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Wastewater and Drinking Water Professional Operator Classifications
These job duties and operator class classifications reflect the requirements of the Ohio Environmental Protection Agency and are specific to the certification exams offered by Water Professionals International (WPI).
Class A
Experience Requirement
1040 hours
Wastewater
(Package Plant)
Performs basic operation and maintenance of extended aeration activated sludge treatment systems.
Conducts routine chemical/biological lab tests.
Maintains operational records and monitors processes.
Drinking Water
Operates treatment equipment (filtration, chlorination, softening, purification, fluoridation).
Performs chemical, biological, and bacteriological lab testing.
Monitors flows and adjusts chemical feed systems; maintains records.
Summary: Primarily technical tasks of a very small system; no supervisory role. May also include serving as the “Operator of Record” for a Class A drinking water or wastewater facility.
Class I
Experience Requirement
12 months
Wastewater
Performs basic operation and maintenance of plant equipment (pumps, lift stations, dewatering systems, airflow, solids).
Conducts routine chemical/biological lab tests.
Maintains operational records and monitors processes via inspection and computer systems.
Drinking Water
Operates treatment equipment (filtration, chlorination, softening, purification, fluoridation).
Performs chemical, biological, and bacteriological lab testing.
Monitors flows and adjusts chemical feed systems; maintains records.
Summary: Primarily technical tasks; no supervisory role. May also include serving as the “Operator of Record” for a Class 1 drinking water or wastewater facility.
Class II
Experience Requirement
24 months
Wastewater
Performs the same technical operations as Class 1.
Maintains full working knowledge of plant systems and processes.
May train or supervise plant employees.
Drinking Water
Performs the same technical operations as Class 1.
Maintains full working knowledge of plant systems and processes.
May train and supervise staff.
Summary: Increased system knowledge and introduction of supervisory responsibilities. May also include serving as the “Operator of Record” for a Class 2 or lower drinking water or wastewater facility.
Class III
Experience Requirement
48 months
Wastewater
Performs technical operations and lab testing; maintains operational and lab records.
Responds to public concerns and emergencies.
Provides training and supervises employees.
Drinking Water
Conducts sampling and lab testing; monitors processes and maintains records.
Maintains deep knowledge of equipment/processes.
Responds to public/emergency issues; trains and supervises staff.
Summary: Broader responsibility including emergency response and multi‑employee supervision. May also include serving as the “Operator of Record” for a Class 3 or lower drinking water or wastewater facility.
Class IV
Experience Requirement
24 months holding Class III + management experience at Class III/IV facility
Wastewater
Oversees the most complex plant maintenance and operations.
Manages laboratory testing programs and all operational records.
Handles public concerns, emergencies, staff training, and supervision.
Drinking Water
Oversees the largest most complex plant operations and maintenance.
Manages sample collection, lab analysis, and operational/lab records.
Responds to public/emergency issues; supervises and trains staff.
Summary: Highest responsibility level—full plant oversight, management duties, and leadership of staff and operations. May also include serving as the “Operator of Record” for a Class 4 or lower drinking water or wastewater facility.
Frequently Asked Questions
About the Career
Can my education count toward my operator certification?
What does “Plant Classifications” mean?
What does it mean to be an “Operator in Training (OIT)”?
What is required for the the Class IV exam?
What is the “Operator of Record”?
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This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement 84034601 to Toledo Metropolitan Area Council of Governments. The contents of this website do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does the EPA endorse trade names or recommend the use of commercial products mentioned in this website.