IHMM Files Comments on Two EPA proposed rules concerning drinking water standards and extension of certain deadlines

IHMM has submitted formal comments to the U.S. Environmental Protection Agency addressing two proposed drinking-water rulemakings involving PFAS. In those comments, IHMM supports EPA’s continued retention of enforceable maximum contaminant levels for PFOA and PFOS, while recognizing that some small, rural, and disadvantaged public water systems may require additional time, funding, and technical assistance to achieve compliance.

IHMM’s position is measured but firm: implementation flexibility must not become regulatory retreat. Any extension of compliance deadlines should be system-specific, documented, transparent, and conditioned on enforceable milestones, meaningful interim public-health protections, and prompt public notice. IHMM urges EPA to require Tier 2 public notice for systems operating under exemptions and to require direct exposure-reduction measures where PFOA or PFOS levels reach or exceed 12 parts per trillion.

IHMM also cautions EPA against creating a regulatory vacuum if it rescinds determinations for PFHxS, PFNA, GenX, PFBS, or related PFAS mixtures. If EPA corrects a procedural defect, IHMM urges the Agency to preserve monitoring, disclosure, and state authority while immediately pursuing a corrected regulatory pathway.

Finally, IHMM emphasizes that PFAS treatment creates residuals requiring competent hazardous materials, waste, transportation, worker protection, and environmental compliance oversight. That is where IHMM certificants bring essential public value, which is why IHMM’s comments incorporate the enormous background and value of the CHMMs and CHMPs involved in these two actions.

IHMM Comments Here

IHMM  had previously issued a memorandum on the two EPA proposed rules concerning drinking water standards and extension of certain deadlines.

Federal Register – Extending Deadlines [Page 1]

Federal Register – Recissions [Page 6]

1. Part 142 Extension of PFOA/PFOS Drinking Water Compliance Deadline

Legal Analysis of EPA’s Proposed Part 142 Rule: Extension of PFOA/PFOS Drinking Water Compliance Deadline

EPA’s proposed rule would amend 40 C.F.R. Part 142 to create a federal “exemption by rule” allowing eligible public water systems to delay compliance with the PFOA and PFOS Maximum Contaminant Levels from April 26, 2029, to April 26, 2031. The rule is grounded in EPA’s asserted authority under Safe Drinking Water Act §§ 1416(f) and 1450(a)(1) and applies to systems that affirmatively request the exemption.

1. What EPA Is Proposing

EPA is not proposing to repeal the PFOA and PFOS drinking water standards. The 4.0 ng/L / ppt MCLs for PFOA and PFOS remain in place. What changes is the compliance date for eligible systems that request relief. The proposal would create a national framework under which public water systems in states, territories, or Tribes that have not yet obtained primacy for the PFAS NPDWR could obtain a two-year federal exemption. EPA would require such systems to submit information showing eligibility, including system identity, operational date, recent PFOA/PFOS sampling results, and certifications that the system cannot meet the 2029 deadline due to economic or other compelling factors.

The rule is narrower than the 2024 PFAS NPDWR. EPA expressly limits this proposed extension to PFOA and PFOS, while noting that in a separate action it is proposing to rescind the MCLs and related provisions for PFHxS, PFNA, HFPO-DA/GenX, and the Hazard Index involving those PFAS and PFBS.

2. Regulated Entities

The proposal affects community water systems and non-transient non-community water systems, as well as state and Tribal drinking water agencies responsible for regulatory development and enforcement. These include systems serving year-round residential populations and certain systems serving at least 25 of the same persons over six months per year.

3. Legal Authority and EPA’s Theory

EPA relies on SDWA § 1416, which allows exemptions from MCLs where statutory criteria are met, and SDWA § 1450(a)(1), which authorizes EPA to prescribe regulations necessary or appropriate to carry out its functions. EPA’s legal theory is that, where states have not yet obtained primacy, § 1416(f) gives the Administrator the same exemption authority that a primacy state would otherwise possess. EPA then takes the additional step of proposing a streamlined, categorical “exemption by rule” rather than requiring individualized case-by-case exemption decisions for every water system.

