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What is changing for water systems?
Originally, the PFAS Rule required systems to comply with new maximum contaminant levels (MCLs) for six chemicals and a Hazard Index by April 1, 2029. Under the EPA’s proposed revisions announced in May 2026:
- Four chemicals and the Hazard Index may be dropped: The EPA plans to rescind the regulatory requirements for PFHxS, PFNA, HFPO-DA, PFBS, and the Hazard Index mixture.
- More time for PFOA and PFOS: The EPA is proposing a modified exemption process to give eligible water systems up to two additional years to meet PFOA and PFOS MCL requirements, pushing the compliance deadline to 2031. This extension framework is largely driven by the significant capital costs, supply chain constraints, and workforce limitations systems face when designing and installing new treatment facilities.
- Interim measures and public notice: An exemption gives systems more time, but requirements during that extension period are dependent on a system's specific PFOA or PFOS levels:
- 12 parts per trillion (ppt) and above: If a system’s PFOA or PFOS levels equal or exceed 12 ppt, they must implement at least two interim control measures. These can include public education efforts and operational adjustments, like blending water sources, or providing point-of-use solutions directly to consumers, such as certified pitcher filters.
- Between 4 ppt and less than 12 ppt: If a system's PFOA or PFOS levels are above 4 ppt and less than 12 ppt, the proposed framework does not require them to implement interim control measures during the exemption period.
- Regardless of contamination levels, all exempted systems will be subject to public notice requirements to ensure their communities remain informed while long-term treatment solutions are built.
(Note: Without an approved exemption, suppliers will still be required to meet the original April 1, 2029 deadline).
What is the department doing?
Because the EPA signaled that these revisions would occur after the deadline for states to submit primacy applications, the EPA strongly encouraged states to request an extension. The department officially requested a six-month primacy extension this spring. This is an administrative step that provides us with the necessary time to review the EPA’s proposed changes and ensure Colorado’s exemption process aligns with the new federal framework. This extension does not impact public drinking water systems or alter the department’s enforcement oversight. It simply ensures our regulatory authority remains intact before the federal rule takes full effect in April 2027.
What are the next steps?
We will continue to update systems as the EPA finalizes these revisions. Currently, the department is communicating directly with the EPA regarding these drafts and the practical feasibility of implementing these PFAS exemptions at the state level.
Importantly, the proposed extensions and revisions do not change immediate testing deadlines. Suppliers must still comply with the initial monitoring requirements for the six PFAS chemicals by April 1, 2027. To satisfy this requirement, systems must complete monitoring and report the results of either two or four samples (depending on system size and source water type) per entry point. If a supplier has completed all required initial monitoring, they should check their monitoring schedule and AIMS Tool to ensure initial monitoring results have been accepted and marked complete.
For more information, visit the department’s PFAS rule webpage, sign up for future PFAS Rule email notifications, or email cdphe_wqcd_DWrules@state.co.us.
