Drinking Water and Per- and Polyfluoroalkyl Substances (PFAS)

Lake Oswego currently meets or exceeds all federal and state requirements for water quality testing. PFAS is an emerging issue that all water providers and systems across the nation are experiencing. The City is committed to protecting public health.

Fortunately, Lake Oswego's drinking water is at low risk for PFAS, and PFAS have not been detected in our drinking water distribution system.

What are PFAS?

Per- and Polyfluoroalkyl substances (PFAS) are a group of human-made chemicals found in a wide range of industry and consumer products. PFAS have been widely used by manufacturers since the 1940s and remain in the environment for a long time. These chemicals provide grease- and water-resistant properties in many everyday products. Some examples of products include:

• Non-stick pans
• Stain-resistant fabric
• Firefighting foam
• Some waxes
• Waterproof rainwear
• Paper food packaging

Why are PFAS a concern?

PFAS do not break down easily, which means they stay in the environment. PFAS move easily through the ground, getting into groundwater that is used for some water supplies or for private drinking water wells. When released into lakes or rivers used as sources of drinking water, they can get into drinking water supplies. Some of the chemicals are now known to be harmful to human health. 

What is the Unregulated Contaminant Monitoring Rule 5?

The purpose of the Unregulated Contaminant Monitoring Rule (UCMR) is to assist the EPA in determining the occurrence of unregulated contaminants in drinking water and whether future regulation is warranted.

The EPA’s fifth UCMR 5 aims to provide the EPA with data to understand the frequency that 29 per- and polyfluoroalkyl substances (PFAS) and lithium are found in the nation’s drinking water systems. It requires sample collection of the Lake Oswego water supply.

PFAS drinking water results for Lake Oswego 

In 2023-2024, as part of the UCMR 5, the Lake Oswego Tigard Water Partnership sampled the water system for a group of 29 PFAS and lithium contaminants. No detections were found in the drinking water supply.

A full list of contaminants tested and their results can be found in the attachments.

How is Lake Oswego protecting our drinking water from PFAS?

The best way to keep drinking water safe is to protect it at its source. In partnership with the Clackamas River Water Providers, a coalition of water providers that get their water from the Clackamas River, the cities of Lake Oswego and Tigard fund and participate in a source water protection and monitoring program.  Through this program, we are working proactively with our local partners on everything from spill response to pesticide collection events, and drinking watershed awareness to keep unwanted chemicals out of our water supply.

To learn more about PFAS, click on the helpful links included on the right hand side bar.