AZ A-10 Water & Sewer Systems
Contractor Exam Questions And
Correct Answers (Verified Answers)
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1. What is the primary purpose of a water distribution system?
A. Treat wastewater
B. Provide irrigation
C. Deliver potable water to consumers
D. Reduce water pressure
Answer: C
Rationale: The main purpose of a water distribution system is to
deliver safe, potable water to residential, commercial, and industrial
users.
2. Which material is commonly used for underground sewer pipes?
A. PVC
B. Copper
C. Ductile iron
D. Aluminum
Answer: C
Rationale: Ductile iron is strong, durable, and suitable for high-
pressure underground sewer applications.
3. What is the standard slope for gravity sewer lines?
A. 0.5%
B. 1%
C. 2%
D. 5%
, Answer: C
Rationale: A 2% slope ensures adequate flow velocity to prevent
sedimentation in gravity sewers.
4. Which device prevents backflow into potable water systems?
A. Gate valve
B. Check valve
C. Backflow preventer
D. Pressure regulator
Answer: C
Rationale: Backflow preventers stop contaminated water from entering
potable water lines, protecting public health.
5. Chlorination in water treatment is primarily used to:
A. Filter sediment
B. Disinfect water
C. Remove hardness
D. Adjust pH
Answer: B
Rationale: Chlorination kills bacteria and pathogens in water to make
it safe for consumption.
6. What is the purpose of a sewer manhole?
A. Reduce pressure
B. Provide access for maintenance and inspection
C. Measure water flow
D. Store excess sewage
Answer: B
Rationale: Manholes allow workers to access underground sewer
systems for inspection, cleaning, and maintenance.
7. Which water system component controls flow direction?
A. Hydrant
B. Pump
C. Valve
D. Reservoir
Answer: C
Rationale: Valves open or close pipelines to control flow direction,
pressure, or isolate sections.
8. The recommended minimum pipe diameter for a residential water
service is:
, A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 2 inches
Answer: C
Rationale: A 1-inch diameter provides adequate flow and pressure for
most residential water systems.
9. What is a common cause of sewer system odor problems?
A. High flow velocity
B. Insufficient venting
C. Excess chlorine
D. Pipe material
Answer: B
Rationale: Proper venting prevents sewer gases from accumulating
and causing odors in the system.
10. What type of sewer system relies on natural slope and gravity?
A. Pressurized sewer
B. Gravity sewer
C. Vacuum sewer
D. Storm sewer
Answer: B
Rationale: Gravity sewers use the slope of the land to move
wastewater without mechanical pumps.
11. The primary function of a water meter is to:
A. Purify water
B. Measure water usage
C. Increase water pressure
D. Control flow direction
Answer: B
Rationale: Water meters record consumption for billing and system
management.
12. Which of the following is a standard water pipe material for
municipal systems?
A. Lead
B. Copper
C. Asbestos cement
D. Wood
Contractor Exam Questions And
Correct Answers (Verified Answers)
Plus Rationale2026 Q&A| Instant
Download Pdf
1. What is the primary purpose of a water distribution system?
A. Treat wastewater
B. Provide irrigation
C. Deliver potable water to consumers
D. Reduce water pressure
Answer: C
Rationale: The main purpose of a water distribution system is to
deliver safe, potable water to residential, commercial, and industrial
users.
2. Which material is commonly used for underground sewer pipes?
A. PVC
B. Copper
C. Ductile iron
D. Aluminum
Answer: C
Rationale: Ductile iron is strong, durable, and suitable for high-
pressure underground sewer applications.
3. What is the standard slope for gravity sewer lines?
A. 0.5%
B. 1%
C. 2%
D. 5%
, Answer: C
Rationale: A 2% slope ensures adequate flow velocity to prevent
sedimentation in gravity sewers.
4. Which device prevents backflow into potable water systems?
A. Gate valve
B. Check valve
C. Backflow preventer
D. Pressure regulator
Answer: C
Rationale: Backflow preventers stop contaminated water from entering
potable water lines, protecting public health.
5. Chlorination in water treatment is primarily used to:
A. Filter sediment
B. Disinfect water
C. Remove hardness
D. Adjust pH
Answer: B
Rationale: Chlorination kills bacteria and pathogens in water to make
it safe for consumption.
6. What is the purpose of a sewer manhole?
A. Reduce pressure
B. Provide access for maintenance and inspection
C. Measure water flow
D. Store excess sewage
Answer: B
Rationale: Manholes allow workers to access underground sewer
systems for inspection, cleaning, and maintenance.
7. Which water system component controls flow direction?
A. Hydrant
B. Pump
C. Valve
D. Reservoir
Answer: C
Rationale: Valves open or close pipelines to control flow direction,
pressure, or isolate sections.
8. The recommended minimum pipe diameter for a residential water
service is:
, A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 2 inches
Answer: C
Rationale: A 1-inch diameter provides adequate flow and pressure for
most residential water systems.
9. What is a common cause of sewer system odor problems?
A. High flow velocity
B. Insufficient venting
C. Excess chlorine
D. Pipe material
Answer: B
Rationale: Proper venting prevents sewer gases from accumulating
and causing odors in the system.
10. What type of sewer system relies on natural slope and gravity?
A. Pressurized sewer
B. Gravity sewer
C. Vacuum sewer
D. Storm sewer
Answer: B
Rationale: Gravity sewers use the slope of the land to move
wastewater without mechanical pumps.
11. The primary function of a water meter is to:
A. Purify water
B. Measure water usage
C. Increase water pressure
D. Control flow direction
Answer: B
Rationale: Water meters record consumption for billing and system
management.
12. Which of the following is a standard water pipe material for
municipal systems?
A. Lead
B. Copper
C. Asbestos cement
D. Wood
