What the proposed PFAS Maximum Contaminant Levels (MCLs) Mean for OWASA and Our Community

14 Mar What the proposed PFAS Maximum Contaminant Levels (MCLs) Mean for OWASA and Our Community

OWASA is committed to protecting public health by providing high-quality drinking water. Our drinking water meets and surpasses all current drinking water standards.

The Environmental Protection Agency (EPA) announced on March 14, 2023, proposed maximum contaminant levels of 4 parts per trillion (ppt) for two compounds in drinking water, PFOA and PFOS, that are part of a group of compounds called PFAS.

Additionally, the EPA proposed four additional PFAS chemicals PFHxS, PFNA, PFBS, and GenX to be regulated through an established approach called a hazard index calculation to determine if the combined levels of these PFAS pose a potential risk.

OWASA has been participating in and supporting research related to PFAS for many years. We are actively working toward solutions for reducing and removing these compounds from our drinking water.

What Are PFAS?

PFAS (per- and polyfluoroalkyl substances) are a group of manufactured chemicals that have been used in industrial settings and production of consumer products like non-stick pans, waterproof clothing, and firefighting foams since the 1940s. Thousands of different PFAS compounds exist; the proposed maximum contaminant levels focus on a small number of these compounds, including PFOS and PFOA. The EPA says most uses of PFOS and PFOA were voluntarily phased out by U.S. manufacturers in the mid-2000s. However, these chemicals remain in the environment due to their persistence and the inability to degrade.

What are Maximum Contaminant Level Goals (MCLGs) and Maximum Contaminant Levels (MCLs)?

Maximum Contaminant Level Goals (MCLGs) are the level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are non-enforceable public health goals.

Maximum Contaminant Levels (MCLs) are the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable drinking water standards.

What has the EPA proposed for Maximum Contaminant Level Goals (MCLGs) and proposed Maximum Contaminant Levels (MCL) and What Does It Mean?

The EPA is proposing a National Primary Drinking Water Regulation (NPDWR) to establish enforceable MCLs, for six PFAS in drinking water. PFOA and PFOS are proposed to be regulated as individual contaminants, whereas PFHxS, PFNA, PFBS, and GenX as a group. EPA is also proposing health-based, non-enforceable Maximum Contaminant Level Goals (MCLGs) for these six PFAS.

The proposed rule would require public water systems to:

• Monitor for these PFAS
• Notify the public of the levels of these PFAS
• Reduce the levels of these PFAS in drinking water if they exceed the proposed standards.

Impact on OWASA’s Drinking Water

OWASA has been proactively monitoring our raw water supply, treated drinking water, and wastewater since 2018. This monitoring was not required but allows OWASA and our community to be positioned to understand the challenges ahead.

In 2016, the EPA established a lifetime Health Advisory Level of 70 parts per trillion (ppt) for the combined amount of two PFAS, PFOA and PFOS, in drinking water. PFOA and PFOS are the two PFAS most-extensively produced and studied. In June of 2022, the EPA set interim health advisory levels for PFOS at .02 ppt and PFOA at .004 ppt. OWASA has consistently shown sampling results of treated drinking water that were below the previously identified health advisory level of 70 ppt for PFOS and PFOA combined. However, OWASA’s sampling has shown results that exceed the interim health advisory levels, proposed MCLGs and the proposed MCLs for PFOS and PFOA in drinking water.

Two additional health advisory levels were also announced June 15, 2022: 10 ppt for GenX and 2,000 ppt for PFBS. The EPA has now proposed a hazard index calculation for: PFNA, PFHxS, PFBS, and GenX. This index takes the levels of each of these compounds and divides them by a health-based water concentration. OWASA has not to this point shown detectable levels of GenX in our water supply or treated drinking water, and levels of PFNA, PFHxS, and PFBS have been below the health-based levels, meaning the hazard index calculation results have been a value less than 1.

Quarterly sampling results dating back to OWASA’s initial proactive monitoring in 2018 are available on the OWASA website. Higher levels of PFAS have been detected in Cane Creek Reservoir than in University Lake or the Quarry Reservoir. As a result, Cane Creek Reservoir has been the focus of source-water sampling in our monitoring effort. We have not identified any major direct sources of PFAS such as industrial facilities, airports, etc. that discharge into our Cane Creek Reservoir watershed. In the past, other utilities have land-applied biosolids in the Cane Creek Reservoir watershed. To our knowledge, that practice has ceased. However, we may continue to see impacts from the previous practice for some time to come.

Next Steps

As the EPA finalizes future drinking water standards, OWASA will continue supporting and participating in research into PFAS compounds in our water. OWASA is working with a consultant to actively identify and pursue treatment technologies to remove these compounds. In the interim, we are working toward feasible strategies to further reduce levels of PFAS in our drinking water, utilizing our current treatment methods. OWASA’s near- and longer-term actions include:

• Compliance Schedule: The issuance of the proposed drinking water MCLs is followed by a 60-day public comment period. The EPA anticipates finalizing the regulation by the end of 2023. Once enacted, the rule is expected to require compliance within three to five years from the effective MCL date. The rule may allow for extensions if facilities are under construction by the compliance date.
• Monitoring: We are continuing, with assistance from our consultant, to monitor source water, drinking water, wastewater, and biosolids.
• Interim Measures: Over the next six months, we will run bench-scale testing to determine feasible strategies to further reduce levels of PFAS in our drinking water, utilizing our current treatment methods. We do not expect these methods to be sufficient to meet future regulatory requirements.
• Preliminary engineering for a treatment solution: Concurrently, we will conduct bench-scale testing on potential water treatment technologies to determine the long-term solution for removal of these compounds for our drinking water. Full-scale pilot testing of one or more technologies may be necessary to determine effectiveness. Pilot testing could take nine to twelve months.
• Design and construction: Once a treatment technology is selected, the detailed design of a new treatment process would take about a year, followed by 18 to 24 months of construction.
• Holistic response: While the upcoming rule is drinking water-based, and our near-term focus is on drinking water treatment, our ultimate response will include addressing PFAS throughout our system.

We will remain in communication with additional details for customers as we know more.

Partner Resources

• Our Current Understanding of the Human Health and Environmental Risks of PFAS (Environmental Protection Agency)
• How Can I Be Exposed to PFAS (Centers for Disease Control and Prevention)
• PFAS Water Testing and Filtration Resources (North Carolina Department of Health and Human Services)
• 10 Things You can Do About Toxic PFAS Chemicals (Clean Water Action)