Emerging Contaminants

Cary is committed to providing high-quality, safe drinking water and closely follows the scientific study of contaminants of emerging concern. More than 100,000 chemicals are registered in the United States, and new chemicals and microorganisms continue to be identified.

Improved technology is measuring substances at lower thresholds every year. Some of these contaminants can now be detected at extremely low levels (parts per trillion, or ppt concentrations). For reference, one ppt is the approximate equivalent of one grain of sugar dissolved in an Olympic-sized swimming pool. The fact that a substance is detectable doesn’t always mean it is harmful. The health significance of these trace contaminants is often under review and the subject of further study and research.

Each year Cary tests your drinking water over 100,000 times for many substances including the contaminants of emerging concern: Per- and polyfluoroalkyl substances (PFAS), and 1,4-dioxane. For a comprehensive report of all laboratory test results, see Cary’s Water Quality Testing Summary.

Per- and Polyfluoroalkyl Substances (PFAS)

PFAS are a class of man-made chemicals used for consumer product applications such as waterproof and stainproof fabrics, nonstick cookware, some food packaging materials, and fire suppression foams. In addition to our already extensive water treatment process, Cary consistently feeds powdered activated carbon, which has been effective at reducing PFAS in drinking water.

Following years of scientific testing and evaluation, on April 10, 2024, EPA finalized a National Primary Drinking Water Regulation (NPDWR) establishing legally enforceable limits for five PFAS in drinking water: PFOA, PFOS, PFHxS, PFNA, and HFPO-DA. Additionally, they set a limit for four PFAS contaminants as a mixture: PFHxS, PFNA, HFPO-DA, and PFBS.

Exposure to these six compounds is linked to adverse health effects at very low concentrations. Cary’s drinking water has consistently tested below these levels over several years since we began our proactive monitoring and testing plan.

Cary Proactively Utilizes Advanced Treatment Technology to Minimize PFAS Substances in Drinking Water

Cary has been actively following the national discussion of PFAS since we first tested for these substances in 2015 as part of UCMR3 or the Unregulated Contaminant Monitoring Rule and then subsequently tested and detected PFAS in late 2017. Cary proactively studied and pilot tested several water treatment optimization processes known to enhance PFAS removal in early 2018. One such process available for implementation was carbon adsorption with a product called powder activated carbon (PAC), which has multiple benefits for other stages of water treatment along with reducing PFAS. Studies indicated this method was beneficial and effective at further reducing PFAS at low concentration levels. As such, Cary immediately implemented this process continuously as part of our already advanced water treatment process during 2018 and we’ve been consistently using this process optimization for the past several years to improve PFAS removal, well before PFAS was proposed to be regulated. The combination of PAC with our existing process including ozonation provides an even higher level of sophisticated multiple barrier water treatment technology to support advanced treatment of both regulated and unregulated substances for removal from Cary’s drinking water. Subsequent testing shows extremely low PFAS levels in finished drinking water that are below the new maximum contaminant levels announced by EPA.

Per and Polyfluoroalkyl (PFAS) Substance

Finished Drinking Water PFOA & PFOS by Year

At the time of publication, 2 parts per trillion is the minimum detection threshold and 4 parts per trillion is the MCL announced by EPA.

Cary's PFAS Fact Sheet 

The latest test results for Per and Polyfluoroalkyl Substances (PFAS) is summarized in the following Fact Sheet:

• Fact Sheet on Per and Polyfluoroalkyl Substances (PFAS)

 What is Cary Doing About PFAS?

Cary recognizes the importance of continued action to further enhance PFAS removal and makes research a priority. We have been engaged in research, study, and treatment for enhanced PFAS removal for several years. Our actions to date include:

• Ongoing testing, monitoring, and reporting of PFAS to the public 
• Treatment and removal with powdered activated carbon
• Engineering study of enhanced removal options
• Coordination with federal and state agencies
• Following research efforts within our region and nationally
• Conducting additional study and pilot testing of new technologies, and
• Upgrading Cary’s already advanced multi-barrier water treatment process

1,4-dioxane

1,4-dioxane is a colorless, flammable liquid often used as a solvent or solvent stabilizer in the manufacture and processing of polyethylene terephthalate (PET), cotton, textile products, automotive coolant, cosmetics, shampoos, and other products. The test results demonstrate that 1,4-dioxane levels in our drinking water have been well below the U.S. EPA's health advisory.

• Fact Sheet on 1,4-dioxane

Lab Reports

Additionally, the individual lab reports containing Per- and polyfluoroalkyl substances (PFAS) and 1,4-dioxane levels can be found in our reports archive (see link below). New reports are added as soon as they become available. (Please note: reports include test results for both raw water - the untreated source water from Jordan Lake, and the Filter Effluent - the treated drinking water.)

• Per- and Polyfluoroalkyl Substances (PFAS) Lab Reports
•  1,4-dioxane Lab Reports

Resources

• EPA PFAS Final National Primary Drinking Water Regulation
• EPA Press Release - First Ever National Standard for PFAS
• Town of Cary Annual Water Quality Report
• Home water testing and filtration information from the North Carolina Department of Health and Human Services
• EPA's PFAS Home Filtration Fact Sheet
• PFAS: What You Need to Know (Environmental Protection Agency)
• EPA PFAS National Primary Drinking Water Regulation Fact Sheet

Contact

Call 311 or (919) 469-4000 outside Cary limits.

For more information about contaminants and potential health effects, call the EPA’s Safe Drinking Water Hotline toll free at: (800) 426-4791 to speak with an information specialist during normal hours of operation. Bilingual service, including recorded messages, is available 24 hours per day, seven days per week, in English and Spanish.