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Wastewater operator certification

A "certified operator" is an individual who has met the requirements of Chapter NR 114, Wisconsin Administrative Code, and has been issued a certificate by the DNR to operate one or more of the classifications of wastewater treatment plants.

To become a certified wastewater treatment plant operator, you must pass both the Wastewater - General exam and at least one subclass exam. The subclass exam(s) which you should take is dependent upon the processes at the treatment plant at which you work or would like to work.

Study guides are a valuable tool to help prepare for exams. There are also several courses listed on our training calendar that help prepare for exams. Prior education or training is not required before taking the exams; however, some classroom or online training is recommended.


Wastewater treatment plants are assigned a basic or advanced classification rating. Subclasses are also assigned to wastewater treatment plants that correspond to the processes used at the plant. Each plant must have a designated operator-in-charge certified at the plant class level and in the same subclasses as the processes used at the plant.

Category Subclass Letter Subclass Name Description
Biological Treatment A1 Suspended Growth Processes Activated Sludge and variants
A2 Attached Growth Processes Trickling filters, RBCs and biotowers
A3 Recirculating Media Filters  
A4 Ponds, Lagoons, and Natural Systems  
A5 Anaerobic Treatment of Liquid Waste High strength liquid waste treatment system
Solids Separation B Solids Separation Clarifiers, membranes, filters, tertiary phosphorus removal, etc.
Solids Treatment C Biological Solids/Sludge Handling, Processing, and Reuse Aerobic and anaerobic digestion, thickening, dewatering, land application
Disinfection D Disinfection Chlorination, ultraviolet radiation, ozone
Laboratory L Laboratory Registered or certified on-site laboratories
Nutrient Removal N Total Nitrogen  
P Total Phosphorus  
Collection System SS Sanitary Sewage Collection System  
Special U Unique Treatment Systems Unique, special treatment plants that use biological, chemical or physical methods


The requirements for wastewater operator certification for each level are:

  • Operator–in–Training (OIT): Pass Basic General Wastewater Exam* and Basic Subclass Exam
  • Basic: One year of subclass specific experience
  • Advanced: Obtain ten advanced points and submit an advanced certification application (see tab#5, Adv Cert, on this web page for more information)

*Note: The Basic General Wastewater Exam is not required for the Collection System certification or the Special U certification.

Experience is documented on the Wastewater Operator Experience Form available on the forms page. One year of experience is based on full–time employment at a treatment plant or 1,000 hours of cumulative experience, over a minimum of twelve months, for part-time operators.


If you have a current wastewater and/or waterworks certificate from another state and are interested in applying for reciprocity to Wisconsin's operator certification program, application materials are available on the forms page.

Subclass Study Guide Edition Date
–– Basic General Wastewater Revised June 2016
A1 Biological Treatment — Suspended Growth Processes August 2015
A2 Biological Treatment — Attached Growth Processes February 2016
A3 Biological Treatment — Recirculating Media Filters August 2015
A4 Biological Treatment — Ponds, Lagoons and Natural Systems August 2015
A5 Biological Treatment — Anaerobic Treatment of Liquid Waste October 2018
B Solids Separation February 2016
C Biological Solids/Sludge — Handling, Processing and Reuse June 2016
D Disinfection February 2016
L Laboratory August 2015
N Nutrient Removal — Total Nitrogen October 2018
P Nutrient Removal — Total Phosphorus August 2015
SS Sanitary Sewage Collection System August 2018
U Unique Treatment Systems September 2015
-- Advanced Wastewater February 2016

In addition to the study guides, wastewater operators can borrow technical manuals from the UW Water Library.

Certification must be renewed every three years. This continuing education requirement is designed to help operators keep current on new requirements and technical innovations. Continuing education also helps operators acquire additional knowledge and skills.

  • Operator–in–training and basic level operators require 18 hours of continuing education.
  • Advanced level operators require 24 hours of continuing education.

Credits must be earned within the three-year license period. For example: If November 1, 2016, is the expiration date of the certification, continuing education credits must be earned between November 1, 2013, and November 1, 2016, to be valid for renewal.

Continuing education must be relevant to the operation of a wastewater treatment plant. Continuing education credits may be obtained in several different ways, including attendance at professional organization meetings or conferences, wastewater related courses (such as those offered at technical schools, colleges, or non-profit organizations), or approved online wastewater courses. Please refer to our training web page for an extensive list of relevant courses and events.

The following criteria determine credit for courses or training:

  1. Each hour spent in course learning constitutes one credit hour of continuing education credit (minus time spent for registration, breaks and lunch).
  2. A maximum of six hours of health and safety-related training may be used per renewal period. Examples of health and safety-related training include first aid/CPR, confined space entry, excavation safety, personal protective equipment, Hazwoper, RCRA, and bloodborne pathogens.

