California Drinking Water Regulations: Permits, PFAS, and Enforcement

California drinking water regulations are enforced by the State Water Resources Control Board (SWRCB) through its Division of Drinking Water (DDW), which issues operating permits, sets contaminant limits that often go beyond federal law, requires tiered public notification of violations, and backs it all with penalties that can reach $1,000 per day under state law and far more under federal law. If you run or advise a public water system in the state, your compliance obligations are expanding: new hexavalent chromium limits phase in starting in 2026, and PFAS rulemaking is actively underway.

Who Regulates Public Water Systems

The DDW is the primary regulator. It issues permits, conducts inspections, enforces the California Safe Drinking Water Act, and implements federal Safe Drinking Water Act standards.1California State Water Resources Control Board. Drinking Water Program

Smaller systems with 200 or fewer service connections are usually regulated by local primacy agencies (LPAs), typically county health departments operating under agreements with the SWRCB. LPAs handle compliance monitoring, sanitary surveys, and day-to-day water quality oversight for those systems.2California State Water Resources Control Board. Glossary – Local Primary Agency (LPA)

The U.S. Environmental Protection Agency retains backup authority. If California fails to meet federal requirements, the EPA can intervene in enforcement, impose monitoring, or begin withdrawing the state’s primary enforcement responsibility.3Federal Register. National Primary Drinking Water Regulations Implementation Primary Enforcement Responsibility – Final Rule That authority has never been exercised against California.

The Operating Permit

No one may operate a public water system in California without first obtaining a permit from the SWRCB. Applications must include engineering reports, proposed water sources, system design plans, and operational procedures. The DDW reviews each application for water supply reliability, source protection, and the system’s ability to meet contaminant limits.4California State Water Resources Control Board. Safe Drinking Water Act Turns 50

A central piece of the review is whether the system can demonstrate technical, managerial, and financial capacity. Technical capacity is the infrastructure and staff expertise to treat and deliver safe water. Managerial capacity covers organizational structure, staffing, and customer communication. Financial capacity means the system can generate and manage enough revenue to stay in compliance over the long term.5EPA. EPA Regional Capacity Development Coordinator’s Handbook Systems that can’t show this capacity are generally ineligible for Drinking Water State Revolving Fund assistance.

Expanding or modifying infrastructure after a permit is issued requires an amended permit before the work proceeds. Temporary permits exist for emergencies, but they carry strict time limits and heightened monitoring. Water systems also pay annual regulatory fees to fund DDW oversight, and failure to obtain or renew a permit can lead to a cease-and-desist order that shuts operations down until compliance is restored.

Contaminant Limits That Go Beyond Federal Rules

California sets maximum contaminant levels (MCLs) for chemicals, metals, and microorganisms, and several of those limits are stricter than federal thresholds.

The clearest current example is hexavalent chromium (chromium-6). California adopted an MCL of 0.010 mg/L, effective October 1, 2024, with compliance deadlines staggered by system size: systems serving 10,000 or more connections must comply by October 1, 2026, mid-size systems by October 2027, and smaller systems by October 2028.6California State Water Resources Control Board. Hexavalent Chromium MCL (SWRCB-DDW-21-003) No separate federal MCL exists for hexavalent chromium, so this is a California-only obligation.

For arsenic, California’s MCL of 0.010 mg/L matches the federal standard.7California State Water Resources Control Board. MCLs, DLRs, PHGs for Regulated Drinking Water Contaminants8US EPA. Drinking Water Arsenic Rule History Where California parts from the federal approach is in its public health goals (PHGs). California’s PHG for arsenic is 0.000004 mg/L, far below the enforceable MCL, and those goals shape how the state prioritizes future rulemaking and treatment upgrades.

Lead and copper testing follows a schedule based on prior results and system size, using action levels rather than traditional MCLs.7California State Water Resources Control Board. MCLs, DLRs, PHGs for Regulated Drinking Water Contaminants All laboratory analyses must be performed by facilities accredited under California’s Environmental Laboratory Accreditation Program (ELAP); out-of-state labs must meet at least equally stringent standards to qualify for reciprocity.9Legal Information Institute. California Code of Regulations Title 22, 64808.10 – Reciprocity Accreditation Secondary standards covering taste, odor, and color also apply.

PFAS: What Is Enforceable Now, and What Is Coming

As of early 2026, California has not adopted enforceable MCLs for any PFAS compound, but monitoring and response obligations already exist, and formal rulemaking is on the calendar.

The DDW has set nonregulatory notification levels of 4.0 ng/L for both PFOA and PFOS, and response levels of 10 ng/L for PFOA and 40 ng/L for PFOS. When a system’s monitoring detects PFAS above the response level, the system must take the source out of service, treat the water, or provide public notification.10California State Water Resources Control Board. PFAS – Per- and Polyfluoroalkyl Substances Drinking Water Systems In December 2025, the DDW issued a general order requiring community and nontransient-noncommunity systems to begin initial PFAS monitoring in line with federal requirements. Stage 1 rulemaking to formally adopt federal PFAS standards is planned for 2026, with a second stage focused on California-specific PFAS regulations to follow.11California State Water Resources Control Board. Agenda Item – Prioritization of 2026 Drinking Water Regulations

At the federal level, the EPA finalized MCLs for six PFAS compounds in April 2024, setting limits of 4.0 ng/L for PFOA and PFOS, and 10 ng/L for PFHxS, PFNA, and GenX chemicals.12Federal Register. PFAS National Primary Drinking Water Regulation The compliance deadline is April 26, 2029, though the EPA has indicated it may extend that to 2031.13US EPA. EPA Announces It Will Keep Maximum Contaminant Levels for PFOA, PFOS In May 2025, the EPA announced its intent to rescind the regulations for PFHxS, PFNA, GenX, and PFBS while keeping the PFOA and PFOS limits in place.11California State Water Resources Control Board. Agenda Item – Prioritization of 2026 Drinking Water Regulations

Monitoring obligations are live even without a state MCL. Waiting for final numbers before testing or planning treatment leaves little room to react once deadlines arrive.

