Stoneridge Well PFAS Treatment System Project


In a continuing effort to supply the Tri-Valley with safe, reliable water that surpasses state and federal drinking water standards, Zone 7 is in the final stages of constructing a water treatment system to address Per- and Polyfluoroalkyl substances (PFAS) found in the local groundwater at the Stoneridge Well. The treatment system went online in September 2023 and final construction at the facility is anticipated to be complete by Spring 2024.

Existing facility
With the proposed treatment facility
  • The purpose of the project is to add necessary water treatment facilities to the existing Stoneridge Well to remove PFAS from the well’s groundwater supply.
    • Installation of Ion Exchange (IX) treatment system for PFAS removal
    • Rerouting of existing site piping, additional new site piping and appurtenances, and new booster pump
    • Chemical systems modifications, new electrical equipment and building, and new instrumentation and controls
  • The cost for the project is $16.3 million for planning, design, and construction
  • Construction is taking place at Zone 7’s Stoneridge Well, located at 3750 Stoneridge Drive in Pleasanton.
  • Download our general one-sheet to get an overview of the new facility. Stoneridge Well General One-Sheet
  • Download our technical one-sheet for detailed information on the technology. Stoneridge Well Technical One-Sheet
Ion Exchange Treatment
How Ion Exchange Treatment works at Stoneridge to remove PFAS



Please contact Brandon Woods at (925) 454-5078 or with any concerns. We appreciate your patience throughout the construction of this project as we make these important improvements to your water treatment system. 

Learn more about PFAS
  • All water supplied to our customers meets the regulatory standards set by the state and federal governments. 
  • In almost all cases, the quality was significantly better than required. 
  • Zone 7 continues to deliver all water below the California Division of Drinking Water’s response levels for PFOA and PFOS.
  • For more information about how we keep your water safe from PFAS click here.
  • To learn about new PFHxS advisory levels click here.