Study says US drinking water may hold twice the PFAS that EPA data shows

Researchers at Texas Christian University have published a study in *Cell Reports Sustainability* arguing that standard reporting methods understate PFAS levels in US drinking water by more than half. The findings were reported by The New Lede on 23 October.

What the researchers did

The team, led by Gehendra Kharel, associate professor of environmental and geological sciences at TCU, analysed more than 1.8 million PFAS test records from EPA's January 2026 release of data under the Fifth Unregulated Contaminant Monitoring Rule (UCMR 5).

Around 98% of those results were below EPA's minimum reporting level. The usual approach is to count those readings as zero when calculating averages. Using statistical modelling instead, the researchers estimated that the conventional method captures only 44% of the average combined concentration of 25 PFAS across 9,991 community water systems.

Techlicious gives a clearer sense of scale: for the six PFAS covered by federal drinking water rules, the conventional average came out at about 2.6 parts per trillion, against a modelled estimate of 5.2 ppt. EPA monitors 29 PFAS, with reporting limits ranging from 2 to 20 ppt, and the enforceable limit for PFOA and PFOS is 4 ppt.

"Below the reporting limit does not mean zero." Gehendra Kharel, associate professor, Texas Christian University

The results are modelled estimates rather than direct measurements. Alongside the paper, they released PFAS-CAST, an open-source tool that agencies can use to apply the same approach to their own monitoring data.

The regulatory backdrop

The study arrives while federal PFAS policy is in flux. According to The New Lede, EPA proposed in May 2026 to drop limits for four cancer-linked PFAS that had been set under the Biden administration. The New Lede also notes a separate Environment America report, published the previous week, which found PFAS in more than 80% of tested US waterways.

Why it matters for the waterworks channel

PFAS is mainly a treatment story, but it shapes how utilities spend their capital budgets. If modelled exposure is higher than reported numbers suggest, some utilities and state regulators may keep PFAS projects on their capital plans even if federal limits are loosened. Those plans compete for the same budget as main replacement, metering and valve programmes, so the direction of PFAS policy is worth watching for anyone forecasting municipal demand.

It also puts monitoring itself in focus. Tools like PFAS-CAST and the debate about reporting limits point to more demand for sampling, data analysis and water quality monitoring, an area where meter and network monitoring suppliers are already building software, as Badger Meter's new OneNetwork platform shows.