TEXAS JOURNEYMAN PLUMBER EXAM
1. What is the primary purpose of a P-trap in a plumbing
system?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Increase drainage speed
D. Filter solid waste
Correct answer: B
The P-trap is designed to retain a small amount of water in its
curved section, forming a seal that blocks sewer gases from
traveling back through the drain and into occupied spaces. This
is a critical health and safety feature in plumbing systems.
2. Which pipe material is most commonly used for water
supply lines in modern residential construction?
A. Cast iron
B. Galvanized steel
C. Copper or PEX
D. Clay pipe
Correct answer: C
Copper and PEX are widely used because they resist corrosion,
are durable, and are easier to install compared to older
materials like galvanized steel, which corrodes internally over
time.
3. What is the minimum slope required for a 3-inch
horizontal drain pipe?
A. 1/8 inch per foot
, B. 1/4 inch per foot
C. 1/2 inch per foot
D. No slope required
Correct answer: B
A 1/4 inch per foot slope ensures adequate gravity flow,
preventing solids from settling in the pipe and reducing the risk
of clogs in drainage systems.
4. What is the function of a vent pipe in a plumbing system?
A. Increase water pressure
B. Carry wastewater to the sewer
C. Allow air into the system to maintain pressure balance
D. Filter contaminants
Correct answer: C
Vent pipes allow air into the drainage system, preventing
vacuum conditions that could slow drainage or siphon water
out of traps.
5. Which fitting is used to change the direction of a pipe by
90 degrees with minimal flow resistance?
A. Tee
B. Coupling
C. Long-sweep elbow
D. Cap
Correct answer: C
Long-sweep elbows are designed to reduce turbulence and
allow smoother directional changes in drainage systems
compared to sharp 90-degree elbows.
, 6. What is the purpose of a cleanout in a plumbing system?
A. Increase water pressure
B. Provide access for clearing blockages
C. Reduce pipe diameter
D. Filter wastewater
Correct answer: B
Cleanouts provide access points for plumbing snakes or augers,
allowing plumbers to remove clogs without dismantling the
system.
7. Which type of pipe is commonly used for underground
sewer lines?
A. PVC
B. Copper
C. Galvanized steel
D. Lead
Correct answer: A
PVC is lightweight, corrosion-resistant, and cost-effective,
making it ideal for underground drainage and sewer
applications.
8. What is the standard color of a hot water pipe in plumbing
identification?
A. Blue
B. Red
C. Green
D. Yellow
Correct answer: B
, Red is commonly used to indicate hot water lines, while blue
typically indicates cold water lines for easy identification.
9. What device prevents backflow in potable water systems?
A. Trap
B. Check valve
C. Tee
D. Reducer
Correct answer: B
A check valve allows water to flow in only one direction,
preventing contaminated water from flowing back into the
clean water supply.
10. What is the minimum size for a residential building
sewer line?
A. 2 inches
B. 3 inches
C. 4 inches
D. 6 inches
Correct answer: C
A 4-inch diameter is the standard minimum size for residential
sewer lines to ensure adequate flow capacity and reduce
blockage risk.
11. Which tool is used to cut large-diameter plastic pipe?
A. Hacksaw
B. Pipe cutter
C. Reciprocating saw
D. Tubing cutter
1. What is the primary purpose of a P-trap in a plumbing
system?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Increase drainage speed
D. Filter solid waste
Correct answer: B
The P-trap is designed to retain a small amount of water in its
curved section, forming a seal that blocks sewer gases from
traveling back through the drain and into occupied spaces. This
is a critical health and safety feature in plumbing systems.
2. Which pipe material is most commonly used for water
supply lines in modern residential construction?
A. Cast iron
B. Galvanized steel
C. Copper or PEX
D. Clay pipe
Correct answer: C
Copper and PEX are widely used because they resist corrosion,
are durable, and are easier to install compared to older
materials like galvanized steel, which corrodes internally over
time.
3. What is the minimum slope required for a 3-inch
horizontal drain pipe?
A. 1/8 inch per foot
, B. 1/4 inch per foot
C. 1/2 inch per foot
D. No slope required
Correct answer: B
A 1/4 inch per foot slope ensures adequate gravity flow,
preventing solids from settling in the pipe and reducing the risk
of clogs in drainage systems.
4. What is the function of a vent pipe in a plumbing system?
A. Increase water pressure
B. Carry wastewater to the sewer
C. Allow air into the system to maintain pressure balance
D. Filter contaminants
Correct answer: C
Vent pipes allow air into the drainage system, preventing
vacuum conditions that could slow drainage or siphon water
out of traps.
5. Which fitting is used to change the direction of a pipe by
90 degrees with minimal flow resistance?
A. Tee
B. Coupling
C. Long-sweep elbow
D. Cap
Correct answer: C
Long-sweep elbows are designed to reduce turbulence and
allow smoother directional changes in drainage systems
compared to sharp 90-degree elbows.
, 6. What is the purpose of a cleanout in a plumbing system?
A. Increase water pressure
B. Provide access for clearing blockages
C. Reduce pipe diameter
D. Filter wastewater
Correct answer: B
Cleanouts provide access points for plumbing snakes or augers,
allowing plumbers to remove clogs without dismantling the
system.
7. Which type of pipe is commonly used for underground
sewer lines?
A. PVC
B. Copper
C. Galvanized steel
D. Lead
Correct answer: A
PVC is lightweight, corrosion-resistant, and cost-effective,
making it ideal for underground drainage and sewer
applications.
8. What is the standard color of a hot water pipe in plumbing
identification?
A. Blue
B. Red
C. Green
D. Yellow
Correct answer: B
, Red is commonly used to indicate hot water lines, while blue
typically indicates cold water lines for easy identification.
9. What device prevents backflow in potable water systems?
A. Trap
B. Check valve
C. Tee
D. Reducer
Correct answer: B
A check valve allows water to flow in only one direction,
preventing contaminated water from flowing back into the
clean water supply.
10. What is the minimum size for a residential building
sewer line?
A. 2 inches
B. 3 inches
C. 4 inches
D. 6 inches
Correct answer: C
A 4-inch diameter is the standard minimum size for residential
sewer lines to ensure adequate flow capacity and reduce
blockage risk.
11. Which tool is used to cut large-diameter plastic pipe?
A. Hacksaw
B. Pipe cutter
C. Reciprocating saw
D. Tubing cutter
