Eliminating PFAS from Drinking Water: Top Treatment Technologies


Eliminating PFAS from Drinking Water Top Treatment Technologies

PFAS are a group of man-made chemicals that have been used extensively in consumer products for decades due to their ability to provide water, oil, and stain resistance. PFAS compounds are also linked with serious health effects including cancer, liver damage, thyroid problems, and high cholesterol. The U.S EPA has set the safety limit for two types of PFAS at 70 parts per trillion (ppt) total combined concentration in drinking water or 10 ppt each type individually.

This article will take you through the different treatment technologies that can be used to remove PFAS from your drinking water supply as well as how effective they are against removing these contaminants.

What is PFAS

Per- and polyfluoroalkyl substances – commonly referred to as PFAS – are a family of man made chemicals that contain carbon, fluorine and other elements. These compounds have been used since the 1940s in products such as fire fighting foam, nonstick cookware, food packaging, and stain repellants. 

Although these compounds have been used in the United States since World War II, they were only discovered to be harmful about two decades ago. One concen is that PFAS are persistent compounds – meaning they accumulate over time in our bodies and don’t break down in the environement.

Health risks of PFAS

The risks associated with many PFAS chemicals are largely unknown. However there is evidence that exposure to low levels of PFOA and PFOS can lead to health impacts in humans. Research has shown potential negative outcomes such as:

  • decreased fertility
  • elevated cholesterol levels
  • altering thyroid hormones
  • liver inflammation
  • cancer

What PFAS concentrations are safe to drink

The EPA has established a non-enforceable health advisory level of 70 parts per trillion (ppt). This level is based on the total concentration of PFOA and PFOS.

Some states have decided to set lower levels, while others have implemented enforceable MCLs.

The large discrepancy between federal and state regulation of PFAS substances has created confusion for those who are trying to source clean drinking water. For example, California has the lowest concentration allowed – 5 ppt (PFOA only). Michigan has the highest allowable level – 140,000 ppt.

With such a wide range of drinking water standards, it is difficult to know what concentrtion of PFAS is safe to drink. Experts suggest avoiding water with any concentration of PFAS. This is the safest way to approach this issue.

How do you test drinking water for PFAS

Laboratories will analyze drinking water for PFAS using either USEPA Method 537, 538. These methods test for multiple compounds and parts that can be found in your tap or city’s source of production.

Sampling drinking water for PFAS
Sampling for PFAS requires specialized equipment and expertise.

Sampling for PFAS in drinking water is challenging because these compounds are found in many household items. This can result in unintentional contamination of the water sample. For example, some fabric softeners contain PFAS, and the clothes you wear will likely have PFAS on them. These fluorinated compounds can be transfererred from the fabric to the water as you collect the sample. This would result in a false positive – meaning the laboratory report shows the presence of PFAS when it might not be in your drinking water.

For this reason, it is best to have a specialty engineering firm or water testing company sample your drinking water for PFAS.

PFAS test kits

With the SimpleLab at-home kit, you can now test for 14 different PFAS compounds in your drinking water. It is easy to use and includes everything that’s needed – they provide comprehensive report along with suggestions on addressing any concerns based off of tested results.

Read my review of the Tap Score test kit here.

When you order the kit, they mail you everything you need. Follow the instructions to collect a sample of your water and mail it back to them. Within a week or two, they provide you with a complete report of what’s in your drinking water.

Tap Score PFAS Test Kit

Test your water

Removing PFAS from Drinking Water

The US Environmental Protection Agency (EPA) is the federal agency responsible for protecting Americans from environmental toxins and hazardous chemicals. They identified several treatment technologies that can remove PFAS from drinking water.

The following treatment processes are effective at removing PFAS from drinking water.

  1. Activated carbon treatment
  2. Ion exchange resins
  3. Reverse osmosis
  4. Nanofiltration

Each of these treatment technologies has its benefits and drawbacks that make it more or less effective at treating PFAS in drinking water. The following sections summarize the effectiveness for each of these PFAS treatment methods in greater detail

 

1. Activated Carbon Filtration to Treat PFAS Drinking Water

Activated carbon has been used for centuries to remove impurities from drinking water. It is a well-known process that is very effective for treating contaminated water. It has been documented as a very effective treatment for PFAS.

Check out our article on how to design a Granular Activated Carbon treatment system.

Activated carbon, also known as charcoal, is made by exposing wood or coal to very high temperatures without allowing it to burn. This process converts the raw material to pure carbon which is then “activated” by exposing it to high-temperature steam. The activation process creates thousands of cracks and fissures in the carbon known as pores. These pores allow activated carbon to bind with contaminants in water, including PFAS compounds.

The OptimH2O Whole House Filter Complete System has both catalytic and activated carbon to remove PFAS compounds from drinking water.

