General information on PFOS/PFOA is below. Details about Cal Water’s position are available on the Leadership on PFAS page.

Common names for PFOS are perfluoroctanesulfonic acid and perfluoroctylsulfonic acid. Some common PFOA names include perfluorocaprylic acid, perfluoroctanoic acid, and perfluoroheptanecarboxylic acid. PFOS and PFOA are manmade compounds that have been used to make carpets, clothing, fabrics for furniture, paper packaging for food, and other materials (e.g., cookware) that are resistant to water, grease, or stains. They are also used for firefighting at airfields and in a number of industrial processes.

Protecting our customers’ health and safety is our highest priority, and Cal Water is committed to complying with all standards set by the public health experts. Although PFOS and PFOA do not have maximum contaminant levels (MCL), Cal Water has been monitoring for the presence of PFOS and PFOA in districts with a population greater than 10,000 as part of the Unregulated Contaminant Monitoring Rule (UCMR) sampling because they are constituents of interest to the U.S. Environmental Protection Agency (EPA).

In early 2020, the State Water Resources Control Board’s Division of Drinking Water announced reduced response levels for PFOA and PFOS (10 ppt for PFOA, and 40 ppt for PFOS). Knowing that these are constituents of emerging concern, Cal Water had already identified water sources and tested sites that would be more likely to have these compounds present. In our Chico, Visalia, and East Los Angeles districts, where we had one well (in each district) that exceeded the previous HA and response level, we discontinued use of those sources. With the updated response levels announced by the State Water Resources Control Board’s Division of Drinking Water (DDW), we are working through our plan to conduct testing for these constituents.

Studies indicate that long-term exposure to PFOS and PFOA over certain levels could have adverse health effects, including developmental effects to fetuses during pregnancy or breastfed infants; cancer; or liver, immunity, thyroid, and other effects. Potential health impacts related to PFAS compounds from all sources (which also include food wrappers, firefighting foam, and non-stick cookware, for example) are still being studied, and research is still evolving on this issue. As such, we will continue to monitor whether DDW will set a maximum contaminant level for PFOA and PFOS, and will comply with any regulations eventually set.

This does shed light on the importance of protecting our water resources. While we are doing our part to treat the water and meet the standards the public health experts have set, it’s important that our population as a whole focuses on being good stewards of the environment and takes steps to prevent impacting the water supply.

More information on PFOS and PFOA is available at: