Iowa wastewater operators
The steps from no certificate to an Iowa wastewater operator certificate, how to qualify for and pass the exam, how to keep your certificate active and what operators earn. Every requirement links to the Iowa Department of Natural Resources (DNR) Operator Certification Program or its rule, Iowa Administrative Code 567—Chapter 81.
DNR makes the final eligibility determination. Check with DNR before you apply.
Why it matters
Iowa law makes it unlawful to run a wastewater treatment plant unless its operator is certified by the DNR director, and unlawful for anyone to do an operator's duties without being certified.
Each plant must have an operator-in-charge: the person on site in direct responsible charge of its daily operation. That operator needs a certificate of the same classification as the plant, at the plant's grade or higher.
Shift operators, who are responsible for a plant during an operating shift, also need a certificate: at least Grade II at Grade III and IV plants, and at least Grade I at Grade I and II plants.
A city manager, city clerk, council member or other administrative official does not count as the operator-in-charge unless their duties include active, daily on-site operation of the plant.
The rule has three classifications: wastewater treatment plants, water treatment plants and water distribution systems. There is no separate wastewater collection certificate.
The owner of a Grade A, I, IL or II plant or system may share a certified operator with other systems by signing an operator by affidavit agreement, which the local DNR field office must approve.
Iowa has seven certificate grades: A, W, I, IL, II, III and IV. Wastewater plants use Grades W, IL and I to IV. Grade A is for small water systems.
A wastewater plant's grade depends on its type of treatment and its design load, measured in pounds of BOD5 a day or design population equivalent. A plant with several kinds of treatment takes the highest grade among them.
Waste stabilization lagoons are Grade IL at any size. Aerated lagoons are Grade IL up to a design population equivalent of 5,000 and Grade I above that. Advanced aerated lagoons are Grade II. A Grade I, II, III or IV wastewater treatment certificate also covers a Grade IL plant.
Fixed film plants, such as trickling filters, are Grade II up to a population equivalent of 5,000, Grade III from 5,001 to 50,000 and Grade IV above 50,000. Activated sludge plants are Grade II under 2,000, Grade III from 2,000 to 15,000 and Grade IV above 15,000.
Grade W is for plants that discharge to Iowa waters using onsite treatment technology.
Step 1
You need a high school diploma or GED for every grade, and operating experience for Grades IL and I to IV before you can take the exam. Experience must be in the same classification you are applying for, so wastewater work for a wastewater exam.
Grades I and IL need 1 year of operating experience and Grade II needs 3 years. Grade W needs a DNR-approved training course instead of experience.
DNR uses the duties you describe on your application to decide whether you can take the exam, so describe your job in detail. If you are a lab technician, mechanic or electrician who helps run the plant, give the share of your time spent on plant operation.
Step 2
Directly related education can replace part of the experience. For Grades I and IL, 2 semester hours, 3 quarter hours or 3 CEUs of directly related education replace half of the one year. For Grades II to IV, each 30 semester hours, 45 quarter hours or 45 CEUs replace one year, up to half of the experience.
Plant lab and maintenance staff, people who review plant operations on site, and certified water treatment operators may get 50 percent credit for that work toward the experience for Grades I and II.
Grades III and IV also need years of post-high school education, part of it directly related to wastewater. A year of operating experience at Grade II or higher (for Grade III) or Grade III or higher (for Grade IV) can replace a year of that education, up to half of it.
The same experience or education can only be counted once, either as experience or as education. Military education, training or service can also count; send the documents with your exam application.
Step 3
Apply for exam eligibility online in DNR's Operator Certification Web, or on the paper Exam Application (542-3118). Each exam costs $30. Attach transcripts for any post-high school education you are counting.
DNR reviews your education and experience and tells you whether you are eligible. You must have DNR eligibility before you can register for any exam. An approved application is valid for one year, and you must pass within that year or the application lapses.
Once DNR emails you that you are eligible, email examopcert@dnr.iowa.gov with your name, operator ID, exam type and grade, whether it is a first try or a retest, and whether you want to test in person or remotely.
If you need a disability accommodation, ask at least 30 days before the exam and send proof of eligibility with your application.
Step 4
After you pass, pay the certification fee within 60 days of DNR's notice. The fee is $20 for each half year until the certificate period ends on June 30 of the next odd-numbered year. Paying after 30 days adds a late penalty, and after 60 days you will not be certified on that exam.
DNR no longer mails paper certificates or wallet cards. You view and print your current certificate from the Operator Certification Web.
Tell DNR within 30 days when your address or employer changes.
Step 5
All certificates expire on June 30 of odd-numbered years and must be renewed every two years. Renew before your certificate expires; the renewal fee is $60, and renewing after it expires adds a late penalty.
Before you renew, earn continuing education units (CEUs) between April 1 and March 31 of the odd-numbered year. Grade III and IV operators need 2 CEUs (20 contact hours) for each certificate; all other operators need 1 CEU (10 contact hours).
Training counts only if an accredited college, university or technical institute, or DNR, approves it and it relates directly to your certificate. Keep your own record of the CEUs you earn and report them to DNR.
If you are newly certified after April 1 of the second year, you do not need CEUs until the next two-year period.
If you do not renew within 60 days after your certificate expires, you lose the right to renew. To be certified again, you must meet the education and experience rules and pass the exam again. You cannot stay operator-in-charge on an expired certificate.
Exam day
Every new operator must pass a certification exam, unless certified by reciprocity. You can move up to a higher grade in the same classification by passing its exam.
You can test in person by appointment at community colleges and DNR field offices around Iowa. The venue will contact you to set a time, so do not walk in or call to schedule.
You can also test remotely through the proctoring company PSI, any day and at any hour, on a laptop or desktop computer with a camera and microphone. Tablets, iPads and phones are not allowed. A proctor watches you by camera and the session is recorded.
To prepare, DNR links WPI's Need-to-Know documents for its exams and the ABC Testing exam preparation pages. WPI says its standardized exams are multiple choice and come with a Formula/Conversion Table to use during the exam.
If you fail, you can apply to retake the exam and pay the $30 exam fee again. You can also ask DNR in writing for your exam grade and results.
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 Iowa was $60,990 a year ($29.32 an hour) in 2025, compared with $60,020 nationally. One in ten earned $46,880 or less, and one in ten earned $76,040 or more.
These federal figures cover drinking water and wastewater operators together, at every grade. Pay for a new operator is usually nearer the low end.
Moving up
Every grade also needs a high school diploma or GED. Directly related education can replace up to half of the experience, as described above.
From another state
If you are certified under another state's mandatory program that DNR has already reviewed and accepted, you can be certified in Iowa at the matching grade without an exam. You must have passed an exam generally equivalent to Iowa's and meet Iowa's education and experience rules.
If your state's program is voluntary, DNR will consider your certificate, but it may require you to pass the Iowa exam.
Send DNR's Reciprocity Application (542-3117) with the certification fee, listing your current certificates, education and work history. Veterans also send proof of veteran status.