This is the most legally important feature of the proposal. EPA acknowledges that § 1416 traditionally has been implemented through individualized exemptions, but argues that the statute does not expressly prohibit a rule-based framework combining categorical findings with system-specific submissions. That argument is plausible, but not immune from challenge. Opponents may argue that § 1416 requires individualized findings before each exemption is granted. Supporters will argue that EPA has preserved the individualized element by requiring each system to submit certifications and sampling data, while using rulemaking to resolve common legal and factual issues.

4. EPA’s Stated Basis for the Extension

EPA identifies several “compelling factors” supporting additional time:

First, EPA states that many systems will need substantial capital improvements to comply with the PFOA/PFOS MCLs. Although EPA continues to recognize treatment technologies as available, it concludes that design, procurement, construction, installation, piloting, and financing may not be completed by April 26, 2029 for many systems.

Second, EPA points to financial limitations and ratepayer impacts. The Agency emphasizes that water systems, particularly small, rural, and disadvantaged systems, may need more time to identify and secure federal, state, or settlement-related funding.

Third, EPA cites workforce limitations, including the availability of qualified operators capable of building and running advanced PFAS treatment systems.

Fourth, EPA points to monitoring and technical-assistance considerations. By allowing more time, EPA expects systems to use full initial monitoring data, UCMR 5 information, and EPA technical assistance programs to make better, more cost-effective treatment decisions.

Finally, EPA suggests additional time may allow emerging PFAS treatment technologies, point-of-use/point-of-entry devices, source water controls, and broader PFAS source-reduction strategies to mature.

5. The 12 ppt “Unreasonable Risk to Health” Threshold

The proposed rule’s most sensitive public-health provision is EPA’s treatment of “unreasonable risk to health.” EPA proposes that a two-year exemption would not present an unreasonable risk for systems with PFOA and PFOS concentrations below 12 ppt. For systems with any recent PFOA or PFOS result at or above 12 ppt, EPA would require implementation of at least two interim control measures during the exemption period.

Those control measures include alternative water supplies, point-of-use or point-of-entry devices, pitcher filters, source water controls, public education, and community outreach. EPA proposes that systems may not satisfy the requirement solely through public education and community outreach; at least one selected measure must be more directly protective.

Legally, this 12 ppt threshold is a major comment target. EPA concedes that the exemption creates some health risk but argues that Congress contemplated some risk when it authorized SDWA exemptions, provided the risk is not “unreasonable.” The Agency further emphasizes that the “unreasonable risk” determination is limited to the SDWA exemption context and does not limit EPA enforcement authority against polluters or potential action under SDWA § 1431.

6. Public Notice and Consumer Confidence Reports

Systems operating under the exemption would remain subject to public notice and Consumer Confidence Report requirements. EPA proposes to treat the operation under the exemption as a Tier 3 public notice situation, requiring notice no later than one year after the system begins operating under the exemption and annually thereafter. EPA requests comment on whether a Tier 2 notice, due within 30 days, should instead be required.

From a legal and public-trust standpoint, Tier 2 notice is likely the stronger position. PFAS contamination is highly salient to consumers, and a two-year extension of compliance with enforceable health-based drinking water standards is materially important information. A Tier 3 notice may satisfy existing regulatory structure, but it is vulnerable to criticism as insufficiently prompt.

7. Economic Analysis

EPA frames the proposal as deregulatory. It estimates annualized cost savings of approximately $90.2 million at a 3% discount rate and $188.2 million at a 7% discount rate, with corresponding forgone benefits of approximately $79.3 million at 3% and $105.7 million at 7%.

EPA’s economic analysis is candid about uncertainty. It assumes, for modeling purposes, that all systems exceeding either MCL will opt into the exemption; that treatment costs and effectiveness remain constant; that pitcher-filter usage can be modeled based on assumptions from lead-control programs; and that certain benefits of reduced PFAS exposure remain unquantified. Those assumptions may overstate or understate the actual effects, depending on real-world system behavior.

8. Legal Vulnerabilities

The proposal has several potential legal weaknesses.

The first is the scope of EPA’s exemption-by-rule authority. SDWA § 1416 plainly allows exemptions, but the statute’s individualized criteria may invite challenges to any categorical or semi-categorical approach. EPA attempts to manage that risk by requiring system-specific submissions, but opponents may argue that automatic granting of any request meeting the paperwork requirements is not the same as an individualized exemption determination.

