filtering water from completely unknown resources.

Reverse Osmosis

Reverse osmosis is one of the best ways to filter water and remove GenX.

A point-of-use reverse osmosis system is generally preferable to a whole house system, as water treated by reverse osmosis can become corrosive and leach metals from the internal pipes of the home. A point-of-use system bypasses this issue.

After the system is set up, you can drink from it without second thoughts.

While reverse osmosis systems should in theory be able to remove GenX we could not find a system that had been tested for it. As such, we are not comfortable recommending one.

However, Water Purification Guide has detailed information on which reverse osmosis systems have been tested to remove other PFAS (including PFOA and PFOS), and may be effective against GenX, available here

Under Sink Filters

Under sink water filters are like any other filters. As you probably guessed from the name, they are installed under the sink to supply fresh water as a point-of-use system.

This type of water filter supplies water directly from the sink, and there is no need to collect water from a pitcher. You can directly consume water from the tap. As far as the effectiveness of this filtration system is concerned, it will depend on the filtration process that the manufacturers are using.

Some under-sink water filters do use ion exchange process to filter the water and should show effectiveness in removing GenX.

However, we were unable to find an under sink filter that has been tested to remove GenX.

It’s important to remember that GenX is considered an emerging contaminant – one we are only just learning about. So, while very few filters have been tested to remove it there are quite a few under sink filters have been tested against other PFAS, and these should in theory be able to remove at least some of the GenX in water.

Water Purification Guide has a detailed list of all the under sink filters that can remove some PFAS available here.

Distillation

Distillation purifies water by eliminating any traces of contaminants. This is one of the oldest processes of water filtration. In this process, you need to heat the liquid to create vapor and then cool the vapor down to get the filtered liquid.

Distillation makes the water free from bacteria, viruses, and other solid contaminants as well. However, it is unknown if distillation removes GenX from water or not.

GenX is particularly persistent in water, it dissolves easily in water, but also has a very high boiling point. At face value, it seems unlikely that distillation would remove GenX from water.

However, we will have to wait for more research to be conducted to determine any potential this method of water purification might have.

Shower Filters

Shower filters are extremely useful when you want to reduce the hardness of water, or perhaps the amount of chlorine or fluoride. But there is no proven evidence that shower filters remove GenX, or any other PFAS.

The longer water can spend being filtered the more effective it can be at removing contaminants. Unfortunately, shower filters are designed to have high flow rates so that your shower is not disturbed by slow or low water flows.

Since shower filters are not effective at removing GenX, if you know you live in a contaminated area avoid consuming any of the water when showering.

Related Questions

What products contain GenX?

GenX, or ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoate, is used in non-stick coating, food packaging and wrappers, cleaning products, waterproof outdoor fabrics, paints, electronics, cell phones and other daily household products.

GenX, like many other high-performance fluoropolymers are used to make oil-resistant products.

Does Brita remove GenX?

Brita doesn’t claim or design its filters to remove GenX. Currently, Brita filters are not suitable for use with PFAS contaminated water.

Brita filters (e.g., LongLast) are suitable for removing other aesthetic contaminants, such as chlorine, and some heavy metals (e.g., lead).

Does Berkey filter out GenX?

Berkey filters can remove 99.9% of impurities from water, including bacteria, viruses, and other organic contaminants. They can also remove PFOA from the water, but they haven’t claimed that their filters can remove GenX.

So, to know the answer, we have to wait till the lab tests are run, and the results are published.

Does boiling water get rid of GenX?

Boiling water cannot remove GenX from the water. The boiling point of GenX is above that of water, and will not be evaporated. The U.S. Environmental Protection Agency (EPA) suggests using an advanced water treatment process to remove GenX from water rather than boiling it.

In fact, GenX is a solid until 406°F and readily dissolves in water (unless acidic with a pH <2.84). GenX also releases its ammonium once it enters water and becomes an acid.

Reverse osmosis and anion exchange resins are currently the only proven method of effectively removing GenX from water.

Resources and Further Reading

Environmental Science and Technology: Legacy and Emerging Perfluoroalkyl Substances Are Important Drinking Water Contaminants in the Cape Fear River Watershed of North Carolina.

Chemical & Engineering News: The hunt is on for GenX chemicals in people.

National Institute of Environmental Health Sciences: Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)

NC Health News: GenX Pollution – What Happened? And When?

NC Policy Watch: EPA: GenX far more toxic that originally thought, could prompt NC to significantly reduce health advisory goal.

NC University: GenX Exposure study.

U.S. EPA: Fact Sheet: Human Health Toxicity Assessment for GenX Chemicals

WECT News: Would GenX study author drink our water?

Theresa Orr

Theresa Orr is an Earth Scientist who specializes in determining past climates from rocks using geochemistry. Her passion for clean water drives her to breakdown the science to provide easy to understand information that everyone can read.

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