B Licensing Exam Practice Test

State Water Distribution Operator Class B Licensing Exam Practice Test Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a water distribution system?
• To treat raw water
• To store wastewater
• To deliver safe drinking water to consumers
• To irrigate farmland

Rationale: Distribution systems are designed to transport potable water

from treatment to end users.

• What is the most common type of pipe material used in modern

distribution systems?

• Lead
• Cast iron 1 / 4

C. PVC/HDPE

• Wood stave

Rationale: PVC and HDPE are lightweight, corrosion-resistant, and widely

used today.

• What is the standard unit for measuring water pressure?
• Gallons per minute
• Pounds per square inch (psi)
• Feet of head
• Cubic feet

Rationale: Distribution system pressure is commonly expressed in psi.

• What is the minimum recommended pressure in a distribution system

under normal conditions?

• 10 psi
• 15 psi
• 20 psi
• 80 psi

Rationale: Most regulations require at least 20 psi to ensure adequate

service and prevent contamination.

• A fire hydrant is typically connected to what type of water main?
• Service line
• Distribution main
• Transmission main 2 / 4

• Pump suction line

Rationale: Hydrants are installed on distribution mains designed to provide

adequate flow for firefighting.

• What device prevents water from returning into the potable system?
• Flow restrictor
• Check valve
• Backflow preventer
• Pressure gauge

Rationale: Backflow preventers protect against contamination from

backpressure or backsiphonage.

• Which of the following is a common cause of low pressure?
• Valve fully open
• Pipe break
• High tank levels
• Low demand

Rationale: Pipe breaks allow water to escape, reducing pressure.

8. Chlorine residual in distribution systems helps protect against:

• Color
• Hardness
• Microbial contamination
• Taste issues only

Rationale: Residual chlorine prevents bacterial regrowth. 3 / 4

9. A water meter is used to measure:

• Pressure
• Volume of water used
• Chemical dosage
• Chlorine residual

Rationale: Meters track water consumption for billing and system

management.

• Which valve is normally used to isolate sections of pipeline?
• Pressure relief valve
• Gate valve
• Air-release valve
• Float valve

Rationale: Gate valves provide full closure for main isolation.

11. Storage tanks in elevated systems supply pressure through:

• Pumps only
• Gravity
• Air pressure
• Vacuum force

Rationale: Elevated tanks rely on gravity to provide system pressure.

• What is water hammer?
• Corrosion in pipes
• Sudden pressure surge
• / 4