If an operator takes training that was not pre-approved but is relevant to wastewater operations, the operator may complete the Operator Training Report Form (4400-190) available on the training page to document the training.

Operator certifications come up for renewal every three years. DNR sends courtesy renewal reminder letters to operators six weeks before their certification expiration date. Operators must keep their address current by notifying their regional coordinator of any changes. The letter serves as a courtesy reminder only; it is the operator's responsibility to keep track of their certification expiration date. When the operator is ready to renew, they should mail in the courtesy reminder letter, their continuing education documentation, and the $45 renewal fee to:

Operator Certification Program - EAS/7
PO Box 7921
Madison WI 53707-7921

The renewal materials must be postmarked by the expiration date on the certificate (there is no grace period). Any renewal postmarked after the expiration date should also include the $25 late penalty fee.

Once a certification expires, an operator has one year from their expiration date to reinstate their lapsed certification. An operator is NOT considered a certified operator during this lapse of certification. If a certification is not renewed within that one year, the operator will need to retake the exams as a new operator.


Ten points total is required to obtain advanced level certification. At least 4 of the points must be obtained through hands-on experience; the operator must have at least four years of hands-on experience to apply for advanced certification. A maximum of 6 years of hands-on experience can be used towards points. An Advanced Wastewater Treatment Plant Operator Certification Application must be submitted, along with the $100 application fee.

Type Point Method Points Minimum Hours
Experience Four years of hands-on 4 4,000
Five years of hands-on 5 5,000
Six years of hands-on 6 6,000
Degree Undergrad or Graduate Degree 6 At least 240 hours of wastewater related courses
Water/Wastewater Associates Degree 6 N/A
Apprenticeship Completion of State Approved Apprenticeship Program 6 N/A
Exam 100 Question Multiple Choice Exam 4 N/A
Advanced Coursework Pre-approved by the DNR and on the list of approved courses 2 80
1.5 60
1 40
0.5 20

Advanced coursework must be from the approved advanced coursework list to be eligible for advanced certification points. This list is updated on September 1 of every year.

There are numerous combinations to obtain 10 points. At least four years of hands-on experience is a requirement for all. See these example combinations.

For questions on the advanced certification application process, please contact


Where can I obtain the application to take an exam?
Applications are available on the exams web page 10 weeks before the exam date.
How much does it cost to take an exam?
Each basic exam is $25. The advanced exam is $50. Exam fees are non-refundable.
Can I pay for the exams with a credit card?
We can only accept payment by check or money order at this time.
When will I be notified of my exam results?
Exam results letters are sent within 30 days after the exam day. A list of missed objectives is printed on the exam results letter to help an operator determine focus areas of the study guide.

Continuing Education

What classes can I take to get continuing education credits?
Check our training calendar for a current list of training opportunities, as well as a list of online training providers.
When should I submit my continuing education documentation?
Courtesy renewal reminder letters are mailed six weeks before your expiration date, provided that we have a current address for you on file. At that time, mail in your reminder letter, credit documentation, and the appropriate fee before the expiration date on your certificate.
What if I earn more credits than I need?
That's great!! Those credits become a part of your record. However, credits cannot be carried over to the next renewal period. They must be earned within your license period printed on your certificate.
What if I don't have enough credits to renew?
Send in the required continuing education documentation when you have accumulated enough credits and a $70 fee ($45 renewal fee and $25 late fee) to the department to get your certification renewed. You have one year after the expiration of your certificate to renew. If you do not renew your certification within that one year, you will need to retake exams and be assigned a new operator certification number.
I took a class a few days before my certification expiration date, and it is not showing up yet on my training history report. What do I need to do to renew my certification on time?
Print your Training History Report and hand-write in the missing class. Mail in your renewal. Once the DNR Operator Certification Program receives the attendance roster from the training provider, we will verify your attendance.

Advanced Certification

What courses are considered "Advanced" and can be used towards advanced certification points?
Advanced coursework must be from the approved advanced coursework list to be eligible for advanced certification points. This list is updated on September 1 of every year.
What is considered "wastewater related" courses in regard to the 240-hour requirement to use a bachelor's degree for advanced points?
The following is a list of courses considered to be "wastewater related" topics. Still, it is not all-inclusive: Aquatic Toxicology, General Chemistry, Water Chemistry, Fluid Mechanics, Hydraulics, Hydrology, Microbiology, Soil Science, Water Resources, and Water Quality Modeling
How many classes is 240 hours?
240 contact hours are equivalent to 15-16 college semester credits.
I have advanced level certification in one or more subclasses already. I want to add a new subclass to my license. Do I have to apply for advanced level certification to advance in that new subclass?
No. If you are advanced in any subclass, you have your 10 points towards advanced level certification. To add a subclass, you must pass that subclass exam. Once you document at least a year of experience in that specific subclass, it will automatically bump up to the advanced level.

