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, dubbed “forever chemicals” by scientists due to their long shelf-life and the fact that they are nearly ubiquitous in the environment, drinking water, food, and now human blood serum samples, have been linked to a host of serious health outcomes including some kinds of cancers (including breast and prostate cancers), liver problems, low birth weight and numerous other health problems including thyroid problems, kidney problems, prostate problems and fertility problems.
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