WASHINGTON – Advanced systems for removing the toxic "forever chemicals" known as PFAS from drinking water can deliver far greater health benefits than previously thought. They also slash levels of other harmful contaminants, a new peer-reviewed Environmental Working Group study finds.
The research underscores the fact that PFAS water filtration systems can also help reduce levels of cancer-causing disinfection byproducts , or DBPs, agricultural nitrates and heavy metals like arsenic and uranium – all chemicals linked to health harms.
The study, published today in ACS ES&T Water, analyzed data from 19 U.S. utilities and the Environmental Protection Agency's national water monitoring program . The findings show that PFAS removal technologies such as granular activated carbon, ion exchange and reverse osmosis can also lower levels of multiple harmful substances found in drinking water.
"PFAS treatment isn't just about 'forever chemicals,'" said Sydney Evans , EWG senior science analyst and lead author of the study. "It's also opening the door to improving water treatment across the board.
"Advanced PFAS water treatment is a turning point that can help us clean up a broader mixture of contaminants and bring drinking water quality in line with today's public health science," added Evans.
A potential game-changer
In the 19 systems EWG studied, installation of advanced PFAS treatment technologies led to an average 42% drop in the level of trihalomethanes in drinking water, while haloacetic acid levels dropped 50%. Trihalomethanes and haloacetic acid are cancer-causing byproducts of water disinfection.
"DBPs and other harmful contaminants in drinking water are not emerging or unknown threats – we've known about them for a while. They're regulated and they're widespread," said Varun Subramaniam , EWG science analyst and co-author.
"These kinds of reductions caused by PFAS filters are a game changer for public health, especially since where there are PFAS, there are always other chemicals, too," he added.
EWG's Tap Water Database , updated earlier this year, shows the extent of widespread drinking water contamination throughout the U.S. The study highlights the levels of several other contaminants in the countless communities relying on PFAS-polluted tap water.
Environmental injustice
EWG's study also identified systemic inequities: Only 7% of very small water systems, defined as those serving fewer than 500 people, use advanced filtration. As a result, millions of Americans in rural and underresourced communities remain exposed to PFAS , hazardous disinfection byproducts and heavy metals.
By contrast, 28% of the largest utilities use the technology.
"This is a textbook case of environmental injustice," Subramaniam said. "The communities least able to afford advanced filtration often face the highest health risks. Without targeted investment, these gaps will only widen."
The research underscores an urgent need to rethink U.S. water policy . Most pressing is a shift away from one-chemical-at-a-time regulation toward holistic strategies that protect the full spectrum of pollutants. This work should start in the communities that need it most.
"This study exposes a dangerous blind spot in federal water policy," said Melanie Benesh , EWG vice president of government affairs. "Communities wouldn't just filter out PFAS, they'd be eliminating multiple toxic chemicals at the same time."
"By ignoring these co-benefits, the EPA is leaving Americans exposed and missing a huge economic and public health opportunity," Benesh said.
Regulatory setbacks threaten progress
The findings come amid backlash over the EPA's recent rollbacks, including a plan to weaken long-sought protections against forever chemicals in drinking water.
In May, less than a full year after new standards were finalized, the EPA announced it would weaken key limits on four PFAS in drinking water and delay compliance deadlines. Critics say the pending rollback could prolong harmful exposures, particularly in communities unable to implement PFAS treatment technology independently.
EWG's study also flags major gaps in national water monitoring. Inconsistent reporting to the EPA's monitoring program hinders tracking co-occurring contaminants and evaluating treatment effectiveness. Standardized, nationwide monitoring and treatment-focused regulations would better reflect real-world water contamination patterns.
Despite the costs of installing advanced PFAS treatment, EWG's research underscores the outsize public health returns of removing multiple hazardous contaminants at once. Today only 8% of U.S. water systems are equipped with filters capable of getting PFAS out, leaving millions of Americans – especially in small and rural communities – vulnerable to health risks.
Health risks of PFAS exposure
PFAS are toxic at extremely low levels. They are known as forever chemicals because once released into the environment, they do not break down, and they can build up in the body. The Centers for Disease Control and Prevention has detected PFAS in the blood of 99 percent of Americans, including newborn babies .
Very low doses of PFAS have been linked to suppression of the immune system . Studies show exposure to PFAS can also increase the risk of cancer , harm fetal development and reduce vaccine effectiveness .
For over 30 years, EWG has been dedicated to safeguarding families from harmful environmental exposures, holding polluters accountable, and advocating for clean, safe water.
EWG's study urges federal and state leaders to:
- Boost federal and state funding for advanced filtration in under-resourced systems.
- Strengthen national water monitoring to guide smarter policies.
- Adopt regulations that account for co-occurring contaminants and expand public health protection.
"This isn't just about PFAS," said Evans. "When we fix one problem, we can solve several others. The opportunity to protect public health at scale is too big to ignore – if we're smart about it."
