Colorado Master Plumber License
Examination Practice Exam 2026 | 100
Questions & Answers with Detailed
Rationales | Complete Colorado Master
Plumber Exam Prep & Study Guide
1. What is the primary purpose of a plumbing code?
A. To establish material prices
B. To regulate plumbing contractors' advertising
C. To protect public health, safety, and welfare
D. To determine plumber wages
Answer: To protect public health, safety, and welfare
Rationale: Plumbing codes establish minimum requirements intended to protect
occupants, the public water supply, buildings, and property from unsafe
plumbing conditions.
2. Which plumbing system carries potable water to fixtures?
A. Sanitary drainage system
B. Storm drainage system
C. Water distribution system
D. Vent system
,Answer: Water distribution system
Rationale: The water distribution system conveys potable water from the water
service or source to plumbing fixtures and other points of use.
3. What is the function of a trap under a plumbing fixture?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Increase drainage flow
D. Supply air to the water system
Answer: Prevent sewer gases from entering the building
Rationale: A properly installed trap maintains a water seal that prevents gases
and odors from the drainage system from entering occupied spaces.
4. What is the purpose of a plumbing vent?
A. To increase water temperature
B. To provide air circulation and protect trap seals
C. To filter drinking water
D. To increase pipe pressure
Answer: To provide air circulation and protect trap seals
Rationale: Venting allows air into the drainage system, helps maintain
atmospheric pressure, and reduces the likelihood that drainage flow will siphon
or blow trap seals.
5. Which fitting is commonly used to change the direction of a drainage pipe?
A. Coupling
B. Elbow
C. Union
D. Bushing
Answer: Elbow
,Rationale: Elbows change the direction of piping. In drainage systems, fittings
must be selected and installed to maintain proper flow and cleaning
characteristics.
6. What is the primary purpose of a cleanout?
A. To increase water pressure
B. To provide access for cleaning and servicing drainage piping
C. To supply air to a fixture
D. To reduce water temperature
Answer: To provide access for cleaning and servicing drainage piping
Rationale: Cleanouts provide access to drainage piping so blockages can be
removed and the system can be inspected or maintained.
7. Which type of valve is commonly used to shut off water to a fixture?
A. Fixture shutoff valve
B. Check valve
C. Pressure-relief valve
D. Vacuum breaker
Answer: Fixture shutoff valve
Rationale: A fixture shutoff valve allows the water supply to an individual
fixture to be isolated without shutting down the entire building water system.
8. What does a backflow preventer protect against?
A. Excessive drainage slope
B. Contamination of the potable water supply
C. Low sewer capacity
D. Excessive hot-water temperature only
Answer: Contamination of the potable water supply
, Rationale: Backflow prevention devices protect potable water from
contamination caused by backpressure or backsiphonage.
9. What is backsiphonage?
A. Backflow caused by increased downstream pressure
B. Backflow caused by negative pressure in the supply system
C. Drainage flowing uphill
D. Water leaking through a trap
Answer: Backflow caused by negative pressure in the supply system
Rationale: Backsiphonage occurs when a pressure reduction in the potable
water system can draw contaminated water backward into the supply.
10.What is backpressure?
A. Pressure below atmospheric pressure
B. Pressure downstream that exceeds the supply pressure
C. Pressure caused by a clogged vent only
D. Pressure caused by a water heater
Answer: Pressure downstream that exceeds the supply pressure
Rationale: Backpressure can force nonpotable water or other contaminants
backward into a potable water system when downstream pressure becomes
greater than supply pressure.
11.Which device is specifically designed to prevent a hose submerged in a
contaminant from creating a backsiphonage condition?
A. Hose connection vacuum breaker
B. Water hammer arrestor
C. Pressure regulator
D. Temperature gauge
Answer: Hose connection vacuum breaker
Examination Practice Exam 2026 | 100
Questions & Answers with Detailed
Rationales | Complete Colorado Master
Plumber Exam Prep & Study Guide
1. What is the primary purpose of a plumbing code?
A. To establish material prices
B. To regulate plumbing contractors' advertising
C. To protect public health, safety, and welfare
D. To determine plumber wages
Answer: To protect public health, safety, and welfare
Rationale: Plumbing codes establish minimum requirements intended to protect
occupants, the public water supply, buildings, and property from unsafe
plumbing conditions.
2. Which plumbing system carries potable water to fixtures?
A. Sanitary drainage system
B. Storm drainage system
C. Water distribution system
D. Vent system
,Answer: Water distribution system
Rationale: The water distribution system conveys potable water from the water
service or source to plumbing fixtures and other points of use.
3. What is the function of a trap under a plumbing fixture?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Increase drainage flow
D. Supply air to the water system
Answer: Prevent sewer gases from entering the building
Rationale: A properly installed trap maintains a water seal that prevents gases
and odors from the drainage system from entering occupied spaces.
4. What is the purpose of a plumbing vent?
A. To increase water temperature
B. To provide air circulation and protect trap seals
C. To filter drinking water
D. To increase pipe pressure
Answer: To provide air circulation and protect trap seals
Rationale: Venting allows air into the drainage system, helps maintain
atmospheric pressure, and reduces the likelihood that drainage flow will siphon
or blow trap seals.
5. Which fitting is commonly used to change the direction of a drainage pipe?
A. Coupling
B. Elbow
C. Union
D. Bushing
Answer: Elbow
,Rationale: Elbows change the direction of piping. In drainage systems, fittings
must be selected and installed to maintain proper flow and cleaning
characteristics.
6. What is the primary purpose of a cleanout?
A. To increase water pressure
B. To provide access for cleaning and servicing drainage piping
C. To supply air to a fixture
D. To reduce water temperature
Answer: To provide access for cleaning and servicing drainage piping
Rationale: Cleanouts provide access to drainage piping so blockages can be
removed and the system can be inspected or maintained.
7. Which type of valve is commonly used to shut off water to a fixture?
A. Fixture shutoff valve
B. Check valve
C. Pressure-relief valve
D. Vacuum breaker
Answer: Fixture shutoff valve
Rationale: A fixture shutoff valve allows the water supply to an individual
fixture to be isolated without shutting down the entire building water system.
8. What does a backflow preventer protect against?
A. Excessive drainage slope
B. Contamination of the potable water supply
C. Low sewer capacity
D. Excessive hot-water temperature only
Answer: Contamination of the potable water supply
, Rationale: Backflow prevention devices protect potable water from
contamination caused by backpressure or backsiphonage.
9. What is backsiphonage?
A. Backflow caused by increased downstream pressure
B. Backflow caused by negative pressure in the supply system
C. Drainage flowing uphill
D. Water leaking through a trap
Answer: Backflow caused by negative pressure in the supply system
Rationale: Backsiphonage occurs when a pressure reduction in the potable
water system can draw contaminated water backward into the supply.
10.What is backpressure?
A. Pressure below atmospheric pressure
B. Pressure downstream that exceeds the supply pressure
C. Pressure caused by a clogged vent only
D. Pressure caused by a water heater
Answer: Pressure downstream that exceeds the supply pressure
Rationale: Backpressure can force nonpotable water or other contaminants
backward into a potable water system when downstream pressure becomes
greater than supply pressure.
11.Which device is specifically designed to prevent a hose submerged in a
contaminant from creating a backsiphonage condition?
A. Hose connection vacuum breaker
B. Water hammer arrestor
C. Pressure regulator
D. Temperature gauge
Answer: Hose connection vacuum breaker
