WATER QUALITY TECHNICIAN PRACTICE
EXAM Questions With Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Water turbidity is primarily a measure of:
A. Water temperature
B. Water clarity
C. Dissolved oxygen
D. Water hardness
Answer: B. Water clarity
Rationale: Turbidity measures how clear or cloudy water is due to
suspended particles.
2. Which chemical is commonly used for disinfection in drinking water
systems?
A. Sodium chloride
B. Chlorine
C. Calcium carbonate
D. Ammonia
Answer: B. Chlorine
Rationale: Chlorine is widely used to kill harmful microorganisms in
water.
,3. The pH of neutral water is approximately:
A. 3
B. 5
C. 7
D. 10
Answer: C. 7
Rationale: A pH of 7 represents neutrality on the pH scale.
4. Hardness in water is mainly caused by:
A. Sodium and potassium
B. Calcium and magnesium
C. Iron and chlorine
D. Oxygen and nitrogen
Answer: B. Calcium and magnesium
Rationale: These minerals are the primary contributors to water
hardness.
5. Which parameter indicates oxygen availability for aquatic life?
A. Total solids
B. Dissolved oxygen
C. Turbidity
D. pH
,Answer: B. Dissolved oxygen
Rationale: Dissolved oxygen is essential for survival of aquatic
organisms.
6. A high BOD (Biochemical Oxygen Demand) indicates:
A. Clean water
B. Low organic pollution
C. High organic pollution
D. Low nutrient levels
Answer: C. High organic pollution
Rationale: High BOD means more oxygen is needed to decompose
organic matter.
7. Which unit is used to measure turbidity?
A. NTU
B. ppm
C. mg/L
D. pH
Answer: A. NTU
Rationale: Nephelometric Turbidity Units (NTU) measure water clarity.
8. Total Dissolved Solids (TDS) refers to:
A. Floating debris only
B. Suspended particles only
, C. Dissolved inorganic and organic substances
D. Bacteria in water
Answer: C. Dissolved inorganic and organic substances
Rationale: TDS includes all dissolved substances in water.
9. Which process removes suspended solids using gravity?
A. Filtration
B. Sedimentation
C. Chlorination
D. Aeration
Answer: B. Sedimentation
Rationale: Heavier particles settle at the bottom under gravity.
10. The primary purpose of water filtration is to:
A. Add oxygen
B. Remove particles and impurities
C. Increase hardness
D. Raise pH
Answer: B. Remove particles and impurities
Rationale: Filtration removes suspended solids and contaminants.
11. Which organism is commonly used as an indicator of fecal
contamination?
EXAM Questions With Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Water turbidity is primarily a measure of:
A. Water temperature
B. Water clarity
C. Dissolved oxygen
D. Water hardness
Answer: B. Water clarity
Rationale: Turbidity measures how clear or cloudy water is due to
suspended particles.
2. Which chemical is commonly used for disinfection in drinking water
systems?
A. Sodium chloride
B. Chlorine
C. Calcium carbonate
D. Ammonia
Answer: B. Chlorine
Rationale: Chlorine is widely used to kill harmful microorganisms in
water.
,3. The pH of neutral water is approximately:
A. 3
B. 5
C. 7
D. 10
Answer: C. 7
Rationale: A pH of 7 represents neutrality on the pH scale.
4. Hardness in water is mainly caused by:
A. Sodium and potassium
B. Calcium and magnesium
C. Iron and chlorine
D. Oxygen and nitrogen
Answer: B. Calcium and magnesium
Rationale: These minerals are the primary contributors to water
hardness.
5. Which parameter indicates oxygen availability for aquatic life?
A. Total solids
B. Dissolved oxygen
C. Turbidity
D. pH
,Answer: B. Dissolved oxygen
Rationale: Dissolved oxygen is essential for survival of aquatic
organisms.
6. A high BOD (Biochemical Oxygen Demand) indicates:
A. Clean water
B. Low organic pollution
C. High organic pollution
D. Low nutrient levels
Answer: C. High organic pollution
Rationale: High BOD means more oxygen is needed to decompose
organic matter.
7. Which unit is used to measure turbidity?
A. NTU
B. ppm
C. mg/L
D. pH
Answer: A. NTU
Rationale: Nephelometric Turbidity Units (NTU) measure water clarity.
8. Total Dissolved Solids (TDS) refers to:
A. Floating debris only
B. Suspended particles only
, C. Dissolved inorganic and organic substances
D. Bacteria in water
Answer: C. Dissolved inorganic and organic substances
Rationale: TDS includes all dissolved substances in water.
9. Which process removes suspended solids using gravity?
A. Filtration
B. Sedimentation
C. Chlorination
D. Aeration
Answer: B. Sedimentation
Rationale: Heavier particles settle at the bottom under gravity.
10. The primary purpose of water filtration is to:
A. Add oxygen
B. Remove particles and impurities
C. Increase hardness
D. Raise pH
Answer: B. Remove particles and impurities
Rationale: Filtration removes suspended solids and contaminants.
11. Which organism is commonly used as an indicator of fecal
contamination?
