Ct Limited Plumbing Journeyperson
(P-4) Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A| Instant
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1. What is the main purpose of a backflow preventer in a plumbing
system?
A) Increase water pressure
B) Filter impurities
C) Prevent reverse flow of contaminated water
D) Reduce water temperature
Rationale: A backflow preventer ensures that water flows in only one
direction, preventing contamination of the potable water supply.
2. What type of pipe is commonly used for high-temperature hot water
supply?
A) PVC
B) Copper
C) PEX
D) Galvanized steel
Rationale: Copper pipes can withstand high temperatures and
pressures, making them ideal for hot water systems.
3. The minimum slope for a horizontal drain pipe is:
A) 1/8 inch per foot
B) 1/2 inch per foot
C) 1 inch per foot
D) 1/4 inch per foot
Rationale: A slope of 1/4 inch per foot ensures proper drainage and
prevents pipe blockages.
,4. Which of the following is the most common method to join PVC pipes?
A) Threading
B) Welding
C) Solvent cementing
D) Compression fitting
Rationale: Solvent cementing chemically bonds PVC pipe and fittings
to create a leak-proof joint.
5. A water hammer is caused by:
A) Low water pressure
B) Sudden closing of valves
C) Corrosion in pipes
D) Air in the system
Rationale: Water hammer occurs when flowing water is suddenly
stopped, causing pressure surges.
6. The primary function of a vent pipe in a drainage system is to:
A) Increase water pressure
B) Allow air to enter the drainage system to prevent siphoning
C) Remove sediment from pipes
D) Heat water in the system
Rationale: Vent pipes maintain atmospheric pressure, preventing trap
siphoning and allowing proper drainage.
7. Which type of valve is typically used to isolate a section of pipe?
A) Check valve
B) Globe valve
C) Gate valve
D) Pressure relief valve
Rationale: Gate valves allow full shut-off or full-flow operation,
suitable for isolating pipe sections.
8. What is the main purpose of a P-trap in plumbing?
A) Increase water flow
B) Reduce water temperature
C) Prevent sewer gases from entering a building
D) Filter water
Rationale: P-traps hold water to form a seal that blocks sewer gases
from escaping into occupied spaces.
9. Which of the following is a common symptom of a clogged aerator?
A) Low water pressure at fixture
, B) Leaking pipes
C) Spraying or uneven flow from faucet
D) Backflow
Rationale: Mineral buildup in an aerator restricts flow and disrupts
the water stream pattern.
10. Which type of fitting allows a change in pipe direction?
A) Coupling
B) Elbow
C) Union
D) Tee
Rationale: Elbows change the direction of piping, typically 45° or 90°
angles.
11. What is the recommended clearance between a water heater and a
combustible wall?
A) 1 inch
B) 2 inches
C) 3 inches
D) 6 inches
Rationale: Building codes require minimum clearance to reduce fire
risk and allow service access.
12. Which material is not recommended for potable water supply?
A) Copper
B) Lead
C) PEX
D) CPVC
Rationale: Lead is toxic and prohibited in potable water systems due
to health risks.
13. When installing a sump pump, it is essential to:
A) Ensure proper drainage away from the foundation
B) Connect it directly to the sewer
C) Use a 1/8 inch slope
D) Only operate during winter
Rationale: Sump pumps remove water from basements and must
discharge it away from the foundation to prevent flooding.
14. What is the primary purpose of a pressure-reducing valve?
A) Increase water flow
B) Reduce incoming water pressure to safe levels
(P-4) Exam Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A| Instant
Download Pdf
1. What is the main purpose of a backflow preventer in a plumbing
system?
A) Increase water pressure
B) Filter impurities
C) Prevent reverse flow of contaminated water
D) Reduce water temperature
Rationale: A backflow preventer ensures that water flows in only one
direction, preventing contamination of the potable water supply.
2. What type of pipe is commonly used for high-temperature hot water
supply?
A) PVC
B) Copper
C) PEX
D) Galvanized steel
Rationale: Copper pipes can withstand high temperatures and
pressures, making them ideal for hot water systems.
3. The minimum slope for a horizontal drain pipe is:
A) 1/8 inch per foot
B) 1/2 inch per foot
C) 1 inch per foot
D) 1/4 inch per foot
Rationale: A slope of 1/4 inch per foot ensures proper drainage and
prevents pipe blockages.
,4. Which of the following is the most common method to join PVC pipes?
A) Threading
B) Welding
C) Solvent cementing
D) Compression fitting
Rationale: Solvent cementing chemically bonds PVC pipe and fittings
to create a leak-proof joint.
5. A water hammer is caused by:
A) Low water pressure
B) Sudden closing of valves
C) Corrosion in pipes
D) Air in the system
Rationale: Water hammer occurs when flowing water is suddenly
stopped, causing pressure surges.
6. The primary function of a vent pipe in a drainage system is to:
A) Increase water pressure
B) Allow air to enter the drainage system to prevent siphoning
C) Remove sediment from pipes
D) Heat water in the system
Rationale: Vent pipes maintain atmospheric pressure, preventing trap
siphoning and allowing proper drainage.
7. Which type of valve is typically used to isolate a section of pipe?
A) Check valve
B) Globe valve
C) Gate valve
D) Pressure relief valve
Rationale: Gate valves allow full shut-off or full-flow operation,
suitable for isolating pipe sections.
8. What is the main purpose of a P-trap in plumbing?
A) Increase water flow
B) Reduce water temperature
C) Prevent sewer gases from entering a building
D) Filter water
Rationale: P-traps hold water to form a seal that blocks sewer gases
from escaping into occupied spaces.
9. Which of the following is a common symptom of a clogged aerator?
A) Low water pressure at fixture
, B) Leaking pipes
C) Spraying or uneven flow from faucet
D) Backflow
Rationale: Mineral buildup in an aerator restricts flow and disrupts
the water stream pattern.
10. Which type of fitting allows a change in pipe direction?
A) Coupling
B) Elbow
C) Union
D) Tee
Rationale: Elbows change the direction of piping, typically 45° or 90°
angles.
11. What is the recommended clearance between a water heater and a
combustible wall?
A) 1 inch
B) 2 inches
C) 3 inches
D) 6 inches
Rationale: Building codes require minimum clearance to reduce fire
risk and allow service access.
12. Which material is not recommended for potable water supply?
A) Copper
B) Lead
C) PEX
D) CPVC
Rationale: Lead is toxic and prohibited in potable water systems due
to health risks.
13. When installing a sump pump, it is essential to:
A) Ensure proper drainage away from the foundation
B) Connect it directly to the sewer
C) Use a 1/8 inch slope
D) Only operate during winter
Rationale: Sump pumps remove water from basements and must
discharge it away from the foundation to prevent flooding.
14. What is the primary purpose of a pressure-reducing valve?
A) Increase water flow
B) Reduce incoming water pressure to safe levels
