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Wastewater operator certification

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

Wisconsin Administration Code NR114 was recently revised to reflect advancements in treatment technologies along with changes in educational training methods. The effective date for these changes is July 1, 2015. See the NR 114 Revisions Webpage for more information.


In order to become a certified wastewater treatment plant operator, you must pass both the general exam (either intro or advanced) and at least one subclass exam (either intro or advanced). The exam(s) which you should take is dependent upon the processes at the treatment plant at which you work, or would like to work. You may download the following document for detailed information on how to become a certified operator in Wisconsin: NR 114 Interpretation

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 class codes from 1 to 4, with 4 being the highest class and 1 being the lowest class. The plant class is based on a number of factors, including plant design flow, the number of treatment processes, permit effluent limits, and types of industries contributing wastewater. 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.

Note: To become certified in Subclasses K (Special K) or L (Electroplating/metal finishing), the general wastewater exam is not required.

Subclass Name
A Primary treatment
B Trickling filters and rotating biological contractors (RBC)
C Activated sludge
D Stabilization ponds and aerated lagoons
E Disinfection
F Anaerobic digestion
G Mechanical sludge de-watering and treatment
H Filtration (tertiary)
I Phosphorus removal
J On-site laboratory testing
K Special K (generally for treatment plants using chemical or physical treatment, or both)
L Electroplating and metal finishing


Once you pass the general exam and subclass exam (or K or L exam), you will be an operator-in-training, Grade T. To go up in Grade Levels, you must have hands-on experience in the operation of a treatment plant. You would need to document your experience on the Wastewater Operator Certification Experience Form [PDF] and submit that to your regional coordinator for approval.

The requirements for wastewater operator certification for each grade level are:

  • Grade T - Pass written introductory or advanced general exam and introductory or advanced subclass exam(s).
  • Grade 1 - Pass written introductory or advanced general exam and introductory or advanced subclass exam(s), plus have one year of satisfactory subclass specific experience.
  • Grade 2 - Have met the requirements of Grade 1, plus have 2 years of general experience in the operation of a wastewater treatment plant.
  • Grade 3 - Pass written advanced general exam and advanced subclass exam(s), plus have one year of satisfactory subclass specific experience and 3 years of general experience in the operation of a wastewater treatment plant.
  • Grade 4 - Have met the requirements of Grade 3, plus have 4 years of general experience in the operation of a wastewater treatment plant.

One year of experience is equivalent to twelve months of wastewater experience with a minimum of at least 1,000 hours in the hands-on operation and maintenance of a wastewater treatment plant.


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. Questions regarding reciprocity can be directed to the statewide operator certification coordinator, Lisa Bushby, 608-266-0498.

Study guides

Study guides are invaluable references for exam preparation. Study guides are designed to provide the critical knowledge necessary to pass the associated exam. You may either download a copy below or request a hard copy from your regional coordinator. There are also several courses, listed on our training calendar, that help prepare for the exams(s). In addition, you may review these study tips [PDF].

SubclassNameStudy guidesEdition date
General Intro [PDF]
Advanced [PDF]
Dec 2011
July 2012
A Preliminary and primary treatment Intro [PDF]
Advanced [PDF]
Aug 1991
B Trickling filter/RBC Intro [PDF]
Advanced [PDF]
Sept. 1995
C Activated sludge Intro [PDF]
Advanced [PDF]
Dec. 2010
D Ponds and aerated lagoons Intro [PDF]
Advanced [PDF]
Dec. 2013
Nov. 1998
E Disinfection Intro [PDF]
Advanced [PDF]
Feb 2010
F Anaerobic digestion Intro [PDF]
Advanced [PDF]
June 1992
G Mechanical sludge Intro [PDF]
Advanced [PDF]
Jan 1994
H Filtration Intro [PDF]
Advanced [PDF]
Nov. 1991
I Phosphorus removal Intro [PDF]
Advanced [PDF]
Jan. 2009
J Laboratory Intro [PDF]
Advanced [PDF]
Aug 2014 Revised
K Special K Study Guide [PDF] Jan. 1994
L Electroplating and metal finishing Study Guide [PDF] Dec. 1995

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

Continuing education

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.

  • Grades T, 1, and 2 require 18 hours of continuing education.
  • Grades 3 and 4 require 24 hours of continuing education

Credits must be earned within the three year certification period. For example: If November 1, 2012 is the expiration date of the certification, continuing education credits must be earned between November 1, 2009 and November 1, 2012 to be valid for renewal.

The continuing education must be relevant towards the operation of a wastewater treatment plant. Continuing education credits may be obtained in a number of 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), in-house training, or online wastewater courses. Please refer to our Training Calendar for an extensive list of applicable courses and trainings.

