Info About PFAS and Drinking Water

Flier showing timeline of monitoring, studying, and evaluating PFAS in Dayton waterLine graph showing PFAS results in parts per trillion for the Ottawa Water Treatment Plant


PFAS – or per- and polyfluoroalkyl substances – are a group of manmade chemicals including PFOA and PFOS found in a wide range of everyday products. These products are used by consumers and in industry. For example, PFAS have been used in coatings for textiles, paper products and cookware, so most people have been exposed to these chemicals at very low levels. They have also been used to make some firefighting foams in the aerospace and aviation industries and at military bases across the nation. For detailed information about PFAS, visit the U.S. EPA’s website on PFAS: Information is also available at the Agency for Toxic Substances and Disease Registry:


The regulations for PFOA and PFOS in drinking water are based upon human studies in populations exposed to them and have found associations between exposure and effects on the immune system, human development, and cancer. These  take into account other potential sources of exposure. The substances have been used for years in many common products, such as fast-food wrappers, stain-resistant carpets and rugs, non-stick cookware, water-resistant clothing, cosmetics, and dozens of other items.  For detailed information about PFAS, visit the U.S. EPA’s website on PFAS: Information is also available at the Agency for Toxic Substances and Disease Registry:


The water we deliver to our customers meets all current regulatory requirements. If you have questions about your water and its potential effect on your health, we strongly encourage following the U.S. EPA’s guidance, Questions and Answers: Drinking Water Health Advisories for PFOA, PFOS, GenX Chemicals and PFBS | US EPA, which includes contacting your health care provider. 

Dayton has an extensive monitoring well network and uses these wells to provide early warning of possible risks. Monitoring wells are used for testing only and do not send water to our customers. This monitoring well network allows scientists and water professionals to act before contaminants reach drinking water and ensuring its quality.

Testing of monitoring wells detected PFAS at low levels in some of the wells. Dayton took quick action by shutting down eight nearby production wells. Production wells send water to the treatment plants. This was a precautionary action and did not affect our water customers. The Great Miami Buried Valley Aquifer has over 1.5 trillion gallons of water, of which Dayton customers only use about 60-65 million gallons each day. 

The chart at the top of this page provides the levels of PFOA/PFOS compounds in the effluent at our Ottawa Water Treatment Plant. These levels are above the current proposed guidelines set by the EPA. The levels of PFOA/PFOS compounds at our Miami Water Treatment Plant are non-detect, which means the levels are below current proposed federal guidelines.


PFAS get into the groundwater through the runoff of substances with PFAS in them. PFAS in the groundwater has been identified at multiple sites. The migration of PFAS in the groundwater toward the City’s wellfields is carefully monitored.


The City operates a robust early warning monitoring system discussed above. In fact, the system detected the new PFAS contaminant. We acted by shutting down production wells closest to possible PFAS sources. 

Our Source Water Protection Program is nationally recognized. In 2019, the program received its 25th award as a Groundwater Guardian Community. The award, from The Groundwater Foundation, is for programs that protect groundwater. For information about The Groundwater Foundation, visit

Dayton proactively and aggressively tests for contaminants, acts on the information, and communicates with its customers. Additionally, Dayton has developed a PFAS Strategy to address this contamination. Dayton is working closely with the Ohio EPA to implement the PFAS Strategy and has received approval for 0% interest, principal forgiveness funding (similar to a grant) for $14.9 million for program year 2023 to begin the implementation of the strategy. This funding is available through the Bipartisan Infrastructure Law (BIL). BIL will distribute funding to Ohio for five years and Dayton will apply for funding for its PFAS Strategy each year. Dayton is applying for over $28 million for program year 2024 to continue the implementation of our PFAS Strategy. 


The City has been taking action on PFAS for years. We test extensively, sampling our water more than is required, to make sure that our water meets or exceeds all drinking water standards.

We have more than 500 groundwater monitoring wells placed around the City’s production wells and wellfields. These monitoring wells are used to identify groundwater contaminants. They do not produce water used by customers. Production wells produce water used by customers. The system is designed so that monitoring wells can detect contaminants in groundwater before it reaches the production wells.

Our water distribution system is tested daily from many locations within the city. Also, water treatment plant employees perform process control testing every two hours each day.

 We share the results of our testing with the Ohio EPA monthly while voluntarily and continually working with the U.S. and Ohio EPA to address PFAS. We work to stop PFAS-contaminated groundwater from reaching monitoring and production wells.  

For the protection of our community, we have proactively shut down production wells close to potential PFAS sources. In addition, we work to use the smartest approaches to pumping in our well fields to ensure our customers receive the highest quality water. In conjunction with the U.S. and Ohio EPA, we’ve studied, evaluated, and are in the final stages of deciding the most cost-effective and safest steps toward our goal of no PFAS in our drinking water.

Click this link:  Water Emergency Preparedness for information about Water Emergency Preparedness.