Journeyman Plumber Licensing Exam
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. Store debris for easy removal
D. Improve drainage speed
Answer: B
Rationale: Traps hold a water seal that blocks sewer gases from
entering occupied spaces.
2. The minimum trap seal depth for most plumbing fixtures is
typically
A. ½ inch
B. 1 inch
C. 2 inches
D. 6 inches
Answer: C
Rationale: A 2-inch trap seal is generally required to ensure an
effective gas barrier.
3. Which pipe material is most commonly used for residential drain,
waste, and vent (DWV) systems?
A. Copper Type L
, B. PVC
C. Galvanized steel
D. Cast iron only
Answer: B
Rationale: PVC is lightweight, corrosion-resistant, and widely
approved for DWV systems.
4. A vent stack primarily serves to
A. Carry wastewater to the sewer
B. Supply potable water
C. Equalize pressure in the drainage system
D. Heat the drainage piping
Answer: C
Rationale: Vent stacks prevent siphoning of traps by equalizing air
pressure.
5. What fitting is commonly used to change direction from horizontal
to vertical in a drainage system?
A. Tee
B. Sanitary tee
C. Long-sweep 90
D. Coupling
Answer: C
Rationale: Long-sweep fittings reduce turbulence and clogging in
drainage.
6. The standard slope for horizontal drainage piping is generally
A. ⅛ inch per foot
B. ¼ inch per foot
C. ½ inch per foot
, D. Level
Answer: B
Rationale: A ¼-inch-per-foot slope ensures proper flow without
solids settling.
7. Cross-connection control is intended to prevent
A. Pipe corrosion
B. Water hammer
C. Contamination of potable water
D. Pressure loss
Answer: C
Rationale: Cross-connections can allow backflow of contaminants
into potable water.
8. Which device protects against back-siphonage?
A. Pressure regulator
B. Air gap
C. Check valve only
D. Expansion tank
Answer: B
Rationale: An air gap is the most reliable method of preventing
back-siphonage.
9. A water hammer arrestor is installed to
A. Increase flow rate
B. Reduce noise from drainage
C. Absorb pressure surges
D. Filter sediment
Answer: C
, Rationale: Arrestors cushion sudden pressure changes when valves
close quickly.
10. The main building drain connects directly to the
A. Fixture trap
B. Vent stack
C. Building sewer
D. Branch drain
Answer: C
Rationale: The building drain terminates at and connects to the
building sewer.
11. Which fixture requires a minimum 3-inch drain in most
codes?
A. Lavatory
B. Bathtub
C. Water closet
D. Dishwasher
Answer: C
Rationale: Water closets require larger drains due to waste
volume.
12. Copper tubing used for potable water distribution is
commonly joined by
A. Threading
B. Soldering or brazing
C. Gluing
D. Compression only
Answer: B
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. Store debris for easy removal
D. Improve drainage speed
Answer: B
Rationale: Traps hold a water seal that blocks sewer gases from
entering occupied spaces.
2. The minimum trap seal depth for most plumbing fixtures is
typically
A. ½ inch
B. 1 inch
C. 2 inches
D. 6 inches
Answer: C
Rationale: A 2-inch trap seal is generally required to ensure an
effective gas barrier.
3. Which pipe material is most commonly used for residential drain,
waste, and vent (DWV) systems?
A. Copper Type L
, B. PVC
C. Galvanized steel
D. Cast iron only
Answer: B
Rationale: PVC is lightweight, corrosion-resistant, and widely
approved for DWV systems.
4. A vent stack primarily serves to
A. Carry wastewater to the sewer
B. Supply potable water
C. Equalize pressure in the drainage system
D. Heat the drainage piping
Answer: C
Rationale: Vent stacks prevent siphoning of traps by equalizing air
pressure.
5. What fitting is commonly used to change direction from horizontal
to vertical in a drainage system?
A. Tee
B. Sanitary tee
C. Long-sweep 90
D. Coupling
Answer: C
Rationale: Long-sweep fittings reduce turbulence and clogging in
drainage.
6. The standard slope for horizontal drainage piping is generally
A. ⅛ inch per foot
B. ¼ inch per foot
C. ½ inch per foot
, D. Level
Answer: B
Rationale: A ¼-inch-per-foot slope ensures proper flow without
solids settling.
7. Cross-connection control is intended to prevent
A. Pipe corrosion
B. Water hammer
C. Contamination of potable water
D. Pressure loss
Answer: C
Rationale: Cross-connections can allow backflow of contaminants
into potable water.
8. Which device protects against back-siphonage?
A. Pressure regulator
B. Air gap
C. Check valve only
D. Expansion tank
Answer: B
Rationale: An air gap is the most reliable method of preventing
back-siphonage.
9. A water hammer arrestor is installed to
A. Increase flow rate
B. Reduce noise from drainage
C. Absorb pressure surges
D. Filter sediment
Answer: C
, Rationale: Arrestors cushion sudden pressure changes when valves
close quickly.
10. The main building drain connects directly to the
A. Fixture trap
B. Vent stack
C. Building sewer
D. Branch drain
Answer: C
Rationale: The building drain terminates at and connects to the
building sewer.
11. Which fixture requires a minimum 3-inch drain in most
codes?
A. Lavatory
B. Bathtub
C. Water closet
D. Dishwasher
Answer: C
Rationale: Water closets require larger drains due to waste
volume.
12. Copper tubing used for potable water distribution is
commonly joined by
A. Threading
B. Soldering or brazing
C. Gluing
D. Compression only
Answer: B