Credit for courses or training is determined by the following criteria:

  1. Each hour spent in course learning constitutes one credit hour of continuing education credit (minus breaks and lunch).
  2. Attendance at the entire course and successful completion of the course are required to receive any credit.
  3. Credit for a course cannot be split between water and wastewater - it has to be one or the other (except statewide conventions).
  4. A maximum of six hours 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 a training that was not pre-approved, but is relevant towards wastewater operations, the operator may complete the Operator Training Report Form [PDF] to document the training. Proof of attendance documentation must be attached to the Training Report Form.


Operator certifications come up for renewal every three years. DNR sends courtesy renewal reminder letters to operators six weeks before their certification expiration date. It is important for operators to 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 - SS/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 time period, the operator will need to re-take the exams as a new operator.


How do I get an application to take an exam?

An exam application will be sent (2 1/2 months prior to the upcoming exam date) to those operators that have taken an exam in the last year and a half. An operator who has not taken an exam in the last year and a half may contact their regional coordinator for an application. New operators may dowload an application on our website.

How much does it cost to take an exam?

Each exam is $25. 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 normally within 30 days of the exam day (maximum 60 days per Act 167 [PDF]). A list of missed key knowledges is printed out on your exam results letter. Refer to your study guide to determine what areas need more study.

I passed a general exam— Why am I not certified?

You need to pass both a General and a subclass exam to become certified. This applies to wastewater operators seeking certification in subclasses A through J. There is no requirement to take a general exam for subclasses K (Special K) & L (Electroplating and metal finishing).

How do I advance in grade level?

Grade levels depend on both passed exams and credited work experience. See the Grade Levels section under the Requirements Tab for more information.

What classes can I take to get continuing education credits?

Check our training calendar for a current list of training opportunities. Contact the sponsor directly for more information on the individual trainings.

When should I submit my continuing education documentation?

Keep your credit slips and other documentation on file. Courtesy renewal reminder letters are mailed six weeks prior to your expiration date, provided that we have a current address for you on file. At that time, mail in your reminder letter, credits, and the appropriate fee before the expiration date on your certificate.

What if I earn more credits than I need?

That's great!! Send along any extra credits you have and they become a part of your record. Credits cannot be carried over to the next renewal period.

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 penalty 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 period, your operator record will be deleted and you will have to retake all exams.

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The Certified Operator

"The Certified Operator" is the annual newsletter of the Operator Certification Program distributed in August to all certified Wastewater and Municipal Waterworks operators. The newsletter highlights program information and updates. DNR has recently begun emailing the newsletter to all operators who have an email address on file. If you are currently receiving the newsletter via regular mail and would like to receive future copies via email, please email your request to (please include your name and certification number in the email).

Current edition of "The Certified Operator"

August 2014 [PDF]

Previous editions of "The Certified Operator"

August 2013 [PDF]

August 2012 [PDF]


Contact your regional coordinator for any questions regarding your certification. Experience forms should be mailed to your regional coordinator. If no regional coordinator is listed, send the experience form to the statewide coordinator.

Regional coordinators
Regional office Coordinator name Counties of responsibility
South Central Region Contact Statewide Coordinator Columbia, Dane, Dodge, Grant, Green, Iowa, Jefferson, Lafayette, Richland, Rock, Sauk
South Eastern Region Contact Statewide Coordinator Kenosha, Milwaukee, Ozaukee, Racine, Sheboygan, Walworth, Washington, Waukesha
DNR - Northeast Region
2984 Shawano Ave
Green Bay WI 54313-6727
Dick Sachs
Brown, Calumet, Door, Fond du Lac, Green Lake, Kewaunee, Manitowoc, Marinette, Marquette, Menomonie, Oconto, Outagamie, Shawano, Waupaca, Waushara, Winnebago
West Central Region
Contact Statewide Coordinator Adams, Buffalo, Chippewa, Clark, Crawford, Dunn, Eau Claire, Jackson, Juneau, LaCrosse, Marathon, Monroe, Pepin, Pierce, Portage, St. Croix, Trempealeau, Vernon, Wood
Northern Region Contact Statewide Coordinator Ashland, Barron, Bayfield, Burnett, Douglas, Florence, Forest, Iron, Langlade, Lincoln, Oneida, Polk, Price, Rusk, Sawyer, Taylor, Vilas, Washburn
Lisa Bushby, DNR Statewide Operator Certification Coordinator
PO Box 7921, Madison WI 53707-7921
Phone 608-266-0498
Fax 608-266-5226

For general questions, contact
Last revised: Tuesday February 10 2015