Wisconsin Journeyman Plumber Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Remove sediment
C. Prevent sewer gases from entering the building
D. Reduce water temperature
Answer: C
Rationale: Plumbing traps maintain a water seal that blocks sewer gases
from entering occupied spaces while allowing wastewater to flow freely.
2. Which venting method allows one vent to serve multiple fixtures on
the same floor?
,A. Island vent
B. Circuit vent
C. Common vent
D. Relief vent
Answer: C
Rationale: A common vent serves two fixtures connected at the same level
and helps protect trap seals from siphonage.
3. A cleanout is primarily installed to:
A. Increase flow velocity
B. Prevent freezing
C. Provide access for cleaning and inspection
D. Improve water pressure
Answer: C
Rationale: Cleanouts provide access points for removing blockages and
inspecting drainage piping.
4. Which pipe material is commonly used for residential drain, waste,
and vent systems?
A. Black steel
B. PVC
,C. Galvanized steel
D. Brass
Answer: B
Rationale: PVC is corrosion-resistant, lightweight, and commonly approved
for DWV installations where permitted.
5. What is the minimum purpose of vent piping?
A. Increase drainage speed
B. Filter wastewater
C. Equalize air pressure in the drainage system
D. Cool wastewater
Answer: C
Rationale: Vent piping maintains atmospheric pressure, protecting trap
seals and ensuring proper drainage.
6. Which fitting is typically used to change the direction of a drainage
pipe by 90 degrees?
A. Tee
B. Long sweep elbow
C. Coupling
D. Cap
, Answer: B
Rationale: Long sweep elbows reduce flow resistance and are preferred in
drainage systems.
7. Backflow prevention devices are installed to:
A. Increase water temperature
B. Prevent contaminated water from entering the potable water supply
C. Improve drainage
D. Reduce water pressure
Answer: B
Rationale: Backflow preventers protect drinking water from contamination
caused by backpressure or backsiphonage.
8. Water hammer is caused by:
A. Low water temperature
B. Excessive drainage slope
C. Sudden stopping of flowing water
D. Sewer gas buildup
Answer: C
Rationale: Rapid valve closure creates pressure surges that produce water
hammer.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Remove sediment
C. Prevent sewer gases from entering the building
D. Reduce water temperature
Answer: C
Rationale: Plumbing traps maintain a water seal that blocks sewer gases
from entering occupied spaces while allowing wastewater to flow freely.
2. Which venting method allows one vent to serve multiple fixtures on
the same floor?
,A. Island vent
B. Circuit vent
C. Common vent
D. Relief vent
Answer: C
Rationale: A common vent serves two fixtures connected at the same level
and helps protect trap seals from siphonage.
3. A cleanout is primarily installed to:
A. Increase flow velocity
B. Prevent freezing
C. Provide access for cleaning and inspection
D. Improve water pressure
Answer: C
Rationale: Cleanouts provide access points for removing blockages and
inspecting drainage piping.
4. Which pipe material is commonly used for residential drain, waste,
and vent systems?
A. Black steel
B. PVC
,C. Galvanized steel
D. Brass
Answer: B
Rationale: PVC is corrosion-resistant, lightweight, and commonly approved
for DWV installations where permitted.
5. What is the minimum purpose of vent piping?
A. Increase drainage speed
B. Filter wastewater
C. Equalize air pressure in the drainage system
D. Cool wastewater
Answer: C
Rationale: Vent piping maintains atmospheric pressure, protecting trap
seals and ensuring proper drainage.
6. Which fitting is typically used to change the direction of a drainage
pipe by 90 degrees?
A. Tee
B. Long sweep elbow
C. Coupling
D. Cap
, Answer: B
Rationale: Long sweep elbows reduce flow resistance and are preferred in
drainage systems.
7. Backflow prevention devices are installed to:
A. Increase water temperature
B. Prevent contaminated water from entering the potable water supply
C. Improve drainage
D. Reduce water pressure
Answer: B
Rationale: Backflow preventers protect drinking water from contamination
caused by backpressure or backsiphonage.
8. Water hammer is caused by:
A. Low water temperature
B. Excessive drainage slope
C. Sudden stopping of flowing water
D. Sewer gas buildup
Answer: C
Rationale: Rapid valve closure creates pressure surges that produce water
hammer.
