TEXAS ENVIRONMENTAL OPERATOR
LICENSING LEVEL III QUESTIONS AND
CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT
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1. What is the primary purpose of coagulation in water treatment?
A. Remove dissolved gases
B. Remove pathogens
C. Destabilize suspended particles
D. Reduce water hardness
Answer: C
Coagulation neutralizes particle charges so they can clump together.
2. Which chemical is most commonly used as a coagulant?
A. Sodium hypochlorite
B. Ferric chloride
C. Calcium hydroxide
D. Potassium permanganate
Answer: B
Ferric chloride is widely used due to high effectiveness in destabilizing
colloids.
3. The optimal pH range for alum coagulation is:
,A. 3–4
B. 5–7
C. 6–8
D. 9–11
Answer: C
Alum performs best in slightly acidic to neutral pH.
4. The primary purpose of sedimentation is to:
A. Disinfect water
B. Remove settleable solids
C. Adjust water pH
D. Remove odors
Answer: B
Sedimentation lets solids settle by gravity before filtration.
5. Turbidity is measured in:
A. MPN
B. MG/L
C. NTU
D. GPH
Answer: C
NTU (Nephelometric Turbidity Units) measure clarity.
6. Chlorine residual ensures:
A. Taste improvement
B. A barrier to recontamination
,C. Lower hardness
D. Higher pH
Answer: B
Residual chlorine prevents regrowth of pathogens in distribution.
7. Which form of chlorine is the strongest disinfectant?
A. Chlorine gas
B. Hypochlorous acid
C. Hypochlorite ion
D. Chloramine
Answer: B
HOCl is the most potent form produced in water.
8. Breakpoint chlorination occurs when:
A. Chloramine forms
B. All pathogens are killed
C. Chlorine demand is met and free chlorine residual rises
D. Chlorine reacts with iron
Answer: C
Breakpoint is when free chlorine increases after demand is satisfied.
9. The primary purpose of filtration is to remove:
A. Dissolved solids
B. Gases
C. Remaining suspended particles
D. Alkalinity
, Answer: C
Filters remove fine particles not removed in sedimentation.
10. Backwashing is required when:
A. Chlorine residual is too low
B. Head loss increases
C. Temperature drops
D. pH increases
Answer: B
Head loss signals clogging in the filter media.
11. What is the most common type of filter media?
A. Sand
B. Gravel
C. Anthracite
D. Activated carbon
Answer: C
Anthracite provides superior filtration and longer runs.
12. A chlorine leak should first be addressed by:
A. Spraying water on it
B. Ventilating the room
C. Putting on PPE
D. Running away
Answer: C
Always wear proper PPE before addressing chlorine leaks.
LICENSING LEVEL III QUESTIONS AND
CORRECT ANSWERS (VERIFIED ANSWERS)
PLUS RATIONALES 2026 Q&A | INSTANT
DOWNLOAD PDF
1. What is the primary purpose of coagulation in water treatment?
A. Remove dissolved gases
B. Remove pathogens
C. Destabilize suspended particles
D. Reduce water hardness
Answer: C
Coagulation neutralizes particle charges so they can clump together.
2. Which chemical is most commonly used as a coagulant?
A. Sodium hypochlorite
B. Ferric chloride
C. Calcium hydroxide
D. Potassium permanganate
Answer: B
Ferric chloride is widely used due to high effectiveness in destabilizing
colloids.
3. The optimal pH range for alum coagulation is:
,A. 3–4
B. 5–7
C. 6–8
D. 9–11
Answer: C
Alum performs best in slightly acidic to neutral pH.
4. The primary purpose of sedimentation is to:
A. Disinfect water
B. Remove settleable solids
C. Adjust water pH
D. Remove odors
Answer: B
Sedimentation lets solids settle by gravity before filtration.
5. Turbidity is measured in:
A. MPN
B. MG/L
C. NTU
D. GPH
Answer: C
NTU (Nephelometric Turbidity Units) measure clarity.
6. Chlorine residual ensures:
A. Taste improvement
B. A barrier to recontamination
,C. Lower hardness
D. Higher pH
Answer: B
Residual chlorine prevents regrowth of pathogens in distribution.
7. Which form of chlorine is the strongest disinfectant?
A. Chlorine gas
B. Hypochlorous acid
C. Hypochlorite ion
D. Chloramine
Answer: B
HOCl is the most potent form produced in water.
8. Breakpoint chlorination occurs when:
A. Chloramine forms
B. All pathogens are killed
C. Chlorine demand is met and free chlorine residual rises
D. Chlorine reacts with iron
Answer: C
Breakpoint is when free chlorine increases after demand is satisfied.
9. The primary purpose of filtration is to remove:
A. Dissolved solids
B. Gases
C. Remaining suspended particles
D. Alkalinity
, Answer: C
Filters remove fine particles not removed in sedimentation.
10. Backwashing is required when:
A. Chlorine residual is too low
B. Head loss increases
C. Temperature drops
D. pH increases
Answer: B
Head loss signals clogging in the filter media.
11. What is the most common type of filter media?
A. Sand
B. Gravel
C. Anthracite
D. Activated carbon
Answer: C
Anthracite provides superior filtration and longer runs.
12. A chlorine leak should first be addressed by:
A. Spraying water on it
B. Ventilating the room
C. Putting on PPE
D. Running away
Answer: C
Always wear proper PPE before addressing chlorine leaks.
