TEXAS WATER OPERATOR LICENSING LEVEL
III 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 taste and odor
B. Stabilize pH
C. Destabilize particles
D. Disinfect the water
Answer: C
Coagulation destabilizes suspended particles so they can clump during
flocculation.
2. Which chemical is most commonly used for disinfection in surface
water treatment?
A. Ammonia
B. Chlorine gas
C. Potassium permanganate
D. Carbon dioxide
Answer: B
Chlorine gas is widely used due to effectiveness and cost.
3. What is the minimum free chlorine residual required in a
distribution system?
,A. 0.1 mg/L
B. 0.2 mg/L
C. 0.5 mg/L
D. 1.0 mg/L
Answer: B
Texas regulations require at least 0.2 mg/L free chlorine residual.
4. A settling basin removes particles primarily by:
A. Filtration
B. Coagulation
C. Sedimentation
D. Adsorption
Answer: C
Sedimentation allows heavier particles to settle out by gravity.
5. Chlorine demand is calculated as:
A. Residual + applied
B. Applied – residual
C. Applied × residual
D. Applied ÷ residual
Answer: B
Chlorine demand equals chlorine added minus what remains.
6. Which device measures water flow in a pipeline?
A. Manometer
B. Turbidimeter
C. Venturi meter
,D. Chlorinator
Answer: C
Venturi meters are commonly used for accurate flow measurement.
7. The optimal pH range for chlorine disinfection is:
A. 3–4
B. 5–6
C. 6.5–7.5
D. 9–11
Answer: C
Chlorine is most effective in slightly acidic to neutral pH.
8. What is the purpose of a backwash in filtration?
A. Add disinfectant
B. Restore filter capacity
C. Remove dissolved solids
D. Introduce oxygen
Answer: B
Backwashing cleans the filter media by reversing flow.
9. What does NTU measure?
A. Hardness
B. pH level
C. Turbidity
D. Alkalinity
Answer: C
NTU (Nephelometric Turbidity Units) indicates cloudiness.
, 10. A finished water turbidity limit for conventional treatment is:
A. 1.0 NTU
B. 0.3 NTU
C. 2.0 NTU
D. 5.0 NTU
Answer: B
Regulations require ≤0.3 NTU 95% of the time.
11. What is the primary purpose of flocculation?
A. Form larger particles
B. Neutralize water
C. Remove taste
D. Kill pathogens
Answer: A
Flocculation gently mixes to form settleable floc.
12. Chloramines are formed by combining chlorine with:
A. Lime
B. Sodium chloride
C. Ammonia
D. Carbon dioxide
Answer: C
Chloramines = chlorine + ammonia.
13. The MCL for nitrate in drinking water is:
III 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 taste and odor
B. Stabilize pH
C. Destabilize particles
D. Disinfect the water
Answer: C
Coagulation destabilizes suspended particles so they can clump during
flocculation.
2. Which chemical is most commonly used for disinfection in surface
water treatment?
A. Ammonia
B. Chlorine gas
C. Potassium permanganate
D. Carbon dioxide
Answer: B
Chlorine gas is widely used due to effectiveness and cost.
3. What is the minimum free chlorine residual required in a
distribution system?
,A. 0.1 mg/L
B. 0.2 mg/L
C. 0.5 mg/L
D. 1.0 mg/L
Answer: B
Texas regulations require at least 0.2 mg/L free chlorine residual.
4. A settling basin removes particles primarily by:
A. Filtration
B. Coagulation
C. Sedimentation
D. Adsorption
Answer: C
Sedimentation allows heavier particles to settle out by gravity.
5. Chlorine demand is calculated as:
A. Residual + applied
B. Applied – residual
C. Applied × residual
D. Applied ÷ residual
Answer: B
Chlorine demand equals chlorine added minus what remains.
6. Which device measures water flow in a pipeline?
A. Manometer
B. Turbidimeter
C. Venturi meter
,D. Chlorinator
Answer: C
Venturi meters are commonly used for accurate flow measurement.
7. The optimal pH range for chlorine disinfection is:
A. 3–4
B. 5–6
C. 6.5–7.5
D. 9–11
Answer: C
Chlorine is most effective in slightly acidic to neutral pH.
8. What is the purpose of a backwash in filtration?
A. Add disinfectant
B. Restore filter capacity
C. Remove dissolved solids
D. Introduce oxygen
Answer: B
Backwashing cleans the filter media by reversing flow.
9. What does NTU measure?
A. Hardness
B. pH level
C. Turbidity
D. Alkalinity
Answer: C
NTU (Nephelometric Turbidity Units) indicates cloudiness.
, 10. A finished water turbidity limit for conventional treatment is:
A. 1.0 NTU
B. 0.3 NTU
C. 2.0 NTU
D. 5.0 NTU
Answer: B
Regulations require ≤0.3 NTU 95% of the time.
11. What is the primary purpose of flocculation?
A. Form larger particles
B. Neutralize water
C. Remove taste
D. Kill pathogens
Answer: A
Flocculation gently mixes to form settleable floc.
12. Chloramines are formed by combining chlorine with:
A. Lime
B. Sodium chloride
C. Ammonia
D. Carbon dioxide
Answer: C
Chloramines = chlorine + ammonia.
13. The MCL for nitrate in drinking water is:
