Skip to main navigation Skip to main content

Per- and Polyfluoroalkyl Substances (PFAS)

​​​What are PFAS?

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Per- and polyfluoroalkyl substances (PFAS) are a large group of chemicals that have been widely used for decades due to their ability to resist heat, oil, grease, and water. Common uses include non-stick cookware, stain-resistant carpets and fabrics, food packaging, and fire-fighting foam. These chemicals break down very slowly in the environment and can be found in water, air, soil, fish, and wildlife. They have also been identified in the blood of people across the globe. There is evidence that exposure to PFAS chemicals may have harmful health effects. Researchers and state and federal agencies continue to investigate the potential health effects, levels of PFAS in the environment, and management options. For additional information, explore the links on this page.​​

​

On May 18, 2026, EPA announced two proposed PFAS rules to revise the existing 2024 PFAS National Primary Drinking Water Regulation (NPDWR). One rule proposes to maintain the established maximum contaminant levels (MCLs) for PFOA and PFOS while providing an opportunity for public water systems to request a federal exemption that would extend the compliance deadline two years (until 2031). The second proposed rule would rescind the regulatory standards for PFHxS, PFNA, HFPO-DO, and the Hazard Index. The 2024 PFAS NPDWR remains in effect until a new final rule is published in the federal register.

Effective June 25, 2024, the Environmental Protection Agency (EPA) established the final National Primary Drinking Water Regulation (NPDWR) to regulate six PFAS in drinking water. The rule set enforceable Maximum Contaminant Levels (MCLs) of 4.0 parts per trillion (ppt) individually for PFOA and PFOS, 10 ppt for PFHxS, PFNA, and HFPO-DA (commonly known as GenX Chemicals) as well as a Hazard Index of 1 for mixtures of two or more PFAS including PFHxS, PFNA, HFPO-DA and PFBS. Public water systems with PFAS levels above the MCLs are required to take action to comply with the new standards to provide safe and reliable drinking water to their communities.

Chemical​Maximum Contaminant Level (​MCL)
PFOA​4.0 ppt (parts per trillion)
PFOS​4.0 ppt
PFHxS​10 ppt
​PFNA10 ppt
HFPO-DA (Gen X Chemicals)​10 ppt
Mixture of two or more:
PFHxS, PFNA, HFPO-DA and PFBS		Hazard Index of 1 (unitless)

To learn more about the final PFAS NPDWR, visit EPA's webpage.

For more information on how drinking water systems will comply with the new regulations, please visit the Division of Water's Drinking Water Compliance page.

The Department for Environmental Protection (DEP) began sampling public drinking water for PFAS in 2019 and has continued to collect additional data at public drinking water treatment plants statewide. Results were shared with water systems and are available on this page to provide information on the presence of PFAS across the state. With the release of the proposed regulations in March 2023, DEP staff engaged with systems to spread awareness of the pending regulations, their potential impacts, and treatment options. Based on currently available data, less than 10% of community drinking water treatment plants have had a result above the newly established MCLs. As additional data are gathered, very few water treatment plants repeatedly exceed the MCLs. DEP will continue to sample and provide assistance to public water systems as they address the challenges of PFAS contamination in drinking water for the protection of public health in the Commonwealth.​

In 2019, staff sampled finished drinking water from 81 community public drinking water treatment plants (WTP). WTPs were selected to represent surface and groundwater sources, urban and rural land-use influence, and varying sizes of populations served. One or more PFAS were detected in 41 of the 81 WTPs.​


​In 2023, staff sampled finished drinking water from an additional 113 water treatment plants not included in the 2019 study:

​
​

In 2020, staff sampled 40 surface water locations across the Commonwealth. Monitoring stations were selected to fill data gaps and represent each of the major river basins in the state. Upstream catchment areas for these monitoring stations ranged from 0.8 to 4,288 square miles. One or more PFAS were detected at 36 of the 40 monitoring stations.

In 2021, the Department for Environmental Protection (DEP) continued its efforts to evaluate potential paths of exposure to PFAS with a pilot project to test for PFAS in fish from state waters. Current scientific research indicates that certain PFAS can build up in fish over time, and consuming fish from PFAS-contaminated waters can be a route of exposure for people. Three streams from the 2020 surface water study with confirmed levels of PFAS were selected initially. Four additional streams were added in early 2022, as well as fish from a separate lake study. Fish sampled included black bass and sunfish species.

PFAS were detected in all 98 samples from the two projects. Perfluorooctane sulfonic acid (PFOS) occurred at the highest concentrations of any PFAS. Results for PFOS ranged between 0.31 and 50 parts per billion (ppb) in fish tissue. Fifteen other PFAS were detected in at least one sample at concentrations of 18 ppb or less. The average concentration of PFOS in fish from the stream study was 13 ppb; the average for fish from the lake study was 5 ppb.

To lower potential health risks associated with PFAS, DEP, Department for Public Health, and Department of Fish and Wildlife Resources recommend that citizens follow existing statewide fish consumption guidance for mercury and any site-specific advisories. Recent information from the US EPA indicates that infants and young children may be particularly sensitive to some health effects associated with PFAS. In the interim while staff collect additional data and information, sensitive populations may want to exercise additional caution when making choices on the frequency and quantity of fish consumed from state waters.


Learn more about current fish consumption advisories

​Additional PFAS fish tissue data:

​
​For more information contact:​​​​​​​
Melanie Arnold​
Kentucky Energy and Environment Cabinet
300 Sower Blvd
Frankfort, KY 40601    

Phone Directory
Contact Us
Civil Rights/Derecho Civiles

The Kentucky Energy and Environment Cabinet does not discriminate against any person on the basis of race, color, national origin, religion, age, disability or sex. This policy protects the rights of Cabinet employees, service applicants and customers. Vendors, agencies and organizations providing services to the Cabinet or its recipients of federally-aided programs also must comply with this policy.

© 2022 Commonwealth of Kentucky. All rights reserved.Kentucky.gov