Carbon is available in various sizes and configurations. These include:

  1. Granular Activated Carbon (GAC): GAC particles come in various sizes. The most commonly used GAC is about the size of kitty litter. GAC works well in filters like those used in home treatment systems. GAC allows water to easily flow through a media bed while effectively removing contaminants.
  2. Powdered Activated Carbon (PAC): Powdered carbon is created by grinding carbon down to the size of flour or talcum powder. This type of activated carbon is used in large public water treatment plants. The small particle size creates too much pressure to be used in an inline filter.
  3. Carbon Pellets: Carbon pellets are formed by extruding powdered activated carbon with a binder. This process produces small cylinders of carbon that look like pet food. Pellets are often used in large carbon filters and special applications.

A carbon filter consists of a pressure vessel, known as a tank, that is filled with activated carbon. Most filters that are used in residential applications are filled with GAC. GAC works very well because it doesn’t foul if the water has suspended particles in it. It can also be removed and replaced very easily.

Read my article Do Carbon Filters Remove PFAS and GenX Chemicals?

2. Ion Exchange Treatment for PFAS

With a long history of use in water filtration, ion exchange resins have been successfully configured as an effective way to remove contaminants such as nitrate and perchlorate. This process has been used to effectively treat PFAS contaminated drinking water.

Ion exchange is a type of filtration that works by exchanging ions with water to form anions (negatively charged) or cations(positively charged). There are two different options when using ion exchange: single-use vs regenerable resins. They both have their benefits depending on the contaminants, the presence of hardness in the water, and the flow rate.

Single-use PFAS-selective ion exchange resins are ideal for treating low-concentration PFAS, such as those found in potable water treatment systems where media change-out is rare. This is what is used in most home treatment systems. Systems that use regenerable resins are more complicated and expensive. As a result, these are mostly used for large public water treatment plants.

Removal of perfluoroalkyl substances by ion exchange is a physical process that involves moving from the aqueous phase onto solid media. It does not involve any form of chemical degradation or transformation.

The sulfonic acid groups on our resins can readily remove PFOA and PFOS compounds due to their positive charges at typical ranges found in natural water pH levels. This allows them to form ionic bonds with negatively charged residues present such as those seen for example between examples like hydrogen fluoride.

3. Reverse osmosis treatment for PFAS

Reverse Osmosis, called RO for short, is a technology used to purify water by pushing it through semipermeable membranes. This process can remove most contaminants found in drinking water, including PFAS molecules.

Read our comprehensive article on using reverse osmosis to treat PFAS.

The main type of membrane setup consists of a plastic membrane sheet wrapped around an inner tube. The membrane is manufactured with tiny holes in it that allow water molecules to pass through but not the PFAS. The contaminated water is pumped through the membrane at high pressures – clean water exits the module and concentrated impurities are retained.

The remaining concentrated solution of PFAS and water is known as brine. Brine is a waste that contains PFAS and must be stored and then disposed of.

Membrane technology is a great way to remove harmful contaminants from the water we drink, but the membranes often become fouled. Membranes will accumulate colloidal and organic matter over time if they’re not cleaned regularly which leads directly into increased rates of fouling.

This fouling can reduce the amount of water that can be purified and increases the amount of energy required to treat water. If not addressed, the quality of water produced will decline over time which can result in dangerous levels of PFAS in the water.

However adequate pretreatment can slow down the fouling process. This includes salt deposition rates (SDR), microrganism growths inside the membrane, and scaling. All of these processes reduce the treatment efficacy.

4. Nanofiltration PFAS treatment

Nanofiltration is very similar to reverse osmosis. A nanofiltration filter has a pore size of 0.001 micron or less. It is very effective at removing PFAS from drinking water.

Nanofiltration is an excellent way to remove most organic molecules, nearly all viruses, and natural matter. It also removes divalent ions which makes water hard so it can be used in places with really high levels of calcium or magnesium.

Nanofiltration is filtration process that uses pressure to drive water through a membrane that can reject molecular or ionic species. It lies between ultrafiltration and reverse osmosis in terms of the molecule size it can filter.

Nanofiltration is not currently used in residential treatment processes because of the cost and pre-treatment requirements. Depending on the water quality and treatment requirements, it is used in commercial and industrial water treatment applications.

Do Home Water Filters Remove PFAS

Many homeowners have water treatment filters that are designed to remove bad tastes, chlorine, lead, and other toxic chemicals. With the recent focus on the widespread presence of PFAS in drinking water, experts have begun to look at these filter to see if they can be used to treat PFAS contamination. Some are effective at treating PFAS, but many don’t remove all of the contaminants, and some actually make the problem worse.

