Maryland wastewater operators
The steps from no certificate to a Maryland wastewater treatment or collection operator certificate, how to apply to the State Board of Waterworks and Waste Systems Operators and take the exam, how to keep your certificate active and what operators earn. Every requirement links to the Maryland Department of the Environment (MDE), the board's regulations in COMAR 26.06.01 or Maryland's Environment Article.
MDE makes the final eligibility determination. Check with MDE before you apply.
Why it matters
Maryland law says a waterworks, wastewater works or industrial wastewater works may employ someone as an operator or superintendent only after the State Board of Waterworks and Waste Systems Operators certifies them in the right classification.
At a wastewater treatment plant, you need a certificate if you make or carry out the decisions that control flow or treatment of wastewater or sludge, read meters, gauges and test results to decide on treatment, or make operating decisions when the superintendent or operator in responsible charge is away.
In a collection system, you need one if you decide what to do in an emergency, make operating decisions when the superintendent or operator in responsible charge is away, or adjust wastewater flow without one of them on site directing you.
The board issues a certificate only for a class of works where you are employed or have a specific job waiting. Superintendents and assistant superintendents need a separate superintendent certificate.
Wastewater treatment plants are classed by the type of treatment: Class 1 (lagoons), Class 2 (physical/biological), Class 3 (package activated sludge plants), Class 4 (trickling filters and rotating biological contactors), Class 5 (activated sludge) and Class 6 (site specific). Class S is for works limited to solids handling, and Class A (advanced wastewater treatment) is used with other classes.
Wastewater collection systems have two classes: Class 1 for gravity flow and Class 2 for gravity plus pumped or vacuum flow. A collection system run by certified treatment plant staff is not classed on its own.
Some certificates cover more than one class. A Class 3 operator may run Class 1, 2 and 3 plants, a Class 4 operator Class 1, 2 and 4 plants and Class 2 collection systems, and a Class 5 operator Class 1, 2, 3 and 5 plants and Class 2 collection systems.
Maryland certifies water treatment, water distribution and industrial wastewater operators separately.
Step 1
Most people start with an Operator-in-Training (OIT) certificate. You must work at a Maryland works, and the designated superintendent or operator in responsible charge signs your application.
An OIT works only under the direction of a certified superintendent or operator. The experience time for full certification starts when your OIT certificate is issued.
The application fee is $50 for each certificate, paid by check or money order to the Board of Waterworks and Waste Systems Operators. Incomplete applications are returned, and fees are not refundable.
MDE's permit guide lists a turnaround of 45 days for new certificates after a complete application.
Step 2
You need a valid Maryland certificate, such as an OIT certificate, before the board lets you take an exam.
Send the Application for Operator Examination with the board's $50 exam fee. The board must receive it at least 21 days before the exam date.
The board holds exam sessions around the state on its 2026 schedule, with firm application deadlines. Seats are limited, and you are accepted by email; paying does not reserve a seat.
You can reschedule a paper exam once. Web-based exams cannot be rescheduled. Cell phones are not allowed in exam rooms.
Step 3
Maryland exams are also given by computer at PSI test centers in Maryland and nearby states. When you get the email confirming you are eligible, schedule online or call PSI at 833-256-1420.
PSI charges its own fee on top of the board's exam fee. PSI's page lists $51 for the Wastewater Treatment Class 1 exam; check PSI's page for your exam.
You can reschedule once at no charge if you contact PSI at least two business days ahead. Arriving more than 15 minutes late forfeits the exam and its fees.
Step 4
Exams are based on the need-to-know criteria the board sets for each classification.
MDE posts a study guide for the Wastewater Treatment 5A exam. It lists the topics on that 125-question exam, from secondary and tertiary treatment to solids handling, disinfection, pump maintenance and safety.
Step 5
After you pass the exam and meet the experience requirement for your class, apply for operator certification. The owner or appointing authority of your works signs the application, and the fee is $50 for each certificate.
Passing the exam does not by itself earn a certificate; every requirement must be met first.
Once you pass, you can ask the board for experience credit (out-of-state operator work or related work) or education credit (math, science or engineering college courses, up to 30 credit hours for 1 year of experience).
Step 6
Certificates are valid for 3 years. Renewal costs $50 for each certification category, and no more than $100 when you renew all your certificates at the same time.
In each 3-year period, operators need board-approved training units: 16 for wastewater treatment Class 1, 2 and A and for collection Class 1 and 2, and 30 for treatment Class 3, 4 and 5. One unit is one hour of approved training. For treatment certificates, at least half must be process related.
Operators-in-training need 24 units (45 for treatment Class 3, 4 and 5) and must attempt the exam for each certificate within the 3 years. Passing is not required to renew an OIT certificate.
Since July 1, 2025, every operator must also complete EPA's free online Cybersecurity Training for Water and Wastewater Systems to renew.
Training must be approved by the board for your class, and a course counts only once per renewal period. The board approves training quarterly and posts the approved courses on its page.
Mail the renewal form with proof of training and the fee. MDE mails forms about 120 days ahead and recommends sending yours at least 60 days before expiration.
Renewing late adds a $100 late fee. After 90 days, a full operator certificate can be reinstated within two years with extra training and a $150 reinstatement fee; after that, you start again as an OIT.
Exam day
The board sets each exam's subject, scope and passing score. You pass with at least 69.5 percent.
Computer-based exams are coordinated through the Association of Boards of Certification (ABC) and given at PSI test centers. Questions appear one at a time, with multiple-choice answers A to D.
At PSI, pencils and ABC's standard formula sheet are provided at check-in, with scratch paper one sheet at a time. Bring a silent, non-programmable calculator without an alphabetic keypad or printing.
Bring two forms of ID: a current government photo ID with your signature, and a second ID showing your name and signature.
Maryland's board sets the subject, scope and passing score of its own exams, and its classes do not follow the four WPI classes. 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 Maryland's exam questions or format. Use MDE's materials, such as its Wastewater Treatment 5A study guide, 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 Maryland was $61,870 a year ($29.75 an hour) in 2025, compared with $60,020 nationally. One in ten earned $44,990 or less, and one in ten earned $88,970 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
Every class needs a high school diploma or equivalency. From treatment Class 3 up and for collection Class 2, up to 1 year (1,800 hours) can come from education or experience credit, such as 30 semester hours of science or engineering college coursework. The board sets Class 6 requirements case by case.
From another state
The board may certify an out-of-state operator without an exam if you hold a valid ABC certificate or one from a state with substantially equivalent exams, meet Maryland's education and experience requirements, and work or have a job pending at a Maryland works.
Send the Application for Reciprocity Certification with the $150 fee. Include a copy of your current certificate, a résumé, letters from your Maryland and previous employers describing the treatment processes, and plant descriptions and diagrams. Your previous employer also returns a Certification of Previous Employment form.
Your certificate and experience must match the treatment processes you will work with in Maryland. Board staff make a recommendation, and the board decides at its monthly meeting. Superintendent certificates are not granted by reciprocity.
