JOURNEYMAN PLUMBER LICENSING EXAMS – PRACTICE QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
*Core Domains*
*1. Plumbing Mathematics and Blueprint Reading*
*2. Drainage, Waste, and Vent (DWV) Systems*
*3. Water Supply and Distribution Systems*
*4. Plumbing Fixtures and Faucets*
*5. Backflow Prevention and Cross-Connection Control*
*6. Gas Piping Systems*
*7. Building Codes and Regulatory Compliance*
*8. Safety, Tools, and Professional Ethics*
*Introduction*
*The purpose of this examination is to rigorously evaluate the technical competency
SECTION ONE: QUESTIONS 1–100
Question 1
What is the minimum size for a standard residential kitchen sink drain tailpiece?
A. 1 inch
B. 1 1/4 inches
🟢 C. 1 1/2 inches
D. 2 inches
,🔴 RATIONALE: Standard plumbing codes require a minimum of 1 1/2 inches for kitchen sink tailpieces to ensure
adequate flow and prevent clogging.
Question 2
Which type of backflow prevention device is best suited for a continuous pressure application on a boiler feed line?
A. Atmospheric vacuum breaker
🟢 B. Reduced pressure principle assembly
C. Double check valve assembly
D. Dual check valve
🔴 RATIONALE: Reduced pressure principle assemblies are the only devices approved for high-hazard, continuous
pressure applications like boiler feeds.
Question 3
When installing copper piping, what is the primary purpose of flux?
A. To increase the pipe diameter
B. To act as a lubricant for threading
🟢 C. To remove oxidation and promote solder flow
D. To prevent the pipe from cooling too quickly
🔴 RATIONALE: Flux is a chemical agent that cleans the metal surfaces of oxides during heating, allowing the molten
solder to wet and bond to the pipe.
Question 4
What is the maximum trap arm length for a 2-inch pipe trap?
🟢 A. 5 feet
B. 6 feet
C. 8 feet
D. 10 feet
🔴 RATIONALE: According to standard code tables, the developed length of a trap arm is restricted based on pipe
diameter; for 2 inches, the limit is 5 feet.
,Question 5
Which valve type is best suited for throttling flow in a water distribution system?
A. Ball valve
B. Gate valve
C. Check valve
🟢 D. Globe valve
🔴 RATIONALE: Globe valves are designed to control or throttle flow, whereas ball and gate valves are primarily
meant for full-open or full-closed positions.
Question 6
In a DWV system, what is the primary function of a stack vent?
A. To provide water to the fixture
🟢 B. To allow air circulation and prevent trap siphonage
C. To collect waste from the basement
D. To increase the water pressure
🔴 RATIONALE: The stack vent provides the necessary atmospheric pressure to the drainage system, preventing the
vacuum effect that would siphon trap seals.
Question 7
When measuring for an offset in piping, what is the multiplier for a 45-degree angle?
A. 1.000
B. 1.155
🟢 C. 1.414
D. 1.732
🔴 RATIONALE: The constant for a 45-degree fitting is the cosecant of 45 degrees, which is approximately 1.414.
Question 8
Which gas pipe material is prohibited from being used in direct contact with concrete?
A. Black iron
B. Galvanized steel
🟢 C. Corrugated stainless steel tubing (CSST)
, D. Schedule 40 PVC
🔴 RATIONALE: CSST manufacturers typically prohibit direct burial or contact with corrosive materials like concrete
without proper protective sleeving.
Question 9
What is the standard requirement for the installation of a temperature and pressure relief valve (T&P) on a water
heater?
A. Installed only on the cold water inlet
B. Must be set to 250 degrees Fahrenheit
🟢 C. Must discharge to a safe location
D. Not required for residential tanks under 30 gallons
🔴 RATIONALE: T&P valves are safety devices that must be capable of discharging dangerous steam or hot water to
a safe, visible location away from occupants.
Question 10
If a plumber discovers an illegal cross-connection between potable and non-potable water, what is the professional
responsibility?
🟢 A. Immediately report the condition and initiate corrective action
B. Wait until the next inspection cycle
C. Only fix it if the homeowner requests it
D. Ignore it if it is not part of the original work order
🔴 RATIONALE: Plumbers are ethically and legally bound to report and eliminate health hazards like cross-
connections to protect the public water supply.
Question 11
What is the minimum diameter of a building sewer line?
