Wastewater Class I — Entry-Level Operator
Entry-level wastewater treatment operator certification (ABC Class I). Covers wastewater characteristics, collection systems, preliminary and primary treatment, activated sludge basics, fixed-film systems, lagoons, disinfection, solids handling, lab and process control, safety, and operator math.
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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 I — Entry-Level Operator
About this practice test
This Wastewater Class I — Entry-Level 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.