___________________________________________________________________
Colorado Plumbing Apprentice
Registration/Qualification Practice
Exam 2026 | 100 Questions & Answers
with Detailed Rationales | Complete
Exam Prep & Study Guide
1. What is the primary purpose of plumbing codes?
A. To establish plumbing material prices
B. To regulate plumbing contractors' advertising
C. To protect public health, safety, and welfare
D. To determine employee wages
Answer: To protect public health, safety, and welfare
Rationale: Plumbing codes establish minimum requirements for safe plumbing
systems, including sanitation, water supply, drainage, and protection against
hazards.
2. What is the main function of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Increase drainage velocity
D. Filter drinking water
Answer: Prevent sewer gases from entering a building
,Rationale: A trap retains a water seal that prevents gases and odors from the
drainage system from entering occupied spaces.
3. Which type of pipe is commonly used for cold-water distribution?
A. Cast iron
B. PVC or approved PEX
C. Clay tile
D. Concrete pipe
Answer: PVC or approved PEX
Rationale: Approved plastic piping such as PVC and PEX is commonly used for
water distribution when permitted by the applicable plumbing code.
4. What does DWV stand for?
A. Drain, Water, Valve
B. Domestic Water Valve
C. Drain, Waste, and Vent
D. Drinking Water Vent
Answer: Drain, Waste, and Vent
Rationale: DWV systems carry wastewater away from fixtures and provide
venting to protect trap seals and maintain proper drainage.
5. What is the purpose of a plumbing vent?
A. To increase water pressure
B. To provide air circulation and protect trap seals
C. To store wastewater
D. To heat water
Answer: To provide air circulation and protect trap seals
Rationale: Venting allows air into the drainage system, helps prevent siphonage
and pressure problems, and protects fixture trap seals.
, 6. What is a water closet?
A. Bathtub
B. Kitchen sink
C. Toilet
D. Water heater
Answer: Toilet
Rationale: A water closet is the plumbing-code term commonly used for a fixture
designed to receive human waste and discharge it through a flush mechanism.
7. What is the purpose of a cleanout?
A. To increase water temperature
B. To provide access for cleaning a drainage pipe
C. To prevent freezing
D. To measure water pressure
Answer: To provide access for cleaning a drainage pipe
Rationale: Cleanouts provide access to drainage piping so blockages can be
removed and the piping can be maintained.
8. Which fitting is commonly used to change the direction of a pipe?
A. Coupling
B. Elbow
C. Union
D. Bushing
Answer: Elbow
Rationale: Elbows are manufactured in various angles and are used to change
the direction of piping.
9. What is the purpose of a coupling?
, A. To connect two sections of pipe
B. To reduce water pressure
C. To vent a trap
D. To prevent backflow
Answer: To connect two sections of pipe
Rationale: A coupling joins two sections of pipe, generally in a straight line.
10.What is a union used for?
A. Permanently joining two pipes
B. Providing a removable connection between piping sections
C. Increasing drainage slope
D. Creating a trap seal
Answer: Providing a removable connection between piping sections
Rationale: A union allows piping to be disconnected without rotating or cutting
the entire piping assembly.
11.What is backflow?
A. Normal flow through a drain
B. Reversal of water flow
C. Increased water pressure
D. Water evaporation
Answer: Reversal of water flow
Rationale: Backflow occurs when water or another substance moves in the
opposite direction from its intended flow.
12.What device is commonly used to prevent backflow from a hose
connection?
A. Hose bibb vacuum breaker
B. Pressure gauge
Colorado Plumbing Apprentice
Registration/Qualification Practice
Exam 2026 | 100 Questions & Answers
with Detailed Rationales | Complete
Exam Prep & Study Guide
1. What is the primary purpose of plumbing codes?
A. To establish plumbing material prices
B. To regulate plumbing contractors' advertising
C. To protect public health, safety, and welfare
D. To determine employee wages
Answer: To protect public health, safety, and welfare
Rationale: Plumbing codes establish minimum requirements for safe plumbing
systems, including sanitation, water supply, drainage, and protection against
hazards.
2. What is the main function of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Increase drainage velocity
D. Filter drinking water
Answer: Prevent sewer gases from entering a building
,Rationale: A trap retains a water seal that prevents gases and odors from the
drainage system from entering occupied spaces.
3. Which type of pipe is commonly used for cold-water distribution?
A. Cast iron
B. PVC or approved PEX
C. Clay tile
D. Concrete pipe
Answer: PVC or approved PEX
Rationale: Approved plastic piping such as PVC and PEX is commonly used for
water distribution when permitted by the applicable plumbing code.
4. What does DWV stand for?
A. Drain, Water, Valve
B. Domestic Water Valve
C. Drain, Waste, and Vent
D. Drinking Water Vent
Answer: Drain, Waste, and Vent
Rationale: DWV systems carry wastewater away from fixtures and provide
venting to protect trap seals and maintain proper drainage.
5. What is the purpose of a plumbing vent?
A. To increase water pressure
B. To provide air circulation and protect trap seals
C. To store wastewater
D. To heat water
Answer: To provide air circulation and protect trap seals
Rationale: Venting allows air into the drainage system, helps prevent siphonage
and pressure problems, and protects fixture trap seals.
, 6. What is a water closet?
A. Bathtub
B. Kitchen sink
C. Toilet
D. Water heater
Answer: Toilet
Rationale: A water closet is the plumbing-code term commonly used for a fixture
designed to receive human waste and discharge it through a flush mechanism.
7. What is the purpose of a cleanout?
A. To increase water temperature
B. To provide access for cleaning a drainage pipe
C. To prevent freezing
D. To measure water pressure
Answer: To provide access for cleaning a drainage pipe
Rationale: Cleanouts provide access to drainage piping so blockages can be
removed and the piping can be maintained.
8. Which fitting is commonly used to change the direction of a pipe?
A. Coupling
B. Elbow
C. Union
D. Bushing
Answer: Elbow
Rationale: Elbows are manufactured in various angles and are used to change
the direction of piping.
9. What is the purpose of a coupling?
, A. To connect two sections of pipe
B. To reduce water pressure
C. To vent a trap
D. To prevent backflow
Answer: To connect two sections of pipe
Rationale: A coupling joins two sections of pipe, generally in a straight line.
10.What is a union used for?
A. Permanently joining two pipes
B. Providing a removable connection between piping sections
C. Increasing drainage slope
D. Creating a trap seal
Answer: Providing a removable connection between piping sections
Rationale: A union allows piping to be disconnected without rotating or cutting
the entire piping assembly.
11.What is backflow?
A. Normal flow through a drain
B. Reversal of water flow
C. Increased water pressure
D. Water evaporation
Answer: Reversal of water flow
Rationale: Backflow occurs when water or another substance moves in the
opposite direction from its intended flow.
12.What device is commonly used to prevent backflow from a hose
connection?
A. Hose bibb vacuum breaker
B. Pressure gauge
