Journeyman Plumber Licensing Exam Practice
with Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Improve drainage speed
D. Reduce pipe corrosion
*Rationale: A trap holds water to form a seal that blocks sewer gases
from entering occupied spaces.
2. The minimum slope for a 3-inch horizontal drainage pipe is:
A. 1 inch per foot
B. 1/4 inch per foot
C. 1/8 inch per foot
D. Level only
*Rationale: Most plumbing codes require a minimum slope of 1/4 inch
per foot for pipes 3 inches or smaller.
3. Which pipe material is commonly used for interior water supply
lines?
A. Cast iron
B. PVC
C. Copper
D. Clay
*Rationale: Copper is durable, corrosion-resistant, and approved for
potable water.
,4. What fitting is used to connect two pipes of the same diameter in a
straight line?
A. Elbow
B. Tee
C. Coupling
D. Wye
*Rationale: A coupling joins two pipes end-to-end.
5. A vent pipe’s main function is to:
A. Remove solid waste
B. Increase drainage speed
C. Allow air into the drainage system
D. Filter sewer gases
*Rationale: Vent pipes equalize pressure and protect trap seals.
6. What type of valve is typically used as a main water shutoff?
A. Gate valve
B. Globe valve
C. Ball valve
D. Check valve
*Rationale: Ball valves provide quick, reliable shutoff and durability.
7. The minimum trap seal depth is generally:
A. 1 inch
B. 2 inches
C. 4 inches
D. 6 inches
*Rationale: A 2-inch seal prevents evaporation and loss of protection.
8. Which material is approved for underground sanitary drainage?
A. Galvanized steel
B. Copper Type L
C. PVC
, D. ABS foam core only
*Rationale: PVC is corrosion-resistant and approved for underground
drainage.
9. A backflow preventer is installed to:
A. Increase water pressure
B. Prevent contamination of potable water
C. Reduce water usage
D. Improve drainage
*Rationale: It stops reverse flow that could contaminate clean water.
10. What is the standard rough-in height for a wall-hung lavatory
drain?
A. 12 inches
B. 18 inches
C. 24 inches
D. 30 inches
*Rationale: Eighteen inches is the typical rough-in height.
11. Which tool is best for cutting copper pipe?
A. Hacksaw
B. Tubing cutter
C. Reciprocating saw
D. Grinder
*Rationale: Tubing cutters provide clean, square cuts.
12. A water hammer is caused by:
A. Low water pressure
B. Air in the pipes
C. Sudden valve closure
D. Pipe corrosion
*Rationale: Rapid valve closure creates shock waves in pipes.
with Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Improve drainage speed
D. Reduce pipe corrosion
*Rationale: A trap holds water to form a seal that blocks sewer gases
from entering occupied spaces.
2. The minimum slope for a 3-inch horizontal drainage pipe is:
A. 1 inch per foot
B. 1/4 inch per foot
C. 1/8 inch per foot
D. Level only
*Rationale: Most plumbing codes require a minimum slope of 1/4 inch
per foot for pipes 3 inches or smaller.
3. Which pipe material is commonly used for interior water supply
lines?
A. Cast iron
B. PVC
C. Copper
D. Clay
*Rationale: Copper is durable, corrosion-resistant, and approved for
potable water.
,4. What fitting is used to connect two pipes of the same diameter in a
straight line?
A. Elbow
B. Tee
C. Coupling
D. Wye
*Rationale: A coupling joins two pipes end-to-end.
5. A vent pipe’s main function is to:
A. Remove solid waste
B. Increase drainage speed
C. Allow air into the drainage system
D. Filter sewer gases
*Rationale: Vent pipes equalize pressure and protect trap seals.
6. What type of valve is typically used as a main water shutoff?
A. Gate valve
B. Globe valve
C. Ball valve
D. Check valve
*Rationale: Ball valves provide quick, reliable shutoff and durability.
7. The minimum trap seal depth is generally:
A. 1 inch
B. 2 inches
C. 4 inches
D. 6 inches
*Rationale: A 2-inch seal prevents evaporation and loss of protection.
8. Which material is approved for underground sanitary drainage?
A. Galvanized steel
B. Copper Type L
C. PVC
, D. ABS foam core only
*Rationale: PVC is corrosion-resistant and approved for underground
drainage.
9. A backflow preventer is installed to:
A. Increase water pressure
B. Prevent contamination of potable water
C. Reduce water usage
D. Improve drainage
*Rationale: It stops reverse flow that could contaminate clean water.
10. What is the standard rough-in height for a wall-hung lavatory
drain?
A. 12 inches
B. 18 inches
C. 24 inches
D. 30 inches
*Rationale: Eighteen inches is the typical rough-in height.
11. Which tool is best for cutting copper pipe?
A. Hacksaw
B. Tubing cutter
C. Reciprocating saw
D. Grinder
*Rationale: Tubing cutters provide clean, square cuts.
12. A water hammer is caused by:
A. Low water pressure
B. Air in the pipes
C. Sudden valve closure
D. Pipe corrosion
*Rationale: Rapid valve closure creates shock waves in pipes.
