New 3 year study: PFAS found in 65% of private water wells sampled in Pennsylvania with 18 percent exceeding EPA’s maximum contaminant levels. No wonder Adolf Orange is declawing the EPA.

Geospatial and socioeconomic factors of PFAS contamination in private drinking water wells: Insights for monitoring and management by Kelly Kosiarski, Tamie L Veith, Faith A Kibuye, Jennifer Fetter, Susan Boser, John P Vanden Heuvel, Cheryl L Thompson, and Heather E Preisendanz, J Environ Manage. 2025 Jul:388:125863.

doi: 10.1016/j.jenvman.2025.125863. Epub 2025 May 27.

Abstract

Due to limited regulation of private wells, individuals who rely on wells as a potable water supply frequently face significant challenges in ensuring safe drinking water. Widespread occurrences of per- and poly-fluoroalkyl substances (PFAS) in groundwater increase these challenges and pose additional threats to public health. Addressing these challenges requires an understanding of the geophysical factors influencing PFAS contamination and the socioeconomic conditions that shape access to resources for testing and mitigation. This study evaluates both within a more densely sampled region than previous studies to increase our understanding of PFAS contamination. Over a three-year period (2021-2023), a community-science campaign sampled 167 private wells across the Commonwealth of Pennsylvania, United States (120,000 km²) with 13 wells re-sampled in a subsequent year to assess variability of the PFAS concentrations between sampling periods. Overall, 65 % of the private wells were found to have detectable levels of PFAS, with perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) detected most frequently, in 52 % and 47 % of the wells, respectively. Eighteen percent of the wells exceeded at least one health-related maximum contaminant level. The percentage of developed land and the Socioeconomic Score correlated positively with PFAS concentration for individual wells and PFAS concentrations varied significantly between samplings. At the county level, developed land and total point sources were positively correlated with detection frequency but Socioeconomic Score was not. Results highlight the importance of both temporal and spatial sampling to understand PFAS drivers. Targeted outreach and sampling of socioeconomically marginalized communities should be prioritized in future private well monitoring efforts.

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MeSH terms

Alkanesulfonic Acids / analysis
Caprylates / analysis
Drinking Water*
Environmental Monitoring*
Fluorocarbons* / analysis
Groundwater
Pennsylvania
Socioeconomic Factors
Water Pollutants, Chemical* / analysis
Water Supply
Water Wells

Substances

Fluorocarbons
Drinking Water
Water Pollutants, Chemical
perfluorooctane sulfonic acid
Caprylates
Alkanesulfonic Acids
perfluorooctanoic acid

PFAS Found in 65% of Private Wells Sampled in Pennsylvania by Cristen Hemingway Jaynes, June 17, 2025, Ecowatch

New research has found that 18 percent of private wells sampled in Pennsylvania exceed the maximum contaminant levels for per- and poly-fluoroalkyl substances (PFAS) in drinking water set by the United States Environmental Protection Agency.

Of the wells sampled, 65 percent had detectable levels of PFAS, and almost half contained several of the chemical compounds.

Researchers from Pennsylvania State University (Penn State) conducted a three-year study with data provided by citizen scientists on the levels of PFAS “forever chemicals” in 167 private wells in the state, a press release from Penn State said.

“Due to limited regulation of private wells, individuals who rely on wells as a potable water supply frequently face significant challenges in ensuring safe drinking water. Widespread occurrences of per- and poly-fluoroalkyl substances (PFAS) in groundwater increase these challenges and pose additional threats to public health,” the authors of the study wrote.

Three-and-a-half million people rely on private well systems in Pennsylvania, according to Penn State Extension.

“My immediate reaction when I saw all the data combined was a little bit of relief, because none of the numbers were as high as I feared they could be,” said senior author of the study Heather Preisendanz, a professor of agricultural and biological engineering in Penn State’s College of Agricultural Sciences, in the press release. “We were happy that most of the numbers we saw were within the drinking water standards. Only 18% of the wells had levels that were higher than the federal standards, but they weren’t thousands of times higher than the drinking water standards, as we have seen in other places. The levels that we saw were relatively low and are treatable with pretty simple technologies that people can use in their households.”

Preisendanz said the results might not be representative of overall PFAS levels in private wells and encouraged concerned residents to test their water.

The research team reported the highest PFAS concentrations in private wells in southeastern Pennsylvania. Many of the wells with no detected PFAS were in the state’s western and central regions.

The team discovered that wells located near developed land were more likely to have been contaminated with PFAS, with levels varying significantly in wells that were sampled multiple times.

The researchers also found that private well owners’ socioeconomic status was a factor in concentrations of PFAS.

Kelly Kosiarski, lead author of the study and a graduate student in Penn State’s Department of Agricultural and Biological Engineering, said the connection between PFAS in wells and socioeconomic status was counterintuitive. It demonstrated no clear connection between levels of the chemical compounds and poverty, but just the opposite.

“One might assume that people who live in lower income areas with higher levels of poverty or lower socioeconomic score would have elevated exposure to environmental contaminants like PFAS, due to factors such as proximity to industrial sites, but we didn’t find that to be true in the PFAS study data,” Kosiarski said. “Among all the socioeconomic factors we considered, poverty was the most consistently significant — exhibiting an inverse relationship with PFAS in private wells. This negative association suggests that wealthier areas may have higher PFAS concentrations.”

The research team also found that it didn’t matter how close wells contaminated with PFAS were to agricultural areas that had biosolids or sewage sludge applied to them.

“This study was originally conceived to answer the question of whether or not biosolids applications were putting people at higher risk of PFAS in their drinking water,” Preisendanz noted. “And so, the participants we selected early in the study were chosen due to their proximity to biosolids application sites.”

The study, “Geospatial and socioeconomic factors of PFAS contamination in private drinking water wells: Insights for monitoring and management,” was published in the Journal of Environmental Management.

“Results highlight the importance of both temporal and spatial sampling to understand PFAS drivers. Targeted outreach and sampling of socioeconomically marginalized communities should be prioritized in future private well monitoring efforts,” the authors wrote.