AL PL PLUMBING CONTRACTOR EXAM QUESTIONS
AND CORRECT ANSWERS (VERIFIED ANSWERS)
Q&A 2027 |INSTANT DOWNLOAD PDF
1. What is the primary purpose of a plumbing drainage
system?
A. Supply hot water
B. Remove wastewater safely
C. Increase water pressure
D. Heat a building
Answer: B. Remove wastewater safely
Rationale: The drainage system collects and conveys
wastewater and sewage away from fixtures and the building to
an approved disposal or treatment system.
2. Which fitting is commonly used to change the direction of a
pipe run?
A. Coupling
B. Elbow
C. Union
D. Cap
Answer: B. Elbow
,Rationale: Elbows change the direction of piping, commonly by
45° or 90°.
3. What is the main purpose of a plumbing vent system?
A. Increase water temperature
B. Provide drainage pressure
C. Protect trap seals and allow proper drainage
D. Store wastewater
Answer: C. Protect trap seals and allow proper drainage
Rationale: Venting allows air movement through the drainage
system and helps prevent siphonage or pressure conditions
that could destroy trap seals.
4. Which device prevents contaminated water from flowing
backward into the potable water supply?
A. Pressure gauge
B. Backflow preventer
C. Water heater
D. Cleanout
Answer: B. Backflow preventer
Rationale: Backflow-prevention devices protect potable water
from contamination caused by backsiphonage or backpressure.
,5. What is the purpose of a P-trap?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Filter drinking water
D. Increase drainage flow
Answer: B. Prevent sewer gases from entering the building
Rationale: The trap retains a water seal that blocks gases from
the drainage system.
6. Which pipe material is commonly used for potable water
distribution?
A. Copper
B. Cast iron sewer pipe only
C. Concrete
D. Clay tile
Answer: A. Copper
Rationale: Copper is an established material for potable water
distribution when properly installed and approved.
7. What does DWV stand for?
A. Drain, Water, Valve
B. Drain-Waste-Vent
, C. Domestic Water Volume
D. Drainage Water Vacuum
Answer: B. Drain-Waste-Vent
Rationale: DWV systems handle drainage, waste removal, and
venting.
8. What is the purpose of a cleanout?
A. Increase water pressure
B. Provide access for cleaning drainage piping
C. Control water temperature
D. Prevent freezing
Answer: B. Provide access for cleaning drainage piping
Rationale: Cleanouts provide access to drainage piping for
maintenance and removal of blockages.
9. Which fitting is normally used to join two pipes of the same
size in a straight line?
A. Coupling
B. Elbow
C. Tee
D. Wye
Answer: A. Coupling
AND CORRECT ANSWERS (VERIFIED ANSWERS)
Q&A 2027 |INSTANT DOWNLOAD PDF
1. What is the primary purpose of a plumbing drainage
system?
A. Supply hot water
B. Remove wastewater safely
C. Increase water pressure
D. Heat a building
Answer: B. Remove wastewater safely
Rationale: The drainage system collects and conveys
wastewater and sewage away from fixtures and the building to
an approved disposal or treatment system.
2. Which fitting is commonly used to change the direction of a
pipe run?
A. Coupling
B. Elbow
C. Union
D. Cap
Answer: B. Elbow
,Rationale: Elbows change the direction of piping, commonly by
45° or 90°.
3. What is the main purpose of a plumbing vent system?
A. Increase water temperature
B. Provide drainage pressure
C. Protect trap seals and allow proper drainage
D. Store wastewater
Answer: C. Protect trap seals and allow proper drainage
Rationale: Venting allows air movement through the drainage
system and helps prevent siphonage or pressure conditions
that could destroy trap seals.
4. Which device prevents contaminated water from flowing
backward into the potable water supply?
A. Pressure gauge
B. Backflow preventer
C. Water heater
D. Cleanout
Answer: B. Backflow preventer
Rationale: Backflow-prevention devices protect potable water
from contamination caused by backsiphonage or backpressure.
,5. What is the purpose of a P-trap?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Filter drinking water
D. Increase drainage flow
Answer: B. Prevent sewer gases from entering the building
Rationale: The trap retains a water seal that blocks gases from
the drainage system.
6. Which pipe material is commonly used for potable water
distribution?
A. Copper
B. Cast iron sewer pipe only
C. Concrete
D. Clay tile
Answer: A. Copper
Rationale: Copper is an established material for potable water
distribution when properly installed and approved.
7. What does DWV stand for?
A. Drain, Water, Valve
B. Drain-Waste-Vent
, C. Domestic Water Volume
D. Drainage Water Vacuum
Answer: B. Drain-Waste-Vent
Rationale: DWV systems handle drainage, waste removal, and
venting.
8. What is the purpose of a cleanout?
A. Increase water pressure
B. Provide access for cleaning drainage piping
C. Control water temperature
D. Prevent freezing
Answer: B. Provide access for cleaning drainage piping
Rationale: Cleanouts provide access to drainage piping for
maintenance and removal of blockages.
9. Which fitting is normally used to join two pipes of the same
size in a straight line?
A. Coupling
B. Elbow
C. Tee
D. Wye
Answer: A. Coupling
