JOURNEYMAN PLUMBER LICENSING
EXAMINATION QUESTIONS AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
| INSTANT DOWNLOAD PDF
1. The primary purpose of a plumbing trap is to
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Improve drainage speed
D. Reduce pipe corrosion
Answer: B
Rationale: Traps retain a water seal that blocks sewer gases from flowing back
into occupied spaces.
2. The minimum slope for a 3-inch horizontal drainage pipe is typically
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Answer: B
Rationale: Plumbing codes generally require 1/8 inch per foot slope for pipes 3
inches or larger.
, 3. Which material is most commonly used for residential water supply piping?
A. Cast iron
B. Galvanized steel
C. Copper
D. Clay
Answer: C
Rationale: Copper is durable, corrosion-resistant, and widely accepted by
plumbing codes for potable water.
4. A vent stack’s main function is to
A. Carry wastewater
B. Allow air into the drainage system
C. Increase pipe pressure
D. Prevent pipe freezing
Answer: B
Rationale: Venting equalizes pressure and prevents trap siphonage.
5. Which fitting is used to change direction by 90 degrees in a drainage
system?
A. Tee
B. Wye
C. Elbow
D. Coupling
Answer: C
Rationale: Elbows are designed to change the direction of flow, commonly at 90
degrees.
6. The standard water pressure range for residential plumbing is
A. 20–40 psi
, B. 40–80 psi
C. 80–120 psi
D. Over 120 psi
Answer: B
Rationale: Most plumbing fixtures are designed to operate efficiently within 40–
80 psi.
7. Which valve is used to prevent backflow in a potable water system?
A. Gate valve
B. Globe valve
C. Check valve
D. Angle stop
Answer: C
Rationale: Check valves allow flow in one direction only, preventing backflow
contamination.
8. The term “DWV” stands for
A. Drainage Water Valve
B. Domestic Water Volume
C. Drain, Waste, and Vent
D. Direct Water Vent
Answer: C
Rationale: DWV refers to the system that removes waste and vents sewer gases.
9. Which pipe material is most commonly used for underground sanitary
sewer lines?
A. Copper
B. PVC
EXAMINATION QUESTIONS AND
CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
| INSTANT DOWNLOAD PDF
1. The primary purpose of a plumbing trap is to
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Improve drainage speed
D. Reduce pipe corrosion
Answer: B
Rationale: Traps retain a water seal that blocks sewer gases from flowing back
into occupied spaces.
2. The minimum slope for a 3-inch horizontal drainage pipe is typically
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Answer: B
Rationale: Plumbing codes generally require 1/8 inch per foot slope for pipes 3
inches or larger.
, 3. Which material is most commonly used for residential water supply piping?
A. Cast iron
B. Galvanized steel
C. Copper
D. Clay
Answer: C
Rationale: Copper is durable, corrosion-resistant, and widely accepted by
plumbing codes for potable water.
4. A vent stack’s main function is to
A. Carry wastewater
B. Allow air into the drainage system
C. Increase pipe pressure
D. Prevent pipe freezing
Answer: B
Rationale: Venting equalizes pressure and prevents trap siphonage.
5. Which fitting is used to change direction by 90 degrees in a drainage
system?
A. Tee
B. Wye
C. Elbow
D. Coupling
Answer: C
Rationale: Elbows are designed to change the direction of flow, commonly at 90
degrees.
6. The standard water pressure range for residential plumbing is
A. 20–40 psi
, B. 40–80 psi
C. 80–120 psi
D. Over 120 psi
Answer: B
Rationale: Most plumbing fixtures are designed to operate efficiently within 40–
80 psi.
7. Which valve is used to prevent backflow in a potable water system?
A. Gate valve
B. Globe valve
C. Check valve
D. Angle stop
Answer: C
Rationale: Check valves allow flow in one direction only, preventing backflow
contamination.
8. The term “DWV” stands for
A. Drainage Water Valve
B. Domestic Water Volume
C. Drain, Waste, and Vent
D. Direct Water Vent
Answer: C
Rationale: DWV refers to the system that removes waste and vents sewer gases.
9. Which pipe material is most commonly used for underground sanitary
sewer lines?
A. Copper
B. PVC
