Understanding California’s Title 22 Water Recycling Criteria
California’s Title 22 Water Recycling Criteria establish the public health safeguards required when treated wastewater is reused. They define acceptable treatment processes, water quality standards, monitoring practices, operational controls, and approved uses for recycled water. The criteria are central to projects ranging from landscape irrigation to indirect and direct potable reuse.
For water and wastewater professionals, Title 22 is more than a collection of technical limits. It is a framework for matching treatment reliability with the level of public exposure. The requirements influence facility design, operator responsibilities, permitting, sampling plans, reporting, and communication with customers and regulators.
In the Los Angeles Basin, water agencies are applying these rules within a complex regional system that includes imported water constraints, groundwater management, ocean discharge reduction, and rising demand. Understanding how the criteria work helps professionals evaluate reuse projects realistically and participate in sound planning.
How The Regulatory Framework Works
Title 22 is part of the California Code of Regulations. The State Water Resources Control Board, particularly its Division of Drinking Water, oversees the regulatory framework for many recycled water applications. Regional Water Quality Control Boards also play important roles involving discharge requirements, groundwater protection, permits, and water quality objectives.
The criteria classify recycled water according to its treatment level and intended use. A project that supplies water for freeway landscaping will face different controls from one that sends purified water to a reservoir or drinking water system. This risk-based approach recognizes that exposure pathways, treatment reliability, and environmental conditions vary by application.
A recycled water project must also satisfy requirements beyond the treatment plant itself. Distribution systems, storage facilities, cross-connection controls, signage, backflow prevention, inspections, and user education can all affect permit approval. Compliance therefore depends on an integrated system rather than a treatment process operating in isolation.
Treatment Categories And Approved Uses
Disinfected tertiary recycled water is commonly associated with unrestricted irrigation, industrial uses, toilet and urinal flushing, and other applications where people may have frequent contact with the water. Tertiary treatment generally includes biological treatment, filtration, and disinfection, although the exact process configuration and performance requirements depend on the approved use.
Disinfected secondary-2.2 and disinfected secondary-23 recycled water may be suitable for more limited applications under specified conditions. The numerical designations relate to treatment performance and disinfection contact requirements. Professionals must review the applicable section of the criteria rather than assume that a general label applies uniformly across every project.
Potable reuse involves a higher level of treatment and a more demanding risk-management structure. Advanced treatment may include reverse osmosis, advanced oxidation, ultraviolet disinfection, biological treatment, engineered storage, and other barriers. The required combination depends on whether the project is indirect potable reuse or direct potable reuse and on the source water, product water, and system design.
The difference between categories is not simply the number of treatment steps. Reliability, redundancy, critical control points, pathogen reduction, chemical monitoring, response procedures, and operator oversight determine whether a project can consistently protect public health.
Monitoring Reliability And Operational Control
Title 22 emphasizes treatment reliability because a single good laboratory result cannot compensate for an unstable process. Facilities need continuous or frequent monitoring of critical parameters, including turbidity, disinfectant residual, flow, pressure, ultraviolet dose, oxidation conditions, and other indicators tied to the treatment train.
Operational requirements often include alarms, automatic diversion, standby equipment, emergency power, validated treatment performance, and documented corrective actions. A failure in filtration or disinfection may require the facility to stop delivery or divert off-specification water until the problem is resolved. The ability to detect and isolate a failure is a core part of compliance.
Sampling programs must address both routine performance and potential contaminants. Depending on the project, monitoring can include total coliform, fecal indicator organisms, turbidity, nitrate, salinity, trace chemicals, and other constituents. Sampling locations and frequencies should reflect the entire reuse system, including treatment, storage, conveyance, and points of delivery.
For agencies developing regional programs, regional reuse planning can clarify how responsibilities, source waters, treatment facilities, and distribution networks fit together. Coordination is especially important when one agency produces recycled water and another manages storage or final delivery.