The second is the 12 ppt unreasonable-risk benchmark. EPA must adequately explain why exposure above the 4 ppt MCL but below 12 ppt for two additional years is not unreasonable, especially given that the MCLG for PFOA and PFOS is zero. A final rule will need a robust administrative record addressing sensitive populations, cumulative PFAS exposures, and the Agency’s rationale for selecting 12 ppt rather than another level.

The third is the adequacy of interim controls. Pitcher filters, public education, and outreach may be useful, but their effectiveness depends heavily on consumer behavior, filter certification, replacement schedules, and equitable distribution. EPA itself acknowledges uncertainty around the effectiveness of public education and the assumed 20% pitcher-filter usage rate.

The fourth is federalism and primacy complexity. Once a state obtains primacy for the PFAS NPDWR, EPA states that it no longer has authority to issue exemptions in that state. States may allow the federal exemptions to continue, may refuse to do so, or may be constrained by state law. That creates potential unevenness across jurisdictions.

9. Practical Implications

For water systems, the proposed rule provides breathing room, but not immunity. Systems seeking the exemption must still monitor, report, certify eligibility, notify the public, and ultimately comply by April 26, 2031. Systems with results at or above 12 ppt must implement interim control measures.

For state regulators, the proposal may reduce immediate administrative pressure but may complicate primacy applications and public communications.

For communities, the proposal trades immediate implementation of the 2024 PFAS MCLs for additional time, planning, funding, and potentially better long-term compliance. The legal and policy question is whether that trade is justified given the known health risks of PFOA and PFOS.

10. Recommended Comment Position

A legally sound comment would likely support reasonable implementation flexibility while insisting on stronger public-health guardrails. Recommended positions include:

1. Support additional time for small, rural, disadvantaged, and technically constrained systems where documented need exists.
2. Oppose automatic or overly broad exemptions unless EPA preserves meaningful system-specific review.
3. Urge EPA to require Tier 2 public notice for systems operating under the exemption.
4. Require systems at or above 12 ppt to implement at least one direct exposure-reduction measure, such as alternative water, certified POU/POE treatment, or certified pitcher filters, rather than relying primarily on education or outreach.
5. Require clear public-facing disclosure of sampling results, selected interim controls, compliance milestones, and funding/treatment plans.
6. Ask EPA to strengthen the administrative record supporting the 12 ppt threshold, particularly for pregnant people, infants, children, and other sensitive populations.

Bottom Line

EPA’s proposed Part 142 rule is a significant implementation-relief measure, not a repeal of the PFOA/PFOS MCLs. Its legal defensibility will turn on whether EPA can justify the exemption-by-rule framework under SDWA § 1416, support the 12 ppt unreasonable-risk threshold, and show that interim controls meaningfully protect consumers during the two-year delay. The proposal is strongest as targeted relief for systems facing genuine capital, workforce, and funding constraints; it is weakest if treated as a broad automatic postponement of enforceable PFAS protections.

2. EPA’s Proposed PFAS Rescission Rule

Legal Analysis of EPA’s Proposed PFAS Rescission Rule

EPA’s proposed rule would rescind the Agency’s prior regulatory determinations and remove the associated drinking water regulatory provisions for PFHxS, PFNA, HFPO–DA/GenX, and the Hazard Index mixture of PFHxS, PFNA, HFPO–DA, and PFBS. EPA frames the rule not as a scientific reconsideration of PFAS risks, but as a legal correction of what it now characterizes as an unlawful rulemaking procedure used in the 2024 PFAS National Primary Drinking Water Regulation.

1. Core Legal Effect of the Proposed Rule

EPA proposes to remove the MCLGs, MCLs, monitoring provisions, analytical-method references, trigger levels, public-notification language, health-effects language, compliance provisions, and best available technology references applicable exclusively to PFHxS, PFNA, HFPO–DA/GenX, and the Hazard Index PFAS. The rule would leave intact the 2024 drinking water standards for PFOA and PFOS, including their MCLGs, MCLs, monitoring, and reporting requirements.

