North Carolina Water Distribution System
Operator — Grade C Certification Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of a water distribution system?
a) To produce treated water
b) To move potable water to consumers
c) To treat wastewater
d) To store raw water
Answer: b
This is the main function of distribution systems—delivering potable
water safely and efficiently.
2. Which pipe material is most commonly used today for new
distribution mains?
a) Asbestos-cement
b) Galvanized steel
c) PVC
d) Lead
Answer: c
PVC is widely used due to durability, low cost, and corrosion resistance.
3. What is the typical pressure range recommended in a distribution
system?
,a) 10–20 psi
b) 20–30 psi
c) 40–80 psi
d) 90–120 psi
Answer: c
40–80 psi maintains adequate service and reduces risk of pipe failure.
4. What is the purpose of flushing hydrants?
a) Increase pressure
b) Remove sediments and stale water
c) Measure static pressure only
d) Reduce chlorine residual
Answer: b
Flushing removes accumulated sediments and ensures good turnover.
5. What instrument is used to measure water pressure?
a) Venturi tube
b) Pressure gauge
c) Turbidimeter
d) Hydrometer
Answer: b
Pressure gauges measure psi in system components.
6. Excessive headloss in pipes is usually caused by:
a) Too much chlorine
b) Corrosion or tuberculation
c) High pH
d) Low turbidity
, Answer: b
Corrosion narrows pipe diameter, increasing friction and headloss.
7. What does “SCADA” stand for?
a) System Control and Drainage Automation
b) Supervisory Control and Data Acquisition
c) Standard Calibration and Distribution Analyzer
d) Safe Control And Distribution Application
Answer: b
SCADA allows operators to monitor and control system processes
remotely.
8. What is the primary purpose of a storage tank?
a) Remove bacteria
b) Provide pressure and reserve supply
c) Add chlorine
d) Prevent corrosion
Answer: b
Tanks help maintain pressure and supply during peak demand.
9. What should be done before repairing a water main?
a) Increase system pressure
b) Shut off power to SCADA
c) Isolate the main through valves
d) Inject chlorine directly into break area
Answer: c
Valving off the section prevents uncontrolled water flow.
10. A positive pressure in the system is important to:
Operator — Grade C Certification Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a water distribution system?
a) To produce treated water
b) To move potable water to consumers
c) To treat wastewater
d) To store raw water
Answer: b
This is the main function of distribution systems—delivering potable
water safely and efficiently.
2. Which pipe material is most commonly used today for new
distribution mains?
a) Asbestos-cement
b) Galvanized steel
c) PVC
d) Lead
Answer: c
PVC is widely used due to durability, low cost, and corrosion resistance.
3. What is the typical pressure range recommended in a distribution
system?
,a) 10–20 psi
b) 20–30 psi
c) 40–80 psi
d) 90–120 psi
Answer: c
40–80 psi maintains adequate service and reduces risk of pipe failure.
4. What is the purpose of flushing hydrants?
a) Increase pressure
b) Remove sediments and stale water
c) Measure static pressure only
d) Reduce chlorine residual
Answer: b
Flushing removes accumulated sediments and ensures good turnover.
5. What instrument is used to measure water pressure?
a) Venturi tube
b) Pressure gauge
c) Turbidimeter
d) Hydrometer
Answer: b
Pressure gauges measure psi in system components.
6. Excessive headloss in pipes is usually caused by:
a) Too much chlorine
b) Corrosion or tuberculation
c) High pH
d) Low turbidity
, Answer: b
Corrosion narrows pipe diameter, increasing friction and headloss.
7. What does “SCADA” stand for?
a) System Control and Drainage Automation
b) Supervisory Control and Data Acquisition
c) Standard Calibration and Distribution Analyzer
d) Safe Control And Distribution Application
Answer: b
SCADA allows operators to monitor and control system processes
remotely.
8. What is the primary purpose of a storage tank?
a) Remove bacteria
b) Provide pressure and reserve supply
c) Add chlorine
d) Prevent corrosion
Answer: b
Tanks help maintain pressure and supply during peak demand.
9. What should be done before repairing a water main?
a) Increase system pressure
b) Shut off power to SCADA
c) Isolate the main through valves
d) Inject chlorine directly into break area
Answer: c
Valving off the section prevents uncontrolled water flow.
10. A positive pressure in the system is important to:
