AK Water Treatment Contractor
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a water treatment system?
A. To increase water temperature
B. To remove contaminants and ensure safe drinking water
C. To color water
D. To store water
Rationale: The main goal of water treatment is to remove physical,
chemical, and biological contaminants to make water safe for human
consumption.
2. Which method is commonly used to remove suspended solids from
water?
A. Chlorination
B. Sedimentation
C. Fluoridation
D. Reverse osmosis
Rationale: Sedimentation allows heavy particles to settle out of water due to
gravity, reducing turbidity.
3. What is the purpose of coagulation in water treatment?
A. To disinfect water
B. To destabilize and aggregate fine suspended particles
C. To add minerals
D. To soften water
,Rationale: Coagulation involves adding chemicals (coagulants) to water,
which causes small particles to clump together for easier removal.
4. Which chemical is commonly used as a coagulant in water treatment?
A. Sodium hypochlorite
B. Aluminum sulfate (alum)
C. Calcium carbonate
D. Fluoride
Rationale: Alum is widely used to promote particle aggregation in the
coagulation process.
5. What is the main purpose of filtration in water treatment?
A. To disinfect water
B. To remove remaining suspended particles after sedimentation
C. To soften water
D. To adjust pH
Rationale: Filtration removes fine particles that remain after
sedimentation, improving water clarity and quality.
6. Which type of filter media is most common in water treatment plants?
A. Sand
B. Granular activated carbon
C. Plastic beads
D. Clay
Rationale: Granular media, such as sand or anthracite, is widely used to
trap suspended particles and improve water clarity.
7. Chlorination is primarily used in water treatment for:
A. pH adjustment
B. Sedimentation
C. Disinfection
D. Softening
Rationale: Chlorination kills or inactivates pathogenic microorganisms,
making water safe to drink.
, 8. Which form of chlorine is commonly used in water treatment?
A. Calcium carbonate
B. Sodium hypochlorite
C. Hydrochloric acid
D. Sodium hydroxide
Rationale: Sodium hypochlorite is commonly used due to its effectiveness
and ease of handling.
9. What is the recommended residual chlorine concentration for drinking
water?
A. 0.1–0.2 mg/L
B. 0.2–0.5 mg/L
C. 1–2 mg/L
D. 2–5 mg/L
Rationale: Maintaining 0.2–0.5 mg/L ensures disinfection without causing
harmful effects or taste issues.
10. What is the purpose of water softening?
A. To remove bacteria
B. To increase water hardness
C. To remove calcium and magnesium ions
D. To disinfect water
Rationale: Softening reduces hardness by removing calcium and
magnesium, preventing scale formation in pipes and appliances.
11. Which method is commonly used for water softening?
A. Sedimentation
B. Filtration
C. Ion exchange
D. Coagulation
Rationale: Ion exchange resins replace calcium and magnesium ions with
sodium or potassium, effectively softening water.
12. What is the typical pH range for treated drinking water?
A. 3–5
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a water treatment system?
A. To increase water temperature
B. To remove contaminants and ensure safe drinking water
C. To color water
D. To store water
Rationale: The main goal of water treatment is to remove physical,
chemical, and biological contaminants to make water safe for human
consumption.
2. Which method is commonly used to remove suspended solids from
water?
A. Chlorination
B. Sedimentation
C. Fluoridation
D. Reverse osmosis
Rationale: Sedimentation allows heavy particles to settle out of water due to
gravity, reducing turbidity.
3. What is the purpose of coagulation in water treatment?
A. To disinfect water
B. To destabilize and aggregate fine suspended particles
C. To add minerals
D. To soften water
,Rationale: Coagulation involves adding chemicals (coagulants) to water,
which causes small particles to clump together for easier removal.
4. Which chemical is commonly used as a coagulant in water treatment?
A. Sodium hypochlorite
B. Aluminum sulfate (alum)
C. Calcium carbonate
D. Fluoride
Rationale: Alum is widely used to promote particle aggregation in the
coagulation process.
5. What is the main purpose of filtration in water treatment?
A. To disinfect water
B. To remove remaining suspended particles after sedimentation
C. To soften water
D. To adjust pH
Rationale: Filtration removes fine particles that remain after
sedimentation, improving water clarity and quality.
6. Which type of filter media is most common in water treatment plants?
A. Sand
B. Granular activated carbon
C. Plastic beads
D. Clay
Rationale: Granular media, such as sand or anthracite, is widely used to
trap suspended particles and improve water clarity.
7. Chlorination is primarily used in water treatment for:
A. pH adjustment
B. Sedimentation
C. Disinfection
D. Softening
Rationale: Chlorination kills or inactivates pathogenic microorganisms,
making water safe to drink.
, 8. Which form of chlorine is commonly used in water treatment?
A. Calcium carbonate
B. Sodium hypochlorite
C. Hydrochloric acid
D. Sodium hydroxide
Rationale: Sodium hypochlorite is commonly used due to its effectiveness
and ease of handling.
9. What is the recommended residual chlorine concentration for drinking
water?
A. 0.1–0.2 mg/L
B. 0.2–0.5 mg/L
C. 1–2 mg/L
D. 2–5 mg/L
Rationale: Maintaining 0.2–0.5 mg/L ensures disinfection without causing
harmful effects or taste issues.
10. What is the purpose of water softening?
A. To remove bacteria
B. To increase water hardness
C. To remove calcium and magnesium ions
D. To disinfect water
Rationale: Softening reduces hardness by removing calcium and
magnesium, preventing scale formation in pipes and appliances.
11. Which method is commonly used for water softening?
A. Sedimentation
B. Filtration
C. Ion exchange
D. Coagulation
Rationale: Ion exchange resins replace calcium and magnesium ions with
sodium or potassium, effectively softening water.
12. What is the typical pH range for treated drinking water?
A. 3–5
