Colorado Adopts Federal PFAS Rule

Resources: 

• Frequently asked questions on PFAS Initial Monitoring 
• PFAS in Finished Drinking Water for PWS interactive and dynamic map 

The State of Colorado’s Water Quality Control Commission recently took final action in August 2025 and has adopted the April 2024 EPA PFAS National Primary Drinking Water Regulation into the Colorado Primary Drinking Water Regulations (Regulation 11). EPA has indicated that they plan to make changes to this rule and finalize them in 2026.  Colorado’s PFAS Rule will adjust to these changes, but remain at least as stringent as the federal rule to maintain program primacy. However, no changes are expected to the initial monitoring rule’s timeline. Many drinking water systems have already started these efforts. For the PFAS rule, all community and non-transient, non-community water systems are required to complete initial monitoring for PFAS in all entry points by April 1, 2027.

This is a public health protection measure to facilitate positive public health outcomes (and environmental protection) in Colorado and the nation. This class of omnipresent chemicals and their serious effects on human health have been recently addressed with this regulation, both in drinking water and PFAS reductions in source waters. Thanks to the new PFAS regulations, this class of chemicals can be monitored and public exposure issues addressed. 

The Water Quality Control Division (WQCD) wants to help water systems start sampling for per- and poly-fluoroalkyl substances (PFAS) now, reducing the sampling demand as systems prepare for this upcoming deadline. To this end, WQCD has been reaching out to systems that have yet to start PFAS sampling to notify them that we are offering to fund one-time sampling through the PFAS Grant Program. The deadline to apply for this free sampling opportunity is January 9, 2026. After this deadline passes, funding for one-time sampling will no longer be available, and systems will need to contact a certified lab and complete the sampling requirements as required under the regulation at their own expense.

The current six regulated PFAS chemicals and their respective Maximum Contaminant Levels (MCLs) include:

• PFOA - 4.0 ppt
• PFOS - 4.0 ppt
• PFHxS - 10 ppt
• PFNA - 10 ppt
• HFPO-DA (GENX) - 10 ppt
• Mixture of two or more: PFNA, PFHxS, GenX, and PFBS - Hazard Index of 1.0

Sampling results from initial monitoring will be used to determine the future compliance monitoring schedule for each system. If PFAS results are found to exceed the current MCLs, completing initial monitoring will also allow systems to fully understand their PFAS system issues and begin the appropriate planning to address the contamination. If treatment is necessary, funds like the PFAS Grant Program, the Emerging Contaminants in Small or Disadvantaged Communities Grant Program (EC-SDC Grant Program), and the State Revolving Fund are available to assist systems.

Unfortunately, some drinking water wells in remote rural areas have been shown to be vulnerable to PFAS contamination due to a variety of potential sources such as fire fighting foams, individual sewage disposal systems (ISDS), biosolids applications on farm fields, various industries, and landfills. PFAS compounds are pervasive in the environment, and early sampling can provide more opportunities for funding support. Fortunately, PFAS in drinking water is treatable, and the Division is here to assist public water systems and communities with technical and financial support.

➽ Adam J. Taubman Emerging Contaminants Coordinator 

➽ Claire Wadler PFAS Program Specialist