California Occupational Guides

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Detailed Guide for

   Water and Liquid Waste Treatment Plant and System Operators in California

May also be called: Process Operators; Wastewater Operators; Wastewater Treatment Operators; Wastewater Treatment Plant Operators; Water Plant Operators; Water Treatment Plant Operators

Specialties within this occupation include: Drinking Water Treatment and Distribution Operators

What Would I Do?

While many Americans take our water for granted, it requires a lot of work to get it from various natural sources and into our taps. Similarly, it is a complicated process to convert the wastewater in our drains and sewers into a form that is safe for environmental release. Water and Liquid Waste Treatment Plant and System Operators* run the equipment, control the processes, and monitor the plants that are responsible for such work.

Fresh water is pumped from wells, rivers, streams, and reservoirs to water treatment plants, where it is treated and distributed to customers. Wastewater travels through sewage pipes to treatment plants where it is treated and either returned to streams, rivers, and oceans, or reused for irrigation. Operators in both types of plants control equipment and monitor processes that remove or destroy harmful materials, chemicals, and microorganisms from the water. They also run tests to make sure that the processes are working correctly and keep records of water quality and other indicators.

Operators operate and maintain the pumps and motors that move water and wastewater through physical, mechanical, biological, and chemical treatment systems. They monitor the indicators, read meters and gauges, and make adjustments as necessary to make sure that plant equipment is working properly. They take samples and run tests to determine the quality of the water being produced. Water and wastewater treatments are similar; however, many tasks are specific to one or the other. Therefore, one should have specific training for the area he or she is entering.

The specific duties of Plant Operators depend on the type and size of the plant. In a small plant, one Operator may be responsible for maintaining all of the systems. This Operator would most likely work during the day and be on call during nights and weekends. In medium-size plants, Operators may work in shifts to monitor the plant at all hours of the day. In large plants, multiple Operators work the same shifts and are more specialized in their duties, often relying on computerized systems to help monitor plant processes.

Occasionally, Operators must work during emergencies. Weather conditions may cause large amounts of storm water and wastewater to flow into sewers, exceeding a plant’s capacity. Emergencies also may be caused by malfunctions within a plant, such as chemical leaks or oxygen deficiencies. Operators are trained in emergency management procedures and use safety equipment to protect their health as well as that of the public.

Both tap water and wastewater are highly regulated by the U.S. Environmental Protection Agency and other State and local agencies. Plant Operators must be familiar and comply with these regulations. Keeping proper records of compliance and documentation is another responsibility of Operators.

Drinking Water Treatment and Distribution Operators work with equipment and processes used to clarify, purify, and disinfect surface or ground water for human consumption.

Tools and Technology

Wastewater Treatment Operators use various filtration equipment such as microstrainers and backwash filters as well as dechlorination equipment, disinfection chlorinators, ion exchangers, agitators, and aerators. Operators also use various computer and software programs, such as material safety data sheet MSDS, human machine interface HMI, and word processing and spreadsheet software.

Important Tasks and Related Skills

*This product was partially funded by a grant awarded by the U.S. Department of Labor’s Employment & Training Administration. The information contained in this product was created by a grantee organization and does not necessarily reflect the official position of the U.S. Department of Labor. All references to non-governmental companies or organizations, their services, products, or resources are offered for informational purposes and should not be construed as an endorsement by the Department of Labor. This product is copyrighted by the institution that created it and is intended for individual organizational, non-commercial use only.

Each task below is matched to a sample skill required to carry out the task.

View the skill definitions
TaskSkill Used in this Task
Add chemicals such as ammonia, chlorine, or lime to disinfect and deodorize water and other liquids.Chemistry
Inspect equipment or monitor operating conditions, meters, and gauges to determine load requirements and detect malfunctions.Operation Monitoring
Collect and test water and sewage samples, using test equipment and color analysis standards.Judgment and Decision Making
Record operational data, personnel attendance, or meter and gauge readings on specified forms.Monitoring
Operate and adjust controls on equipment to purify and clarify water, process or dispose of sewage, and generate power.Operation and Control
Maintain, repair, and lubricate equipment, using hand tools and power tools.Equipment Maintenance
Clean and maintain tanks and filter beds, using hand tools and power tools.Mechanical
Direct and coordinate plant workers engaged in routine operations and maintenance activities.Coordination
Source: U.S. Department of Labor Occupational Information Network (O*NET)

Working Conditions

Water and Wastewater Treatment Operators work indoors and outdoors. They may be exposed to noise from machinery and unpleasant odors. Work is often physically demanding and performed in unclean locations. Operators must pay close attention to safety procedures because of the presence of hazardous conditions, such as slippery walkways, dangerous gases and chemicals, and malfunctioning equipment.

