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Free sample questions

Wastewater Operator Practice Questions

Free operator-reviewed questions by topic for Level I through IV wastewater treatment operator exams. Each one shows the answer.

Level 1 · Entry

Level 1 · Entry Sample Questions

Plant Operations54 questions
Math and Calculations50 questions
Laboratory13 questions
Safety13 questions
Biological Treatment12 questions
Disinfection10 questions
Pumps and Hydraulics8 questions
Regulations and Compliance8 questions
Solids Handling8 questions
Primary Treatment6 questions
Secondary Clarification5 questions
Grit Removal4 questions
Headworks and Screening4 questions

Washington Group I Study Guide→

Level 2 · Intermediate

Level 2 · Intermediate Sample Questions

Math and Calculations62 questions
Biological Treatment49 questions
Plant Operations43 questions
Pumps and Hydraulics21 questions
Laboratory20 questions
Safety11 questions
Solids Handling11 questions
Disinfection10 questions
Regulations and Compliance10 questions
Primary Treatment8 questions
Secondary Clarification8 questions
Grit Removal4 questions
Headworks and Screening3 questions

Washington Group II Study Guide→

Level 3 · Advanced

Level 3 · Advanced Sample Questions

Math and Calculations79 questions
Plant Operations41 questions
Laboratory22 questions
Biological Treatment19 questions
Regulations and Compliance18 questions
Disinfection11 questions
Safety11 questions
Solids Handling10 questions
Pumps and Hydraulics7 questions
Primary Treatment6 questions
Headworks and Screening3 questions
Grit Removal2 questions

Start Level 3 · Advanced Practice→

Level 4 · Expert

Level 4 · Expert Sample Questions

Plant Operations60 questions
Math and Calculations55 questions
Laboratory22 questions
Biological Treatment15 questions
Regulations and Compliance15 questions
Safety12 questions
Solids Handling11 questions
Disinfection9 questions
Pumps and Hydraulics6 questions
Secondary Clarification6 questions
Headworks and Screening5 questions
Primary Treatment3 questions
Grit Removal2 questions

Start Level 4 · Expert Practice→

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Operator Master is independent. It is not affiliated with WPI, PSI, ABC, the Washington State Department of Ecology or any other state or provincial certification agency, does not reproduce live exam content and does not guarantee a passing score.