In practical terms, public water systems would no longer be federally required under this rule to monitor, report, or treat for those four rescinded PFAS categories as independent regulated contaminants under the 2024 PFAS NPDWR. The remaining federal PFAS drinking water rule would focus on PFOA and PFOS.

2. EPA’s Stated Legal Basis

EPA’s central argument is statutory sequencing. The Agency now reads SDWA § 1412(b)(1)(E) to require a two-step, sequential process:

First, EPA must issue a preliminary regulatory determination, take public comment, and then issue a final regulatory determination.

Second, only after the final determination may EPA propose a substantive NPDWR, though EPA may publish that proposed regulation concurrently with the final determination.

EPA contends that, in the 2024 PFAS NPDWR, it followed the required procedure for PFOA and PFOS but not for PFHxS, PFNA, HFPO–DA, PFBS, and the mixture/Hazard Index approach. For those additional PFAS, EPA says it simultaneously proposed preliminary regulatory determinations and proposed regulatory standards, then simultaneously finalized the determinations and the NPDWR. EPA now characterizes that approach as unlawful.

3. The Role of Loper Bright

EPA expressly cites the Supreme Court’s decision in Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024), as part of its reconsideration. Its invocation of Loper Bright is legally significant. EPA appears to be repositioning its interpretation of SDWA away from a deferential agency-reading framework and toward what it now calls the “best reading” of the statute.

That move strengthens EPA’s explanation in a post-Chevron world, but it also exposes the Agency to a classic arbitrary-and-capricious challenge: EPA must explain why its new statutory reading is superior to the reading it used in 2024, particularly where the practical effect is to remove existing federal drinking water protections for several PFAS.

4. EPA’s Anti-Backsliding Argument

One of the most important legal issues is whether rescinding the MCLs violates SDWA’s anti-backsliding provision. SDWA § 1412(b)(9) provides that revisions to NPDWRs must maintain or increase protection of public health. EPA acknowledges D.C. Circuit precedent interpreting that language to mean revised drinking water regulations may not decrease health protection, including Arizona v. EPA and City of Waukesha v. EPA.

EPA offers two responses. First, it argues that anti-backsliding applies only to the revision of a lawfully promulgated NPDWR after review, not to rescission of regulations that were unlawful from inception. Second, EPA argues that even if anti-backsliding applies, the rescission does not reduce the level of protection “actually provided” because the compliance deadlines for those PFAS standards have not yet passed.

That is a legally aggressive argument. EPA is essentially saying that an unenforced future compliance obligation provides no present health protection for anti-backsliding purposes. Opponents will likely argue that the existence of a federal MCL itself changes system planning, capital investment, monitoring, public disclosure, and regulatory expectations, and therefore provides real present protection even before the compliance deadline.

5. The NRDC v. Regan Problem

EPA also attempts to distinguish NRDC v. Regan, 67 F.4th 397 (D.C. Cir. 2023), where the D.C. Circuit held that EPA lacked authority to withdraw a regulatory determination for perchlorate based on later scientific information. EPA argues that this proposed rescission is different because it is not withdrawing a determination based on new science; rather, it is correcting a legal defect in the process by which the determinations and standards were issued.

That distinction is plausible but contestable. A reviewing court may ask whether SDWA permits EPA to rescind a final regulatory determination at all, even where EPA now claims the original determination was procedurally defective. The Agency’s position is strongest if framed as vacatur-like correction of ultra vires action; it is weakest if viewed as an ordinary policy reversal dressed in procedural language.

6. Economic Analysis

EPA estimates annualized quantified cost savings of approximately $11.57 million from rescinding the provisions, with approximately $6.66 million in quantified forgone benefits, using 2022 dollars and a 2% discount rate. EPA also notes a sensitivity analysis suggesting possible additional cost savings of approximately $82.4 million per year, though EPA cautions that those estimates are less certain because they rely on modeled and extrapolated occurrence data.

EPA candidly acknowledges that the benefits side is incomplete. It states that quantified benefits were unavailable for several of the affected PFAS due to data limitations, while also recognizing evidence linking these substances to adverse health effects including developmental and reproductive toxicity, immune suppression, liver damage, thyroid disruption, and cancer risks.

