PFAS in Drinking Water: What You Need To Know

What are PFAS chemicals?

PFAS, commonly referred to as "forever chemicals," is an abbreviation for per- and polyfluoroalkyl substances-a class of thousands of synthetic compounds found in numerous everyday household items such as non-stick cookware and water-resistant fabrics. These chemicals entered widespread industrial use in the 1950s, and numerous variants remain in production today. A central issue with PFAS is their persistence, as they accumulate both in the environment and in human tissues over long periods.

According to a study published by the National Institutes of Health, the half-lives of different PFAS compounds in humans range from approximately 0.12 years on the low end to nearly 3 years at the upper end. For instance, a PFAS compound with a three-year half-life would still retain about 12.5% of its original concentration nine years after entering the body. While the full health implications of PFAS exposure are not yet fully understood, their prolonged presence in the body is a significant cause for concern.

What is the best water filter for PFAS?

Granular activated carbon (GAC)

Activated carbon filtration is among the most widely adopted home water treatment technologies. Consequently, the U.S. Environmental Protection Agency (EPA) recognizes it as the most extensively researched filtration method for reducing PFAS. These filters operate through adsorption, a process where contaminants accumulate on the surface of the carbon material as water passes through. The highly porous structure of granular activated carbon (GAC) provides a vast surface area, making it exceptionally good at capturing a wide array of contaminants.

While commonly employed to eliminate organic compounds and enhance the taste of tap water, activated carbon can also be effective in reducing PFAS concentrations. Its performance is optimized when sediment is pre-filtered from the water; thus, using a sediment pre-filter can improve the percentage of PFAS removed. GAC filters are particularly more effective at adsorbing long-chain PFAS compounds, like PFOA and PFOS, compared to their short-chain counterparts.

It is important to note that while effective, activated carbon filters are generally not as thorough as reverse osmosis (RO) systems for PFAS removal, though they do reduce a moderate amount. Consumers should verify that their specific filter model is certified to reduce PFAS, as not all carbon filters meet this standard.

Ion exchange

Ion exchange water treatment systems operate by passing water through a bed of resin beads that carry either a positive or negative electrical charge. These charged beads attract and hold contaminants possessing the opposite charge. Specifically, anion exchange resin, which is positively charged, is highly effective at capturing the negatively charged ions commonly associated with PFAS compounds.

The performance of ion exchange in PFAS removal can vary based on the condition and saturation level of the resin, making it less consistently reliable than reverse osmosis technology. A key advantage over Granular Activated Carbon (GAC) filters is that ion exchange is capable of removing both long-chain and short-chain PFAS molecules. A notable drawback, however, is that ion exchange systems are generally more costly to install and maintain compared to GAC filter systems.