A. 2 inches
B. 3 inches
🟢 C. 4 inches
D. 6 inches
ANSWERS) PLUS RATIONALES 2026 Q&A | INSTANT DOWNLOAD PDF.
*Core Domains*
*1. Plumbing Mathematics and Blueprint Reading*
*2. Drainage, Waste, and Vent (DWV) Systems*
*3. Water Supply and Distribution Systems*
*4. Plumbing Fixtures and Faucets*
*5. Backflow Prevention and Cross-Connection Control*
*6. Gas Piping Systems*
*7. Building Codes and Regulatory Compliance*
*8. Safety, Tools, and Professional Ethics*
*Introduction*
*The purpose of this examination is to rigorously evaluate the technical competency
SECTION ONE: QUESTIONS 1–100
Question 1
What is the minimum size for a standard residential kitchen sink drain tailpiece?
A. 1 inch
B. 1 1/4 inches
🟢 C. 1 1/2 inches
D. 2 inches
,🔴 RATIONALE: Standard plumbing codes require a minimum of 1 1/2 inches for kitchen sink tailpieces to ensure
adequate flow and prevent clogging.
Question 2
Which type of backflow prevention device is best suited for a continuous pressure application on a boiler feed line?
A. Atmospheric vacuum breaker
🟢 B. Reduced pressure principle assembly
C. Double check valve assembly
D. Dual check valve
🔴 RATIONALE: Reduced pressure principle assemblies are the only devices approved for high-hazard, continuous
pressure applications like boiler feeds.
Question 3
When installing copper piping, what is the primary purpose of flux?
A. To increase the pipe diameter
B. To act as a lubricant for threading
🟢 C. To remove oxidation and promote solder flow
D. To prevent the pipe from cooling too quickly
🔴 RATIONALE: Flux is a chemical agent that cleans the metal surfaces of oxides during heating, allowing the molten
solder to wet and bond to the pipe.
Question 4
What is the maximum trap arm length for a 2-inch pipe trap?
🟢 A. 5 feet
B. 6 feet
C. 8 feet
D. 10 feet
🔴 RATIONALE: According to standard code tables, the developed length of a trap arm is restricted based on pipe
diameter; for 2 inches, the limit is 5 feet.
,Question 5
Which valve type is best suited for throttling flow in a water distribution system?
A. Ball valve
B. Gate valve
C. Check valve
🟢 D. Globe valve
🔴 RATIONALE: Globe valves are designed to control or throttle flow, whereas ball and gate valves are primarily
meant for full-open or full-closed positions.
Question 6
In a DWV system, what is the primary function of a stack vent?
A. To provide water to the fixture
🟢 B. To allow air circulation and prevent trap siphonage
C. To collect waste from the basement
D. To increase the water pressure
🔴 RATIONALE: The stack vent provides the necessary atmospheric pressure to the drainage system, preventing the
vacuum effect that would siphon trap seals.
Question 7
When measuring for an offset in piping, what is the multiplier for a 45-degree angle?
A. 1.000
B. 1.155
🟢 C. 1.414
D. 1.732
🔴 RATIONALE: The constant for a 45-degree fitting is the cosecant of 45 degrees, which is approximately 1.414.
Question 8
Which gas pipe material is prohibited from being used in direct contact with concrete?
A. Black iron
B. Galvanized steel
🟢 C. Corrugated stainless steel tubing (CSST)
, D. Schedule 40 PVC
🔴 RATIONALE: CSST manufacturers typically prohibit direct burial or contact with corrosive materials like concrete
without proper protective sleeving.
Question 9
What is the standard requirement for the installation of a temperature and pressure relief valve (T&P) on a water
heater?
A. Installed only on the cold water inlet
B. Must be set to 250 degrees Fahrenheit
🟢 C. Must discharge to a safe location
D. Not required for residential tanks under 30 gallons
🔴 RATIONALE: T&P valves are safety devices that must be capable of discharging dangerous steam or hot water to
a safe, visible location away from occupants.
Question 10
If a plumber discovers an illegal cross-connection between potable and non-potable water, what is the professional
responsibility?
🟢 A. Immediately report the condition and initiate corrective action
B. Wait until the next inspection cycle
C. Only fix it if the homeowner requests it
D. Ignore it if it is not part of the original work order
🔴 RATIONALE: Plumbers are ethically and legally bound to report and eliminate health hazards like cross-
connections to protect the public water supply.
Question 11
What is the minimum diameter of a building sewer line?
A. 2 inches
B. 3 inches
🟢 C. 4 inches
D. 6 inches