Home water filters are designed to remove things that can have a negative impact on your health. We expect these protective devises to keep us safe, especially when it comes to contaminants like PFAS.

There are some home treatment systems available which use nanofiltration, reverse osmosis, and activated carbon technologies in their design. These filters can remove PFAS from drinking water, but they can be expensive and may not have the life expectancy required for a large scale application. They are most effective when used in conjunction with other treatment technologies such as activated carbon or ion exchange resins.

Related articles:
Do Brita Filters Remove PFAS – Real World Testing Data
Do ZeroWater Filters Remove PFAS? The Definitive Answer
New Brita Filter Removes 11 PFAS Compounds – Purefast
Can Distillation Remove PFAS From Water? What the Experts Say

Recent study results

Scientists at Duke University and North Carolina State University conducted a comprehensive study of home water filters to see how well they were at removing PFAS from drinking water. They found a wide range of benefit from one filter to another.

In general, they reported that using any treatment system is better than nothing. However, most household filters are only partially effective at removing PFAS from drinking water.

Even worse – some filters can make matters worse if improperly maintained!

All of the under-sink reverse osmosis and two stage filters achieved near complete removal of chemicals they tested for. In contrast, activated carbon filters were shown to be ineffective in many pitcher styles as well as faucet mounted ones. Whole House Systems varied widely and some actually increased the concentration of PFAS in the drinking water.

 


Type of Treatment
PFAS Removal Efficiency

Comments
Reverse osmosis filters94%RO filters and two-stage filters were very effective at reducing PFAS levels, including GenX, in drinking water. However, since so few two-stage filters were subjected to testing, more research is required to discover why they worked so well.
Activated carbon filters73%Researchers saw no clear trends between the efficiency of activated carbon filters and their ability to remove PFAS. Results varied – some completely removed PFAS while others had only a small reduction. They recommend changing out your filter regularly for maximum protection.
Whole house systemWide rangeWhole house systems had highly variable PFAS-removal efficiencies. Concentrations of PFSA and PFCA levels actually increased after filtration iIn 4 of the 6 systems tested.

Do Brita filters remove PFAS

If you’re looking for a way to get rid of bad-tasting chlorine and heavy metal contaminants in your tap water, then Brita or Pur pitchers will do the trick. However they were not designed specifically for removing PFAS or even reducing their concentration in tapwater.

Brita filters were not designed to remove PFAS from drinking water. And, Brita does not claim their filters remove PFAS.

Duke conducted a study of various home filtration systems. They found the effectiveness of activated carbon filters for PFAS treatment used in many pitcher filters was inconsistent and unpredictable. 

Key takeaway: You should not rely on Brita (or any other pitcher-type filter) to remove PFAS from water you and your family are drinking.

Do refrigerator filters remove PFAS

Almost every refrigerator that dispenses water comes with a filter. Some of these filters are only particle filters that remove suspended particles. Other come with activated carbon filters that remove taste, chlorine, and other contaminants.

The vast majority of refrigerator filters do not remove PFAS from your drinking water. They were not designed to treat PFAS and none of the manufacturers claim that their filters are suitable for this use.

A recent study conducted by Duke University and North Carolina University found that small household carbon filters performed inconsistently and unpredictably at reducing concentrations of PFAS in drinking water.

Find out if your refrigerator filter can treat PFAS here.

Can you boil PFAS out of water

It turns out that you cannot just boil water to get rid of per- and polyfluoroalkyl substances (PFAS). The chemicals will only become more concentrated when heated, which means they’re even more dangerous than before.

PFAS compounds are known as forever molecules because they are very resistant to heat. This is why Teflon makes a great anti-stick fying pan.

For this reason, boiling water won’t remove PFAS because these molecules don’t break down when exposed to heat.

Does bottled water contain PFAS

Some bottled water contains PFAS

Non-carbonated bottled water products in the U.S., tested as part of a new study conducted by Johns Hopkins University researchers, contained potentially toxic PFAS chemicals. As shocking as this sounds, bottled water contains PFAS.

The study found that 39 out of more than 100 samples tested positive for these PFAS substances. The researchers discovered, however, that bottled waters marketed as “purified”—which are usually filtered through reverse osmosis—contained less total PFAS than “spring” water, which is not processed in that manner.

The Environmental Protection Agency, which is in charge of tap water regulation, has yet to issue PFAS standards. However, it has issued voluntary advice urging water utilities to keep PFAS levels below 70 parts per trillion.

Do Public Water Treatment Plants Remove PFAS

Unfortunately, most public water plants do not have treatment process to remove PFAS. Some facilities have treatment for PFAS, but it is more the exception than the rule.

Why? In most instances, the concentrations of PFAS are below state standards. However, this is not always the case. Some public water supplies have PFAS above safe levels and don’t treat their water.

Chief Guru

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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