JOURNEYMAN PLUMBER LICENSING
EXAM QUESTION AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A INSTANT
DOWNLOAD PDF
1. The primary purpose of a plumbing vent system is to:
A. Increase water pressure
B. Protect trap seals by equalizing pressure
C. Remove solids from waste
D. Supply air to fixtures
Rationale: Venting prevents siphonage and backpressure, protecting trap
seals.
2. What is the minimum slope required for a 3-inch horizontal drainage pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. Level
Rationale: Codes require 1/4 inch per foot for pipes 3 inches or smaller.
3. Which material is approved for potable water supply?
A. ABS
B. Galvanized steel only
C. Copper tubing
D. Clay pipe
Rationale: Copper is corrosion-resistant and approved for potable water.
4. A trap seal is the water depth that:
A. Prevents leaks
B. Prevents sewer gases from entering the building
, C. Increases flow
D. Reduces pipe size
Rationale: The water seal blocks sewer gas intrusion.
5. The minimum trap seal depth required by most plumbing codes is:
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
Rationale: Standard minimum is 2 inches to ensure gas protection.
6. Which fitting provides the smoothest flow change in a drainage system?
A. Tee
B. Long sweep 90
C. Short 90
D. Sanitary tee
Rationale: Long sweeps reduce turbulence and clogging.
7. What device prevents backflow into a potable water system?
A. Pressure regulator
B. Check valve
C. Backflow preventer
D. Air admittance valve
Rationale: Backflow preventers protect potable water from
contamination.
8. What type of valve is commonly used to control water flow to fixtures?
A. Gate valve
B. Angle stop valve
C. Globe valve
D. Relief valve
Rationale: Angle stops allow fixture isolation.
9. Which pipe is commonly used for DWV systems?
A. Copper Type L
B. PVC
C. PEX
D. Steel
, Rationale: PVC is lightweight, corrosion-resistant, and code-approved for
DWV.
10.The purpose of a cleanout is to:
A. Vent the system
B. Provide access for cleaning and maintenance
C. Increase drainage speed
D. Prevent leaks
Rationale: Cleanouts allow removal of blockages.
11.Which plumbing component controls water pressure entering a building?
A. Expansion tank
B. Pressure-reducing valve
C. Check valve
D. Relief valve
Rationale: PRVs regulate incoming pressure.
12.What is the minimum distance a cleanout must be from a change of
direction over 45°?
A. 1 foot
B. Within 5 feet
C. 10 feet
D. 20 feet
Rationale: Codes require accessibility near direction changes.
13.Which pipe size is typically used for a main building drain in residential
construction?
A. 2 inches
B. 3 or 4 inches
C. 1½ inches
D. 5 inches
Rationale: Main drains must handle total fixture load.
14.What does DWV stand for?
A. Drainage Water Volume
B. Drain, Waste, and Vent
EXAM QUESTION AND CORRECT
ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A INSTANT
DOWNLOAD PDF
1. The primary purpose of a plumbing vent system is to:
A. Increase water pressure
B. Protect trap seals by equalizing pressure
C. Remove solids from waste
D. Supply air to fixtures
Rationale: Venting prevents siphonage and backpressure, protecting trap
seals.
2. What is the minimum slope required for a 3-inch horizontal drainage pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. Level
Rationale: Codes require 1/4 inch per foot for pipes 3 inches or smaller.
3. Which material is approved for potable water supply?
A. ABS
B. Galvanized steel only
C. Copper tubing
D. Clay pipe
Rationale: Copper is corrosion-resistant and approved for potable water.
4. A trap seal is the water depth that:
A. Prevents leaks
B. Prevents sewer gases from entering the building
, C. Increases flow
D. Reduces pipe size
Rationale: The water seal blocks sewer gas intrusion.
5. The minimum trap seal depth required by most plumbing codes is:
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
Rationale: Standard minimum is 2 inches to ensure gas protection.
6. Which fitting provides the smoothest flow change in a drainage system?
A. Tee
B. Long sweep 90
C. Short 90
D. Sanitary tee
Rationale: Long sweeps reduce turbulence and clogging.
7. What device prevents backflow into a potable water system?
A. Pressure regulator
B. Check valve
C. Backflow preventer
D. Air admittance valve
Rationale: Backflow preventers protect potable water from
contamination.
8. What type of valve is commonly used to control water flow to fixtures?
A. Gate valve
B. Angle stop valve
C. Globe valve
D. Relief valve
Rationale: Angle stops allow fixture isolation.
9. Which pipe is commonly used for DWV systems?
A. Copper Type L
B. PVC
C. PEX
D. Steel
, Rationale: PVC is lightweight, corrosion-resistant, and code-approved for
DWV.
10.The purpose of a cleanout is to:
A. Vent the system
B. Provide access for cleaning and maintenance
C. Increase drainage speed
D. Prevent leaks
Rationale: Cleanouts allow removal of blockages.
11.Which plumbing component controls water pressure entering a building?
A. Expansion tank
B. Pressure-reducing valve
C. Check valve
D. Relief valve
Rationale: PRVs regulate incoming pressure.
12.What is the minimum distance a cleanout must be from a change of
direction over 45°?
A. 1 foot
B. Within 5 feet
C. 10 feet
D. 20 feet
Rationale: Codes require accessibility near direction changes.
13.Which pipe size is typically used for a main building drain in residential
construction?
A. 2 inches
B. 3 or 4 inches
C. 1½ inches
D. 5 inches
Rationale: Main drains must handle total fixture load.
14.What does DWV stand for?
A. Drainage Water Volume
B. Drain, Waste, and Vent