Collection System Certification

Do I need to take the new collection system exam?
If the treatment plant owns the sanitary sewer collection systems associated with it, then at least one person will need to be certified in the collection system subclass. For satellite sewerage collection systems, this certification will be voluntary. However, the department highly recommends that satellite systems have a certified operator in collection systems.
To become certified, the person will need to take the 50-question multiple-choice collection systems exam. No operator certification will be converted into the collections system subclass since it is an entirely new certification type.
Do I need to pass the basic general wastewater exam, too, to become certified in collection systems?
The basic general wastewater exam is not required for collection system certification.
By when does the collection system certification need to be obtained?
The collection system study guide and exam have not yet been developed and will tentatively be complete in 2018. Once the collection system study guide and exam have been developed by the department, and at the time of WPDES permit issuance, collection system operators will have a permit term of 5 years to obtain collection system certification.
If the treatment plant is classified as advanced, does the collection system operator need advanced certification?
No, basic level certification is the only level required for all collection systems.

New Subclasses: Nutrient Removal- Total Nitrogen and Anaerobic Treatment of Liquid Waste

I operate a treatment plant that has total nitrogen limits and acts to remove total nitrogen. Will I need to take the new Nutrient Removal - Total Nitrogen exam?
The designated operator-in-charge will need to pass the new Nutrient Removal - Total Nitrogen exam. This exam will be 25 questions, multiple-choice. There is a grace period of 12 months to obtain this new certification once the subclass is added to a facility's classification.
I operate a treatment plant that has an anaerobic treatment of liquid waste. Will I need to take the new Anaerobic Treatment of Liquid Waste exam?
The designated operator-in-charge will need to pass the new Anaerobic Treatment of Liquid Waste exam. This exam will be 25 questions, multiple-choice. There is a grace period of 12 months to obtain this new certification once the subclass is added to a facility's classification.

You may also refer to this PowerPoint presentation regarding the new subclasses and the advanced point system.

The Certified Operator

"The Certified Operator" is the annual newsletter of the Operator Certification Program distributed annually to all certified wastewater and municipal waterworks operators. The newsletter highlights program information and updates. This newsletter is emailed to operators who have an email address on file. Operators that request hard copies will receive the newsletter via regular mail.

Previous editions of "The Certified Operator"

September 2018

Contact your regional coordinator for any questions regarding your certification. Wastewater experience forms should be mailed or emailed to your regional coordinator.

If no regional coordinator is listed, send questions and the wastewater experience form to the statewide coordinator (contact information listed below).

Regional coordinators

Regional office Coordinator name Counties of responsibility
DNR - South Central Region
3911 Fish Hatchery Road
Fitchburg WI 53711
Jordan Main
Columbia, Dane, Dodge, Grant, Green, Iowa, Jefferson, Lafayette, Richland, Rock, Sauk
DNR - Southeast Region
1155 Pilgrim Rd
Plymouth WI
Curt Nickels
Kenosha, Milwaukee, Ozaukee, Racine, Sheboygan, Walworth, Washington, Waukesha
DNR - Northeast Region
2984 Shawano Ave
Green Bay WI 54313-6727
Heidi Schmitt Marguez
Brown, Calumet, Door, Fond du Lac, Green Lake, Kewaunee, Manitowoc, Marinette, Marquette, Menomonie, Oconto, Outagamie, Shawano, Waupaca, Waushara, Winnebago
DNR - West Central Region
1300 W Clairmont Ave
Eau Claire WI 54701
Nicholas Lindstrom
Adams, Buffalo, Chippewa, Clark, Crawford, Dunn, Eau Claire, Jackson, Juneau, La Crosse, Marathon, Monroe, Pepin, Pierce, Portage, St. Croix, Trempealeau, Vernon, Wood
DNR - Northern Region
810 W Maple St
Spooner WI 54801
Carson Johnson
Ashland, Barron, Bayfield, Burnett, Douglas, Florence, Forest, Iron, Langlade, Lincoln, Oneida, Polk, Price, Rusk, Sawyer, Taylor, Vilas, Washburn

Statewide Coordinator

PO Box 7921, EAS/7
Madison WI 53707-7921

Program Assistant

Jordan Schutz
Phone: 608-228-5190