Maryland Water & Wastewater Operator Practice Tests

Maryland's Board of Waterworks and Waste Systems Operators (COMAR 26.06.01, under MDE) classifies operators by the TYPE of plant they run, not by its size, which makes it one of the most unusual systems in the country. Water treatment runs Classes 1 through 5 plus Class G, where Class 1 is disinfection only, Class 2 adds chemical treatment, Class 3 is simple iron removal, Class 4 is complete treatment, Class 5 is site-specific alternative technology (reverse osmosis, diatomaceous earth, arsenic, or GWUDI), and Class G is a well with storage and UV and no chemicals. Classes 1 through 4 stack: a Class 4 certificate authorizes Classes 1, 2, 3, G, and Water Distribution, while Classes 5 and G stand alone. Water Distribution is a single class with no sublevels. Wastewater runs Classes 1 through 6 plus S and A, ordered by process rather than difficulty: 1 lagoons, 2 physical/biological, 3 package activated sludge, 4 trickling filters and RBCs, 5 activated sludge, 6 site specific. Class 5 is the top and authorizes Classes 1, 2, 3, 5 and Collection Class 2, but note that Class 4 authorizes 1, 2, 4 and Collection 2 while skipping Class 3. Class S applies only to solids-only works and Class A is always used alongside another class. Wastewater Collection has two classes split by hydraulics, Class 1 gravity and Class 2 gravity plus pumped or vacuum, and a Class 2 certificate does not cover Class 1. There is also a separate Industrial Wastewater Works ladder, Classes 1 through 7, for operators at industrial works that make process decisions, though nine industry categories are exempt by default. Two Maryland rules catch people out. First, you cannot sit for any exam until you already hold a certificate, which in practice means getting an Operator-in-Training certificate first: apply, pay $50, be employed at a Maryland works, and then register for the exam. Second, the Board only issues a certificate for a class of works at which you are employed or awaiting specific employment, so you cannot collect Maryland certificates speculatively. Exams are written to the Board's own need-to-know criteria and delivered by PSI at computer-based sites across Maryland and neighboring states, with a passing score of 69.5 percent. The exam fee is $50, but a retake is $100. Above the Operator certificate sits a Superintendent certificate for every category, which requires holding the Operator certificate first, additional education and experience, and an actual appointment by the employer, but no separate exam. It is tied to one specific works, its first year is provisional until you complete the Board's superintendent training, and it can never be granted by reciprocity. Certificates renew every three years at $50 per category (capped at $100 if you renew everything together), on training units that scale with class: 16 units for Water Classes 1 and 2, Distribution, and Collection, and 30 units for Water Classes 3 and 4 and Wastewater Classes 3 through 5. At least half of those units must be process related for most categories. Since July 1, 2025 every operator must also complete EPA's free Cybersecurity 101 training and quiz as part of renewal.

No. These are independent practice tests designed to mirror the technical material and difficulty of the Maryland certification exam. The official exam is administered by MDE — State Board of Waterworks and Waste Systems Operators (or its testing vendor) and the exact questions are not public.

Yes. Every practice test on this site is 100% free, and always will be. To keep it that way, the site may feature sponsors or offer optional paid resources like study courses, but the practice tests themselves stay free.