PA Master Plumber Licensing Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. 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) 3/8 inch per foot
d) 1/2 inch per foot
A 3-inch or smaller horizontal drain requires a slope of at least 1/4
inch per foot for proper drainage per code.
2. The minimum size water service pipe for a single-family dwelling is:
a) 1/2 inch
b) 3/4 inch
c) 1 inch
, d) 1-1/4 inch
Most plumbing codes require at least 3/4 inch service for adequate
supply to a single-family dwelling.
3. What is the maximum horizontal spacing for pipe supports on 1-inch
copper tubing?
a) 4 feet
b) 6 feet
c) 8 feet
d) 10 feet
Copper tubing requires support every 6 feet horizontally to prevent
sagging.
4. What type of fitting is prohibited in drainage piping?
a) Wye
b) 1/8 bend
c) Double sanitary tee
d) Sanitary tee
Double sanitary tees can cause cross-flow and are prohibited in
drainage piping.
5. What is the minimum trap seal depth required?
a) 1/2 inch
b) 1 inch
c) 2 inches
d) 4 inches
, Trap seals must be between 2 and 4 inches to prevent sewer gas
entry while avoiding evaporation issues.
6. A cleanout must be installed for a building drain at a distance not
exceeding:
a) 25 feet
b) 50 feet
c) 100 feet
d) 150 feet
Cleanouts are required every 100 feet in building drains to allow for
maintenance and cleaning.
7. Which type of valve is best suited for throttling water flow?
a) Gate valve
b) Check valve
c) Globe valve
d) Ball valve
Globe valves are designed to regulate and throttle flow, unlike gate
or ball valves which are better for on/off control.
8. Which type of pipe should not be used for hot water distribution?
a) Copper
b) CPVC
c) PEX
d) PVC
, PVC is not rated for hot water use; CPVC, copper, and PEX are
acceptable.
9. What is the minimum size of a vent stack serving a building drain 3
inches in diameter?
a) 1-1/2 inches
b) 2 inches
c) 3 inches
d) 4 inches
A vent stack must be at least the same size as the building drain it
serves.
10. What is the maximum developed length of a trap arm for a 2-
inch trap?
a) 2 feet
b) 4 feet
c) 5 feet
d) 8 feet
A 2-inch trap arm can be up to 5 feet in developed length before
needing additional venting.
11. Which material is NOT approved for underground drainage?
a) Cast iron
b) PVC
c) ABS (in some jurisdictions)
d) Clay
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. 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) 3/8 inch per foot
d) 1/2 inch per foot
A 3-inch or smaller horizontal drain requires a slope of at least 1/4
inch per foot for proper drainage per code.
2. The minimum size water service pipe for a single-family dwelling is:
a) 1/2 inch
b) 3/4 inch
c) 1 inch
, d) 1-1/4 inch
Most plumbing codes require at least 3/4 inch service for adequate
supply to a single-family dwelling.
3. What is the maximum horizontal spacing for pipe supports on 1-inch
copper tubing?
a) 4 feet
b) 6 feet
c) 8 feet
d) 10 feet
Copper tubing requires support every 6 feet horizontally to prevent
sagging.
4. What type of fitting is prohibited in drainage piping?
a) Wye
b) 1/8 bend
c) Double sanitary tee
d) Sanitary tee
Double sanitary tees can cause cross-flow and are prohibited in
drainage piping.
5. What is the minimum trap seal depth required?
a) 1/2 inch
b) 1 inch
c) 2 inches
d) 4 inches
, Trap seals must be between 2 and 4 inches to prevent sewer gas
entry while avoiding evaporation issues.
6. A cleanout must be installed for a building drain at a distance not
exceeding:
a) 25 feet
b) 50 feet
c) 100 feet
d) 150 feet
Cleanouts are required every 100 feet in building drains to allow for
maintenance and cleaning.
7. Which type of valve is best suited for throttling water flow?
a) Gate valve
b) Check valve
c) Globe valve
d) Ball valve
Globe valves are designed to regulate and throttle flow, unlike gate
or ball valves which are better for on/off control.
8. Which type of pipe should not be used for hot water distribution?
a) Copper
b) CPVC
c) PEX
d) PVC
, PVC is not rated for hot water use; CPVC, copper, and PEX are
acceptable.
9. What is the minimum size of a vent stack serving a building drain 3
inches in diameter?
a) 1-1/2 inches
b) 2 inches
c) 3 inches
d) 4 inches
A vent stack must be at least the same size as the building drain it
serves.
10. What is the maximum developed length of a trap arm for a 2-
inch trap?
a) 2 feet
b) 4 feet
c) 5 feet
d) 8 feet
A 2-inch trap arm can be up to 5 feet in developed length before
needing additional venting.
11. Which material is NOT approved for underground drainage?
a) Cast iron
b) PVC
c) ABS (in some jurisdictions)
d) Clay
