AWWA Water Treatment Operator Certification Grade II Exam Questions and Correct Answers

AWWA WATER TREATMENT OPERATOR
CERTIFICATION GRADE II EXAM QUESTIONS AND
CORRECT ANSWERS (VERIFIED ANSWERS Q&A
2026 |INSTANT DOWNLOAD PDF

1. What is the primary purpose of coagulation in water
treatment?
A. Disinfection of pathogens
B. Removal of dissolved salts
C. Neutralizing electrical charges of particles
D. Increasing water pH
Rationale: Coagulation destabilizes suspended particles so they
can clump together.
Correct Answer: C


2. Which chemical is most commonly used as a coagulant?
A. Chlorine
B. Aluminum sulfate
C. Sodium chloride
D. Fluoride
Rationale: Alum is widely used to form flocs in water
treatment.
Correct Answer: B

,3. What is flocculation?
A. Rapid mixing of chemicals
B. Slow mixing to form larger particles
C. Filtration process
D. Chlorination process
Rationale: Flocculation gently brings particles together into
larger flocs.
Correct Answer: B


4. The main purpose of sedimentation is to:
A. Kill bacteria
B. Remove dissolved gases
C. Allow solids to settle by gravity
D. Increase turbidity
Rationale: Heavier particles settle in sedimentation basins.
Correct Answer: C


5. What is turbidity?
A. Water hardness
B. Clarity of water
C. Color of water
D. Temperature of water
Rationale: Turbidity measures cloudiness caused by suspended
particles.
Correct Answer: B

,6. Which process removes fine particles after sedimentation?
A. Aeration
B. Filtration
C. Chlorination
D. Coagulation
Rationale: Filtration traps remaining suspended solids.
Correct Answer: B


7. The most common disinfectant in water treatment is:
A. Ozone
B. Chlorine
C. Fluoride
D. Lime
Rationale: Chlorine is widely used due to effectiveness and
cost.
Correct Answer: B


8. What is the purpose of chlorination?
A. Remove solids
B. Kill microorganisms
C. Adjust hardness
D. Increase turbidity

, Rationale: Chlorine disinfects water by killing pathogens.
Correct Answer: B


9. What is residual chlorine?
A. Chlorine before treatment
B. Chlorine remaining after disinfection
C. Chlorine in raw water
D. Solid chlorine particles
Rationale: Residual ensures continued disinfection in
distribution.
Correct Answer: B


10. pH measures:
A. Temperature
B. Acidity or alkalinity
C. Hardness
D. Turbidity
Rationale: pH indicates hydrogen ion concentration.
Correct Answer: B


11. Optimal drinking water pH range is generally:
A. 1–3
B. 4–5
C. 6.5–8.5