Colorado Plumbing Journeyman Exam
Practice Questions With Correct
Answers (Verified Answers) Plus
Rationales 2026 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 sewer gases from entering a building
C. To improve drainage speed
D. To filter debris from water lines
Answer: B. To prevent sewer gases from entering a building
Rationale: A plumbing trap retains a small amount of water that forms
a seal, preventing dangerous and unpleasant sewer gases from entering
occupied spaces. Traps are required fixtures in drainage systems and are
essential for sanitation and safety.
2. Which type of pipe is most commonly used for residential DWV
systems?
A. Galvanized steel
B. Copper Type K
,C. PVC
D. Black iron
Answer: C. PVC
Rationale: PVC (Polyvinyl Chloride) pipe is widely used in residential
drain, waste, and vent (DWV) systems because it is corrosion-resistant,
lightweight, affordable, and easy to install.
3. What is the minimum slope generally required for a 3-inch
horizontal drainage pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: A. 1/8 inch per foot
Rationale: Plumbing codes commonly require a minimum slope of 1/8
inch per foot for horizontal drainage piping 3 inches or larger to ensure
proper flow while minimizing solids buildup.
4. Which fitting is designed to change the direction of flow in a
drainage system by 45 degrees?
A. Tee
B. Wye
C. 45-degree elbow
D. Coupling
,Answer: C. 45-degree elbow
Rationale: A 45-degree elbow changes pipe direction gradually,
reducing turbulence and improving drainage efficiency in plumbing
systems.
5. What is the purpose of a vent stack?
A. To increase water flow
B. To carry waste to the sewer
C. To equalize air pressure in the drainage system
D. To store wastewater temporarily
Answer: C. To equalize air pressure in the drainage system
Rationale: Vent stacks provide airflow within the plumbing system,
preventing siphonage of traps and ensuring smooth drainage by
balancing pressure.
6. Which plumbing fixture requires the largest minimum trap size in
most residential systems?
A. Lavatory sink
B. Floor drain
C. Water closet
D. Kitchen sink
Answer: C. Water closet
, Rationale: Water closets typically require a larger trap size due to the
volume and nature of waste discharged. Proper trap sizing prevents
clogging and maintains system efficiency.
7. What is the standard test pressure for many residential DWV water
tests?
A. 1 psi
B. 5 psi
C. 10 psi
D. 20 psi
Answer: B. 5 psi
Rationale: Plumbing inspectors often require a 5 psi air test or
equivalent water test to verify the integrity of DWV systems before
approval.
8. What tool is commonly used to cut cast-iron pipe?
A. Pipe wrench
B. Tubing cutter
C. Snap cutter
D. Reamer
Answer: C. Snap cutter
Rationale: A snap cutter uses chain pressure to score and break cast-iron
pipe cleanly and efficiently.
Practice Questions With Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To improve drainage speed
D. To filter debris from water lines
Answer: B. To prevent sewer gases from entering a building
Rationale: A plumbing trap retains a small amount of water that forms
a seal, preventing dangerous and unpleasant sewer gases from entering
occupied spaces. Traps are required fixtures in drainage systems and are
essential for sanitation and safety.
2. Which type of pipe is most commonly used for residential DWV
systems?
A. Galvanized steel
B. Copper Type K
,C. PVC
D. Black iron
Answer: C. PVC
Rationale: PVC (Polyvinyl Chloride) pipe is widely used in residential
drain, waste, and vent (DWV) systems because it is corrosion-resistant,
lightweight, affordable, and easy to install.
3. What is the minimum slope generally required for a 3-inch
horizontal drainage pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
Answer: A. 1/8 inch per foot
Rationale: Plumbing codes commonly require a minimum slope of 1/8
inch per foot for horizontal drainage piping 3 inches or larger to ensure
proper flow while minimizing solids buildup.
4. Which fitting is designed to change the direction of flow in a
drainage system by 45 degrees?
A. Tee
B. Wye
C. 45-degree elbow
D. Coupling
,Answer: C. 45-degree elbow
Rationale: A 45-degree elbow changes pipe direction gradually,
reducing turbulence and improving drainage efficiency in plumbing
systems.
5. What is the purpose of a vent stack?
A. To increase water flow
B. To carry waste to the sewer
C. To equalize air pressure in the drainage system
D. To store wastewater temporarily
Answer: C. To equalize air pressure in the drainage system
Rationale: Vent stacks provide airflow within the plumbing system,
preventing siphonage of traps and ensuring smooth drainage by
balancing pressure.
6. Which plumbing fixture requires the largest minimum trap size in
most residential systems?
A. Lavatory sink
B. Floor drain
C. Water closet
D. Kitchen sink
Answer: C. Water closet
, Rationale: Water closets typically require a larger trap size due to the
volume and nature of waste discharged. Proper trap sizing prevents
clogging and maintains system efficiency.
7. What is the standard test pressure for many residential DWV water
tests?
A. 1 psi
B. 5 psi
C. 10 psi
D. 20 psi
Answer: B. 5 psi
Rationale: Plumbing inspectors often require a 5 psi air test or
equivalent water test to verify the integrity of DWV systems before
approval.
8. What tool is commonly used to cut cast-iron pipe?
A. Pipe wrench
B. Tubing cutter
C. Snap cutter
D. Reamer
Answer: C. Snap cutter
Rationale: A snap cutter uses chain pressure to score and break cast-iron
pipe cleanly and efficiently.
