Wastewater Operator Certification Cheat Sheet 2026

The 30 highest-yield Wastewater Operator Certification facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which of the following routine maintenance tasks is MOST critical for ensuring the long-term health of an electric motor's bearings? → Adhering to a proper lubrication schedule with the correct type and amount of grease.
2. What is the weir overflow rate (WOR) in gpd/ft for a circular clarifier that has a diameter of 80 feet and receives a flow of 3.0 MGD? → 11,943 gpd/ft
3. What is the most critical first step that must be taken before an employee enters a manhole? → Test the atmosphere with a calibrated gas meter
4. Which of the following processes is commonly used in primary wastewater treatment? → Grit removal
5. A major operational advantage of UV disinfection over chlorination is: → No chemical residual or formation of harmful disinfection byproducts
6. Which type of microorganism is most responsible for breaking down organic matter in secondary treatment? → Bacteria
7. In a primary clarifier, the physical process responsible for the removal of settleable solids is: → Gravity
8. Which federal regulation primarily governs wastewater treatment and discharge in the United States? → Clean Water Act (CWA)
9. In the context of secondary treatment, what is the primary role of protozoa? → To consume free-swimming bacteria, promoting floc formation and clarifying the effluent.
10. What is the primary purpose of a grit chamber in the preliminary treatment phase of a wastewater treatment plant? → To remove heavy, abrasive inorganic particles like sand and gravel.
11. What is considered the greatest potential hazard when entering a confined space like a manhole or wet well? → Hazardous atmosphere
12. A circular clarifier with a diameter of 80 feet treats a flow of 2.5 MGD. What is the surface overflow rate (SOR) in gpd/ft²? → 497 gpd/ft²
13. Which effluent quality parameter most significantly limits UV disinfection performance? → Turbidity and UV transmittance (UVT)
14. Why is dechlorination performed on wastewater effluent before it is discharged to receiving waters? → To remove toxic chlorine residual that is harmful to aquatic organisms
15. What is the primary purpose of a Lockout/Tagout (LOTO) procedure? → To isolate equipment from energy sources during maintenance
16. What is the primary operational disadvantage of ozone disinfection compared to chlorination for wastewater reuse applications? → Ozone provides no persistent residual disinfection after treatment
17. A circular clarifier is 60 feet in diameter and 12 feet deep. If the influent flow rate is 2.5 MGD, what is the detention time in hours? → 2.4 hours
18. In the operation of a belt filter press, what is the primary purpose of adding polymer to the sludge before it enters the press? → To condition the sludge by promoting flocculation
19. Against which pathogen does UV disinfection have a significant advantage over conventional chlorination? → Cryptosporidium parvum oocysts
20. What is the most common cause of cavitation in a centrifugal pump? → Suction lift is too high
21. The procedure for Total Suspended Solids (TSS) requires filtering a sample through what? → A pre-weighed glass-fiber filter
22. Which of the following pieces of equipment is MOST commonly used for dewatering sludge into a solid cake? → Belt Filter Press
23. When is a 'grab sample' more appropriate than a 'composite sample'? → When measuring pH and chlorine residual
24. What is the generally accepted minimum self-cleansing velocity in a sanitary sewer to prevent the deposition of solids? → 2.0 fps
25. Which of the following is an example of a disinfection method used in wastewater treatment? → Chlorination
26. What information can be found on a Safety Data Sheet (SDS)? → Hazards, handling procedures, and first aid measures
27. A mechanical bar screen repeatedly shuts down on high torque. What is the most probable cause? → Excessive debris or rags accumulating on the screen
28. A pump is required to move 500 gallons per minute (gpm) against a total head of 45 feet. What is the water horsepower (WHP) required? → 5.7 WHP
29. Unwanted groundwater entering the sewer system through cracks, faulty joints, or porous pipe walls is known as: → Infiltration
30. What is the primary purpose of a facility's Emergency Response Plan (ERP)? → To provide clear procedures for handling emergencies to protect life and property