Median Pay by Area
- Columbus
- $63,700 a year
- Cleveland
- $63,260 a year
- Cincinnati (OH-KY-IN)
- $61,460 a year
- Dayton-Kettering-Beavercreek
- $61,050 a year
- Toledo
- $58,740 a year
Ohio wastewater operators
The steps from no certificate to an Ohio Class A or Class I Water Reclamation (wastewater treatment) or Wastewater Collection certificate, how to take the exam through WPI at PSI, how to keep your certificate active and what operators earn. Every requirement links to the Ohio Environmental Protection Agency (Ohio EPA) Operator Certification program or its rules, Ohio Administrative Code Chapter 3745-7.
Ohio EPA makes the final eligibility determination. Check with Ohio EPA before you apply.
Why it matters
Every classified treatment works and public sewerage (collection) system in Ohio must name at least one operator of record to oversee its technical operation. That operator must hold a valid certificate of a class equal to or higher than the facility's class.
The operator of record must be the owner's employee, or be provided under a contract with an approved contract operator or contract operations company.
Larger plants need more time on site. For example, the operator of record at a Class III or IV treatment works must be present 5 days a week for at least 40 hours a week, and at a Class II treatment works 5 days a week for at least 20 hours a week.
Ohio EPA's operator certification rules are adopted under Ohio Revised Code 6111.46, which gives the agency general supervision of sewage treatment works.
Ohio certifies wastewater treatment operators as Class A, I, II, III and IV Water Reclamation operators, and collection system operators as Class I and II Wastewater Collection operators. Ohio EPA replaced the name wastewater treatment with water reclamation for these certificates in its November 2024 rule update.
Treatment works are classed by design flow and permit limits. A plant of 0.025 million gallons a day (MGD) or less is Class A, and Class A covers the plant and its sewers. Class IV starts at 5 MGD for plants with the strictest limits and 7.5 MGD for the rest.
A sewerage system that feeds a Class I treatment works is a Class I sewerage system; one that feeds a Class II, III or IV treatment works is Class II.
Higher certificates replace lower ones. Once you earn Class II Water Reclamation, you can no longer hold a lower Water Reclamation or Wastewater Collection certificate.
Step 1
You need a high school diploma or the equivalent. A GED, a statement of high school equivalence or a vocational training program in the field counts.
Before you apply for an exam or certificate, review Ohio EPA's Professional Operator Certification Required Training document and confirm you have read it.
Some criminal convictions can disqualify an applicant. Ohio EPA publishes the list of disqualifying offenses on its Exam Information page, and you can ask the agency for a determination before you apply.
Step 2
Most operator tasks, including applications and renewals, are done in the Ohio EPA eBusiness Center. You sign in with an OHID account, add the Water/Wastewater Operators service and request a PIN, which you need to submit applications.
Keep a working email address on your account. Ohio EPA sends eBusiness Center correspondence by email.
Step 3
Ohio EPA gives its Class A to III exams through its approved exam provider, Water Professionals International (WPI). Sign up on PSI's Ohio EPA page: choose Water/Wastewater, then Ohio EPA, then the exam you want, such as Ohio EPA Water Reclamation Class 1.
Before you can schedule, you answer PSI's pre-approval questions confirming you meet Ohio's requirements and plan to apply for Ohio certification.
Ohio test centers include Cleveland, Cincinnati, Columbus, Akron, Cambridge, Troy and Toledo, and you can also test at PSI centers in other states. You can schedule online or by calling PSI at 833-256-1420.
You may reschedule once at no charge if you contact PSI at least two business days ahead. Arriving more than 15 minutes late, missing the appointment or rescheduling a second time forfeits your exam fees. Bring two forms of ID, one current and government issued with your photo and signature.
Step 4
You may take the Class A, I, II or III exam before you have the experience. If you pass, you become an operator in training and have up to five years (60 months) to complete the experience. An operator in training is not certified and cannot be an operator of record.
Operating experience means doing the day-to-day work that keeps a treatment works or sewerage system running properly. Daily hands-on plant operation and maintenance and on-site troubleshooting count in full.
Some duties count for at most 25% of the requirement when they are your only duties, such as on-site SCADA monitoring, lab work at the plant owner's lab and sludge handling at a treatment works. Clerical work, commercial lab work, meter reading and septage hauling do not count.
Step 5
Once you score 70 or higher and have the experience, apply for certification in the eBusiness Center by choosing Third Party Exam. There is a $45 nonrefundable application fee, separate from PSI's exam fee.
List each job separately, with a detailed description of your duties, and add any courses that earn experience credit. After you submit and pay, print the application, sign it and have your supervisor sign it in ink, then mail it to Ohio EPA.
When your application is approved, Ohio EPA emails you and prints and mails your certificate.
Step 6
Class IV needs a valid Class III certificate in the same field and two years of management experience at a Class III or IV facility. Shift supervisor experience at such a facility counts as management experience.
Class IV is not a WPI exam. You apply in the eBusiness Center (the exam fee is $145 through November 30, 2028), and once approved you submit a written exam in your own words covering your experience, administration, budget, plant, safety, planning and staff training. The advisory council may ask you to discuss it in person.
Step 7
Certificates expire on December 31 of the second year after they are issued or renewed. Renewal opens August 1 of your renewal year in the eBusiness Center, the only way to renew, and your complete application is due by November 30.
Each two-year cycle, Class A Water Reclamation operators need 8 contact hours, Class I Water Reclamation and Class I and II Wastewater Collection operators need 12, and Class II to IV Water Reclamation operators need 24. Holding more than one certificate cuts each requirement by 25%.
Courses must be approved by Ohio EPA, and at least half your hours must be operations and maintenance (OM) courses. Individual membership in a state or national water organization can count for 1 hour.
The two-year renewal fee is $25 for Class A, $35 for Class I, $45 for Class II, $55 for Class III and $65 for Class IV. A renewal paid more than 30 days late costs $20 more.
After your certificate expires you cannot act as an operator of record until it is renewed. If no complete renewal reaches Ohio EPA by June 30 of the next year, you must retake the exam.
Exam day
The Class A to III exams are taken on computer at PSI. PSI's Ohio handbook lists the Class I, II and III exams at 110 multiple-choice questions, 100 of them scored, with a 3-hour time limit, and the Class A exam at 50 questions in 2 hours. (The handbook still uses the older name Wastewater Treatment.)
You need a score of 70 or higher to pass.
Pencils and the ABC Formula Table booklet are handed out at check-in. Ohio EPA's exam page links the WPI Wastewater Treatment and Collection formula sheet so you can study with it.
Bring only a silent, non-programmable calculator without an alphabetic keypad or printing. Phones and other personal items are not allowed in the testing room.
Ohio EPA posts WPI's Need-to-Know Criteria for each Ohio certificate. The level printed on WPI's document may differ from the Ohio certificate, so always pick the Ohio EPA exam when you sign up. You can retake an exam every 30 days.
Operator Master has free practice questions with an explanation after every answer, a timed full-length practice exam and step-by-step math help built on the WPI formula table. It is an independent study tool, not the official exam.
Pay
The median pay for water and wastewater treatment plant and system operators in Ohio was $59,170 a year ($28.45 an hour) in 2025, compared with $60,020 nationally. One in ten earned $45,350 or less, and one in ten earned $75,200 or more.
These federal figures cover drinking water and wastewater operators together, at every class. Pay for a new operator is usually nearer the low end.
Moving up
These are the high school diploma paths. Related college study in a physical or natural science or in chemical, civil or environmental engineering, or a two-year water or wastewater degree, can shorten the Class A, II and III experience. Listed courses can also shorten Class A, II or III. For Class II or III, a drinking water certificate at the same or higher class can cut the experience in half. Class II and III still need at least one year of actual experience in the field.
From another state
If you hold a current certificate or license from another state or province, earned by written exam, by reciprocity or through WPI certification, you can apply for reciprocity in the eBusiness Center. You must also meet Ohio's own education and experience requirements for the class.
Ohio's advisory council compares the exam you passed with Ohio's exams to decide the class. If a copy of your exam cannot be obtained, Ohio EPA can issue a Class A certificate if you have the experience, or review the size and complexity of the plants you ran for a Class I, II or III certificate.
Ohio EPA's wastewater reciprocity comparison chart shows how other programs' classes have matched Ohio's. It is guidance only; each application is reviewed case by case.
You pay a certification fee when you apply and, once the class is set, a fee equal to the exam fee for that class.