Studying for a Ohio water or wastewater operator exam? You're in the right place. Pick your discipline below: each tab has the certification levels, how Ohio names them, and the practice tests that match.
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Choose your certification
How Ohio classifies drinking-water operators
Ohio EPA uses one class scheme across all four disciplines, so water supply, water distribution, wastewater treatment and wastewater collection all run Class A, then Class I, II, III and IV.
Full breakdown in the FAQ below.
Choose your Ohio certification
Water Supply (Class A, then Classes I through IV)
Ohio Class A, Water Supply Practice Test
Class A is Ohio's entry tier for very small systems, and it sits at the BOTTOM of the ladder rather than the top. It takes 1,040 hours of experience, and Operator-in-Training status is available once you pass the exam.
Ohio EPA · Class IOhio Class I, Water Supply Practice Test
Class I is the first numbered class, needing 12 months of operating experience on top of the exam.
Ohio EPA · Class IIOhio Class II, Water Supply Practice Test
Class II requires 36 months of experience and covers treatment at a working-operator level.
Ohio EPA · Class IIIOhio Class III, Water Supply Practice Test
Class III takes 60 months of experience including at least 12 months already certified at Class II, so it cannot be reached directly from Class I.
Ohio EPA · Class IV (highest)Ohio Class IV, Water Supply Practice Test
Class IV is Ohio's highest class. It needs 36 months as a Class III operator plus 24 months as a manager at a Class III or IV facility, and unlike the lower classes there is no Operator-in-Training route into it.
Ohio wastewater practice tests
Wastewater in Ohio is certified by the same Ohio EPA program and uses the same Class A through Class IV scheme as drinking water, with Class A the entry tier and Class IV the highest. Ohio refers to wastewater as water reclamation in parts of its own paperwork, so the two terms mean the same thing here. Collection systems are a separate discipline with their own certificate, covered under Collections, so an operator running both a plant and its sewers holds one of each. Examinations come through Water Professionals International and are scheduled via PSI, with a pass mark of 70, and the Operator-in-Training route applies to Classes A, I, II and III.
Ohio Class A and I, Wastewater Practice Test
The two entry wastewater classes. Ohio calls this discipline water reclamation in some of its own materials, but it is the wastewater treatment certificate.
Ohio EPA · Class IIOhio Class II, Wastewater Practice Test
Class II covers conventional secondary treatment and routine process control, and takes 36 months of experience.
Ohio EPA · Class IIIOhio Class III, Wastewater Practice Test
Class III moves into advanced biological treatment, nutrient removal and solids handling. It needs 60 months including 12 at Class II.
Ohio EPA · Class IV (highest)Ohio Class IV, Wastewater Practice Test
Class IV is Ohio's highest wastewater class, for the largest and most complex facilities, and it requires management experience rather than just operating time.
Water distribution is one of Ohio EPA's four certification disciplines and it uses the same class scheme as everything else: Class A at the bottom for very small systems, then Classes I through IV with IV the highest. The experience requirements and the Operator-in-Training route work identically to the water supply side. Distribution is a separate certificate from water supply, so an operator responsible for both a plant and the mains behind it holds one in each discipline.
Ohio Class A and I, Water Distribution Practice Test
Covers the two entry distribution classes: Class A for very small systems and Class I. Mains, valves, hydrants, storage and safety basics.
Ohio EPA · Class IIOhio Class II, Water Distribution Practice Test
Class II covers main disinfection, flushing, cross-connection control and pressure management, and takes 36 months of experience.
Ohio EPA · Class IIIOhio Class III, Water Distribution Practice Test
Class III moves into hydraulics, pumping and storage operation, and distribution system water quality. It needs 60 months including 12 at Class II.
Ohio EPA · Class IV (highest)Ohio Class IV, Water Distribution Practice Test
Class IV is the highest distribution class, covering system-wide planning, capital work and regulatory compliance for the largest networks.
Wastewater collection is a full Ohio EPA certification discipline, mandatory and separate from the treatment plant certificate, and it runs the same Class A through Class IV scheme. Ohio refers to the wastewater side as water reclamation in some of its materials, so do not be thrown if you see that phrasing on the agency's forms. As with the other disciplines, Operator-in-Training status covers Classes A, I, II and III, and the exams come through WPI.
Ohio Class A and I, Collection System Practice Test
The two entry collection classes: pipe, manholes, basic maintenance, safety and confined space awareness.
Ohio EPA · Class IIOhio Class II, Collection System Practice Test
Class II covers cleaning and inspection, lift station operation, infiltration and inflow, and overflow response.
Ohio EPA · Class IIIOhio Class III, Collection System Practice Test
Class III covers pump station hydraulics, force mains, odor and corrosion control, and rehabilitation methods.
Ohio EPA · Class IV (highest)Ohio Class IV, Collection System Practice Test
Class IV is the highest collection class: asset management, capacity assurance, capital planning and regulatory reporting.
About the Ohio operator exams
Operator certification in Ohio covers several disciplines, drinking water, wastewater, distribution, and collections, which may be handled by the same agency or by separate programs (drinking water is administered by Ohio EPA, Division of Drinking and Ground Waters / Division of Surface Water, Operator Certification). The exact certification structure, exam format, levels, and continuing-education requirements vary by discipline and change over time, so always confirm the current scope and eligibility directly with the certifying agency. Our practice content focuses on the underlying technical material: the same operating principles, math, regulations, and process knowledge that show up on water and wastewater operator exams nationwide.
Frequently asked questions
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Disclaimer: WaterOperatorPracticeTest.com is an independent study aid. We are not affiliated with Ohio EPA, Division of Drinking and Ground Waters / Division of Surface Water, Operator Certification or any state primacy agency. Always confirm current exam requirements with your state's certification body.