A study published October 23, 2026, in Cell Reports Sustainability estimates that U.S. drinking water may contain about twice the PFAS levels that standard reports show: roughly 5.2 nanograms per liter on average for the six EPA-regulated PFAS, versus the 2.6 nanograms per liter reported when low results are counted as zero.
PFAS are man-made “forever chemicals” linked in earlier research to cancer, liver damage and developmental problems in children. A team led by Gehendra Kharel of Texas Christian University analyzed more than 1.8 million records from the EPA’s national monitoring data, released in January 2026, and found that 98% of results fell below the minimum reporting level. Those results are usually recorded as zero. Using models that generated 500 estimates for each below-limit value, the researchers found that the usual method captures only 44% of the average concentration of 25 PFAS across 9,991 community water systems. The authors note that the figures are model predictions, not direct measurements, and do not show that every below-limit result is a health risk. For readers, “not detected” on a water quality report means below the reporting limit, not zero.
Image: Filling a glass with water in a kitchen sink, Shixart1985, CC BY 2.0, via Wikimedia Commons.