Our water quality experts have tested for PFAS-related compounds in the source water that comes into our treatment plants and the drinking water that leaves our treatment plants since 2017 and have not detected anything above the Environmental Protection Agency’s proposed regulatory limits. The results below are sampling results from 2023.

Current laboratory equipment can reliably detect and quantify compounds down to slightly less than 2 parts per trillion in a sample. Below that level, the tiny trace amounts are so small that test results at these extreme detection limits are only estimations.

The Environmental Protection Agency's regulatory approach to PFAS compounds in drinking water has evolved over the years, including a health advisory in 2016 on two kinds of PFAS (called PFOA and PFOS), and a second, interim health advisory in 2022. Learn more about EPA health advisories.

In March 2023, the EPA proposed the first-ever national standard to limit PFAS in drinking water. The proposed standard covered six PFAS compounds, with limits set for PFOA and PFOS, and a combined limit for the other four compounds (PFNA, PFHxS, PFBS and GenX). Learn more here.

The EPA’s proposed PFAS regulation would require public water systems to: 

• Monitor for these six PFAS compounds in our drinking water. 
• Notify the public if the levels of the six regulated PFAS compounds are above EPA’s regulatory limits.
• Reduce the levels of these six PFAS compounds in drinking water if test results are above the EPA’s regulatory limits. 

A review of the EPA’s proposed PFAS regulation indicates the drinking water Denver Water provides to customers tests well below the EPA’s proposed regulatory limits for the six PFAS compounds included in the agency’s draft rule.

Denver Water will continue testing for PFAS as part of our monitoring protocols. We regularly review our treatment processes and adjust these processes as part of our mission to provide a clean, safe, reliable water supply to our customers.

If PFAS test results go above the EPA’s regulatory limits, Denver Water might be required to add new and potentially costly treatment methods or find alternative sources of water — which isn’t always an available option in the water-starved West.  

*Test results from first half of 2023.
**The “weighted combined score” is the weighted sum of the test results of four specific PFAS compounds: GenX, PFBS, PFHxS and PFNA. The EPA calls this a Hazard Index and any sum above 1 for a year would be considered a violation of the EPA’s proposed PFAS drinking water regulations. Learn more about the EPA’s proposed PFAS Hazard Index.

Note 1: Denver Water’s 2023 test results in the above chart reflect the detection limits of our laboratory’s capabilities. The EPA’s proposed laboratory detection and reporting limits for PFAS are higher.

Note 2: Denver Water also monitors its water for PFAS-related compounds that are not included in the EPA’s proposed regulations, as well as other nonregulated emerging contaminants. In the summer of 2023, test results of treated water at Marston Treatment Plant indicated a PFAS compound called PFBA at a level of 1.9 parts per trillion, which is at the lower limit of laboratory detection and analysis capabilities. The EPA’s list of compounds in the agency’s proposed PFAS regulation for drinking water doesn’t include PFBA, although that may change in the future. More information about PFBA is available at the EPA’s website.