PFAS Information

Drinking water provided to DSRSD’s customers is supplied by the Tri-Valley’s wholesale water supplier, Zone 7 Water Agency (Zone 7). The drinking water supplied by Zone 7 is comprised of a blend of groundwater from local wells and surface water from the State Water Project. Zone 7 monitors for PFAS in groundwater and surface water sources on a quarterly schedule.

Federal Environmental Protection Agency (EPA) Efforts

On April 10, 2024, the EPA finalized the first national primary drinking water regulation to establish legally enforceable levels called Maximum Contaminant Levels (MCLs) for six (6) PFAS compounds. 

All public water systems will have three years from the time the rule was finalized to complete their initial monitoring. If PFAS are found to exceed primary standards, systems must implement a solution to reduce PFAS in their drinking water within five years of the rule being finalized.  

Beginning in 2029, public water systems that have PFAS in drinking water which violates one or more of these primary standards must take action to reduce levels of these PFAS in their drinking water and must provide notification of the public violation.

State of California Division of Drinking Water (DDW) Efforts

California has implemented drinking water advisory levels for four PFAS compounds including perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and perfluorohexanesulfonic acid (PFHxS). See the following table for DDW’s current health-based advisory levels:

State Regulatory Advisory Levels for PFAS in Drinking Water Sources (nanogram per liter or parts per trillion [ppt])

At this time, final federal regulatory limits on PFAS in drinking water have been issued. Public water systems will need to complete initial monitoring for PFAS by 2027 and if PFAS is detected above the MCL, public water systems will have until 2029 to implement solutions that reduce PFAS. Beginning in 2029, public water systems that have PFAS in drinking water which violated one or more of these MCLs must take action to reduce levels of these PFAS in their drinking water and must provide notification to the public of the violation.

Zone 7 manages the water supply served to DSRSD. Zone 7 has conducted and completed a PFAS Potential Source Investigation; a PFAS mobilization analysis is available on Zone 7’s website. In addition to the studies, Zone 7 is actively monitoring for PFAS across its groundwater basin and surface water supply. 

Zone 7 has opened a new treatment facility at their Stoneridge well location and is in the process of planning, designing, and building another PFAS treatment facility that is projected to be in operation in Summer 2024. 

Zone 7 continues to be proactive in operating its water supply systems to ensure the water supply from PFAS-affected groundwater wells remains below the response levels. These operational proactive measures include treatment at the Stoneridge Treatment Facility, blending well water and/or treatment through the Mocho Groundwater Demineralization Facility. 

DSRSD is conducting testing for PFAS compounds during the EPA’s Unregulated Contaminant Monitoring Rule study in 2023–2025. Results will be available in the Annual Water Quality Report of the testing year.

People are exposed to PFAS primarily by eating food contaminated by the migration of PFAS from packaging, and some foods (e.g., fish, meat, eggs, and leafy vegetables) that may contain PFAS due to bioaccumulation and crop uptake.

People can also be exposed to PFAS by breathing in or touching products treated with PFAS (carpets, upholstery, cosmetics, or clothing). Industry experts estimate that 20% of an individual’s normal exposure to PFAS is from the water they drink.

• DSRSD’s Annual Water Quality Reports
  
• Zone 7’s PFAS Information Webpage