IOWA WATER DISTRIBUTION OPERATOR LEVEL I
EXAM QUESTIONS AND CORRECT ANSWERS
1. What is the primary purpose of a water distribution system?
A. Provide stormwater drainage
B. Convey treated water to consumers
C. Supply water only for firefighting
D. Dispose of wastewater
Answer: B
The main goal of a distribution system is to deliver potable water to end users.
2. Which type of pipe material is most commonly used today for
small-diameter distribution mains?
A. Steel
B. Asbestos-cement
C. PVC
D. Lead
Answer: C
PVC is widely used due to corrosion resistance and ease of installation.
3. What does “C-factor” in the Hazen-Williams equation represent?
A. Pipe diameter
B. Pipe roughness
C. Pipe pressure rating
D. Chlorine decay constant
Answer: B
The C-factor indicates internal pipe roughness and affects flow resistance.
4. The normal minimum pressure in a water distribution system
should not fall below:
,A. 10 psi
B. 20 psi
C. 35 psi
D. 60 psi
Answer: B
Most standards require at least 20 psi to maintain adequate service and prevent
backflow.
5. The most common type of valve used to isolate sections of a
distribution system is:
A. Check valve
B. Blow-off valve
C. Gate valve
D. Pressure-reducing valve
Answer: C
Gate valves are used to shut of f flow for maintenance.
6. Which reservoir type is typically installed at ground level?
A. Elevated tank
B. Hydropneumatic tank
C. Standpipe
D. Ground storage tank
Answer: D
Ground storage tanks hold large volumes at ground level.
7. The main purpose of flushing hydrants is to:
A. Increase chlorine residuals
B. Remove sediment and improve water quality
C. Raise system pressure
D. Test main breaks
Answer: B
Flushing clears sediments and maintains water quality.
, 8. What device prevents backflow due to back-siphonage?
A. Meter
B. PRV
C. Vacuum breaker
D. Altitude valve
Answer: C
Vacuum breakers stop reverse flow when system pressure drops.
9. A common cause of water hammer is:
A. Slow valve closing
B. Pump lubrication failure
C. Rapid valve closure
D. Temperature change
Answer: C
Sudden flow stoppage generates pressure surges.
10. The part of a hydrant designed to break during impact to prevent
main damage is called:
A. Bonnet
B. Breakaway flange
C. Nozzle
D. Valve seat
Answer: B
Breakaway flanges protect underground piping.
11. The chlorine residual measured after at least 30 minutes of contact
time is called:
A. Free residual
B. Combined residual
C. Total residual
D. CT residual
Answer: A
EXAM QUESTIONS AND CORRECT ANSWERS
1. What is the primary purpose of a water distribution system?
A. Provide stormwater drainage
B. Convey treated water to consumers
C. Supply water only for firefighting
D. Dispose of wastewater
Answer: B
The main goal of a distribution system is to deliver potable water to end users.
2. Which type of pipe material is most commonly used today for
small-diameter distribution mains?
A. Steel
B. Asbestos-cement
C. PVC
D. Lead
Answer: C
PVC is widely used due to corrosion resistance and ease of installation.
3. What does “C-factor” in the Hazen-Williams equation represent?
A. Pipe diameter
B. Pipe roughness
C. Pipe pressure rating
D. Chlorine decay constant
Answer: B
The C-factor indicates internal pipe roughness and affects flow resistance.
4. The normal minimum pressure in a water distribution system
should not fall below:
,A. 10 psi
B. 20 psi
C. 35 psi
D. 60 psi
Answer: B
Most standards require at least 20 psi to maintain adequate service and prevent
backflow.
5. The most common type of valve used to isolate sections of a
distribution system is:
A. Check valve
B. Blow-off valve
C. Gate valve
D. Pressure-reducing valve
Answer: C
Gate valves are used to shut of f flow for maintenance.
6. Which reservoir type is typically installed at ground level?
A. Elevated tank
B. Hydropneumatic tank
C. Standpipe
D. Ground storage tank
Answer: D
Ground storage tanks hold large volumes at ground level.
7. The main purpose of flushing hydrants is to:
A. Increase chlorine residuals
B. Remove sediment and improve water quality
C. Raise system pressure
D. Test main breaks
Answer: B
Flushing clears sediments and maintains water quality.
, 8. What device prevents backflow due to back-siphonage?
A. Meter
B. PRV
C. Vacuum breaker
D. Altitude valve
Answer: C
Vacuum breakers stop reverse flow when system pressure drops.
9. A common cause of water hammer is:
A. Slow valve closing
B. Pump lubrication failure
C. Rapid valve closure
D. Temperature change
Answer: C
Sudden flow stoppage generates pressure surges.
10. The part of a hydrant designed to break during impact to prevent
main damage is called:
A. Bonnet
B. Breakaway flange
C. Nozzle
D. Valve seat
Answer: B
Breakaway flanges protect underground piping.
11. The chlorine residual measured after at least 30 minutes of contact
time is called:
A. Free residual
B. Combined residual
C. Total residual
D. CT residual
Answer: A
