Division of Environmental and Community Health

Maine Center for Disease Control & Prevention

A Division of the Maine Department of Health and Human Services

DHHSMeCDCEnvironmental and Community HealthDrinking WaterWater ResourcesWater Operator Licensure
How to Become a Licensed Operator and Advance within the Profession

How to Become a Licensed Operator and Advance within the Profession

Levels of Water Operator Licenses

Water systems are defined through a process of grading points, Class I to IV in both treatment and distribution categories according to complexity and population served. See Appendix A of the Rules. Operators of these systems must show competency by successfully completing examinations in both treatment and distribution categories and possess the appropriate experience. Very Small Water Systems (VSWS) operators are another classification that covers both treatment and distribution characteristics of systems with less than a population of 500.

Guidance on Becoming a VSWS Operator, (pdf)

Characteristics of a Water Operator

An operator must possess the knowledge, skills, ability and judgment to assure safe drinking water. This is measured through a review of education, experience and examination.

Education & Experience

Operators must have a high school diploma or GED. Experience is based on work in a public water system as well as credit for related professions. The Board offers Operator - In - Training (OIT) license status for persons that have successfully passed examinations but have not achieved the required experience. Holding an OIT license shows employers or prospective employers your capability and interest in the profession.

Operator Experience Requirements
License Experience Required
Very Small Water System Six months
Class I One year
Class II Two year
Class III Three year
Class IV Four year

Board Policy for Evaluating Experience to Qualify for Level of Operator Licenses (PDF)


Examinations are standardized exams produced by ABC, Association of Boards of Certification. These exams are nationally based, multiple choice, validated and reviewed. The Board welcomes operators to become subject matter experts and participate in the exam development process.

Exams may be taken in the traditional paper-based process by special request or by a computer-based process at a testing center. Exams do not need to be taken in the sequential process (pass lower levels and work one's way up) and can be taken in a direct process (take one exam at the desired level of licensure).

For more information on Exams, visit the Water Operator Examination page.

Once you have passed the exam, you may apply for licensure. Note: Exam results are accepted for one calendar year from the exam date.

Initial License or Upgraded License

Once you have passed the exam, you may apply for licensure. Your first license is the initial license. This may be a license in one or both treatment and distribution disciplines. When you take and pass a higher level of exam you may apply for an upgraded license.


Water operators certified or licensed by other state or provincial certification authorities most often are recognized. Each person's education and experience is evaluated. Licenses or certificates from states with similar examination requirements may not require re-examination. Please use the application for licensure (PDF).