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US tap water may contain about twice the 'forever chemicals' EPA data shows

A new study says counting low PFAS readings as zero hides roughly half of the contamination in America's drinking water, as the EPA moves to loosen limits.

By Newsheir Staff, Newsroom

· 2 min read

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In this article
  1. The problem with zeros
  2. What PFAS are
  3. What the study does not show
  4. Policy context

Official data may be significantly underestimating how much PFAS, the so-called "forever chemicals", is in America's drinking water, according to a new study.

Researchers led by Texas Christian University found that the standard way of handling very low test results means the US Environmental Protection Agency's (EPA) data captures only about 44 percent of the actual average concentration of these chemicals in community water systems. The study was published on October 23 in the journal Cell Reports Sustainability.

The problem with zeros

The team did not collect new samples. Instead, it re-analysed more than 1.8 million measurements of 25 PFAS chemicals from 9,991 community water systems, collected under an EPA monitoring programme known as UCMR 5 and released in January 2026.

About 98 percent of individual results fell below the laboratories' reporting limits, the lowest level they can reliably quantify. In calculating averages, those results were treated as zero.

But a result below the limit does not mean the chemical is absent. "Below the reporting limit does not mean zero," the lead author said. Using statistical methods that estimate the likely concentration of those low readings, the researchers concluded that the zero method misses about 56 percent of the contamination. For the six PFAS covered by the EPA's 2024 drinking water rule, the gap was about 50 percent.

What PFAS are

PFAS, short for per- and polyfluoroalkyl substances, are a family of thousands of synthetic chemicals used since the 1940s in non-stick pans, waterproof clothing, food packaging and firefighting foam. They are called forever chemicals because they break down extremely slowly in the environment and the human body. Exposure to some PFAS has been linked to certain cancers, liver and immune effects, and developmental problems.

What the study does not show

The authors stress that their findings are about national averages. The study does not show that any particular water system exceeds federal limits or that any household's water is unsafe. It is a modelling analysis, so its estimates depend on the statistical assumptions used.

Policy context

The study comes as the EPA moves to relax PFAS regulation. In May the agency proposed dropping limits on four of the chemicals that were set under the Biden administration. The EPA had not commented on the study at the time of reporting.

People concerned about their water can check their utility's annual water quality report. Certified home filters, including some reverse osmosis and activated carbon systems, can reduce PFAS levels.

Sources and references

  1. 1.EPA could be vastly under-reporting PFAS levels in drinking water, study finds — The New Lede
  2. 2.EPA May Significantly Underestimate PFAS in U.S. Drinking Water, Study Suggests — Food Safety Magazine
  3. 3.Drinking water may have much more 'forever chemicals' than EPA reports — The Spokesman-Review
  4. 4.US Drinking Water Could Contain Double The Reported PFAS Levels, Model Estimates — Eurasia Review

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