California Plumbing Contractor Exam
With Actual Questions & Verified
Answers,Plus Rationales/Expert
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1. The minimum size of a building sewer serving one water closet shall be:
A. 2 inches
B. 3 inches
C. 4 inches
D. 5 inches
The California Plumbing Code (CPC) requires a minimum 3-inch diameter
for a building sewer serving a single water closet.
2. What is the minimum slope required for a 4-inch horizontal drain?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. Level
CPC requires a 1/4 inch per foot slope for pipes 4 inches or smaller to
maintain proper flow velocity.
3. The vent system is designed primarily to:
A. Supply air to fixtures
B. Prevent trap seal loss by equalizing pressure
C. Drain wastewater faster
D. Stop leaks
Vents prevent siphonage or back pressure from removing trap seals.
,4. Which of the following materials is NOT approved for potable water
distribution?
A. Copper
B. PEX
C. CPVC
D. ABS
ABS is used for drainage, not potable water systems.
5. The purpose of a trap seal is to:
A. Prevent leaks
B. Reduce flow rate
C. Prevent sewer gases from entering the building
D. Filter solids
The water in a trap acts as a barrier to prevent sewer gases from
entering habitable spaces.
6. A cleanout must be installed:
A. Every 100 feet on horizontal drains
B. At every 90° change of direction
C. At the base of each soil stack
D. At all fixture connections
Cleanouts are required at the base of each stack to allow maintenance
access.
7. What is the minimum cover required for underground water piping?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
CPC requires at least 12 inches of cover for underground water piping for
protection.
8. A vacuum breaker is used to:
A. Increase pressure
B. Prevent back-siphonage
C. Control flow rate
D. Drain condensation
, Vacuum breakers prevent contaminated water from being drawn back
into the potable water system.
9. What is the maximum distance between a trap and its vent for a 2-inch
pipe?
A. 2 feet
B. 5 feet
C. 6 feet
D. 8 feet
CPC limits trap arm length to 5 feet for a 2-inch diameter pipe.
10.The minimum size of a water service pipe is:
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 1 1/4 inch
CPC specifies 3/4 inch as the minimum size for a water service pipe.
11.The minimum trap seal depth required is:
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
CPC requires a trap seal depth of 2 to 4 inches.
12.What is the maximum allowable distance between pipe supports for 2-
inch copper tubing?
A. 4 feet
B. 6 feet
C. 8 feet
D. 10 feet
Copper tubing up to 2 inches must be supported at intervals not
exceeding 6 feet.
13.Which fitting is used to connect a vertical pipe to a horizontal pipe in a
drainage system?
With Actual Questions & Verified
Answers,Plus Rationales/Expert
Verified For Guaranteed Pass Graded
A+/2026 /Latest Update/Instant
Download Pdf
1. The minimum size of a building sewer serving one water closet shall be:
A. 2 inches
B. 3 inches
C. 4 inches
D. 5 inches
The California Plumbing Code (CPC) requires a minimum 3-inch diameter
for a building sewer serving a single water closet.
2. What is the minimum slope required for a 4-inch horizontal drain?
A. 1/8 inch per foot
B. 1/4 inch per foot
C. 1/2 inch per foot
D. Level
CPC requires a 1/4 inch per foot slope for pipes 4 inches or smaller to
maintain proper flow velocity.
3. The vent system is designed primarily to:
A. Supply air to fixtures
B. Prevent trap seal loss by equalizing pressure
C. Drain wastewater faster
D. Stop leaks
Vents prevent siphonage or back pressure from removing trap seals.
,4. Which of the following materials is NOT approved for potable water
distribution?
A. Copper
B. PEX
C. CPVC
D. ABS
ABS is used for drainage, not potable water systems.
5. The purpose of a trap seal is to:
A. Prevent leaks
B. Reduce flow rate
C. Prevent sewer gases from entering the building
D. Filter solids
The water in a trap acts as a barrier to prevent sewer gases from
entering habitable spaces.
6. A cleanout must be installed:
A. Every 100 feet on horizontal drains
B. At every 90° change of direction
C. At the base of each soil stack
D. At all fixture connections
Cleanouts are required at the base of each stack to allow maintenance
access.
7. What is the minimum cover required for underground water piping?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
CPC requires at least 12 inches of cover for underground water piping for
protection.
8. A vacuum breaker is used to:
A. Increase pressure
B. Prevent back-siphonage
C. Control flow rate
D. Drain condensation
, Vacuum breakers prevent contaminated water from being drawn back
into the potable water system.
9. What is the maximum distance between a trap and its vent for a 2-inch
pipe?
A. 2 feet
B. 5 feet
C. 6 feet
D. 8 feet
CPC limits trap arm length to 5 feet for a 2-inch diameter pipe.
10.The minimum size of a water service pipe is:
A. 1/2 inch
B. 3/4 inch
C. 1 inch
D. 1 1/4 inch
CPC specifies 3/4 inch as the minimum size for a water service pipe.
11.The minimum trap seal depth required is:
A. 1 inch
B. 2 inches
C. 3 inches
D. 4 inches
CPC requires a trap seal depth of 2 to 4 inches.
12.What is the maximum allowable distance between pipe supports for 2-
inch copper tubing?
A. 4 feet
B. 6 feet
C. 8 feet
D. 10 feet
Copper tubing up to 2 inches must be supported at intervals not
exceeding 6 feet.
13.Which fitting is used to connect a vertical pipe to a horizontal pipe in a
drainage system?
