Wisconsin Journeyman Plumber
Examination Questions and Correct
Answers (Verified Answers) Plus Rationale
2027 Q&A| Instant Download Pdf
1. What is the primary purpose of a plumbing drainage system?
A. To supply potable water
B. To increase water pressure
C. To safely convey wastewater away from a building
D. To provide hot water to fixtures
Answer: C. To safely convey wastewater away from a building
Rationale: The drainage system is designed to collect wastewater from
fixtures and convey it safely to the building sewer or an approved
disposal system. Proper drainage also helps prevent contamination,
odors, and unsanitary conditions.
, 2. Which component prevents sewer gases from entering a building
through a plumbing fixture?
A. Water meter
B. Trap
C. Pressure-reducing valve
D. Check valve
Answer: B. Trap
Rationale: A plumbing trap retains a specific amount of water after the
fixture is used. This water seal acts as a barrier against sewer gases
entering occupied areas of the building.
3. What is the most common type of trap used beneath modern
plumbing fixtures?
A. Bell trap
B. Drum trap
C. P-trap
D. Running trap
Answer: C. P-trap
,Rationale: The P-trap is widely used because its configuration provides a
reliable water seal while allowing access for cleaning and maintenance.
It is commonly installed beneath sinks, lavatories, and similar fixtures.
4. What is the purpose of a plumbing vent system?
A. To increase fixture water pressure
B. To introduce air into the drainage system and protect trap seals
C. To heat drainage piping
D. To remove sediment from water lines
Answer: B. To introduce air into the drainage system and protect trap
seals
Rationale: Vent piping allows air movement within the drainage system.
This helps maintain atmospheric pressure, prevents excessive pressure
fluctuations, and protects fixture trap seals from siphonage and
backpressure.
5. What condition occurs when wastewater flowing through a
drainage pipe creates negative pressure that can pull water from
a trap?
, A. Backpressure
B. Siphonage
C. Water hammer
D. Thermal expansion
Answer: B. Siphonage
Rationale: Siphonage occurs when flowing wastewater creates negative
pressure in the drainage system. Without proper venting, this pressure
can draw water out of a fixture trap and eliminate its protective water
seal.
6. Which condition can force wastewater or sewer gases toward a
fixture because of positive pressure in the drainage system?
A. Backpressure
B. Siphonage
C. Cavitation
D. Thermal contraction
Answer: A. Backpressure
Rationale: Backpressure is a positive pressure condition that can force
air or wastewater in an undesirable direction. Properly designed and
Examination Questions and Correct
Answers (Verified Answers) Plus Rationale
2027 Q&A| Instant Download Pdf
1. What is the primary purpose of a plumbing drainage system?
A. To supply potable water
B. To increase water pressure
C. To safely convey wastewater away from a building
D. To provide hot water to fixtures
Answer: C. To safely convey wastewater away from a building
Rationale: The drainage system is designed to collect wastewater from
fixtures and convey it safely to the building sewer or an approved
disposal system. Proper drainage also helps prevent contamination,
odors, and unsanitary conditions.
, 2. Which component prevents sewer gases from entering a building
through a plumbing fixture?
A. Water meter
B. Trap
C. Pressure-reducing valve
D. Check valve
Answer: B. Trap
Rationale: A plumbing trap retains a specific amount of water after the
fixture is used. This water seal acts as a barrier against sewer gases
entering occupied areas of the building.
3. What is the most common type of trap used beneath modern
plumbing fixtures?
A. Bell trap
B. Drum trap
C. P-trap
D. Running trap
Answer: C. P-trap
,Rationale: The P-trap is widely used because its configuration provides a
reliable water seal while allowing access for cleaning and maintenance.
It is commonly installed beneath sinks, lavatories, and similar fixtures.
4. What is the purpose of a plumbing vent system?
A. To increase fixture water pressure
B. To introduce air into the drainage system and protect trap seals
C. To heat drainage piping
D. To remove sediment from water lines
Answer: B. To introduce air into the drainage system and protect trap
seals
Rationale: Vent piping allows air movement within the drainage system.
This helps maintain atmospheric pressure, prevents excessive pressure
fluctuations, and protects fixture trap seals from siphonage and
backpressure.
5. What condition occurs when wastewater flowing through a
drainage pipe creates negative pressure that can pull water from
a trap?
, A. Backpressure
B. Siphonage
C. Water hammer
D. Thermal expansion
Answer: B. Siphonage
Rationale: Siphonage occurs when flowing wastewater creates negative
pressure in the drainage system. Without proper venting, this pressure
can draw water out of a fixture trap and eliminate its protective water
seal.
6. Which condition can force wastewater or sewer gases toward a
fixture because of positive pressure in the drainage system?
A. Backpressure
B. Siphonage
C. Cavitation
D. Thermal contraction
Answer: A. Backpressure
Rationale: Backpressure is a positive pressure condition that can force
air or wastewater in an undesirable direction. Properly designed and
