JOURNEYMAN PLUMBER LICENSE EXAM
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES
2025 Q&A | INSTANT DOWNLOAD PDF
1. What is the minimum slope for a 3-inch horizontal drainage pipe?
1/8 inch per foot
1/4 inch per foot
1/2 inch per foot
No slope required
A 1/4 inch per foot slope ensures proper gravity flow and minimizes
solids buildup.
2. What type of fitting is used to connect two pipes of different sizes in a
straight line?
Tee
Reducer coupling
Elbow
, Union
Reducer couplings allow for a smooth transition between different
pipe sizes.
3. What is the purpose of a trap in a plumbing system?
To regulate pressure
To prevent sewer gases from entering the building
To filter debris
To increase water pressure
Traps retain water to form a barrier against sewer gas entry.
4. Which material is most commonly used for residential water supply
lines?
PEX
Cast iron
PVC
ABS
PEX is flexible, resistant to scale and chlorine, and easier to install.
5. A branch vent connects to:
A waste pipe and a vent stack
Only to a fixture
The building sewer
The hot water line
Branch vents provide air to waste lines and connect to the main vent
system.
, 6. What is the function of a backflow preventer?
Increase flow rate
Reduce noise
Prevent contamination of potable water
Reduce water pressure
It protects potable water from reverse flow contamination.
7. Which code sets minimum standards for plumbing systems?
National Fire Protection Association
Uniform Plumbing Code (UPC)
National Electrical Code
International Mechanical Code
The UPC governs plumbing design and installation.
8. A water heater relief valve protects against:
Low temperatures
Excessive pressure and temperature
Sediment buildup
Water hammer
Relief valves prevent tank rupture due to overheating or
overpressure.
9. What type of valve is used for throttling flow?
Gate valve
Check valve
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES
2025 Q&A | INSTANT DOWNLOAD PDF
1. What is the minimum slope for a 3-inch horizontal drainage pipe?
1/8 inch per foot
1/4 inch per foot
1/2 inch per foot
No slope required
A 1/4 inch per foot slope ensures proper gravity flow and minimizes
solids buildup.
2. What type of fitting is used to connect two pipes of different sizes in a
straight line?
Tee
Reducer coupling
Elbow
, Union
Reducer couplings allow for a smooth transition between different
pipe sizes.
3. What is the purpose of a trap in a plumbing system?
To regulate pressure
To prevent sewer gases from entering the building
To filter debris
To increase water pressure
Traps retain water to form a barrier against sewer gas entry.
4. Which material is most commonly used for residential water supply
lines?
PEX
Cast iron
PVC
ABS
PEX is flexible, resistant to scale and chlorine, and easier to install.
5. A branch vent connects to:
A waste pipe and a vent stack
Only to a fixture
The building sewer
The hot water line
Branch vents provide air to waste lines and connect to the main vent
system.
, 6. What is the function of a backflow preventer?
Increase flow rate
Reduce noise
Prevent contamination of potable water
Reduce water pressure
It protects potable water from reverse flow contamination.
7. Which code sets minimum standards for plumbing systems?
National Fire Protection Association
Uniform Plumbing Code (UPC)
National Electrical Code
International Mechanical Code
The UPC governs plumbing design and installation.
8. A water heater relief valve protects against:
Low temperatures
Excessive pressure and temperature
Sediment buildup
Water hammer
Relief valves prevent tank rupture due to overheating or
overpressure.
9. What type of valve is used for throttling flow?
Gate valve
Check valve
