New EPA monitoring data shows more than 37 million Americans drink water from systems that currently exceed the Biden EPA’s PFAS drinking water limits, complicating any Trump administration efforts to revisit and revise the novel drinking water limits.
“The impacts of PFAS are very non-discriminatory, meaning that PFAS can affect all of us,” Ned Witte, an attorney with Earth & Water Law, told Inside PFAS Policy.
“PFAS is -- I don’t like to use the word ‘everywhere,’ because I think that there are probably some places where PFAS is not as prevalent -- but it is extremely prevalent. And I think that there’s enough of a nonpartisan effect that . . . there probably would be voices that would object to no action being taken,” he adds.
Although environmentalists and legal experts are expecting the Trump EPA to revisit the Biden EPA’s drinking water maximum contaminant levels (MCLs) for six per- and polyfluoroalkyl substances (PFAS), they believe it will be difficult for the new administration to scrap such rules given that the awareness of its widespread, severe contamination has grown significantly in recent years.
In addition, EPA’s original determination under the Safe Drinking Water Act (SDWA) that regulation of the two most studied PFAS -- perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) -- is necessary came during the first Trump administration.
PFAS regulations were also notably absent from EPA Administrator Lee Zeldin’s March 12 “momentous” deregulatory announcement that the agency will reconsider dozens of Biden-era rules and other policies, suggesting EPA is comparatively uncertain on how to address PFAS contamination unlike other environmental issues.
But any move to weaken PFAS regulations appears likely to face pushback, as new data from EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5) shows that more than 37 million Americans drink water from 667 systems that exceed the Biden-era MCLs, according to a USA Today analysis of the latest UCMR 5 data.
EPA recently released the seventh set of data collected under UCMR 5, which monitors 29 PFAS and lithium in public water systems (PWSs). However, EPA noted that the data is still incomplete, as it only represents approximately 66 percent of the total results the agency expects to receive by the completion of data reporting in 2026.
But according to EPA’s summary of the available data, approximately 8 percent of small PWSs, which serve less than or equal to 10,000 people, and 15 percent of large PWSs, serving more than 10,000 people, had one or more sampling location averages greater than the MCL for a regulated PFAS or the Hazard Index (HI).
The SDWA rule, issued last April, sets first-time regulatory limits for PFAS in drinking water, establishing a MCL of 4 parts per trillion (ppt) individually for PFOA and PFOS, and an MCL of 10 ppt individually for hexafluoropropylene oxide dimer acid (HFPO-DA), commonly referred to as a GenX chemical; perfluorononanoate (PFNA), and perfluorohexanesulfonic acid (PFHxS).
It also establishes novel dose-additivity approach, a HI, for regulating mixtures of up to four PFAS that incorporates perfluorobutane sulfonic acid (PFBS).
Compliance
PWSs are only required to comply with the rule starting April 2029, and so “UCMR 5 results for the regulated PFAS do not indicate compliance or noncompliance with the MCLs,” EPA noted.
But considering “many are interested in comparing UCMR 5 data to the MCLs, the EPA calculated annual averages for the UCMR 5 results where such a calculation was possible,” EPA continued.
EPA said it only compared UCMR 5 results for the regulated PFAS to their associated MCLs if there was sufficient data available to calculate an annual average for a sampling location, which requires a full set of UCMR 5 results.
EPA in its data summary also said different PFAS can often be found in varying combinations as mixtures, noting that “decades of research show mixtures of different chemicals can have additive health effects, even if the individual chemicals are each present at lower levels,” and only six PFAS out of the 29 monitored in UCMR 5 are regulated.
“The EPA established drinking water standards for certain PFAS to provide health protection against these individual and co-occurring PFAS in PWSs,” EPA said. “In cases where the PFAS included in the final PFAS [National Primary Drinking Water Regulation (NPDWR)] occur at concentrations above their respective regulatory standards, there is also an increased probability of co-occurrence of additional unregulated PFAS.”
According to the data summary, “65% of sampling locations with at least one PFAS result at or above the UCMR 5 MRL have results for multiple PFAS at or above the UCMR 5 [Minimum Reporting Levels (MRLs)].”
EPA also pointed out that 21 PFAS monitored in UCMR 5 do not have non-regulatory health-based reference concentrations in drinking water, and of those 21 PFAS, 16 PFAS have been measured at or above their respective UCMR 5 MRLs in at least one sample from at least one PWS.
New Limits
However, as the USA Today analysis pointed out, EPA in its January data summary dropped a sentence that was included in the October 2024 data summary for the previous data, which read “ . . . the EPA expects that compliance actions taken under the final rule will remove unregulated co-occurring PFAS contaminants and provide additional public health protection and benefits because the best available drinking water treatment technologies have been demonstrated to co-remove other PFAS and non-PFAS contaminants that may have adverse health effects.”
The line’s removal from the most recent UCMR 5 data release -- the first under the Trump EPA -- may indicate that EPA is likely to review the drinking water rule, as it appears to be downplaying its benefits.
Although it appears unlikely that the Trump EPA will completely repeal the drinking water MCLs, some suggest the new administration may challenge the science that was used to derive the MCLs, thereby not getting rid of them entirely but possible implementing significantly less strict limits.
“I wouldn’t be surprised if that is the tip of the spear, that they’re saying the science doesn’t create quite as much of a threat as what the prior administration had identified,” Witte said.
The U.S. Court of Appeals for the District of Columbia Circuit most recently granted a stay request from the Trump EPA in a case involving challenges against the drinking water limits.
Moreover, a spokesperson for EPA told Inside PFAS Policy that the agency is waiting on a new “lead” official before it takes any action. -- Pavithra Rajesh (prajesh@iwpnews.com)