New Jersey Master Plumber Licensing Exam
Newest (2025 - 2026 Update) From Real Past
Papers Questions – Set 100 Most Common
Exam Frequently Tested Questions And
Answers In Details 100% Verified Exam Highly
Recommendable For Grade A+
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Remove solid waste
C. Answer: C. Allow air into the drainage system to protect trap seals
D. Heat the drainage system
Explanation: Venting equalizes pressure, protects trap seals, and ensures proper
drainage.
2. Which fitting is commonly used to change the direction of drainage piping
by 90 degrees in the direction of flow?
A. Street elbow
B. Answer: B. Long sweep quarter bend
C. Coupling
D. Bushing
Explanation: Long sweep fittings reduce flow resistance and are required for
drainage direction changes.
3. What is the minimum purpose of a plumbing trap?
A. Increase flow velocity
B. Support piping
, C. Answer: C. Prevent sewer gases from entering the building
D. Filter wastewater
Explanation: A water seal in the trap blocks sewer gases.
4. Which pipe material is commonly approved for residential water
distribution?
A. Clay
B. Concrete
C. Answer: C. Copper
D. Cast aluminum
Explanation: Copper is durable, corrosion-resistant, and widely approved.
5. What is the required function of a backflow preventer?
A. Improve water pressure
B. Answer: B. Prevent contaminated water from flowing into the potable
water supply
C. Reduce pipe noise
D. Increase water temperature
Explanation: Backflow devices protect drinking water from contamination.
6. Which fixture requires a trap?
A. Hose bibb
B. Water meter
C. Answer: C. Lavatory
D. Pressure regulator
Explanation: Plumbing fixtures connected to the drainage system require traps.
7. Water hammer is caused by:
A. Low water temperature
B. Air leaks
C. Answer: C. Sudden stopping of flowing water
D. Excessive venting
Explanation: Rapid valve closure creates a pressure surge.
, 8. Which valve is commonly installed to isolate fixtures for maintenance?
A. Relief valve
B. Check valve
C. Answer: C. Angle stop valve
D. Float valve
Explanation: Angle stops allow individual fixture servicing.
9. A cleanout is installed primarily to:
A. Increase pipe size
B. Answer: B. Provide access for cleaning drainage piping
C. Reduce pressure
D. Improve water quality
Explanation: Cleanouts allow maintenance of drain systems.
10.Which plumbing fixture has the highest drainage fixture unit value in a
typical residence?
A. Lavatory
B. Kitchen sink
C. Answer: C. Water closet
D. Laundry tray
Explanation: Toilets produce the greatest drainage load.
11.Which fitting joins two pipes of the same diameter?
A. Reducer
B. Answer: B. Coupling
C. Bushing
D. Cap
Explanation: Couplings connect pipes of equal size.
12.What is the purpose of pipe insulation on hot water lines?
A. Reduce pressure
B. Answer: B. Minimize heat loss
Newest (2025 - 2026 Update) From Real Past
Papers Questions – Set 100 Most Common
Exam Frequently Tested Questions And
Answers In Details 100% Verified Exam Highly
Recommendable For Grade A+
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Remove solid waste
C. Answer: C. Allow air into the drainage system to protect trap seals
D. Heat the drainage system
Explanation: Venting equalizes pressure, protects trap seals, and ensures proper
drainage.
2. Which fitting is commonly used to change the direction of drainage piping
by 90 degrees in the direction of flow?
A. Street elbow
B. Answer: B. Long sweep quarter bend
C. Coupling
D. Bushing
Explanation: Long sweep fittings reduce flow resistance and are required for
drainage direction changes.
3. What is the minimum purpose of a plumbing trap?
A. Increase flow velocity
B. Support piping
, C. Answer: C. Prevent sewer gases from entering the building
D. Filter wastewater
Explanation: A water seal in the trap blocks sewer gases.
4. Which pipe material is commonly approved for residential water
distribution?
A. Clay
B. Concrete
C. Answer: C. Copper
D. Cast aluminum
Explanation: Copper is durable, corrosion-resistant, and widely approved.
5. What is the required function of a backflow preventer?
A. Improve water pressure
B. Answer: B. Prevent contaminated water from flowing into the potable
water supply
C. Reduce pipe noise
D. Increase water temperature
Explanation: Backflow devices protect drinking water from contamination.
6. Which fixture requires a trap?
A. Hose bibb
B. Water meter
C. Answer: C. Lavatory
D. Pressure regulator
Explanation: Plumbing fixtures connected to the drainage system require traps.
7. Water hammer is caused by:
A. Low water temperature
B. Air leaks
C. Answer: C. Sudden stopping of flowing water
D. Excessive venting
Explanation: Rapid valve closure creates a pressure surge.
, 8. Which valve is commonly installed to isolate fixtures for maintenance?
A. Relief valve
B. Check valve
C. Answer: C. Angle stop valve
D. Float valve
Explanation: Angle stops allow individual fixture servicing.
9. A cleanout is installed primarily to:
A. Increase pipe size
B. Answer: B. Provide access for cleaning drainage piping
C. Reduce pressure
D. Improve water quality
Explanation: Cleanouts allow maintenance of drain systems.
10.Which plumbing fixture has the highest drainage fixture unit value in a
typical residence?
A. Lavatory
B. Kitchen sink
C. Answer: C. Water closet
D. Laundry tray
Explanation: Toilets produce the greatest drainage load.
11.Which fitting joins two pipes of the same diameter?
A. Reducer
B. Answer: B. Coupling
C. Bushing
D. Cap
Explanation: Couplings connect pipes of equal size.
12.What is the purpose of pipe insulation on hot water lines?
A. Reduce pressure
B. Answer: B. Minimize heat loss
