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This story was originally published by The New Lede.

US drinking water could contain double the PFAS levels currently reported by regulators, according to a new study from Texas Christian University.

The study, published in Cell Reports Sustainability, used computer modeling to estimate that the latest reports from the Environmental Protection Agency (EPA) capture only 44% of the average combined concentration of 25 polyfluoroalkyl substances (PFAS) in US water systems.

PFAS, also known as “forever chemicals,” are known to persist in the environment and are linked to some cancers, high cholesterol, reproductive issues, and other health problems.

Researchers analyzed more than 1.8 million PFAS measurement records from the EPA’s January 2026 release of monitoring data from water systems across the country. They found most individual PFAS test results in the dataset fall below the EPA’s minimum reporting levels (MRLs).

These data points are often treated as zero when agencies and researchers summarize average PFAS levels in drinking water.

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The authors found that 98% of PFAS test results were below the MRL. The MRL generally means a concentration that most laboratories can reliably measure and report. However, the study’s authors argue that this doesn’t mean that the water tested is PFAS-free or that it’s safe.

“Below the reporting limit does not mean zero. Our study shows why that distinction matters when summarizing PFAS concentrations,” said lead author Gehendra Kharel, associate professor of environmental and geological sciences at Texas Christian University.

Kharel and his team used computer models applied to data from the........

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