If you are like many people who are trying to prevent toxic chemicals common in U.S. water supplies from getting to your family, you may be distressed to learn that many popular home water filtration systems are not filtering out toxic PFAS chemicals. This was the finding of a recent scientific study on the topic.
Major study findings
Scientists tested 76 point-of-use filters and 13 point-of-entry or whole-house systems and found their effectiveness varied widely. Their overall conclusion: Many household filters are only partially effective at removing toxic perfluoroalkyl substances, commonly known as PFAS, from drinking water. A few, if not properly maintained, can even make the situation worse.
“All of the under-sink reverse osmosis and two-stage filters achieved near-complete removal of the PFAS chemicals we were testing for. In contrast, the effectiveness of activated-carbon filters used in many pitcher, countertop, refrigerator and faucet-mounted styles was inconsistent and unpredictable. The whole-house systems were also widely variable and in some cases actually increased PFAS levels in the water.”
-Dr. Heather Stapleton, Associate Professor of Environmental Health, Duke’s Nicholas School of the Environment
- Reverse osmosis filters and two-stage filters reduced PFAS levels (including GenX), by 94% or more in water, though the small number of two-stage filters tested necessitates further testing to determine why they performed so well.
- Activated-carbon filters, on average, removed only 73% of PFAS contaminants; results varied greatly. In some cases, the chemicals were completely removed; in other cases they were not reduced at all. Researchers saw no clear trends between removal efficiency and filter brand, age or source water chemical levels.
- The PFAS-removal efficiency of whole-house systems using activated carbon filters varied widely. In four of the six systems tested, PFSA and PFCA levels actually increased after filtration. Additionally, because the systems remove disinfectants used in city water treatment, these filtration systems can also leave home pipes susceptible to bacterial growth. Source
Why be concerned about PFAS chemicals in your drinking water?
PFAS chemicals (per- and polyfluoroalkyl substances) are toxic to humans, animals and the environment. They are comprised of approximately 12,000 compounds. They are ubiquitous in the U.S., appearing in thousands of consumer and industrial products and are typically used to make products resist water, stains and heat, including household products (like carpeting, curtains, furniture upholstery, waterproof and stain-resistant flooring, etc.), cooking supplies (including cooking utensils and bake ware), clothing, personal care products (like cosmetics, including waterproof mascara) and even food (PFAS appears in processed food packaging for humans and pets) and public drinking water (tap water) that affects an estimated 2 million Americans. PFAS chemicals are usually found in products labeled “stain-proof” and “waterproof”. PFAS chemicals also appear in fire-fighting foam and other industrial products used at airports and military bases across the country, where the chemicals have leached into the groundwater. PFAS chemicals are known as “forever chemicals” because they do not readily break down in the environment or human body. PFAS chemicals have been linked in scientific and medical studies to a variety of serious health conditions including cancer (including testicular cancers), kidney disease, heart disease, thyroid problems, reproductive problems, endocrine problems (PFAS has been found to disrupt hormonal functions with some research suggesting that the PFAS chemicals are linked to accelerated ovarian aging, period irregularities and ovarian disorders like polycystic ovarian syndrome) and liver problems. Some newer PFAS have been found to accumulate in organs, so in some cases, science simply cannot detect the toxic chemicals when testing for it in blood.
See other research findings here:
Journal Reference: Herkert, N.J., et al. (2020). Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFASs), Environmental Science and Technology Letters, American Chemical Society Journal, February 5, 2020. https://doi.org/10.1021/acs.estlett.0c00004