New Jersey Master Plumber Exam With
Actual Questions & Correct Answers,
Plus Rationales/Expert Verified For
Guaranteed Pass 2026/Latest
Update/Instant Download Pdf
1. What is the minimum slope required for a horizontal drainage
pipe 3 inches or less in diameter?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: B. 1/4 inch per foot
Rationale: Most plumbing codes, including those adopted in New
Jersey, require a minimum slope of 1/4 inch per foot for pipes 3
inches or smaller to ensure proper flow and prevent clogging.
2. What type of valve is typically used to prevent backflow in potable
water systems?
A. Gate valve
B. Globe valve
C. Check valve
D. Ball valve
Answer: C. Check valve
Rationale: A check valve allows flow in one direction and prevents
reverse flow, protecting potable water from contamination.
,3. What is the primary purpose of a vent in a plumbing system?
A. Remove waste
B. Equalize pressure
C. Increase flow
D. Store water
Answer: B. Equalize pressure
Rationale: Vents prevent siphoning of traps by maintaining
atmospheric pressure in the drainage system.
4. What is the minimum trap seal depth?
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
Answer: B. 2 inches
Rationale: A minimum of 2 inches ensures an effective barrier
against sewer gases.
5. What material is commonly used for DWV piping?
A. PVC
B. Copper
C. Steel
D. Aluminum
Answer: A. PVC
Rationale: PVC is widely used due to its corrosion resistance and
ease of installation.
6. What is the boiling point of water at sea level?
A. 100°F
B. 180°F
C. 212°F
D. 250°F
, Answer: C. 212°F
Rationale: Standard boiling point is 212°F at atmospheric
pressure.
7. What is the function of a cleanout?
A. Vent air
B. Access for cleaning
C. Control pressure
D. Measure flow
Answer: B. Access for cleaning
Rationale: Cleanouts allow removal of blockages in drainage
systems.
8. What is a wet vent?
A. A leaking vent
B. A vent that carries water
C. A vent under pressure
D. A vent for rainwater
Answer: B. A vent that carries water
Rationale: A wet vent also serves as a drain for another fixture.
9. What is the typical water pressure range for residential systems?
A. 10–20 psi
B. 20–40 psi
C. 40–80 psi
D. 80–120 psi
Answer: C. 40–80 psi
Rationale: This range ensures proper fixture performance without
damage.
10. What does DWV stand for?
A. Drain Water Valve
B. Drain Waste Vent
Actual Questions & Correct Answers,
Plus Rationales/Expert Verified For
Guaranteed Pass 2026/Latest
Update/Instant Download Pdf
1. What is the minimum slope required for a horizontal drainage
pipe 3 inches or less in diameter?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: B. 1/4 inch per foot
Rationale: Most plumbing codes, including those adopted in New
Jersey, require a minimum slope of 1/4 inch per foot for pipes 3
inches or smaller to ensure proper flow and prevent clogging.
2. What type of valve is typically used to prevent backflow in potable
water systems?
A. Gate valve
B. Globe valve
C. Check valve
D. Ball valve
Answer: C. Check valve
Rationale: A check valve allows flow in one direction and prevents
reverse flow, protecting potable water from contamination.
,3. What is the primary purpose of a vent in a plumbing system?
A. Remove waste
B. Equalize pressure
C. Increase flow
D. Store water
Answer: B. Equalize pressure
Rationale: Vents prevent siphoning of traps by maintaining
atmospheric pressure in the drainage system.
4. What is the minimum trap seal depth?
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
Answer: B. 2 inches
Rationale: A minimum of 2 inches ensures an effective barrier
against sewer gases.
5. What material is commonly used for DWV piping?
A. PVC
B. Copper
C. Steel
D. Aluminum
Answer: A. PVC
Rationale: PVC is widely used due to its corrosion resistance and
ease of installation.
6. What is the boiling point of water at sea level?
A. 100°F
B. 180°F
C. 212°F
D. 250°F
, Answer: C. 212°F
Rationale: Standard boiling point is 212°F at atmospheric
pressure.
7. What is the function of a cleanout?
A. Vent air
B. Access for cleaning
C. Control pressure
D. Measure flow
Answer: B. Access for cleaning
Rationale: Cleanouts allow removal of blockages in drainage
systems.
8. What is a wet vent?
A. A leaking vent
B. A vent that carries water
C. A vent under pressure
D. A vent for rainwater
Answer: B. A vent that carries water
Rationale: A wet vent also serves as a drain for another fixture.
9. What is the typical water pressure range for residential systems?
A. 10–20 psi
B. 20–40 psi
C. 40–80 psi
D. 80–120 psi
Answer: C. 40–80 psi
Rationale: This range ensures proper fixture performance without
damage.
10. What does DWV stand for?
A. Drain Water Valve
B. Drain Waste Vent
