PFAS information

What are PFAS?

Per- and Polyfluoroalkyl Substances (PFAS) are human-made compounds that are typically manufactured for their non-stick, heat-resistant, water and oil resistant properties. PFAS are widespread in the environment, they are used in many consumer products including cookware, carpets, clothes, furniture fabrics, food packaging, and fire-fighting foams. They degrade extremely slowly and remain persistent in the environment.

There are thousands of different PFAS. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are two PFAS that have been well studied. Certain PFAS are no longer manufactured in the US. However, they may still be produced internationally and are imported into the US in consumer goods.

Most people have been exposed to these chemicals through consumer products, and virtually all Americans have detectable levels of PFAS in their blood. These chemicals have been widely used for decades in industrial applications and consumer products.

PFAS are not naturally occurring; when PFAS are spilled into to the environment they can seep into groundwater and stay there for many years and potentially travel great distances. PFAS have been found in surface water as a result of a release from industrial facilities using these chemicals. PFAS have been found in groundwater below industrial sites, particularly airports, firefighting/training sites, and landfills.

EPA finalized new enforcable standards for six PFAS compounds in drinking water in April 2024.The six newly-regulated PFAS are PFOA, PFOS, PFBS, PFNA, HFPO-DA, and PFHxS.  Water suppliers including EBMUD are required to sample for PFAS and if necessary, treat the water to ensure compliance with the new levels. Initial monitoring must be done by 2027, and the standards must be met by 2029.

In 2019, California developed "Notification Levels" for two specific PFAS. PFOS has a notification of 6.5 ppt, and PFOA’s is 5.1 ppt. Exceeding the notification level would require notification of the State Water Board. In 2020, California adopted a "Response Level" of 10 ppt for PFOA and 40 ppt for PFOS. Exceeding the Response Level would require that the source be taken out of service or that formal, written public notification be made.

In California, AB 756 (effective Jan 1, 2020) authorized the State Water Board to require water systems to sample for PFAS. Monitoring is being done in phases, with high-risk systems starting first in accordance with specific Monitoring Orders from the State Water Board. Results are posted on DDW’s website. EBMUD has not yet been included in the Monitoring Orders under AB 756 except for the supplemental supply from the Sacramento River at Freeport.


EBMUD's drinking water sources are fairly well protected from human-made contaminants. The Mokelumne River watershed and Pardee Reservoir are located in the Sierra Nevada foothills, far from industrial contamination sources. Our local reservoirs, such as Upper San Leandro and San Pablo Reservoirs are also well protected, surrounded by sparsely populated watershed lands. Nonetheless, PFAS are widespread in the environment and they are detected at very low levels nearly everywhere.

EBMUD tested for PFOA and PFOS in 2013-2015 as required by EPA's Unregulated Contaminant Monitoring Rule 3 (UCMR3). No PFAS were detected at that time.

Analytical methods have improved since UCMR3, and detection levels today are much lower. Based on prior sampling, and the protected nature of our watersheds, EBMUD is not required to sample under existing State Water Board Monitoring Orders because EBMUD’s system is not considered at risk.

Although not required, EBMUD sampled its source waters and treated waters in 2020 and 2021 for PFAS.In this descretionary monitoring, all results (all locations and all parameters) were below the state's Notification Levels. Some low concentrations of some PFAS compounds were detected, including PFOA and PFOS. Some individual PFOA and PFOS results were slightly higher than the new enforceable standards set by EPA of 4 ppt (results varied from <1.8 ppt to 4.9 ppt).

EBMUD is currently sampling for a longer list of PFAS using two analytical methods, EPA method 537.1 and EPA method 533. This monitoring is requried by EPA under the UCMR5. Monitoring began in early 2023 and must be completed by 2025. All results so far are lower than EPA's proposed regulatory standards and lower than California's Notification Levels, however there were some low-level detections of some PFAS.

EPA will release PFAS monitoring data from all water systems, including EBMUD, as it becomes available here. EPA also has a Data Finder Website for UCMR5 results here.


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