PFAS: Frequently Asked Questions


Often referred to as “forever chemicals,” perfluorinated compounds – or PFAS – are manufactured, fully fluorinated compounds that are not naturally found in the environment. They are used to protect surfaces that are critical to many consumer products – and, as part of fire-fighting foam, they can even play a role in saving lives. These are products with a clear benefit. But when they reach the water supply, they can cause great harm.

These man-made chemicals, which include PFOS (perfluorooctane sulfonate), PFOA (perfluorooctanoic acid), and GenX, have been manufactured and used in a variety of industries around the globe, including in the United States for nearly 80 years. In the U.S., the manufacture of PFOA and PFOS was phased out and replaced with new PFAS compounds, which are classified as “short-chain” compounds (these compounds contain 7 or fewer carbon molecules). But large amounts of PFAS produced during past manufacturing processes remain in the air, soil, and water. Because PFOA and PFOS don’t break down in the environment, over time they can accumulate in humans and exposure to PFAS can lead to adverse health effects for humans.



Humans and animals can ingest PFAS by eating or drinking food or water that contain the chemicals. Once absorbed into the body, PFAS stays in humans for long periods of time. With exposure to PFAS coming from a variety of sources over the course of time, increasing levels of PFAS in the body can eventually become harmful to a person’s health.

Animal toxicology studies have found potential developmental, reproductive, and systematic effects from PFAS. Human studies have discovered that PFAS can result in higher cholesterol levels and potentially impact the immune system and can cause cancer, thyroid hormone disruption, and low infant birth weights.

Due to their chemical stability and low volatility, PFAS and PFOS are persistent and difficult to remove as they are resistant to direct oxidation, photolytic degradation, biodegradation and air stripping/vapor extraction.



There are a variety of ways that people can be exposed to these chemicals and at different levels of exposure. For example, low levels of PFAS can appear in food, which can become contaminated through:

  • Contaminated soil and water used to grow the food
  • Food packaging containing PFAS
  • Equipment that used PFAS during food processing

People can also be exposed to PFAS chemicals if they are released during normal use, biodegradation, or disposal of consumer products that contain PFAS. This could include products that have been treated to make them stain- and water-repellent or nonstick, such as carpets, leather and apparel, textiles, paper and packaging materials, and nonstick cookware.

People who work at PFAS production facilities, or facilities that manufacture goods made with PFAS, may be exposed in certain occupational settings or through contaminated air.

Drinking water can be a source of exposure in communities where PFAS have contaminated water supplies. These sources, which are typically localized and associated with a specific facility, could include:

  • Industrial facility where PFAS were produced or used to manufacture other products
  • Oil refinery, airfield, or other location at which PFAS were used for firefighting



PFOS and PFAS are on the EPA’s Contaminant Candidate List 4 (CCL 4). The EPA has taken steps to further investigate PFAS and related chemicals as well as to reduce their emissions and use in products.



The EPA is responsible for identifying maximum contaminant levels (MCLs) to regulate drinking water, as outlined in the Safe Drinking Water Act, but there are currently no federal regulations on the maximum levels of PFAS allowed in drinking water.

The EPA has established a non-enforceable health advisory level of 70 parts per trillion (ppt) for the sum of PFOA and PFOS. Health advisories are non-regulatory and provide technical information to state agencies and other public health officials on health effects, analytical methodologies, and treatment technologies associated with drinking water contamination. The EPA is working to determine future PFAS regulations.

In the absence of federal limits, states such as California have established their own regulatory limits on PFAS. In California, the state Department of Drinking Water has established notification levels of 6.5 ppt for PFOS and 5.1 ppt for PFOA, as well as response levels of 10 ppt for PFOA and 40 ppt for PFOS. Other states, such as Arizona, currently rely solely upon the EPA health advisory level to assess and determine necessary actions related to PFOA and PFOS.



Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been in use since the 1940s, and are (or have been) found in many consumer products like cookware, food packaging, and stain repellents. PFAS manufacturing and processing facilities, airports, and military installations that use firefighting foams are some of the main sources of PFAS. PFAS may be released into the air, soil, and water, including sources of drinking water.

PFOA and PFOS are the most studied PFAS chemicals and have been voluntarily phased out by industry, though they are still persistent in the environment. There are many other PFAS, including GenX chemicals and PFBS in use.

