Image of Water Quality Lab tech.The Environmental Protection Agency recently proposed a national primary drinking water rule for a group of manufactured chemicals called PFAS. While this rulemaking process is not yet final, Louisville Water is prepared to meet these new standards to protect public health.

Learn more about PFAS compounds and what we’re doing to limit their occurrence in our drinking water.

What Are PFAS Compounds and Where Do You Find Them?

PFAS or per- and polyfluoroalkyl substances are a group of manufactured chemicals that do not naturally occur.

Since the 1940s PFAS chemicals have been used in industry and consumer products worldwide.
PFAS contain chains of carbon and fluorine atoms linked together. These carbon–fluorine bonds are strong and do not easily breakdown, which make them useful for many products, such as nonstick cookware, water-repellent clothing, stain-resistant fabrics and carpets, cosmetics, firefighting foams, and products that resist grease, water, and oil. Perhaps the best-known PFAS is polytetrafluoroethylene (PTFE), which also goes by the brand name “Teflon,” trademarked by the DuPont Company in 1945.

chemical structure of Teflon
Chemical Structure of Teflon

Why the Concern for Drinking Water?

Most of our exposure to PFAS chemicals, approximately 90 percent, comes from consumer goods and not drinking water. But through manufacturing and consumer goods, PFAS can travel into the soil, water, and air.  Since most PFAS do not break down, scientists detect PFAS chemicals in rivers, lakes, and groundwater.

Because of their widespread use and their persistence, scientists find PFAS in blood samples of people and animals all over the world. PFAS are also present at low levels in a variety of food products and in the environment. Some PFAS can build up in people and animals with repeated exposure over time.

In the mid-2000s, following research that indicated there may be health concerns with low-level exposure to two PFAS chemicals, Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), these chemicals were phased out of production. However, PFOA and PFOS are persistent; they are long-lasting, and their components break down very slowly.

New forms of PFAS are constantly being developed. For example, Hexafluoropropylene Oxide Dimer Acid (HFPO-DA) and its ammonium salt are also known as “GenX chemicals.” GenX is a trade name for a processing aid technology used to make high-performance fluoropolymers without the use of PFOA. Likewise, perfluorobutane sulfonate (PFBS) is considered a replacement for PFOS.

What is the EPA Proposed Rule and What Do Louisville Water Scientists See?

Chris Bobay in Water Quality labThe EPA has proposed to regulate six PFAS compounds and our research indicates levels in our water that are below the proposed regulatory standards.

EPA has proposed to set standards for PFOA and PFOS in drinking water at a level of 4 parts per trillion (ppt). These standards, also called maximum contaminant levels (or MCLs) would be calculated on a running annual average of quarterly monitoring data. For perspective, one part per trillion is equal to one second in 32,800 years or 1 drop in 20 Olympic-size swimming pools.

Since 2013 Louisville Water has monitored the Ohio River, groundwater, and finished drinking water for PFAS levels. Over this time technology has improved, allowing our scientists to test for PFAS at lower concentrations. Our research indicates levels of PFOA and PFOS below the proposed EPA regulatory standard.

Our monitoring data indicates a running annual average for PFOA of 2.3 ppt for PFOA and 0 ppt for PFOS at the Crescent Hill Water Treatment Plant and 2.2 ppt at the B.E. Payne Water Treatment Plant. The running annual average for PFOS is zero at both plants.

(N.B., EPA’s proposed NPDWR requires that in calculating the Running Annual Average any value below the Practical Quantification Level (PQL) shall be assigned a value of zero.)

The other four PFAS compounds EPA proposes to regulate include HFPO-DA (or Gen X), Perfluorononanoic acid (PFNA), Perfluorohexanesulphonic acid (PFHxS), and Perfluorobutane sulfonic acid (PFBS). EPA has proposed a MCL using a Hazard Index of 1.0. The Hazard Index is the sum of the Hazard Quotients of each of the four PFAS above. The Hazard Quotient for each compound is calculated by dividing the concentration of the PFAS compound by the Health-Based Water Concentration (ex. HQGenX = Conc. GenX (ppt)/10 (ppt)).

For these four PFAS compounds our monitoring indicates the calculated Hazard Index at the Crescent Hill Plant of = 0.12, and the Hazard Index for the B.E. Payne Plant at = 0.00, both well below the Hazard Index regulatory threshold of 1.0 proposed by EPA.

What is Louisville Water Doing to Reduce PFAS Levels?

Even though our current research shows levels of PFAS that are below the EPA’s proposed regulation, Louisville Water wants to do more to further reduce these small amounts.

PFAS travels into the Ohio River from a wide range of activities: manufacturing facilities producing or using products containing PFAS chemicals, publicly owned wastewater treatment plants, urban and even agricultural runoff. Louisville Water continues to research treatment options to reduce levels even lower than what we currently detect. One of the options we are evaluating is using powdered activated carbon, a treatment technique Louisville Water already uses to address many water-quality conditions. Currently, our scientists are researching how effective this strategy is in removing PFAS compounds under water-quality conditions at each of the treatment plants. We also continue to monitor the Ohio River and the aquifer to determine whether PFAS levels vary based on seasonal patterns or with other water conditions.

In 2023, Louisville Water and thousands of other drinking water utilities will monitor for other PFAS compounds as required by EPA’s Fifth Unregulated Contaminant Monitoring Rule. We will share this data when we complete this monitoring.

Louisville Water also supports actions to minimize these contaminants entering our source water. We are actively working with leaders and industry peers on approaches to limit PFAS getting into drinking water and provide financial help to drinking water utilities to meet the treatment challenges presented by PFAS in their source water.

What’s Next?

 The EPA’s announcement of the proposed rule on March 14, 2023, was the first step.

This action follows years of research, which included learning about the potential health impacts of PFAS at certain levels and how water utilities can manage the risk. EPA’s goal is to set the regulatory standard at the lowest levels to protect public health considering feasibility and affordability.

The EPA accepted public comments on the proposed rule until May 30, 2023. The agency expects to finalize the rule by late 2023 or early 2024. Once the rule is final, public water utilities across the U.S. will have three years to implement any standards to comply with the regulation.

In the meantime, research and innovation never end at Louisville Water. Protecting the public’s health is at the core of our mission. You can learn more about your drinking water in the annual water quality report. We love to talk about our drinking water, and you can always contact us.

You can also check out the EPA’s section on PFAS.