ABC Cheat Sheet 2026

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

1. What is the primary purpose of a double check valve assembly (DCVA)? → Protect against back-pressure and backsiphonage for low-hazard connections
2. Under the Lead and Copper Rule, action must be taken if lead levels exceed the action level at what percentage of tap samples? → 10%
3. In a parallel pump configuration, what happens to total flow and head compared to a single pump? → Flow increases, head remains approximately the same
4. When should an operator use a portable gas detector before entering a wet well? → Before every entry regardless of previous conditions
5. What type of hazard is represented by confined spaces in water treatment facilities? → Permit-required confined space hazard
6. What is the function of test cock #4 on a reduced pressure principle assembly? → To measure or bleed pressure downstream of check #2
7. Which action is considered a best practice for maintaining accurate plant records under regulatory requirements? → Completing log entries in real time or as soon as possible after readings are taken
8. To test check valve #2 of the reduced pressure assembly for tightness against backpressure, which test kit control valves must be in the open position? → High and Bypass
9. What does the term 'backsiphonage' refer to in backflow prevention? → Negative pressure in the supply line drawing contaminants back
10. What is the role of a process control plan in a water or wastewater facility? → Document operating procedures to maintain consistent, compliant treatment
11. Which of the following locations represents a high-hazard cross-connection requiring an RPZ assembly? → Chemical feed system connected to the potable water supply
12. In the context of ABC certification grades, what does a higher grade number generally indicate? → Greater system complexity and operator responsibility
13. Which indicator best reflects the biological health and stability of activated sludge? → Sludge volume index (SVI)
14. Which approach is most effective for problem-solving in Distribution and Collection? → Systematic analysis followed by evidence-based decision making
15. Which approach is most effective for problem-solving in Water Treatment Operations? → Systematic analysis followed by evidence-based decision making
16. After a backflow incident occurs in a distribution system, which is the FIRST priority action for the water system operator? → Isolate the affected area and protect public health
17. What phenomenon causes backflow from a high-pressure non-potable source into the potable water system? → Back-pressure backflow
18. What is the purpose of a Maximum Contaminant Level (MCL) in drinking water regulations? → The highest permissible level of a contaminant in public water
19. The wire-to-water efficiency of a pumping system accounts for losses in which components? → The motor, mechanical drive, and pump hydraulic efficiency combined
20. What quality metrics are most important in Laboratory Procedures? → Measurable outcomes, process compliance, and stakeholder satisfaction
21. The term 'priming' as applied to centrifugal pumps means: → Filling the pump and suction line with liquid to remove air before startup
22. A wastewater inspector observes foam formation in an activated sludge aeration basin. The MOST likely cause is: → Excessive filamentous organism or surfactant presence
23. Which of the following installation conditions would DISQUALIFY a pressure vacuum breaker? → Installed below the highest downstream outlet
24. Which ABC certification exam covers the operation and maintenance of wastewater collection systems? → Collection System Operator
25. When collecting a bacteriological sample for compliance monitoring, the operator must: → Use a sterile container with sodium thiosulfate for dechlorination
26. A composite sample for wastewater analysis is best described as: → Multiple grab samples combined proportionally over time or flow
27. What is the most important foundational concept in Wastewater Treatment? → Understanding core principles and their practical application in Wastewater Treatment
28. Which regulation requires water systems to notify the public when a water quality violation occurs? → Public Notification Rule
29. What is the primary purpose of standardized procedures in Water Treatment Operations? → To ensure consistency, safety, and quality across all practitioners
30. A sewer main inspection reveals root intrusion at multiple joints. The BEST long-term corrective measure is: → Cured-in-place pipe (CIPP) lining or joint replacement