Filling The Federal Void: State-by-State PFAS Regulations In An Era OfDeregulation – Part III

Given the deregulatory approach taken by the Trump administration on PFAS maximum contaminant levels (MCLs) (as detailed in Part I) and the money his administration is making available for states (as detailed in Part II), this Part III analyzes the other side of the Trump administration’s environmental federalism – what the states are doing. States have responded in varying ways to the reduced federal action for PFAS MCLs, including some acting directly in response to the Trump administration’s recent MCL changes.

This post reviews the states in which Nossaman has offices, which run the gamut from classically blue (California) to classically red (Texas) to and classically purple (Colorado). The list below is ordered roughly from most active to least active with regard to state-level MCLs.

Colorado

Colorado passed updates to its Regulation 11 in August 2025 that provided for enforceable MCLs. Some of the requirements in Regulation 11 go into effect starting April 1, 2027, and suppliers must comply with the MCLs by April 1, 2029.

Resources, including those showing non-MCL state action

• https://cdphe.colorado.gov/pfas
• https://cdphe.colorado.gov/dwpfas
• https://cdphe.colorado.gov/environment/water-quality/engage-with-the-water-quality-control-division/regulating-per-and
• https://cdphe.colorado.gov/chemicals-from-toxic-firefighting-foam-pfas/pfas-action-plan
• https://www.usatoday.com/story/news/nation/2024/05/09/pfas-ban-forever-chemicals-tied-to-cancer/73630401007/

Washington

Washington issued MCLs in December 2021 and then updated them in December 2025 to more closely match the Biden administration’s proposed MCLs. The updated MCLs went into effect as of January 15, 2026 and generally match and expand upon the Biden administration’s proposed MCLs. (See information here.)

Resources, including those showing non-MCL state action

• https://ecology.wa.gov/waste-toxics/reducing-toxic-chemicals/reducing-toxic-chemicals-washington/pfas
• https://ecology.wa.gov/regulations-permits/laws-rules-rulemaking/rulemaking/wac-173-337-nov2023
• https://doh.wa.gov/community-and-environment/contaminants/pfas/rules-regulations-and-government-roles-our-state

New York

New York has existing PFAS MCLs dating back to 2020. However, it also recently passed a bill that would provide for updated MCLs in response to the Trump administration’s deregulatory actions. That bill also provides for an evaluation related to the hazard index proposed by the Biden administration, with recommendations due by May 1, 2028.

Resources, including those showing non-MCL state action

• https://www.health.ny.gov/environmental/water/drinking/emerging_pfas_publicwater.htm
• https://dec.ny.gov/environmental-protection/per-and-polyfluoroalkyl-substances-pfas

California

California has not issued any PFAS MCLs. It is unclear at this time if the state will respond to the Trump administration’s deregulatory approach by developing its own MCLs. Despite that, California has created other regulatory levels related to PFAS that each lead to different requirements or outcomes.

Resources, including those showing non-MCL state action

• https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/pfas.html
• https://www.waterboards.ca.gov/pfas/ca_pfas_timeline.html
• https://www.nossaman.com/newsroom-insights-epa-releases-long-awaited-proposed-pfas-standards
• https://www.californiawaterviews.com/oehha-releases-long-awaited-proposed-public-health

Arizona

Arizona has not issued any state-level MCLs nor does it appear that there is any plan for the state to do so in the near future. Despite that, Arizona has taken other actions focused on PFAS, including testing and developing a Drinking Water PFAS Mitigation Plan.

Resources, including those showing non-MCL state action

• https://azdeq.gov/pfas-resources
• https://azdeq.gov/PFAS_DW

Washington DC

Washington D.C. does not appear to have taken any action specific to PFAS. Despite that,

Washington D.C.’s actions through D.C. Water have been focused on testing and monitoring.

Texas

Texas appears to be solely relying on federal action on PFAS.

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As shown by New York’s recent actions, states are still evaluating to what extent they need to change their approach to PFAS given the Trump administration’s deregulatory/environmental federalism approach. California is certainly a state to watch here as it currently does not have any PFAS MCLs despite taking numerous other regulatory actions. Nossaman will continue to track state-level action and provide updates going forward.