‘Forever chemicals’ in well water: Study finds private wells commonly exceed PFAS health standards, especially near known sources

The study, which used a participatory science approach, also offers insight on how well users respond to test results and risk communication

RESEARCH TRIANGLE PARK, N.C. — A new study led by North Carolina State University and RTI International, an independent scientific research institute, has found that 49% of private wells tested across the U.S. contained per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” at levels exceeding federal health guidelines. 

“This research underscores the need for expanded testing and support for the estimated 17% of Americans who rely on private wells for drinking water,” said Erica Wood, lead author, study outreach coordinator, and an environmental health scientist at RTI. “What’s especially noteworthy is that even in areas with no known PFAS sources, we still found contamination.”

In total, 271 households participated from communities in four states (NC, MN, IN, and WA)—three with known PFAS sources nearby and one without. RTI analyzed well water samples for 25 PFAS.  PFAS were detected in 63% of all samples, and in some areas with known contamination sources, detection rates reached as high as 88%. Areas with no known PFAS sources had a detection rate of 15%.

Total PFAS concentrations were significantly higher in wells located closer to PFAS production facilities, Superfund sites, spill sites and federal facilities. The concentrations ranged from none detected to 1,401 ppt PFAS. 

“Similar to PFAS in beer, private wells commonly contain PFAS, but are not covered by existing regulatory frameworks,” said study co-principal investigator Jennifer Hoponick Redmon, the senior director of the environmental health and water quality program at RTI. “Our findings demonstrate the need for targeted testing in higher-risk areas along with greater public health support for private well users.”

The research team used a participatory science model to engage communities and provide actionable data to households. The study also evaluated the effectiveness of risk communication strategies. Participants reported high satisfaction with the clarity of the results and the guidance provided. Among participants who received a recommendation to install a water filter, 49% did so based on the post-study survey.

Findings from the study are also being used to develop a nationwide mapper to help private well users understand the risk of PFAS in their water. 

“Our study was designed using a multi-pronged approach that will empower private well users to make informed decisions about their water safety,” said Jackie MacDonald Gibson, study principal investigator and Twisdale Family head of the Civil, Construction, and Environmental Engineering Department at North Carolina State University.  “One of the most striking findings is how much study participants valued being able to get their water tested for PFAS, which ordinarily costs homeowners hundreds of dollars but was free for participants in this study, and the confidence they gained from understanding how they can improve their water quality.” 

The findings were published in Environmental Science & Technology and conducted in collaboration with North Carolina State University. The additional model and mapper publications are pending.

The study was funded by the EPA through its Science to Achieve Results Program, administered in the EPA’s Office of Research and Development (Grant R84008102 administered to North Carolina State University).

Read the full study

View the study website: Forever chemicals in well water - Clean Water for US Kids™

Learn more about RTI’s PFAS research and expertise

Related: RTI study reveals drinking water as primary source of contamination in brewing