California wastewater regulations require almost anyone who discharges wastewater, whether from a factory, a treatment plant, a construction site, or a home septic system, to file a Report of Waste Discharge with the appropriate regional water board, obtain the correct permit, meet its monitoring and reporting conditions, and report spills immediately. Violations can trigger administrative penalties up to $10,000 per day and, where federal Clean Water Act standards apply, criminal prosecution. The governing statute is the Porter-Cologne Water Quality Control Act, administered by the State Water Resources Control Board and nine Regional Water Quality Control Boards.
Who Regulates Wastewater in California
The State Water Resources Control Board sets statewide policy. Nine Regional Water Quality Control Boards do the day-to-day work: issuing permits, inspecting facilities, and bringing enforcement actions in geographic areas drawn around watersheds rather than county lines.1California State Water Resources Control Board. About Us
Each regional board writes a Basin Plan for its area. The plan identifies the beneficial uses of local waters, such as drinking supply, agriculture, recreation, and fish habitat, and sets water quality objectives to protect those uses.2California State Water Resources Control Board. Porter-Cologne Water Quality Control Act and Related Water Code Sections Every permit condition and enforcement decision ties back to that plan, which is why a food processor in the Central Valley and a coastal refinery can operate under the same statute yet face different numeric limits.
When You Need a Permit
Water Code Section 13260 requires a Report of Waste Discharge from anyone who discharges or proposes to discharge waste that could affect water quality.2California State Water Resources Control Board. Porter-Cologne Water Quality Control Act and Related Water Code Sections The duty covers discharges within a region, out-of-state discharges that affect California water quality, and injection well construction or operation. The main exemption is a discharge into a community sewer system, because the sewer operator holds its own permit.
The report must describe the expected volume, chemical composition, discharge location, and treatment process. It is filed under penalty of perjury. Any material change in the character, location, or volume of an existing discharge requires a new filing. Until the regional board has the report and has either issued waste discharge requirements or confirmed none are needed, you cannot lawfully begin discharging.3Cornell Law Institute. California Code of Regulations Title 23 Section 783 – Waste Discharge Requirements
Which Permit You Need
Two parallel permit systems cover the full range of discharges, and which one applies depends on where the water goes.
NPDES permits are required for any discharge of pollutants from a point source into waters of the United States, including rivers, lakes, bays, and the ocean. California administers its own NPDES program, so the regional boards issue these permits rather than the EPA.4US EPA. NPDES Permit Basics An NPDES permit implements both federal Clean Water Act standards and any stricter state requirements.
Waste Discharge Requirements, usually called WDRs, cover discharges to land or groundwater that fall outside federal NPDES jurisdiction. Typical examples include land application of treated wastewater, disposal into evaporation ponds, and food-processing discharges to land.5California State Water Resources Control Board. Waste Discharge Requirements Program
When a regional board prescribes WDRs, it must implement the Basin Plan and consider the beneficial uses at stake, the water quality objectives needed to protect them, other discharges in the area, and the need to prevent nuisance.6California Legislative Information. California Water Code WAT 13263 No discharge creates a vested right to continue. Every permit is treated as a privilege that the board can revise or revoke.
What Permits Cost
Annual fees are set on a matrix of threat to water quality and discharge complexity. For fiscal year 2025–26, annual WDR fees run from $3,945 at the low end (threat category 3, complexity C) to $206,106 at the top (threat category 1, complexity A, meaning a discharge that could cause long-term loss of a beneficial use and involves toxic wastes or extensive monitoring).7California State Water Resources Control Board. FY 2025-26 Water Quality Fee Schedule
Threat category 1 means a discharge that could permanently destroy a beneficial use; category 2 covers discharges that could impair a beneficial use or cause short-term violations; category 3 involves degradation that doesn’t violate objectives. Complexity ratings A, B, and C reflect whether the facility handles toxic waste, uses active chemical or physical treatment, or relies on passive systems. NPDES permits carry their own fee schedule on top of this, calculated by facility type and discharge volume.7California State Water Resources Control Board. FY 2025-26 Water Quality Fee Schedule
Septic Systems and Other Onsite Treatment
Onsite wastewater treatment systems, including residential septic systems, fall under a statewide policy organized into four tiers.
- Tier 1 applies to low-risk new or replacement systems that meet standard siting and design rules in areas without an approved local management program. When Tier 1 governs by default, the maximum system flow is capped at 3,500 gallons per day.8State Water Resources Control Board. Water Quality Control Policy for Siting, Design, Operation, and Maintenance of Onsite Wastewater Treatment Systems
- Tier 2 covers new or replacement systems in counties with an approved Local Agency Management Program, which lets the county tailor permitting, inspection, and maintenance to local soils and geology within state minimums.
- Tier 3 applies near impaired water bodies. New or replacement systems within 600 feet of certain impaired waters must meet stricter performance standards unless a total maximum daily load program or special local provisions govern instead.
- Tier 4 addresses systems that are currently failing or that fail at any time while the policy is in effect, and requires corrective action.
In practice, most property owners deal with their county’s Local Agency Management Program, which sets the permit process, setback distances from wells and property lines, percolation testing, and inspection schedules.
