Journeyman Plumber Licensing Exam
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. Which type of pipe is most commonly used for hot water supply in
residential plumbing?
A. PVC
B. CPVC
C. ABS
D. Galvanized steel
CPVC (Chlorinated Polyvinyl Chloride) is designed to handle higher
temperatures than standard PVC, making it ideal for hot water supply
lines.
2. What is the minimum slope required for a 2-inch horizontal drain
pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
, C. 1/4 to 1/2 inch per foot
D. 1/2 inch per foot
A horizontal drain must have a slope between 1/4 inch and 1/2 inch
per foot to ensure proper gravity flow without causing backups.
3. The main purpose of a P-trap is to:
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Filter debris
D. Provide support for the drain pipe
A P-trap holds a small amount of water, which acts as a barrier
preventing foul-smelling sewer gases from escaping into occupied
spaces.
4. What is the standard water pressure range for residential
plumbing systems?
A. 20–40 psi
B. 40–60 psi
C. 50–80 psi
D. 80–100 psi
Most residential plumbing systems are designed to operate safely
within 50–80 psi, balancing performance and minimizing pipe stress.
, 5. Which valve is used to stop water flow in a specific section of pipe
for maintenance?
A. Ball valve
B. Gate valve
C. Both A and B
D. Check valve
Both ball valves and gate valves can be used to isolate sections of a
plumbing system for repair or maintenance.
6. When soldering copper pipes, which flux type should be used?
A. Acid-based
B. Rosin-based or water-soluble
C. Oil-based
D. None; flux is not required
Proper flux removes oxides from the pipe surface and facilitates the
flow of solder to create a leak-free joint.
7. Which of the following is a code-approved material for
underground potable water supply?
A. PVC
B. CPVC
C. HDPE
D. Galvanized steel
, High-Density Polyethylene (HDPE) is flexible, durable, and approved
for underground potable water supply.
8. What is the maximum distance allowed between supports for a 3-
inch copper water pipe?
A. 3 feet
B. 4 feet
C. 6 feet
D. 8 feet
Copper water pipes require support at intervals not exceeding 6 feet to
prevent sagging and joint stress.
9. A backflow preventer is installed to:
A. Increase water pressure
B. Prevent contamination of the potable water supply
C. Reduce water temperature
D. Control water flow rate
Backflow preventers stop water from flowing backward into the main
water supply, protecting the potable water from contamination.
10. What is the primary function of a vent in a plumbing system?
A. Increase water pressure
B. Allow air to enter the drain system to maintain proper flow
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which type of pipe is most commonly used for hot water supply in
residential plumbing?
A. PVC
B. CPVC
C. ABS
D. Galvanized steel
CPVC (Chlorinated Polyvinyl Chloride) is designed to handle higher
temperatures than standard PVC, making it ideal for hot water supply
lines.
2. What is the minimum slope required for a 2-inch horizontal drain
pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
, C. 1/4 to 1/2 inch per foot
D. 1/2 inch per foot
A horizontal drain must have a slope between 1/4 inch and 1/2 inch
per foot to ensure proper gravity flow without causing backups.
3. The main purpose of a P-trap is to:
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Filter debris
D. Provide support for the drain pipe
A P-trap holds a small amount of water, which acts as a barrier
preventing foul-smelling sewer gases from escaping into occupied
spaces.
4. What is the standard water pressure range for residential
plumbing systems?
A. 20–40 psi
B. 40–60 psi
C. 50–80 psi
D. 80–100 psi
Most residential plumbing systems are designed to operate safely
within 50–80 psi, balancing performance and minimizing pipe stress.
, 5. Which valve is used to stop water flow in a specific section of pipe
for maintenance?
A. Ball valve
B. Gate valve
C. Both A and B
D. Check valve
Both ball valves and gate valves can be used to isolate sections of a
plumbing system for repair or maintenance.
6. When soldering copper pipes, which flux type should be used?
A. Acid-based
B. Rosin-based or water-soluble
C. Oil-based
D. None; flux is not required
Proper flux removes oxides from the pipe surface and facilitates the
flow of solder to create a leak-free joint.
7. Which of the following is a code-approved material for
underground potable water supply?
A. PVC
B. CPVC
C. HDPE
D. Galvanized steel
, High-Density Polyethylene (HDPE) is flexible, durable, and approved
for underground potable water supply.
8. What is the maximum distance allowed between supports for a 3-
inch copper water pipe?
A. 3 feet
B. 4 feet
C. 6 feet
D. 8 feet
Copper water pipes require support at intervals not exceeding 6 feet to
prevent sagging and joint stress.
9. A backflow preventer is installed to:
A. Increase water pressure
B. Prevent contamination of the potable water supply
C. Reduce water temperature
D. Control water flow rate
Backflow preventers stop water from flowing backward into the main
water supply, protecting the potable water from contamination.
10. What is the primary function of a vent in a plumbing system?
A. Increase water pressure
B. Allow air to enter the drain system to maintain proper flow