Notifying the Public When Something Goes Wrong

Title 22 of the California Code of Regulations sorts violations into three tiers by health risk, each with its own deadline.

All notices must use SWRCB-mandated language describing the violation, potential health effects, corrective actions, and what consumers should do. The SWRCB can also reclassify a violation upward, requiring Tier 1 notice for a situation that would normally be Tier 2, if the health risk warrants a faster response.

Operator Certification

Every public water system must employ operators certified through the SWRCB’s Operator Certification Program. Certification is divided into five grade levels for both treatment operators (T1 through T5) and distribution operators (D1 through D5), with higher grades required for more complex systems.17Legal Information Institute. California Code of Regulations Title 22, 63770 – Distribution System Staff Certification Requirements A small groundwater system with basic disinfection needs only a T1 or D1 operator; large surface water treatment plants and direct potable reuse facilities require T5 operators.18Legal Information Institute. California Code of Regulations Title 22, 64669.35 – Operator Certification

Candidates must pass an examination, meet education and experience prerequisites, and hold at least a high school diploma or equivalent. Federal guidelines let states substitute relevant training or on-the-job experience for formal education at certain levels.19EPA. Operator Certification Guidelines Implementation Guidance Continuing education is required to maintain the credential. Certified operators carry direct responsibility for compliance, water quality testing, and corrective actions.

A system that fails to employ properly certified personnel can face fines and permit revocation. Operators who falsify records or show gross negligence face proceedings that can lead to suspension or permanent revocation.

Enforcement Tools and Penalties

Enforcement generally starts informally. The SWRCB and LPAs issue compliance assistance letters or notices of violation, giving systems a chance to fix problems before penalties attach. Persistent violations draw formal compliance orders with deadlines for corrective action.

For serious or repeated violations, the SWRCB can impose administrative penalties of up to $1,000 per day for each day a violation occurs, with separate penalties for each distinct violation.20California Legislative Information. California Health and Safety Code 116650 In cases of willful noncompliance or immediate public health danger, regulators can issue cease-and-desist orders, mandate emergency water supply provisions, or refer cases for civil or criminal prosecution. Federal penalties run higher: the inflation-adjusted maximum for Safe Drinking Water Act violations assessed in 2025 or later reaches $71,545 per day for standard violations.21eCFR. Part 19 – Adjustment of Civil Monetary Penalties for Inflation

Mandatory Consolidation

When a public water system or a small system in a disadvantaged community consistently fails to provide safe drinking water, the SWRCB can order it to consolidate with a nearby receiving water system. Consolidation can be physical or operational, and the board can also order interim service extension while consolidation is arranged.22California Legislative Information. SB 88 Senate Bill – Enrolled The authority comes from SB 88, enacted in 2015, and has been used increasingly in communities with chronic water quality failures, particularly in the San Joaquin Valley.

Administrator Appointment

In extreme cases, the SWRCB can appoint an administrator to take over operations of a failing system under Health and Safety Code section 116686. The board considers appointments when necessary to provide affordable, safe drinking water to disadvantaged communities and to prevent fraud, waste, and mismanagement. In emergencies involving an imminent threat of serious harm, the SWRCB can appoint an administrator without the standard public comment process. Those emergencies include system abandonment, loss of water supply due to drought, and acute contamination events.23California State Water Resources Control Board. Administrator Policy Handbook

Challenging an Enforcement Order or Permit Decision

Water systems and operators who disagree with an enforcement action, permit denial, or certification decision have a structured route to challenge it. For enforcement orders issued by DDW staff, the first step is to petition the SWRCB for reconsideration within 30 days of the order. That petition must exhaust the administrative remedy before court review is available.24California State Water Resources Control Board. California Safe Drinking Water Laws

SWRCB hearings operate as quasi-judicial proceedings. A hearing officer or board panel presides, and parties can present expert testimony, submit technical reports, and cross-examine witnesses.25California State Water Resources Control Board. Hearings Program – Hearing Regulations The board can affirm, modify, or rescind the original action.

A system that disagrees with the SWRCB’s final decision can file a petition for writ of mandate in California Superior Court within 30 days. Courts generally defer to the agency’s expertise but will overturn a decision that lacks substantial evidence or reflects an abuse of discretion. Federal enforcement actions under the Safe Drinking Water Act go to the U.S. Court of Appeals, with a 45-day filing deadline from the date of final agency action.26Office of the Law Revision Counsel. 42 USC 300j-7 – Judicial Review

Federal Funding to Help Meet the Standards

Meeting the state’s expanding requirements costs money, and federal funding streams help cover it. The Bipartisan Infrastructure Law created a $5 billion grant program for small and disadvantaged communities to address emerging contaminants, with appropriations running through federal fiscal year 2026. The program is administered through states on a noncompetitive basis, and covers contaminant evaluation, treatment installation, and household water quality testing.27EPA. Draft National Water Program Guidance FY 2025-2026

The Drinking Water State Revolving Fund also received supplemental appropriations under the Bipartisan Infrastructure Law, including a dedicated Emerging Contaminant Supplemental that states can use for principal forgiveness and grants on PFAS-related infrastructure. For systems facing hexavalent chromium treatment upgrades or PFAS remediation, these are the most accessible paths to federal support. Eligibility generally requires the system to demonstrate the same technical, managerial, and financial capacity the DDW evaluates at the permitting stage.