Comparing Reuse Applications
The following summary illustrates how treatment expectations and management concerns change as public exposure increases. Actual requirements depend on the current regulations, project-specific engineering report, permit conditions, and regulator determinations.
| Reuse application | Typical treatment emphasis | Main management concerns |
|---|---|---|
| Landscape irrigation | Filtration and disinfection appropriate to the approved use | Worker and public contact, signage, cross-connection control |
| Industrial process water | Treatment matched to process needs and human exposure | Corrosion, scaling, aerosols, chemical compatibility |
| Toilet and urinal flushing | High-quality disinfected recycled water | Dual-plumbing protection, backflow prevention, indoor exposure |
| Indirect potable reuse | Advanced treatment plus environmental or engineered storage | Pathogen and chemical barriers, residence time, source water protection |
| Direct potable reuse | Advanced treatment, monitoring, and multiple independent barriers | Real-time control, treatment reliability, response plans, public confidence |
Designing A Compliant Treatment Train
A successful project begins with the source water. Municipal wastewater characteristics may vary with industrial discharges, wet-weather flows, infiltration, salinity, pharmaceuticals, and seasonal changes. Characterizing these conditions helps engineers select processes that address both regulated constituents and operational challenges.
Biological treatment remains an important foundation for many facilities. Nutrient removal can reduce nitrogen and phosphorus loading, improve downstream water quality, and support stable performance before filtration and disinfection. Operational decisions involving dissolved oxygen, solids retention time, internal recycle, carbon availability, and clarification can affect the reliability of the complete reuse train. Guidance on biological nutrient removal provides useful context for connecting process optimization with broader treatment objectives.
Advanced treatment should be evaluated as a series of barriers rather than a single solution. Membranes may remove salts and many trace constituents, while ultraviolet light and advanced oxidation can address pathogens and selected chemical compounds. Each barrier has limitations, so a sound design considers treatment credits, bypass risks, maintenance requirements, concentrate management, and the consequences of equipment failure.
Engineers also need to plan for startup, shutdown, changing feedwater quality, membrane cleaning, calibration, and unusual events. The design should make the safe operating state clear and provide practical ways for operators to keep noncompliant water out of the distribution system.
The People And Procedures Behind Compliance
Operators translate regulatory requirements into daily decisions. They verify instruments, inspect equipment, respond to alarms, document process changes, collect samples, review trends, and communicate with supervisors and regulators. Even highly automated plants depend on knowledgeable staff who understand why each control limit exists.
Training should cover treatment fundamentals, laboratory results, permit conditions, emergency procedures, and cross-connection protection. Professionals preparing for advancement can use resources such as this operator certification exam to strengthen their understanding of process control and certification expectations.
Written standard operating procedures should explain normal operations and abnormal conditions in clear, usable language. A procedure is most valuable when staff can follow it during a power interruption, failed analyzer, high turbidity event, disinfection upset, or suspected contamination incident.
Recordkeeping is equally important. Logs should show what happened, when it happened, who responded, what water was diverted, and how the facility returned to compliance. These records support regulatory reporting, internal review, maintenance planning, and continuous improvement.
Building Public Confidence In Recycled Water
Technical compliance does not automatically produce public acceptance. Customers want to know where the water comes from, how it is treated, how it is monitored, and what happens if a process fails. Clear explanations are especially important when a project involves groundwater recharge or potable reuse.
Communication should avoid vague assurances and focus on measurable safeguards. Agencies can describe treatment barriers, monitoring frequencies, automatic shutdown features, regulatory oversight, and the distinction between recycled water uses. Facility tours, workshops, professional presentations, and community events help make complex processes understandable.
Regional collaboration also supports consistent messaging. When utilities share data, coordinate emergency procedures, and align public information, customers receive a clearer account of how the system operates. This is particularly valuable in Southern California, where water may cross agency boundaries before reaching its final use.
Professionals can apply these principles through practical preparation:
- Review the current Title 22 provisions that apply to the intended reuse category.
- Map every treatment barrier, monitoring point, diversion location, and responsible role.
- Test alarm, backup power, sampling, and emergency response procedures regularly.
- Train operators and maintenance staff on both routine performance and failure conditions.
- Explain the project’s safeguards and limitations using plain, specific language.
California’s recycled water standards continue to shape how agencies protect public health while expanding local water supplies. For Los Angeles Basin professionals, learning the criteria is a practical step toward better design, stronger operations, and more effective collaboration. Explore technical programs, workshops, facility tours, and professional development opportunities through LABS of CWEA to stay engaged with the people and practices advancing water reuse.