Treatment plants operate 24 hours a day, 7 days a week. Operators in small plants may work during the day and be on call during the evening, nights, and weekends. Medium and large plants that require constant monitoring may employ workers in three 8-hour shifts. Because larger plants require constant monitoring, weekend and holiday work is generally required. Operators may often be required to work overtime.

Operators may become members of various unions including Stationary Engineers, International Brotherhood of Electrical Workers, or International Union of Operating Engineers.

Will This Job Fit Me?

The job of Water and Wastewater Treatment Workers may appeal to those who enjoy activities that include practical, hands-on problems and solutions. Duties often involve working independently and with various tools and machinery.

What Wages and Benefits Can I Expect?


The median wage in 2020 for Water and Liquid Waste Treatment Plant Workers in California is $74,083 annually, or $35.62 hourly. The median is the point at which half of the workers earn more and half earn less.

Change to Hourly Wages
Annual Wages for 2020Low
(25th percentile)
(50th percentile)
(75th percentile)
Source: EDD/LMID Occupational Employment Statistics Survey, 2020 Wages do not reflect self-employment.
View Wages for All Areas


Water and Wastewater Treatment Operators usually receive benefits that may include health and life insurance, a retirement plan, and educational reimbursement for job-related courses. Holidays, vacation, and sick leave are also provided.

What is the Job Outlook?

An increasing population, the retirement of the baby boomer generation, and an increased focus on environmentally sustainable business practices are expected to boost demand for water and wastewater treatment services. As new treatment plants are constructed to meet this increased demand, new Water and Wastewater Treatment Plant and System Operator jobs will become available. Furthermore, the number of applicants for these jobs is normally low, due primarily to the physically demanding and unappealing nature of some of the work. Opportunities should be best for persons with mechanical aptitude and problem solving skills.

Projections of Employment

In California, the number of Water and Liquid Waste Treatment Plant Workers is expected to decline between 2016 and 2026.

Estimated Employment and Projected Growth
Water and Liquid Waste Treatment Plant Workers
Geographic Area
(Estimated Year-Projected Year)
Source: EDD/LMID Projections of Employment by Occupation
View Projected Growth for All Areas

How Do I Qualify?

Education, Training, and Other Requirements

An associate degree or certificate in water quality and wastewater treatment technology is often the educational requirement for many employers. Many prefer to hire such candidates, because completion of a program minimizes the training needed at the plant and also shows a commitment to working in the industry. These programs are offered by community colleges, technical schools, and trade associations. In some cases, a degree or certificate program can be substituted for experience, allowing a worker to become licensed at a higher level more quickly.

Water and Wastewater Treatment Plant Operators need mechanical aptitude and the ability to solve problems intuitively. They must have the ability to apply data to formulas that determine treatment requirements, flow levels, and concentration levels. Basic familiarity with computers also is necessary because Operators generally use them to record data. Some plants also use computer-controlled equipment and instrumentation.


Trainees usually start as attendants or operators-in-training and learn their skills on the job under the direction of an experienced Operator. They learn by observing and doing routine tasks such as recording meter readings, taking samples of wastewater and sludge, and performing simple maintenance and repair work on pumps, electric motors, valves, and other plant equipment. Larger treatment plants generally combine this on-the-job training with formal classroom or self-paced study programs.

Early Career Planning

A high school diploma or equivalent is usually required for an individual to become a Water or Wastewater Treatment Plant Operator. High school students interested in entering this occupation should focus on courses in mathematics, chemistry, biology, and computer-related courses.

Work-Study Programs

Training programs for Operators are available through Regional Occupational Program (ROP). To find an ROP program near you, go to the California Association of Regional Occupational Centers and Programs Web site.

Continuing Education

Certification renewal for Water Operators is every three years and requires completion of continuing education units (CEUs) or contact hours. The number of contact hours required depends on the certificate grade (more hours for higher grade). Operators can fulfill up to 25 percent of their contact hours with safety training. Check with Department of Health Services (DHS) and the State Water Resources Control Board (SWRCB) for specific requirements. Operators should be aware of and keep current with State and federal regulations as well as Occupational Safety and Health Association (OSHA) standards.

Licensing and Certification

Water Treatment Plant Operators are required to have the proper certification which is offered by the SWRCB. Contact the agency that issues the license for additional information. Click on the license title below for details.

