Wastewater Treatement Operator Certification

Water Protection Program fact sheet
Division of Environmental Quality Director: Ed Galbraith

A Challenging and Rewarding Career

Working in the water and wastewater industry can be extremely rewarding since you are providing an important service to your community. It just might be one of the most important positions in the world since no one can live without water. It takes knowledgeable, conscientious people to deliver clean, potable water and to ensure wastewater treatment plants are discharging water in an environmentally safe manner.

It takes special people to do this job. People who like to work with their hands and have an interest in biology, chemistry and mathematics are well suited for the career. One this is for sure – no two days are the same for water or wastewater professionals. They may be repairing a water line, running a backhoe, adjusting chemical feed rates and fixing a pump one day and the next day working in the laboratory testing samples for pathogens and microorganisms or presenting information to the town board or the public. Water and wastewater professionals wear many hats.

If you like a challenge and the responsibility of protecting the public and the environment – this could be the career for you! This document discusses how to become a Missouri certified operator for wastewater treatment. The Missouri Department of Natural Resources also issues operator certificates for drinking water treatment and drinking distribution professionals as well.

What certification levels are available in the state of Missouri for wastewater treatment systems?

Levels available are A, B, C, and D (A being the highest and D the lowest). The department determines the minimum level needed for the chief operator of the system based on the size and complexity of the system.

How do I become a certified operator?

Step 1: Based on your work experience, determine the level you might qualify for using the table below from 10 CSR 20-9.030.

Certificate Level

Minimum Actual and Equivalent Experience


Five and one-half (5½)  years of wastewater treatment facility operating experience (of which two (2) years may be equivalent)


Three and one-half (3½) years of wastewater treatment facility operating experience (of which one (1) year may be equivalent)


One and one-half (1½) years of wastewater treatment facility operating experience (of which one (1) year may be equivalent)


Six (6) months of wastewater treatment facility operating experience (which may be equivalent)

Actual wastewater treatment operating experience means the skills and knowledge acquired from making or acting upon day-to-day process control and system integrity decisions rather than from textbook study or supervisory observation. The applicant should have experience in some combination of wastewater system operational tasks such as: sample collection, routine operational monitoring, interpretation of test results, calculation of chemical dosages and subsequent adjustment of chemical feeders and aeration, flow rate and pumping adjustments, disinfection, and completion of operational reports. Equivalent experience is based on criteria established in 10 CSR 20-9.030.

Do I need a high school diploma as part of my educational experience?

An operator must have one of the following:

Step 2: Complete and submit an application for examination at least 30 days prior to exam date. See our website for an application and list of exam dates and locations. The departments hosts monthly exam sessions in Jefferson City and quarterly in five regional locations. Applicants must submit a fee of $45 with the application for examination. This fee covers the cost of the exam and issuance of the certificate when qualified.

What type of examination is given?

The exam is multiple choice. A score of 70% or higher is required to pass.

What information does the exam cover?

The exam is based on subjects an operator needs to know such as: Missouri wastewater regulations, general wastewater systems knowledge, water quality, applied mathematics, chemistry, laboratory test procedures as applied to wastewater treatment, hydraulics, pumps and operation. Exam questions are not limited to this list.

What happens when I pass the exam?

When you pass the exam, the department will review the education and employment history sections of your exam application to determine if you have the necessary work experience for the level of certification. If you possess the required experience and education, the department will issue you a certificate valid for three years.

What happens if I pass the exam, but don’t have the needed work experience?

If it is determined by the department after reviewing your education and employment history, that you do not possess the needed work experience, you will receive a letter stating that you passed, but do not have sufficient experience or education. You have 18 months from the date of the exam to obtain the necessary additional experience or education.

What happens if I fail the exam?

You may retake the exam after waiting 60 days from the previous exam date. You must submit a new application for examination and a $20 fee to retake the same type and level of exam. If you fail the same type and level of exam three times, you must complete a department-approved multi-day training course prior to retaking the exam.

Now that I’m a certified operator, how do I maintain my certificate?

The department issues certificates that are valid for a three-year period. In order to renew the certificate, the operator must:

What training is available?

You can choose from classroom training, virtual, online, and correspondence courses that the Missouri Department of Natural Resources has approved for operator certification credit. Visit our website dnr.mo.gov/env/wpp/opcert/oprtrain.htm for a current list of courses available.

How will I know it is time to renew my certificate?

The department will send a renewal notice to your last known address approximately 60 days before your certificate expires. If you fail to receive you renewal notice, you are still responsible for renewing the certificate. Please call us or go online to apps5.mo.gov/operator/ to submit updated contact information, review your training history, and renew online.

What if I fail to renew by the expiration date of my certificate?

If you have completed all the required training by the expiration date of the certificate, there is a 60-day grace period to submit your renewal application and fee. There is a $10 per month penalty for late applications. Failure to complete training and submit the renewal application by these timeframes will result in the deactivation of your certificate. There is no grace period for obtaining the minimum hours of renewal training.

What does it mean if my certificate has been deactivated?

You will have to submit a new application for examination to retake the exam.

For more information

The following regulations related to wastewater treatment operator certification are available on the Web at dnr.mo.gov/env/wpp/opcert/oprtrain.htm.

Contact the Operator Certification Section at Missouri Department of Natural Resources, Division of Environmental Qualit, Operator Certification Section, P.O. Box 176, Jefferson City, MO 65102-0176, 573-751-1600, 800-361-4827, dnr.mo.gov/env/wpp/opcert/oprtrain.htm