PFAS regulation in California: What lawyers need to know

Per- and polyfluoroalkyl substances (PFAS), colloquially known as "forever chemicals," are rapidly moving from an emerging environmental concern to a key area of regulatory and litigation risk in California. PFAS are a group of more than 14,000 chemicals that have been widely used in consumer products like nonstick cookware, waterproof clothing, stain-resistant carpeting and furniture, food packaging such as fast-food wrappers and pizza boxes, cosmetics, dental floss, cleaners and paints. As a result of their presence in these products, they are often found in landfills where these items are disposed. PFAS also have many industrial and other uses, such as fire-fighting foam used at airports and firefighter training facilities to extinguish jet fuel and other high-intensity fires. This ubiquitous use has meant ubiquitous presence in the environment--and in human beings. PFAS compounds have been detected at the top of Mt. Everest, in polar bear blood and in the blood of most people tested.

They are now the subject of an evolving regulatory framework that is becoming both more fragmented and more enforceable, as distinct from prior non-binding guidelines. For lawyers in California, the key challenge is not simply understanding the science regarding PFAS but rather advising clients in a landscape where regulatory standards are tightening and proliferating, and litigation and regulatory risk is growing.

The regulatory framework for PFAS in California includes several key areas. The first area arises because, in 2024, the U.S. Environmental Protection Agency (EPA) designated two common PFAS compounds as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act, also known as the Superfund law. This designation significantly expands liability for any past or former property owner or operator of property impacted by these PFAS compounds, and for generators and transporters of waste containing them to off-site disposal facilities.

This risk means the purchasers of PFAS-impacted property may also buy a regulatory enforcement action or lawsuit from neighboring property owners who assert migrating impacts, employees who assert on-site exposure and other litigation. Real estate lawyers should carefully consider these risks when conducting Phase I and II environmental site assessments and drafting representations and warranties, indemnification, and other liability-shifting provisions in purchase and sale agreements. Corporate counsel should similarly consider these risks in mergers and acquisitions.

Class actions against manufacturers that have used PFAS involving personal injury and property damage claims, including suits by municipalities over alleged impacts to drinking and surface water, are becoming more common too.

The second key area of PFAS regulation involves legally enforceable federal drinking water standards called Maximum Contaminant Levels (MCLs) promulgated by the EPA. In 2024, the EPA established MCLs for five PFAS compounds and a sixth "hazard index" that involves calculating the health hazard posed by mixtures of two or more of the other compounds. Municipal water agencies must test their drinking water for these compounds and had three years, until 2027, to implement that testing. Those agencies then have five years from promulgation, until 2029, to implement measures to reduce these PFAS compounds--or the hazard index--below the MCLs if there are exceedances.

In an example of the ever-shifting PFAS regulatory landscape, in 2025, the EPA announced its intent to rescind the PFAS MCL regulation for three of the five compounds and the hazard index, leaving only two of them federally regulated in drinking water. This new rule would also extend the MCL compliance deadline to 2031. It is expected to be finalized this spring.

A third and related key regulatory area involves regulations promulgated by the State Water Resources Control Board Division of Drinking Water that apply to drinking water served by municipal water agencies in California. These requirements overlap with the federal regulatory structure established by the EPA. The California regime involves a two-tiered system that includes notification levels and response levels. Notification levels are chemical concentrations below which, according to the state, there are no significant health risks to individuals consuming the drinking water daily. Exceedance of a notification level triggers requirements to notify the Division of Drinking Water and include the exceedance in the agency's annual Consumer Confidence Report.

Exceedance of the more stringent response level on an annual average basis --or a one-time basis for certain chemicals with a higher toxicology risk--triggers an additional requirement remove the water source from service immediately, treat or blend the water, or notify the public about the exceedance within 30 days.

The Division of Drinking Water has promulgated notification and response levels for four PFAS chemicals, some of which are consistent with the revised EPA drinking water regulation and some of which are not covered by the federal regulation.

Counsel advising municipal water agencies in California should understand and communicate the federal and state notice and response requirements and craft a communication strategy for exceedances.

PFAS risk is no longer an emerging issue--it has arrived. California counsel across practice areas should treat PFAS exposure as a standard element of due diligence, compliance review, and litigation risk assessment going forward.