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US Water Testing Misses Half of 'Forever Chemicals'
23 Oct
Summary
- US may underestimate PFAS water levels by half.
- Current methods capture only 44% of average PFAS concentrations.
- Below-reporting-limit results are key to accurate PFAS measurement.
A recent study indicates that the United States might be underestimating the levels of per- and polyfluoroalkyl substances (PFAS), commonly known as 'forever chemicals,' in its drinking water systems by nearly 50%. These chemicals resist environmental breakdown and have become widespread, appearing in community water supplies across the nation.
The findings, published in Cell Reports Sustainability, highlight a critical gap in current PFAS reporting. By treating results below minimum reporting thresholds as zero, existing methods capture only about 44% of the average concentration of 25 types of PFAS. Researchers emphasize that values below reporting limits are not zero but rather indicate a concentration between zero and the limit.
Scientists with the Environmental Protection Agency (EPA) monitor PFAS due to potential health concerns, linking exposure to various conditions like cancers and reproductive issues. An analysis of EPA data from January 2026 revealed that while 176 million Americans may be drinking water with PFAS, most individual test results fall below minimum reporting levels and are thus disregarded.
To address this, researchers used statistical methods on millions of test results. Their model-based estimates suggest conventional reporting methods miss a substantial amount of PFAS. The study clarifies that it provides an estimate of occurrence, not a determination of water safety. Kharel, the lead author, suggests agencies could improve transparency by reporting which chemicals were tested, their limits, and the frequency of below-limit results.
He also proposed that agencies could present estimates accounting for below-limit results alongside traditional averages, with clear explanations of uncertainty. Implementing more sensitive testing and lowering reporting limits for common PFAS like PFOA and PFOS could significantly improve data accuracy. Kharel hopes this framework will aid utilities and researchers in identifying areas needing further investigation and encourage communities to inquire about their water quality reports.
