Journeyman Plumber Licensing Exam
Practice Test Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
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1. What is the primary purpose of a trap in a plumbing system?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To filter debris from water
D. To store excess water
Rationale: Traps, such as P-traps and S-traps, create a water seal that prevents
sewer gases from entering buildings while allowing wastewater to flow.
2. What is the minimum slope for a 3-inch horizontal drainage pipe according
to standard plumbing codes?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/8 to 1/4 inch per foot
D. 1/2 inch per foot
Rationale: Drainage pipes must slope properly to ensure gravity drainage. A 3-
inch pipe typically requires a slope of 1/8 to 1/4 inch per foot.
, 3. Which of the following is a common material used for water supply piping
in residential construction?
A. Cast iron
B. Copper
C. Brick
D. PVC for hot water
Rationale: Copper piping is widely used for water supply due to its durability,
corrosion resistance, and heat tolerance.
4. Backflow preventers are installed to:
A. Increase water flow
B. Reduce water pressure
C. Prevent contaminated water from flowing back into the potable water
system
D. Trap debris in the water
Rationale: Backflow preventers protect the public water supply by stopping
contaminated water from reversing flow into potable systems.
5. What type of valve is commonly used to control water flow to a fixture?
A. Ball valve
B. Gate valve
C. Check valve
D. Pressure reducing valve
Rationale: Gate valves are used to shut off water flow completely to fixtures,
while ball valves offer quick shutoff but less fine control.
6. What is the typical size of a residential water service line?
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 2 inches
Rationale: Residential water service lines are commonly 1 inch, sufficient to
supply normal household demand.
, 7. When joining two copper pipes with solder, what is the necessary step
before applying heat?
A. Apply flux and clean the pipe ends
B. Apply sealant
C. Clean the pipe ends and apply flux
D. Heat the pipe immediately
Rationale: Proper preparation involves cleaning the pipe and applying flux to
ensure the solder bonds correctly without leaks.
8. Which type of pipe is suitable for underground drainage in direct contact
with soil?
A. Copper
B. PVC or ABS
C. Galvanized steel
D. PEX
Rationale: PVC and ABS are corrosion-resistant and commonly used for
underground drainage applications.
9. What is the primary reason for venting a plumbing system?
A. To reduce water pressure
B. To increase water flow speed
C. To prevent siphoning of traps and allow sewer gases to escape
D. To store excess water
Rationale: Vents allow air to enter the drainage system, preventing traps from
being siphoned and allowing sewer gases to escape safely.
10.Which tool is used to thread a steel pipe?
A. Pipe wrench
B. Pipe die
C. Hacksaw
D. Plunger
Rationale: A pipe die is used to cut threads on steel pipe so fittings can be
screwed on.
Practice Test Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
1. What is the primary purpose of a trap in a plumbing system?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To filter debris from water
D. To store excess water
Rationale: Traps, such as P-traps and S-traps, create a water seal that prevents
sewer gases from entering buildings while allowing wastewater to flow.
2. What is the minimum slope for a 3-inch horizontal drainage pipe according
to standard plumbing codes?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/8 to 1/4 inch per foot
D. 1/2 inch per foot
Rationale: Drainage pipes must slope properly to ensure gravity drainage. A 3-
inch pipe typically requires a slope of 1/8 to 1/4 inch per foot.
, 3. Which of the following is a common material used for water supply piping
in residential construction?
A. Cast iron
B. Copper
C. Brick
D. PVC for hot water
Rationale: Copper piping is widely used for water supply due to its durability,
corrosion resistance, and heat tolerance.
4. Backflow preventers are installed to:
A. Increase water flow
B. Reduce water pressure
C. Prevent contaminated water from flowing back into the potable water
system
D. Trap debris in the water
Rationale: Backflow preventers protect the public water supply by stopping
contaminated water from reversing flow into potable systems.
5. What type of valve is commonly used to control water flow to a fixture?
A. Ball valve
B. Gate valve
C. Check valve
D. Pressure reducing valve
Rationale: Gate valves are used to shut off water flow completely to fixtures,
while ball valves offer quick shutoff but less fine control.
6. What is the typical size of a residential water service line?
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 2 inches
Rationale: Residential water service lines are commonly 1 inch, sufficient to
supply normal household demand.
, 7. When joining two copper pipes with solder, what is the necessary step
before applying heat?
A. Apply flux and clean the pipe ends
B. Apply sealant
C. Clean the pipe ends and apply flux
D. Heat the pipe immediately
Rationale: Proper preparation involves cleaning the pipe and applying flux to
ensure the solder bonds correctly without leaks.
8. Which type of pipe is suitable for underground drainage in direct contact
with soil?
A. Copper
B. PVC or ABS
C. Galvanized steel
D. PEX
Rationale: PVC and ABS are corrosion-resistant and commonly used for
underground drainage applications.
9. What is the primary reason for venting a plumbing system?
A. To reduce water pressure
B. To increase water flow speed
C. To prevent siphoning of traps and allow sewer gases to escape
D. To store excess water
Rationale: Vents allow air to enter the drainage system, preventing traps from
being siphoned and allowing sewer gases to escape safely.
10.Which tool is used to thread a steel pipe?
A. Pipe wrench
B. Pipe die
C. Hacksaw
D. Plunger
Rationale: A pipe die is used to cut threads on steel pipe so fittings can be
screwed on.
