Texas Master Plumber Licensing Exam
With Actual Questions & Verified
Answers,Plus Rationales/Expert
Verified For Guaranteed Pass Graded
A+/2026 /Latest Update/Instant
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1. Which of the following 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) 3/4 inch per foot
B) 1/4 inch per foot
Rationale: Texas Plumbing Code requires a 1/4 inch per foot slope for 3-inch
drain pipes to ensure proper drainage and prevent clogging.
2. What is the maximum allowable water velocity in a horizontal drainage
pipe?
A) 2 feet per second
B) 5 feet per second
C) 8 feet per second
D) 10 feet per second
C) 8 feet per second
Rationale: To avoid pipe erosion and ensure proper drainage, water velocity
in horizontal drain pipes should not exceed 8 feet per second.
, 3. A plumber installs a water heater 10 feet from a fixture. What is the
minimum pipe size required?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1-1/4 inch
A) 1/2 inch
Rationale: For short runs under 20 feet, 1/2-inch piping is typically sufficient
for standard fixtures according to Texas Plumbing Code.
4. Which type of pipe is approved for underground potable water supply in
Texas?
A) PVC
B) ABS
C) Cast Iron
D) Galvanized Steel
A) PVC
Rationale: PVC is widely approved for underground potable water lines due
to its durability and corrosion resistance.
5. What is the required minimum distance between a water heater and
combustible materials?
A) 3 inches
B) 6 inches
C) 12 inches
D) 18 inches
C) 12 inches
Rationale: Texas Plumbing Code requires a 12-inch clearance around water
heaters to reduce fire hazards and allow maintenance access.
6. When installing a vent stack, what is the minimum distance it must
extend above the roof?
A) 6 inches
B) 12 inches
, C) 18 inches
D) 24 inches
B) 12 inches
Rationale: Vent stacks must extend at least 12 inches above the roof to
prevent sewer gases from entering the building.
7. Which fitting is used to connect a horizontal drain to a vertical stack?
A) Elbow
B) Tee
C) Wye
D) Coupling
C) Wye
Rationale: A wye fitting is used to connect horizontal drain pipes into a
vertical stack at an angle that promotes smooth flow and reduces clogging.
8. What is the minimum diameter for a building drain in a one-family
dwelling?
A) 2 inches
B) 3 inches
C) 4 inches
D) 5 inches
B) 3 inches
Rationale: The Texas Plumbing Code specifies that the minimum diameter of
a building drain in a one-family dwelling is 3 inches.
9. Which type of backflow prevention device is required for a lawn
irrigation system?
A) Double check valve assembly
B) Reduced pressure zone assembly
C) Atmospheric vacuum breaker
D) Pressure vacuum breaker
C) Atmospheric vacuum breaker
Rationale: An atmospheric vacuum breaker is suitable for irrigation systems
to prevent contamination of the potable water supply.
With Actual Questions & Verified
Answers,Plus Rationales/Expert
Verified For Guaranteed Pass Graded
A+/2026 /Latest Update/Instant
Download Pdf
1. Which of the following 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) 3/4 inch per foot
B) 1/4 inch per foot
Rationale: Texas Plumbing Code requires a 1/4 inch per foot slope for 3-inch
drain pipes to ensure proper drainage and prevent clogging.
2. What is the maximum allowable water velocity in a horizontal drainage
pipe?
A) 2 feet per second
B) 5 feet per second
C) 8 feet per second
D) 10 feet per second
C) 8 feet per second
Rationale: To avoid pipe erosion and ensure proper drainage, water velocity
in horizontal drain pipes should not exceed 8 feet per second.
, 3. A plumber installs a water heater 10 feet from a fixture. What is the
minimum pipe size required?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1-1/4 inch
A) 1/2 inch
Rationale: For short runs under 20 feet, 1/2-inch piping is typically sufficient
for standard fixtures according to Texas Plumbing Code.
4. Which type of pipe is approved for underground potable water supply in
Texas?
A) PVC
B) ABS
C) Cast Iron
D) Galvanized Steel
A) PVC
Rationale: PVC is widely approved for underground potable water lines due
to its durability and corrosion resistance.
5. What is the required minimum distance between a water heater and
combustible materials?
A) 3 inches
B) 6 inches
C) 12 inches
D) 18 inches
C) 12 inches
Rationale: Texas Plumbing Code requires a 12-inch clearance around water
heaters to reduce fire hazards and allow maintenance access.
6. When installing a vent stack, what is the minimum distance it must
extend above the roof?
A) 6 inches
B) 12 inches
, C) 18 inches
D) 24 inches
B) 12 inches
Rationale: Vent stacks must extend at least 12 inches above the roof to
prevent sewer gases from entering the building.
7. Which fitting is used to connect a horizontal drain to a vertical stack?
A) Elbow
B) Tee
C) Wye
D) Coupling
C) Wye
Rationale: A wye fitting is used to connect horizontal drain pipes into a
vertical stack at an angle that promotes smooth flow and reduces clogging.
8. What is the minimum diameter for a building drain in a one-family
dwelling?
A) 2 inches
B) 3 inches
C) 4 inches
D) 5 inches
B) 3 inches
Rationale: The Texas Plumbing Code specifies that the minimum diameter of
a building drain in a one-family dwelling is 3 inches.
9. Which type of backflow prevention device is required for a lawn
irrigation system?
A) Double check valve assembly
B) Reduced pressure zone assembly
C) Atmospheric vacuum breaker
D) Pressure vacuum breaker
C) Atmospheric vacuum breaker
Rationale: An atmospheric vacuum breaker is suitable for irrigation systems
to prevent contamination of the potable water supply.
