PFAS drinking water regulations: Understanding the present to navigate the unknown
T. J. Stroebl, senior market leader at Kurita America and presidentelect of the American Water Works Association, discusses the EPA’ s recent proposed rules and ongoing litigation challenging it
Recent attention to per- and polyfluoroalkyl substances( PFAS) limits in drinking water suggests that the regulatory landscape is evolving rapidly. In April 2024, the US Environmental Protection Agency( EPA) finalised a National Primary Drinking Water Regulation( NPDWR) for select PFAS, providing long-awaited regulatory direction for water systems.
However, subsequent litigation and actions by the EPA, including new proposed rules, have left some utilities confused and others concerned that requirements could change while they execute compliance plans.
While coverage has focused heavily on potential changes, the existing regulation remains in effect today. Understanding the EPA’ s recent proposed rules in the context of the existing rule and the ongoing litigation challenging it separately provides utilities important perspective as they continue working toward compliance.
Existing PFAS regulation
The 2024 NPDWR established federal drinking water standards for six PFAS compounds and introduced monitoring and compliance requirements for public water systems. 1 The rule includes the following maximum contaminant limits( MCLs) for five PFAS:
• 4.0 ppt for perfluorooctanoic acid( PFOA) and perfluorooctane sulfonic acid( PFOS)
• 10 ppt for perfluorononanoic acid( PFNA), perfluorohexane sulfonic acid( PFHxS) and hexafluoropropylene oxide dimer acid( HFPO-DA, or GenX chemicals)
In addition to individual MCLs, the rule includes a formulaic hazard index approach for mixtures containing two or more PFAS compounds. Specifically, the hazard index applies to PFNA, PFHxS, HPFO-DA and perfluorobutane sulfonic acid( PFBS), referred to throughout the article as‘ index PFAS’. A hazard index value of > 1 indicates that the mixture exceeds the regulatory threshold.
Under the current rule, public water systems must complete initial monitoring by 2027 and comply with all PFAS limits by 2029.
Although the 2024 PFAS drinking water regulation is currently in effect, it remains the subject of ongoing litigation. Following the EPA’ s final PFAS rule, the American Water Works
Table 1- Proposed mitigation options for water systems seeking extensions with ≥ 12 ppt PFOA or PFOS
Note: *- Systems may not select both public education options for their two measures
Association( AWWA) and the Association of Metropolitan Water Agencies( AMWA) filed a joint petition challenging the regulation on several grounds that may not align with the requirements established under the Safe Drinking Water Act( SDWA).
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