GenX is a trade name for a technology that is used to make high performance fluoropolymers (e.g., some nonstick coatings) without the use of perfluorooctanoic acid (PFOA). HFPO dimer acid and its ammonium salt are the major chemicals associated with the GenX technology. GenX chemicals have been found in surface water, groundwater, finished drinking water, rainwater, and air emissions in some areas.



Multiple technologies have proven capable of removing PFAS from drinking water, including the following list of treatments proven as effective by the EPA:

  • Granular Activated Carbon (GAC) – Chemicals like PFAS stick to the small pieces of carbon as the water passes through
  • Powdered Activated Carbon (PAC) – The carbon is powdered and is added to the water; the chemicals then stick to the powdered carbon as the water passes through
  • Ion Exchange Resins – Small beads (called resins) are made of hydrocarbons that work like magnets; the chemicals stick to the beads and are removed as the water passes through
  • Nanofiltration and Reverse Osmosis – A process where water is pushed through a membrane with small pores; the membrane acts like a wall that can stop chemicals and particles from passing into drinking water

Calgon Carbon has provided proven solutions for PFAS treatment of both drinking water and wastewater applications for more than 15 years, offering ways to treat water everywhere from the source to the tap.



Granular activated carbon (GAC) filters have been recognized as effective technologies for reducing perfluorinated compounds from water. Calgon Carbon’s FILTRASORB® GAC is a reagglomerated GAC produced from bituminous coal that has demonstrated superior PFAS-removal capabilities compared to other carbon solutions.

Calgon Carbon provides temporary and permanent GAC system services that can be rapidly deployed to exchange spent carbon and thermally reactivate the material, removing PFAS from the carbon as it safely destroys the PFAS in a high-temperature process. Once reactivated, the carbon can be recycled and reused.

Calgon Carbon – which set the standard for the industry with hundreds of patents and a team of scientists and engineers dedicated to developing new processes, standards, and methods – offers a full range of GAC adsorption equipment and activated carbon products to treat PFAS. This simple, effective solution requires little operator involvement.



Thorough testing determines the best option for each customer’s PFAS treatment needs. This philosophy serves as a foundation and is why Calgon Carbon performs more tests than any other manufacturer and offers the widest range of capabilities in the industry. Our technical and engineering teams perform laboratory and field tests as needed, and tailor solutions for various application and customer needs.

Since each water source contains different combinations and levels of PFAS, as well as TOCs, it is advised that a lab or pilot test (such as an Accelerated Column Test or ACT) be performed on a representative water sample to determine the adsorption zone needed, as well as the estimated carbon exhaustion rate to properly design an activated carbon adsorption system.

Recent Accelerated Column Tests (ACTs) of Calgon Carbon type FILTRASORB 400 and FILTRASORB 600virgin GAC shows successful removal of perfluorinated compounds including Perfluorobutanoic Acid (PFBA), Perfluoropentanoic Acid (PFPA), Perfluorohexanoic Acid (PFHxA), Perfluoroheptanoic Acid (PFHtA), Perfluorooctanoic Acid (PFAS), Perfluorodeconaoic Acid (PFDA).

The strong fluorine-carbon bond and low vapor pressure makes PFAS/PFOS resistant to a number of conventional water treatment technologies, including direct oxidation, biodegradation, air stripping, vapor extraction and direct photolysis (UV).



Many industrial operations that currently use, or have used PFAS in the past, are being prompted to treat their wastewater or stormwater for these chemicals. Additionally, steps are being taken to address legacy PFAS sources in the environment.

There are challenges associated with PFAS removal, but Calgon Carbon has solutions. We can treat not just water, but also the environment, offering PFAS treatment solutions for wastewater, air, process water, landfill leachate, and groundwater remediation.

Taking a project from the laboratory, to pilot system, to full-scale treatment, we can assist with PFAS removal process development and provide the activated carbon materials and equipment to fully address PFAS sources. Our activated carbon products can be thermally reactivated by Calgon Carbon, destroying PFAS compounds, and the carbon returns to service.

For industrial customers, Calgon Carbon provides emergency response equipment and services that can be deployed quickly to customer locations. Learn more about our technologies and resources, including Calgon Carbon’s FILTRASORB® GAC.