IDPH – Plumber’s License Examination (Master
Plumber) Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
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1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent freezing of the drainage system
C. To prevent sewer gases from entering a building
D. To increase drainage velocity
Answer: C. To prevent sewer gases from entering a building
Rationale: A plumbing trap retains a water seal that separates the
building drainage system from occupied spaces. This water seal helps
prevent sewer gases and odors from entering the building through
plumbing fixtures.
2. Which fitting is generally used to change the direction of a
drainage pipe by 90 degrees while maintaining proper drainage
flow?
,A. Sanitary tee
B. Long-sweep elbow
C. Straight coupling
D. Reducing bushing
Answer: B. Long-sweep elbow
Rationale: A long-sweep elbow provides a gradual change in direction
and reduces turbulence and resistance to flow. Drainage systems
generally require fittings designed to promote smooth, self-scouring
flow.
3. What is the principal function of a cleanout in a drainage system?
A. To regulate water pressure
B. To provide access for cleaning and removing obstructions
C. To prevent backflow
D. To increase vent capacity
Answer: B. To provide access for cleaning and removing obstructions
Rationale: Cleanouts provide accessible openings into drainage piping
so that blockages can be located and cleared. Proper placement and
accessibility are important for maintaining the drainage system.
, 4. Which plumbing system carries wastewater from plumbing
fixtures to the building sewer?
A. Water distribution system
B. Stormwater system
C. Sanitary drainage system
D. Fuel-gas system
Answer: C. Sanitary drainage system
Rationale: The sanitary drainage system conveys wastewater from
fixtures such as sinks, lavatories, showers, and water closets to the
building sewer. Stormwater systems are designed for rainwater and
other surface drainage.
5. What is the primary purpose of a plumbing vent system?
A. To supply potable water
B. To maintain proper trap seals and allow drainage systems to operate
properly
C. To increase water temperature
D. To reduce water pressure
Answer: B. To maintain proper trap seals and allow drainage systems
to operate properly
, Rationale: Venting allows air movement within the drainage system
and helps prevent pressure fluctuations that could siphon or blow trap
seals. Proper venting is essential for sanitary and effective drainage.
6. A water closet is typically classified as which type of plumbing
fixture?
A. Indirect fixture
B. Flush fixture
C. Pressure-reducing fixture
D. Atmospheric fixture
Answer: B. Flush fixture
Rationale: A water closet normally uses a flush valve or flush tank to
discharge water and waste into the drainage system. The fixture's
discharge is substantially greater than that of many other plumbing
fixtures.
7. What is the purpose of a water service pipe?
A. To carry sewage from the building
B. To carry potable water from the water supply source to the building
Plumber) Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent freezing of the drainage system
C. To prevent sewer gases from entering a building
D. To increase drainage velocity
Answer: C. To prevent sewer gases from entering a building
Rationale: A plumbing trap retains a water seal that separates the
building drainage system from occupied spaces. This water seal helps
prevent sewer gases and odors from entering the building through
plumbing fixtures.
2. Which fitting is generally used to change the direction of a
drainage pipe by 90 degrees while maintaining proper drainage
flow?
,A. Sanitary tee
B. Long-sweep elbow
C. Straight coupling
D. Reducing bushing
Answer: B. Long-sweep elbow
Rationale: A long-sweep elbow provides a gradual change in direction
and reduces turbulence and resistance to flow. Drainage systems
generally require fittings designed to promote smooth, self-scouring
flow.
3. What is the principal function of a cleanout in a drainage system?
A. To regulate water pressure
B. To provide access for cleaning and removing obstructions
C. To prevent backflow
D. To increase vent capacity
Answer: B. To provide access for cleaning and removing obstructions
Rationale: Cleanouts provide accessible openings into drainage piping
so that blockages can be located and cleared. Proper placement and
accessibility are important for maintaining the drainage system.
, 4. Which plumbing system carries wastewater from plumbing
fixtures to the building sewer?
A. Water distribution system
B. Stormwater system
C. Sanitary drainage system
D. Fuel-gas system
Answer: C. Sanitary drainage system
Rationale: The sanitary drainage system conveys wastewater from
fixtures such as sinks, lavatories, showers, and water closets to the
building sewer. Stormwater systems are designed for rainwater and
other surface drainage.
5. What is the primary purpose of a plumbing vent system?
A. To supply potable water
B. To maintain proper trap seals and allow drainage systems to operate
properly
C. To increase water temperature
D. To reduce water pressure
Answer: B. To maintain proper trap seals and allow drainage systems
to operate properly
, Rationale: Venting allows air movement within the drainage system
and helps prevent pressure fluctuations that could siphon or blow trap
seals. Proper venting is essential for sanitary and effective drainage.
6. A water closet is typically classified as which type of plumbing
fixture?
A. Indirect fixture
B. Flush fixture
C. Pressure-reducing fixture
D. Atmospheric fixture
Answer: B. Flush fixture
Rationale: A water closet normally uses a flush valve or flush tank to
discharge water and waste into the drainage system. The fixture's
discharge is substantially greater than that of many other plumbing
fixtures.
7. What is the purpose of a water service pipe?
A. To carry sewage from the building
B. To carry potable water from the water supply source to the building
