Commentary: New Drinking Water Data Uncovers Flaws in EPA’s Proposed PFAS Rules

| By Chad Seidel

Recently released drinking water quality testing data calls into doubt major assumptions underpinning the U.S. Environmental Protection Agency’s (EPA) proposed National Drinking Water Standards for PFOA and PFOS.

Most importantly, these water quality testing results from water systems across the United States clearly show that the agency significantly overestimated the number of large water systems impacted and underestimated the impact on small water systems. These discrepancies have major implications on the public health benefits and costs of the EPA’s proposed PFAS drinking water rule.

The Safe Drinking Water Act requires the EPA to periodically identify and analyze currently unregulated contaminants in drinking water that may pose potential risks to public health. This periodic testing is mandated under the Unregulated Contaminants Monitoring Rule (UCMR) and the most recent analysis (referred to as UCMR5) focused on 29 different Per- and Polyfluoroalkyl Substances (PFAS), including PFOA and PFOS, and lithium. This represents the most current and comprehensive results for PFAS occurrence in U.S. drinking water supplies.

In March 2023, the EPA proposed national drinking water regulations for PFOA and PFOS as individual contaminants and 4 other PFAS as a mixture. Their proposed PFOA and PFOS MCLs – the maximum allowable concentration for those compounds in drinking water – are set at 4 parts per trillion (ppt), which are the lowest levels of reliable detection. These levels are significantly lower than international standards like those set by Health Canada and Australia and others.   

Careful analysis of the UCMR5 PFAS findings uncovered two major flaws in the EPA’s rationale for such stringent rules. First, EPA’s estimated public health benefit of the proposed PFAS rule assumed that PFAS would be found at levels above the proposed MCLs in many more of the largest drinking water systems serving millions of Americans than the UCMR 5 data have found. The UCMR 5 data, with observed PFAS occurrence above the MCLs being lower in large water systems and higher in small water systems than estimated by EPA, demonstrate EPA overestimated the number of people exposed to higher levels of PFAS in drinking water.

The UCMR5 data also illuminates a second major flaw in the EPA’s PFAS drinking water rule proposal: EPA assumed that high compliance costs could be managed by the largest municipalities and water utilities with significant operating budgets. In fact, the cost burden and economic impact will disproportionally fall on small water systems and small, underserved communities. The UCMR5 PFAS results indicate a greater economic burden of this rule will fall on the smallest, underserved communities.  

With ongoing research, inconsistent interpretations of the science and such large uncertainty associated with EPA’s proposed PFAS MCLs, it is unclear that such a stringent and costly 4 ppt rule is necessary to protect public health.  

What is the cost of compliance? The EPA’s initial economic impact estimates suggest that national compliance cost for remediating PFAS in drinking water will be $772 million annually. However, the American Water Works Association suggests that more than $45 billion in water utility compliance costs will be required to meet the requirements of EPA’s proposed rule. Such high compliance costs will be economically debilitating for small communities even with record federal investment in drinking water infrastructure of $50 billion from the Bipartisan Infrastructure Law.  

All of this begs an important question: is exposure to trace levels of PFAS in drinking water a meaningful public health risk?

For context, consider that regulators and the scientific community today have vastly differing opinions on the potential health risks associated with low levels of PFAS exposure. Regulatory agencies around the globe have set drinking water standards that differ by over 100,000 times. The EPA claims human epidemiological studies show associations between PFOA and PFOS and various health risks, but many scientists have spoken out about the significant uncertainty in the available studies. With ongoing research, inconsistent interpretations of the science and such large uncertainty associated with EPA’s proposed PFAS MCLs, it is unclear that such a stringent and costly 4 ppt rule is necessary to protect public health.  

More importantly, such high compliance costs will have the unintended consequence of forcing smaller communities to divert limited funds away from more pressing drinking water needs like water supply reliability and failing infrastructure.

The EPA must follow the Safe Drinking Water Act process and let the science and data lead their rulemaking to ensure their regulations do more good for our nation’s drinking water supply than harm. Everyone deserves safe, affordable, and reliable water. We must prioritize our resources to accomplish that most effectively. 

Chad Seidel, Ph.D., P.E., is president of Corona Environmental Consulting. He is an environmental engineer and has worked in the drinking water community for more than 20 years. He obtained his Ph.D. in Environmental Engineering from CU-Boulder and is a registered engineer in several states.

More from Chad Seidel: What Our Nation’s Drinking Water Systems Need Now

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