Texas Class C Water Operator certification
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Verified For Guaranteed Pass 2025/2026
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1. What is the primary source of water for most small Class C water systems in Texas?
A) Groundwater from wells
B) Surface water from lakes
C) Purchased water from a larger system
D) Rainwater harvesting
Answer: C) Purchased water from a larger system
Rationale: Most small Class C systems rely on purchased water because they often do not
have their own source.
2. Which of the following is the primary purpose of water treatment?
A) To remove harmful contaminants and ensure safe drinking water
B) To increase water hardness
C) To add minerals to water
D) To improve the taste only
Answer: A) To remove harmful contaminants and ensure safe drinking water
Rationale: Water treatment ensures the removal of contaminants to protect public health.
3. What is the maximum allowable turbidity level for treated water under Texas
standards?
A) 1 NTU
B) 5 NTU
C) 10 NTU
D) 0.3 NTU
,Answer: D) 0.3 NTU
Rationale: The EPA requires turbidity to be below 0.3 NTU for effective filtration and safety.
4. Which disinfectant is most commonly used in Texas water systems?
A) Chlorine dioxide
B) Chlorine
C) Ozone
D) Ultraviolet light
Answer: B) Chlorine
Rationale: Chlorine is the most common disinfectant due to its effectiveness and cost.
5. What is the primary reason for maintaining chlorine residual in the distribution system?
A) To improve taste
B) To reduce pipe corrosion
C) To prevent microbial regrowth
D) To soften water
Answer: C) To prevent microbial regrowth
Rationale: Maintaining chlorine residual ensures microbial control throughout the system.
6. What is the standard test used to measure chlorine residual in water?
A) DPD test
B) Turbidity test
C) pH test
D) Fluoride test
Answer: A) DPD test
Rationale: DPD is the standard colorimetric method to test free chlorine residual.
7. What is the typical pH range for potable water?
A) 3.0 – 5.0
B) 6.5 – 8.5
C) 9.0 – 11.0
D) 10.5 – 12.5
, Answer: B) 6.5 – 8.5
Rationale: Water pH should be between 6.5 and 8.5 to be safe and non-corrosive.
8. What is the primary purpose of coagulation in water treatment?
A) To remove dissolved gases
B) To remove suspended particles
C) To add minerals to water
D) To adjust pH levels
Answer: B) To remove suspended particles
Rationale: Coagulation helps in aggregating suspended particles for easier removal.
9. Which chemical is commonly used as a coagulant in water treatment?
A) Sodium bicarbonate
B) Alum
C) Calcium carbonate
D) Potassium permanganate
Answer: B) Alum
Rationale: Alum is a widely used coagulant in water treatment processes.
10. What is the purpose of flocculation in water treatment?
A) To settle out large particles
B) To mix chemicals thoroughly
C) To form larger aggregates from smaller particles
D) To disinfect the water
Answer: C) To form larger aggregates from smaller particles
Rationale: Flocculation helps in forming larger aggregates (flocs) for easier removal.
11. What is the primary source of groundwater?
A) Rivers
B) Wells
C) Lakes
D) Reservoirs
Real Exam With Actual Questions &
Verified Answers,Plus Rationales/Expert
Verified For Guaranteed Pass 2025/2026
/Latest Update/Instant Download Pdf
1. What is the primary source of water for most small Class C water systems in Texas?
A) Groundwater from wells
B) Surface water from lakes
C) Purchased water from a larger system
D) Rainwater harvesting
Answer: C) Purchased water from a larger system
Rationale: Most small Class C systems rely on purchased water because they often do not
have their own source.
2. Which of the following is the primary purpose of water treatment?
A) To remove harmful contaminants and ensure safe drinking water
B) To increase water hardness
C) To add minerals to water
D) To improve the taste only
Answer: A) To remove harmful contaminants and ensure safe drinking water
Rationale: Water treatment ensures the removal of contaminants to protect public health.
3. What is the maximum allowable turbidity level for treated water under Texas
standards?
A) 1 NTU
B) 5 NTU
C) 10 NTU
D) 0.3 NTU
,Answer: D) 0.3 NTU
Rationale: The EPA requires turbidity to be below 0.3 NTU for effective filtration and safety.
4. Which disinfectant is most commonly used in Texas water systems?
A) Chlorine dioxide
B) Chlorine
C) Ozone
D) Ultraviolet light
Answer: B) Chlorine
Rationale: Chlorine is the most common disinfectant due to its effectiveness and cost.
5. What is the primary reason for maintaining chlorine residual in the distribution system?
A) To improve taste
B) To reduce pipe corrosion
C) To prevent microbial regrowth
D) To soften water
Answer: C) To prevent microbial regrowth
Rationale: Maintaining chlorine residual ensures microbial control throughout the system.
6. What is the standard test used to measure chlorine residual in water?
A) DPD test
B) Turbidity test
C) pH test
D) Fluoride test
Answer: A) DPD test
Rationale: DPD is the standard colorimetric method to test free chlorine residual.
7. What is the typical pH range for potable water?
A) 3.0 – 5.0
B) 6.5 – 8.5
C) 9.0 – 11.0
D) 10.5 – 12.5
, Answer: B) 6.5 – 8.5
Rationale: Water pH should be between 6.5 and 8.5 to be safe and non-corrosive.
8. What is the primary purpose of coagulation in water treatment?
A) To remove dissolved gases
B) To remove suspended particles
C) To add minerals to water
D) To adjust pH levels
Answer: B) To remove suspended particles
Rationale: Coagulation helps in aggregating suspended particles for easier removal.
9. Which chemical is commonly used as a coagulant in water treatment?
A) Sodium bicarbonate
B) Alum
C) Calcium carbonate
D) Potassium permanganate
Answer: B) Alum
Rationale: Alum is a widely used coagulant in water treatment processes.
10. What is the purpose of flocculation in water treatment?
A) To settle out large particles
B) To mix chemicals thoroughly
C) To form larger aggregates from smaller particles
D) To disinfect the water
Answer: C) To form larger aggregates from smaller particles
Rationale: Flocculation helps in forming larger aggregates (flocs) for easier removal.
11. What is the primary source of groundwater?
A) Rivers
B) Wells
C) Lakes
D) Reservoirs
