Median Pay by Area
- Rochester
- $78,270 a year
- Minneapolis-St. Paul-Bloomington
- $77,170 a year
- St. Cloud
- $74,670 a year
- Mankato
- $69,830 a year
- Duluth
- $65,640 a year
Minnesota wastewater operators
The steps from no certificate to a Minnesota Class D wastewater treatment or Class S-D collection system operator certificate, how to apply for and pass the exam, how to keep your certificate active and what operators earn. Every requirement links to the Minnesota Pollution Control Agency (MPCA), Minnesota Rules chapter 9400 or Minnesota Statutes sections 115.71 to 115.77.
MPCA makes the final eligibility determination. Check with MPCA before you apply.
Why it matters
In Minnesota, wastewater treatment operators, the people responsible for the daily, on-site operation of wastewater facilities and collection systems, must be certified. Their class of certification must be equal to or higher than the class of the facility.
State law says a wastewater treatment facility may not be operated unless it has at least one person certified at or above its class who has full and active responsibility for its daily on-site operation. Other certified operators may cover parts of the facility.
A wastewater treatment facility here means any plant, disposal field, lagoon or other works for collecting, pumping, treating, stabilizing or disposing of sewage that is used, or meant to be used, by the public or by a considerable number of people.
The MPCA issues wastewater operator certificates; drinking water operator certificates come from the Minnesota Department of Health. A city manager, superintendent of public works or other administrator is not considered an operator unless their duties include the day-to-day operation of a wastewater facility.
Treatment facilities are Class A, B, C or D, set by a point system based on the unit processes, the loading to the plant and the permit's final effluent limits. Class A is the highest (76 or more points) and Class D the lowest (30 points or less).
Type S systems are collection, pumping and conveyance facilities that run separately from a treatment facility. They are Class S-A (serving 50,000 people or more), S-B (15,000 to 49,999), S-C (1,500 to 14,999) and S-D (fewer than 1,500). A collection system that is not separate counts as part of the treatment facility.
The MPCA also certifies Type IV operators, who land-apply biosolids, and Type V operators, who run spray irrigation systems. Each has its own course and exam.
Step 1
For the entry-level Class D or S-D exam, you need a high school diploma or GED and one year of operating experience at a Class A, B, C or D facility. Instead of the experience, you can complete an approved post-secondary program in water and wastewater treatment technology; the MPCA lists St. Cloud Technical and Community College and Vermilion Community College in Ely.
You must have hands-on wastewater facility operating experience to be eligible for a certification exam. For the S classes, the experience must come from a wastewater treatment facility or a collection system.
For a treatment certificate, at least half of the required experience must be at a treatment facility. The other half may come from a Type S collection system or a drinking water system no more than one class below the certificate you want.
For Class C, B and A (and S-C, S-B and S-A), every 40 contact hours of water supply or wastewater treatment courses from an accredited institution can take one month off the experience required, but never below one year.
Step 2
The MPCA publishes Need to Know criteria for wastewater treatment and collection system operators, suggested study materials for each, and an exam description for each of Class A to D that shows which topics the questions cover.
MPCA courses such as Wastewater Treatment Basic, Collection System Basic and the Stabilization Pond Seminar are 16 contact hours and offer exams on the last day. Exam refresher sessions (12 contact hours) review need-to-know content and exam math, but they do not replace experience or independent study.
The courses and exams need basic, GED-level math. The MPCA also posts math workbooks for treatment and collection system operators.
Step 3
Fill out the MPCA's Application for Wastewater Certification Examination (wq-wwtp8-00) for one exam. List your job duties, length of service, hours per week and supervisor's name and phone for each employer. Class A and S-A applicants also attach a position description and an organization chart.
The exam fee on the application is $55 for each Class A to D and S-A to S-D exam, and it is nonrefundable even if you are found ineligible. Pay by check to the Minnesota Pollution Control Agency or with the MPCA's credit card authorization form; the bank adds a card service fee.
Apply at least 15 days before the exam; each exam date lists its own deadline for the application and payment to be postmarked or faxed. Online registration is not available. If you are using education in place of experience, include a diploma or transcript.
Step 4
Exams are given at MPCA training seminars on the last day of class and on exam dates held around the state. The MPCA's certification page lists upcoming exam dates and places.
You must register in advance; walk-ins are not accepted. Bring a pencil and a nonprogrammable calculator.
Step 5
The MPCA tells you if you pass. You then have 90 days to send the $45 certification fee. If you miss that deadline, you must apply to take the exam again.
Your certificate shows the class of facility you may operate and must be displayed at the plant or in your office. It stays valid for its full term if you leave your job.
Step 6
Certificates expire three years after they are issued. In those three years you need 32 contact hours for Class A and S-A, 24 for B and S-B, 16 for C and S-C, 8 for D and S-D, and 6 for Type IV or Type V.
A contact hour is 50 to 60 minutes of training. At least half of your hours must be wastewater courses approved by the MPCA; the rest may be water or other related courses the MPCA has approved.
The MPCA mails you a personal Request for Renewal form three months before your certificate expires. Send it back complete, signed and dated, with the renewal fee and proof of any training taken outside the MPCA program, within 30 days after the expiration date. If the form has not arrived three months ahead, contact the MPCA.
If your certificate expires, you can apply for reinstatement for up to one year, showing continuing education for the whole time since it was last issued or renewed. After a year, you apply and test as a new applicant.
Exam day
Minnesota's wastewater exams are prepared by the MPCA, with a separate exam for each class. They can cover basic science, math, operating procedures, treatment processes, equipment and its maintenance, management, and state law and rules.
All exams are closed book. You are given a formula book. Bring a No. 2 pencil and your own scientific calculator that can do square roots and exponents; programmable (graphing) calculators and smartphones are not allowed, and the MPCA does not lend calculators.
A passing grade is 70 out of 100.
If you fail, you can retake the exam after three months. On request, the MPCA can tell you the topics of the questions you missed, and you can review your exam if you ask within 60 days of being told your results.
Breaking the exam rules, such as copying answers, talking with other test takers or photographing the exam, forfeits the exam and can bar you from future exams.
Minnesota's wastewater certification exams are prepared by the MPCA. They are closed book, and the MPCA gives you a formula book at the exam. Operator Master's free practice questions, timed practice exam and math help are built on the WPI exam format and the WPI formula table, so they cover general wastewater knowledge and math, not the MPCA's exam questions, format or formula book. Use the MPCA's Need to Know criteria, exam descriptions and study materials as your main guide. Operator Master is an independent study tool, not the official exam.
Pay
The median pay for water and wastewater treatment plant and system operators in Minnesota was $74,670 a year ($35.90 an hour) in 2025, compared with $60,020 nationally. One in ten earned $52,130 or less, and one in ten earned $87,250 or more.
These federal figures cover drinking water and wastewater operators together, at every level. Pay for a new operator is usually nearer the low end.
Moving up
These are the treatment classes on the high school diploma or GED path; the S classes need the same, with experience from a treatment facility or collection system (S-A needs S-B or B, and S-B needs S-C or C). A bachelor's degree in engineering or a physical or biological science shortens the experience, and approved courses can shorten it further for Class C and above.
From another state
If you hold a current license from another state or territory, earned by passing an exam, and you have a good compliance history and good standing, you may apply for reciprocity.
Send the MPCA's Application for Reciprocity (wq-wwtp8-10) with the $40 nonrefundable fee, a copy of your current license and copies of any training or education certificates.
The MPCA checks your status with the other state and decides which Minnesota class matches. If the other state's standards are lower than Minnesota's, the MPCA tells you in writing what else you must do; if you are denied, the fee counts as your exam application fee.