The State Water Resources Control Board heard a midway update Aug. 6 on a statewide PFAS testing effort required by Assembly Bill 178 that is sampling disadvantaged-community drinking‑water wells. Division of Drinking Water staff said the 2024 order covers roughly 3,600 wells and that crews have sampled about 70% (approximately 2,500 wells) so far.

The testing program uses multiple laboratory methods to capture both established PFAS analytes and a broader proxy of total PFAS mass. "PFAS is a four‑letter acronym, but it is a class of chemicals that is over 10,000 strong," Dan Newton, assistant deputy director for the Northern Field branch in the Division of Drinking Water, told the board. He and Division of Water Quality staff described results from targeted, ultra‑short, total‑mass, and non‑target analyses.

Why this matters: the project is intended to produce a statewide snapshot in disadvantaged communities to inform future monitoring and potential regulatory work. The dataset—staff said the sampling program is uncommon in scale for drinking water—will also shape decisions on monitoring orders and on whether class‑based regulatory or treatment approaches are appropriate.

Key findings presented

- Scope and partners: Staff described the project as a multi‑partner effort involving US EPA Office of Research and Development (ORD), California State University Sacramento (contracted through a DFA grant), the contract field firm Geosyntec, and an expanded statewide lab contract with Babcock Lab. The department said it pooled federal and state grant funds to design and execute the work.

- Targeted analyses (EPA Method 533): Using the federally recognized targeted method that tests roughly 25 PFAS analytes, staff reported detections in about 1 in 10 sampled wells (roughly a 10% detection rate). Median concentrations for the commonly studied analytes were low: for PFOA the median seen so far was about 3.5 nanograms per liter (ng/L), below the U.S. EPA MCL of 4 ng/L. Staff said most detected concentrations were well under 20 ng/L and that outliers exist.

- Absorbable organic fluorine (AOF), a total‑mass proxy: AOF screening, chosen after method comparison work, returned presence in roughly 36% of sampled wells. Staff cautioned that current AOF detection limits are relatively high (on the order of several hundred parts per trillion) and that lowering the method detection limit could increase the measured presence. "We have a presence of 30% 36% of our wells have AOF presence," Newton said during the briefing.

- Ultra‑short PFAS subset and TFA: Because of budget limits, ultra‑short PFAS (including trifluoroacetic acid, TFA) and non‑target analyses were run on a subset of about 300–350 samples intended to represent statewide coverage. In that subset staff reported a 100% detection rate for TFA, with a median concentration around 780 ng/L. Staff noted international screening levels range widely (for example, the Netherlands has reported a guideline of ~2,200 ng/L for TFA), and that health effects for ultra‑short PFAS remain an area of active study.

- Non‑target analysis (NTA): Using high‑resolution mass spectrometry and a spectral library developed with EPA ORD, the NTA work identified a large number of compounds. Staff reported they are "about 94% confident" in most identifications but that roughly 53 compounds remain low‑confidence and will be re‑evaluated as spectral libraries expand. Importantly, staff said roughly 90% of unique chemicals flagged by NTA so far are not fluorinated, underscoring that much of the non‑target signal represents non‑PFAS organics.

Technical and program context

- Methods and limits: Staff emphasized the program used multiple complementary methods—targeted EPA 533, IC‑MS/MS for ultra‑short PFAS, EPA Method 1621 AOF for fluorine mass, and academic‑grade NTA at high resolution—because no single commercial test today captures the entire PFAS chemical space. The board heard that AOF has limits and that staff will also evaluate extractable organic fluorine (EOF) going forward.

- Timing and next steps: Staff said sampling should be completed early in 2026 and that a new order to finish monitoring required by the federal PFAS rule is planned for January 2026. Staff also said they will re‑run NTA analyses as the spectral library grows and will refine AOF/EOF detection limits.

- Treatment and recycling: Board members asked about removal in advanced treatment and reuse systems. Staff said reverse osmosis as part of direct or indirect potable reuse provides a barrier that prevents PFAS passage into the treated product but moves PFAS into a concentrated reject stream that still requires management.

Board and public comments

Chair Joaquin Esquivel said the work should reassure the public about California’s approach to water safety: "we have the strongest standards in the nation here as a state when it comes to the safety of our water," he said while noting PFAS remain an emerging challenge.

Public commenters and stakeholder groups welcomed the data but urged attention to funding and operational implications for water systems. Megan Murphy of the California Municipal Utilities Association asked that state funding accompany monitoring and treatment requirements. Nick Blair of the Association of California Water Agencies and Sue Mossberg of the California‑Nevada section of AWWA noted the operational challenges systems face when new advisory or regulatory levels are set.

What staff said they will do next

- Finish the 2024 order sampling early in 2026 and publish a target schedule for completing federal monitoring obligations.
- Lower AOF/EOF detection limits where possible and refine methods for ultra‑short PFAS.
- Re‑run non‑target analyses as spectral libraries improve and validate low‑confidence identifications.
- Work with OEHHA on health guidance and with other CalEPA agencies on source controls and pretreatment options to reduce PFAS loads to wastewater.

Limitations and caveats

Staff repeatedly cautioned that the results presented were interim, that some subsets (ultra‑short and NTA) represent only a few hundred samples because of budget constraints, and that many findings (particularly AOF and NTA) are method‑dependent and subject to revision as methods and libraries improve.

The board did not take formal action on the report. Staff framed the update as a midpoint briefing intended to share emerging trends and to solicit feedback before completing the full dataset and analyses.

Ending note

Division staff and the board characterized the results as mixed: targeted detections are less widespread than some had feared, but broader mass measures and non‑target chemistry show the issue is complex and evolving. Staff said the data will guide monitoring, method development, and potential treatment or regulatory approaches as the state finishes sampling and prepares next steps.