From a legal perspective, the economic analysis is secondary because EPA says the rule is based solely on legal error. But it still matters under Executive Order review and in the court of public and administrative-record reasonableness. A court may not require EPA to prove that benefits justify costs for a rescission based solely on legal invalidity, but the acknowledged nonquantified health effects may strengthen opposition arguments that EPA is minimizing health consequences.

7. Public Participation and Scope of Comments

EPA is seeking comment principally on its legal interpretation of “determination to regulate,” the rescission of the regulatory determinations, the economic analysis, and the regulatory edits removing the affected PFAS provisions. EPA states that comments on the underlying substantive health-risk, cost, or occurrence findings are beyond the scope because the proposal is based solely on legal grounds.

That limitation is strategically important. Commenters opposing rescission should still address health effects, but they should tie those points to legal issues: anti-backsliding, reliance interests, arbitrary-and-capricious review, adequacy of EPA’s explanation, and whether rescission is an appropriate remedy for the alleged sequencing error.

8. Practical Consequences for Public Water Systems

For public water systems, the proposal would reduce federal compliance obligations for PFHxS, PFNA, HFPO–DA/GenX, PFBS, and the Hazard Index. Systems already planning treatment for PFOA or PFOS may still remove some of these PFAS through co-treatment, but they would not be independently required by federal law to meet the rescinded MCLs.

For states, the proposal creates primacy complications. EPA states that if the rescission is finalized, states, territories, and Tribes would need to revise primacy submissions only for the portions of the PFAS rule that remain in effect. States also would not be required to adopt the rescinded portions of the 2024 PFAS NPDWR.

States remain free, as a matter of state law, to regulate these PFAS more stringently than federal law. Accordingly, rescission of the federal provisions may produce a patchwork: PFOA and PFOS remain federally regulated, while the other PFAS may be governed by state-specific requirements.

9. Legal Vulnerabilities

EPA’s proposal has several litigation risks.

First, EPA must overcome the argument that SDWA does not authorize rescission of final regulatory determinations once made. EPA’s distinction from NRDC v. Regan may succeed, but it is not risk-free.

Second, EPA’s anti-backsliding theory may be challenged. The claim that no protection is lost because compliance deadlines have not yet passed may be viewed as too narrow, particularly if systems have already begun monitoring, planning, or investing in treatment.

Third, EPA’s limitation of the rulemaking record to “legal” issues may be attacked if commenters argue that rescission has obvious public-health consequences that EPA cannot lawfully ignore.

Fourth, EPA’s changed statutory interpretation must be adequately explained under the Administrative Procedure Act. A change in legal interpretation is allowed, but EPA must acknowledge the change, explain its reasons, and address reliance interests created by the 2024 rule.

10. Recommended Comment Position

A legally strong comment should focus on the statutory remedy. Even if EPA believes the 2024 rulemaking sequence was flawed, the Agency should consider whether full rescission is the only lawful or appropriate remedy. Alternatives could include:

1. Re-proposing the affected PFAS determinations and standards on an expedited schedule.
2. Staying, rather than rescinding, the affected MCLs pending completion of a corrected SDWA sequence.
3. Preserving monitoring and public-disclosure requirements while reconsidering the MCLs.
4. Clarifying that states may retain or adopt more protective standards for PFHxS, PFNA, HFPO–DA/GenX, PFBS, and PFAS mixtures.
5. Establishing a firm timeline for renewed regulatory determinations if EPA proceeds with rescission.

Bottom Line

EPA’s proposed rescission rule is a procedurally driven deregulatory action. EPA is not asserting that PFHxS, PFNA, HFPO–DA/GenX, PFBS, or PFAS mixtures are safe, nor is it withdrawing the scientific basis for concern. Instead, EPA argues that the 2024 PFAS rule violated SDWA’s required sequencing and that the resulting determinations and standards are unlawful. The proposal’s defensibility will turn on whether a court accepts EPA’s new reading of SDWA § 1412(b)(1)(E), EPA’s distinction from NRDC v. Regan, and EPA’s conclusion that rescission does not violate SDWA’s anti-backsliding provision.