Wastewater Class IV — Expert / Large System Operator
Highest-level wastewater treatment operator certification (ABC Class IV). Covers process modeling and optimization, advanced BNR and sidestream treatment, energy recovery and digestion (thermal hydrolysis, co-digestion, CHP), membranes and advanced clarification, instrumentation and automation, advanced operator math, plant management and capital planning, regulatory programs, safety management, and complex troubleshooting.
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Browse all testsBoth options pull from the same 100-question bank. The quick quiz randomly selects 25 questions each time you take it.
Wastewater Class IV — Expert / Large System Operator
About this practice test
This Wastewater Class IV — Expert / Large System Operator practice test is a free study tool for water operators preparing for state and national certification exams. The 100 questions on this exam cover the most common topics tested at this level, and every question comes with a plain-English explanation so you can actually learn the material.
If you're studying for the certification exam, we recommend taking this test once, reviewing the explanations for any questions you missed, and then taking it again later. You can also explore the other practice tests covering specific topics like disinfection, filtration, and operator math. If you want a structured walk-through of what to study and in what order, see our 30-day study plan.