CO Journeyman Plumber Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the minimum slope required for a 2-inch horizontal drain pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
B. 1/4 inch per foot
A 2-inch drain pipe requires a slope of 1/4 inch per foot to ensure
proper flow and prevent clogging.
2. What type of valve is typically used to prevent backflow in a plumbing
system?
A. Gate valve
B. Check valve
C. Ball valve
D. Globe valve
B. Check valve
Check valves allow water to flow in one direction only, preventing
backflow into the potable water system.
3. The minimum water pressure required at a residential plumbing fixture
is:
A. 5 psi
B. 15 psi
C. 20 psi
D. 30 psi
C. 20 psi
, Most plumbing codes require a minimum of 20 psi to ensure
adequate flow at fixtures.
4. What is the primary purpose of a vent in a drainage system?
A. To prevent freezing
B. To allow sewer gases to escape
C. To increase water pressure
D. To filter debris
B. To allow sewer gases to escape
Vents provide a pathway for sewer gases to exit safely and maintain
proper drain function.
5. Which of the following is considered a potable water source?
A. Reclaimed water
B. Rainwater collected from rooftops
C. Municipal treated water
D. Greywater
C. Municipal treated water
Potable water is water that is safe for human consumption, such as
properly treated municipal water.
6. What is the standard size for a residential water service line?
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 1 1/4 inch
B. 3/4 inch
Most single-family homes use a 3/4-inch water service line to provide
adequate flow.
7. What is the recommended clearance from the top of a water closet to
any obstruction?
A. 12 inches
B. 15 inches
C. 18 inches
D. 24 inches
C. 18 inches
Building codes require at least 18 inches in front of a toilet for
accessibility and comfort.
8. What is the main function of a P-trap in plumbing?
A. To increase water pressure
, B. To trap debris
C. To prevent sewer gases from entering the building
D. To filter water
C. To prevent sewer gases from entering the building
A P-trap holds water to block sewer gases while allowing waste to
flow.
9. When soldering copper pipes, which flux type should be used for
potable water?
A. Acid-core flux
B. Lead-core flux
C. Water-soluble flux
D. Rosin-core flux
C. Water-soluble flux
Water-soluble flux is safe for drinking water systems and ensures a
proper joint seal.
10. Which pipe material is most commonly used for underground
residential water supply lines?
A. PVC
B. CPVC
C. PEX
D. Galvanized steel
A. PVC
PVC is durable, corrosion-resistant, and commonly approved for
underground water lines.
11. The maximum allowable distance between cleanouts for a 3-inch
horizontal drain is:
A. 25 feet
B. 50 feet
C. 75 feet
D. 100 feet
B. 50 feet
Code requires cleanouts at intervals to allow access for clearing
obstructions.
12. Which type of joint is used with cast iron soil pipes?
A. Threaded joint
B. Solvent weld
C. Hub and spigot with lead and oakum
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the minimum slope required for a 2-inch horizontal drain pipe?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. 1 inch per foot
B. 1/4 inch per foot
A 2-inch drain pipe requires a slope of 1/4 inch per foot to ensure
proper flow and prevent clogging.
2. What type of valve is typically used to prevent backflow in a plumbing
system?
A. Gate valve
B. Check valve
C. Ball valve
D. Globe valve
B. Check valve
Check valves allow water to flow in one direction only, preventing
backflow into the potable water system.
3. The minimum water pressure required at a residential plumbing fixture
is:
A. 5 psi
B. 15 psi
C. 20 psi
D. 30 psi
C. 20 psi
, Most plumbing codes require a minimum of 20 psi to ensure
adequate flow at fixtures.
4. What is the primary purpose of a vent in a drainage system?
A. To prevent freezing
B. To allow sewer gases to escape
C. To increase water pressure
D. To filter debris
B. To allow sewer gases to escape
Vents provide a pathway for sewer gases to exit safely and maintain
proper drain function.
5. Which of the following is considered a potable water source?
A. Reclaimed water
B. Rainwater collected from rooftops
C. Municipal treated water
D. Greywater
C. Municipal treated water
Potable water is water that is safe for human consumption, such as
properly treated municipal water.
6. What is the standard size for a residential water service line?
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 1 1/4 inch
B. 3/4 inch
Most single-family homes use a 3/4-inch water service line to provide
adequate flow.
7. What is the recommended clearance from the top of a water closet to
any obstruction?
A. 12 inches
B. 15 inches
C. 18 inches
D. 24 inches
C. 18 inches
Building codes require at least 18 inches in front of a toilet for
accessibility and comfort.
8. What is the main function of a P-trap in plumbing?
A. To increase water pressure
, B. To trap debris
C. To prevent sewer gases from entering the building
D. To filter water
C. To prevent sewer gases from entering the building
A P-trap holds water to block sewer gases while allowing waste to
flow.
9. When soldering copper pipes, which flux type should be used for
potable water?
A. Acid-core flux
B. Lead-core flux
C. Water-soluble flux
D. Rosin-core flux
C. Water-soluble flux
Water-soluble flux is safe for drinking water systems and ensures a
proper joint seal.
10. Which pipe material is most commonly used for underground
residential water supply lines?
A. PVC
B. CPVC
C. PEX
D. Galvanized steel
A. PVC
PVC is durable, corrosion-resistant, and commonly approved for
underground water lines.
11. The maximum allowable distance between cleanouts for a 3-inch
horizontal drain is:
A. 25 feet
B. 50 feet
C. 75 feet
D. 100 feet
B. 50 feet
Code requires cleanouts at intervals to allow access for clearing
obstructions.
12. Which type of joint is used with cast iron soil pipes?
A. Threaded joint
B. Solvent weld
C. Hub and spigot with lead and oakum
