Mississippi wastewater operators
The steps from no certificate to a Mississippi 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 Mississippi Department of Environmental Quality (MDEQ) Wastewater Operator Training and Certification Program or its rule, 11 Miss. Admin. Code Pt. 6 Ch. 3.
MDEQ makes the final eligibility determination. Check with MDEQ before you apply.
Why it matters
Since July 1, 1987, Mississippi law has required every municipal and domestic wastewater treatment plant to be operated by a certified operator. The rule does not cover a plant that treats only its own industry's wastewater and is owned and run by that industry.
The certified operator in charge of a facility must be certified at the facility's class or higher, and must visit it at least 1 day a week for Class I, 2 days for Class II, 3 days for Class III and 5 days for Class IV, unless the permit says otherwise. Each visit must be written down.
To serve as the certified operator for a facility, your home must be no more than 50 miles from it, unless MDEQ grants a written waiver.
If a facility loses its certified operator, the owner must tell MDEQ right away. It may keep operating without one for up to 180 days.
Mississippi has four treatment classes, Class I to IV, and two collection classes, Class I-C and II-C. Facilities are classed by type of treatment and design flow.
Class I covers waste stabilization lagoons and septic tank-sand filters of any size. Class II covers aerated lagoons of any size, trickling filters under 0.3 MGD and activated sludge under 0.1 MGD.
Class III covers trickling filters from 0.3 to 3.0 MGD and activated sludge from 0.1 to 2.0 MGD. Class IV covers larger trickling filter and activated sludge plants.
Collection certification is voluntary: Class I-C covers collection systems up to 1.0 MGD and Class II-C those over 1.0 MGD. MDEQ classes special cases one by one.
Step 1
Experience means watching or taking part in running and maintaining a wastewater facility, such as process control, maintenance, record keeping and permit monitoring.
One year of your experience must be under the supervision of an operator certified at the class you want or higher, in a system of that class or higher. That operator signs to confirm it.
Class I and I-C need no diploma. For Class II, III and II-C you can use extra years of experience in place of a high school diploma or GED; Class IV needs a diploma or GED.
Step 2
To sit for an exam, you must have attended an MDEQ-sponsored wastewater operator short course for your class, or another course MDEQ approves, within the previous 12 months.
Four-day operator and collections short courses are held around the state by the Mississippi Water and Pollution Control Operators Association and the Mississippi Rural Water Association. The certification exam is offered on the Friday, and each course has a registration fee. MDEQ lists the dates on its training calendar.
You cannot take a Class III or IV exam until you show you have passed a Class II exam.
After you pass, you have three years to become certified. After that, you must pass the exam again.
Step 3
Mail MDEQ the original New Certification application, signed in blue ink, with the $75 application fee by check or money order payable to the State of Mississippi. Copies are not accepted.
Attach a copy of your high school diploma, GED or college transcript and proof of your exam. List all the experience and technical training you want counted, and have your current supervisor, owner or mayor sign to confirm your experience.
Include Professional Reference forms from certified operators at your class or higher who know your work, but not a relative or someone you supervise. Class I, II and I-C need one reference; Class III, IV and II-C need two.
MDEQ staff review new and renewal applications at certification staff meetings. Allow 6 to 8 weeks for your certificate. If you are denied, MDEQ returns the application and fee.
For questions, call your regional MDEQ operator trainer: North in Oxford (662-371-1828), Central in Pearl (601-961-5646) or South in Biloxi (228-432-3454).
Step 4
Certificates last three years. Send the renewal application with the $45 fee and copies of your training certificates before your certificate expires. If you file more than 60 days after it expires, you must pass the exam again.
Treatment operators need 36 hours of continuing education every three years, at least 18 of them from MDEQ-sponsored training. Collection operators need 18 hours.
After three full three-year periods, the requirement drops to 24 hours, at least 12 of them from MDEQ-sponsored training or Association short courses.
Training must be approved by MDEQ. One day of MDEQ-sponsored training counts as 6 hours and a week-long Association short course as 32 hours. MDEQ also lists approved online courses.
Courses you use in place of experience cannot also count as continuing education.
Exam day
In 2026, MDEQ moved to the standardized wastewater exams developed by Water Professionals International (WPI) through its ABC Testing service. MDEQ points you to WPI's Need-to-Know Criteria for what each exam covers.
WPI's 2025 Class I wastewater treatment exam has 100 scored multiple-choice questions with four answer choices, some needing calculations. Up to 10 unscored trial questions may be mixed in.
WPI's standardized exams are closed book and come with WPI's Formula/Conversion Table. Bring photo ID, a non-programmable calculator, two soft-lead pencils and an eraser.
If you fail, you can retake the exam at the next scheduled exam. Exam papers are not returned, but you can ask MDEQ in writing within 30 days of your grade to review yours.
MDEQ's older Operations and Training Manual and exam study guide are still good reading but are no longer used as exam references.
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 Mississippi was $46,480 a year ($22.34 an hour) in 2025, compared with $60,020 nationally. One in ten earned $35,230 or less, and one in ten earned $64,130 or more.
These federal figures cover drinking water and wastewater operators together, at every class. Pay for a new operator is usually nearer the low end.
Moving up
Without a diploma or GED, Class II needs 3 years, Class III 6 years and Class II-C 4 years. MDEQ-approved training can stand in for some experience: 128 contact hours of approved courses count as one year, and each year of college in engineering, biology, math, chemistry or physics counts as two. Training can never replace the first year of wastewater experience, and a bachelor's degree in one of those subjects plus 1 year in a Class IV plant qualifies for Class IV.
From another state
MDEQ's reciprocity application applies Mississippi's Universal Recognition of Occupational Licenses Act, which recognizes occupational licenses from other states. You must show proof of Mississippi residence, such as a utility bill, a lease or a job in the state.
Send both the New Certification and Reciprocity applications, a copy of the front and back of your current certificate or license, the reference forms your class needs and the $75 fee. You must meet Mississippi's education and experience requirements for the class you ask for.