Certification depends upon the method of water treatment and class of water facility—either a distribution system (D) or a treatment facility (T). There are five levels of certification for water facilities, Water Treatment Operators, and Distribution Operators. Applicants must meet experience requirements and pass an examination for each of the five levels of certification. Thus a Grade T3 Water Treatment Plant Operator is certified to treat water, and a Grade D3 Water Treatment Plant Operator is certified for water distribution system operation. Operators may be cross-certified for both treatment and distribution Operator tasks.

The certification process requires both types of Operators (T and D) to have specific amounts of on-the-job training, complete training courses, and pass a competency examination for each grade level of certification—Grades 1 through 5. Operators with no prior experience generally begin as operators-in-training and work under direct supervision of certified Operators. As a condition of continued employment, trainees are required to obtain a Grade 1 certificate within two years.

There are also five levels of certification for Wastewater Operators. The certification requirements for various positions (Operator, Supervisor, and Chief Plant Operator) depend upon the classification of the facility related to the treatment levels and flow capacities. For more information, go to the U.S. Department of Labor's Career InfoNet Web site and scroll down to "Career Tools." Click on "Certification Finder" and follow the instructions to locate certification programs.

Where Can I Find Training?

There are two ways to search for training information:

  • Search by Field of Study to find what programs are available and what schools offer those programs. You may use keywords such as: Groundwater, Wastewater, and Water Distribution.
  • Search by Training Provider to find schools by name, type of school, or location.

Contact the schools you are interested in to learn about the classes available, tuition and fees, and any prerequisite course work.

Where Would I Work?

The largest industries employing Water and Liquid Waste Treatment Plant Workers are as follows:

Industry TitlePercent of Total Employment for Occupation in California
Local Government76.0%
Waste Management and Remediation Service4.2%
State Government1.2%
Source: EDD/LMID Staffing Patterns

Finding a Job

Direct application to employers is one of the most effective job search methods. Jobs may also be found through classified advertisements in newspapers and online job boards. Online job opening systems include JobCentral at and CalJOBSSM at

To find your nearest One-Stop Career Center, go to Service Locator. View the helpful job search tips for more resources. (requires Adobe Reader).

Yellow Page Headings

You can focus your local job search by checking employers listed online or in your local telephone directory. Below are some suggested headings where you might find employers of Water and Liquid Waste Treatment Plant Workers.

  • Government Office
  • Ground Treatment
  • Municipal
  • Waste Water Treatment
  • Water Filtration & Purification Equipment
  • Water Treatment Equipment-Service & Supplies

Find Possible Employers

To locate a list of employers in your area, go to "Find Employers" on the Labor Market Information Web site:

  • Select one of the top industries that employ the occupation. This will give you a list of employers in that industry in your area.
  • Click on "View Filter Selections" to limit your list to specific cities or employer size.
  • Click on an employer for the street address, telephone number, size of business, Web site, etc.
  • Contact the employer for possible employment.

Where Could This Job Lead?

Operators in smaller treatment plants may find it difficult to advance in their careers without changing employers or locations. As plants get larger and more complicated, Operators need more skills before they are allowed to work without supervision. Operators in these plants who have the highest level of certification work as shift supervisors and may be in charge of large teams of Operators. They can start as trainees and work through the different levels of certification until advancing to the level of shift supervisor.

Some experienced Operators get jobs as technicians with the State drinking water control or water pollution control agencies. In that capacity, they monitor and provide technical assistance to plants throughout the State. Experienced Operators may transfer to related jobs with industrial liquid waste treatment plants, water or liquid waste treatment equipment and chemical companies, engineering consulting firms, or vocational-technical schools.

Related Occupations

Below is a list of occupations related to Water and Liquid Waste Treatment Plant Workers with links to more information.

Chemical Equipment Operators and TendersProfile
Chemical Plant and System OperatorsProfile
Gas Plant OperatorsProfile
Pump Operators, Except Wellhead PumpersProfile

Other Sources

These links are provided for your convenience and do not constitute an endorsement by EDD.

For the Career Professional

The following codes are provided to assist counselors, job placement workers, or other career professionals.

SOC - Standard Occupational Classification51-8031
O*NET - Occupational Information Network
   Water and Wastewater Treatment Plant and System Operators51-8031.00
   Interest Codes (RIASEC)RCI
CIP - Classification of Instructional Programs
   Water Quality & Wastewater Treatment Management & Recycling 150506
TOP - Taxonomy of Programs (California Community Colleges)
   Water and Wastewater Technology095800