Resources:
- CDPHE - Regulating per- and polyfluoroalkyl substances (PFAS) in drinking water
- CDPHE - PFAS mapping (includes PFAS in treated drinking water map and data)
- CDPHE - PFAS Grant program
EPA’s Announced Changes
In May 2025, the EPA announced that it may significantly revise the 2024 PFAS Rule. Proposed changes include:
- Removing and reconsidering regulations for four PFAS compounds: PFNA, PFHxS, HFPO-DA (GenX), and PFBS.
- Retaining Maximum Contaminant Levels (MCLs) and monitoring requirements for PFOA and PFOS only.
- Eliminating the Hazard Index concept and its associated MCL for PFAS mixtures.
- Extending the compliance deadline for PFOA and PFOS MCLs from 2029 to 2031.
These changes are planned to occur via a revised PFAS Rule proposal in Fall 2025, and anticipated finalization in Spring 2026.
It’s important to note that, so far, EPA’s announcement has not indicated changes to the requirements for initial monitoring of six PFAS compounds by the April 2027 compliance deadline.
Colorado’s Approach
Colorado is moving forward with adopting the PFAS rule this summer to retain full Safe Drinking Water Act primacy. This ensures that the division, not EPA, will continue to oversee PFAS compliance, monitoring, and enforcement across Colorado systems.
To account for the evolving federal landscape, the division has included a “federal flexibility provision” in its rule language. This provision allows for the automatic extension or stay of any deadlines or requirements altered by the final federal PFAS Rule, minimizing disruption for water systems.
Why Primacy Matters
Colorado’s decision to adopt the rule in 2025 avoids a primacy extension agreement with EPA. Under such an agreement, EPA would have authority over PFAS compliance while the state catches up. This would fragment regulatory oversight, complicate compliance for Colorado’s water systems, and limit our decision-making authority during this period. We believe that the division can provide the best decisions for water systems and their customers in Colorado.
The division’s experience with the Lead and Copper Rule Revisions (LCRR) demonstrated the benefit of timely rule adoption. Being one of the few states to implement LCRR on schedule allowed the division to retain control and better support systems through technical and operational challenges. The same advantages apply here.
Operational Implications for Water Systems
Drinking water data across Colorado shows that PFOA and PFOS are the primary PFAS compounds detected in public water supplies in Colorado. The removal of other compounds from the federal rule should not change which systems require PFAS treatment in Colorado. However, there may be impacts to treatment plant design and operation, which the division will work to consider during rule implementation.
In the meantime, systems are encouraged to stay engaged and continue monitoring for PFAS to meet initial monitoring requirements. The division will provide ongoing updates and technical assistance throughout this evolving process.
Stay Informed
The division is committed to supporting Colorado’s water systems during this transition. As the revised federal rule develops, Colorado will adapt, but always with the goal of maintaining clarity, consistency, and strong public health protections.