Recycled Water and Greywater
Title 22 of the California Code of Regulations ties recycled water use to treatment level. The highest grade, disinfected tertiary recycled water, can irrigate parks, school yards, residential landscaping, and food crops where the edible portion contacts the water. Lower treatment grades carry progressively stricter restrictions on what the water can touch.9Cornell Law School. California Code of Regulations Title 22 Section 60304 – Use of Recycled Water for Irrigation Regional boards coordinate with the State Water Board’s Division of Drinking Water on every recycled water project.10California State Water Resources Control Board. Recycled Water in California
Direct potable reuse regulations, which allow highly treated recycled water to enter a public drinking water system or a raw water supply just upstream of a treatment plant, took effect on October 1, 2024 under Water Code section 13561.2.11California State Water Resources Control Board. Regulating Direct Potable Reuse in California
Household greywater from showers, bathroom sinks, and washing machines can be reused for subsurface irrigation under the California Plumbing Code. Simple single-residence systems below a set daily volume can be installed without a permit in most jurisdictions, provided the water stays on your property, discharges below the soil surface, and never reaches an edible-root-crop garden. Larger or more complex systems require a construction permit and may need engineering review. All greywater plumbing must be labeled, and backflow prevention is mandatory. Kitchen sink water and toilet water are not greywater and must go to the sewer or septic system.
Operator Certification
Every wastewater treatment plant in California must be run by a certified operator. The State Water Board administers a five-grade program, Grades I through V, with each grade requiring a written exam plus a combination of education and hands-on experience.12California State Water Quality Control Board. Wastewater Operator Certification Program Higher-grade plants require higher-grade operators. Experience earned while holding an Operator-in-Training certificate or a lower-grade certificate counts, with part-time work prorated. Out-of-state experience counts if you were certified there and performed duties that would require certification in California.
Certifications renew every three years, with continuing education contact hours and a renewal fee required each cycle.13California State Water Resources Control Board. Renewals and Continuing Education FAQs One limit to be aware of: operations work at agricultural, industrial, or manufacturing facilities, or on ships, does not count as qualifying experience even if it involves wastewater treatment.12California State Water Quality Control Board. Wastewater Operator Certification Program
Monitoring and Reporting
Regional boards can require any discharger, or anyone suspected of discharging, to produce technical and monitoring reports. The burden and cost must bear a reasonable relationship to the need for the information, and the board must put its justification in writing.14California Legislative Information. California Water Code WAT 13267
Most permits require regular self-monitoring: laboratory results from effluent samples, flow measurements, and treatment system performance records. Data is submitted electronically through the California Integrated Water Quality System, which also makes compliance and enforcement records public.15California State Water Resources Control Board. Data and Databases – Compliance and Enforcement Stormwater general permits file through a separate portal, the Stormwater Multiple Application and Report Tracking System. Inspectors conduct periodic site visits, review onsite records, and sometimes collect independent samples. Late reports and mismatches between filed data and field conditions are two of the most common triggers for enforcement.
Reporting Spills and Unauthorized Discharges
If you cause or allow any hazardous substance or sewage to reach state waters, or to be deposited where it will probably reach state waters, you must immediately notify the Office of Emergency Services as soon as you know and notification is feasible. OES then alerts the regional board, the local health officer, and the director of environmental health.2California State Water Resources Control Board. Porter-Cologne Water Quality Control Act and Related Water Code Sections A written follow-up report is due to the regional board within ten business days of the unauthorized discharge.16State Water Resources Control Board. Reporting Unauthorized Waste Discharges (Spills and Leaks)
The one exception: a discharge that fully complies with your existing waste discharge requirements or permit conditions does not trigger these notification rules. Everything else does. This is a strict liability obligation, meaning it applies even when the spill was accidental and you did everything reasonably possible to prevent it.
Penalties for Violations
The water boards use a graduated enforcement approach, moving from informal notices to formal orders and monetary penalties. A first offense does not necessarily mean a warning. Regional boards have authority to impose administrative civil liability on the first violation when circumstances warrant.
Administrative Civil Penalties
The State Water Board’s Water Quality Enforcement Policy frames how penalties are calculated. For non-discharge violations such as late reports, missed monitoring, or breached permit conditions, assessments can reach $10,000 per violation per day.17State Water Resources Control Board. Water Quality Enforcement Policy Discharge violations, where pollutants actually reach state waters without authorization, carry separate penalty provisions under the Water Code that can be steeper depending on the volume and toxicity involved.
Starting in 2026, AB 460 requires the State Water Board to adjust maximum penalty amounts for inflation every year.18California State Water Resources Control Board. Summary of Report on Implementation of AB 460 The initial 2026 adjustments primarily affect water rights violations, but the annual inflation mechanism means penalty ceilings will ratchet upward every January.
Federal Criminal Liability
Because California administers the federal NPDES program, Clean Water Act criminal provisions apply to discharges into navigable waters, and the exposure is far more serious than administrative fines.
- Negligent violations: up to one year in prison and fines of $2,500 to $25,000 per day for a first offense, doubling for subsequent convictions.19US EPA. Criminal Provisions of Water Pollution
- Knowing violations: up to three years in prison and fines of $5,000 to $50,000 per day, with six years and $100,000 per day for repeat offenders.
- Knowing endangerment, meaning a knowing violation committed with awareness that it places another person in imminent danger of death or serious bodily injury: up to 15 years in prison and $250,000 in fines, rising to $1,000,000 for organizations.
- False statements and tampering, including knowingly falsifying a required document or tampering with monitoring equipment: up to two years in prison and $10,000 in fines per incident.
Criminal prosecution is not reserved for industrial catastrophes. Cases are built on patterns of falsified monitoring data, repeated late reporting that conceals exceedances, and knowing failure to report spills. The “knowing” standard does not require intent to harm; it requires knowledge that you were discharging pollutants in violation of your permit.