100+ Free CA Plumber Practice Questions

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Under the CPC as adopted in California, what is the minimum size drain pipe required for a water closet?

2 inches

3 inches

4 inches

1-1/2 inches

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Key Facts: CA Plumber Exam

Scaled scoring

Passing Score

Contractors State License Board (CSLB)

100

Questions

3.5 hours time limit

$450+

Exam Fee

PSI

CPC

Code Basis

California uses the California Plumbing Code (CPC), which is based on the UPC with extensive state amendments

California's journeyman plumber exam has approximately a 55% pass rate. The 100-question exam requires Scaled scoring to pass and is based on the CPC. California uses the California Plumbing Code (CPC), which is based on the UPC with extensive state amendments.

Sample CA Plumber Practice Questions

Try these sample questions to test your CA Plumber exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the CPC as adopted in California, what is the minimum size drain pipe required for a water closet?

A.2 inches

B.3 inches

C.4 inches

D.1-1/2 inches

Explanation: Per CPC drainage pipe sizing tables, the minimum drain size for a water closet is 3 inches. This applies to all types of water closets and ensures adequate capacity to convey solid waste through the drainage system.

2According to the CPC as enforced in California, what is the minimum slope for a 4-inch horizontal drainage pipe?

A.1/16 inch per foot

B.1/8 inch per foot

C.1/4 inch per foot

D.1/2 inch per foot

Explanation: Per CPC slope requirements, horizontal drainage pipes 3 inches and larger must have a minimum slope of 1/8 inch per foot. Pipes smaller than 3 inches require 1/4 inch per foot. Proper slope ensures self-scouring velocity.

3Under California's plumbing code, what is the DFU value for a residential lavatory?

A.1 DFU

B.2 DFU

C.3 DFU

D.0.5 DFU

Explanation: Per CPC fixture unit tables, a residential lavatory is assigned 1 DFU. This value represents the probable discharge rate and is used to size drainage and venting systems.

4Per the CPC as adopted in California, what is the minimum depth of a fixture trap seal?

A.1 inch

B.2 inches

C.3 inches

D.4 inches

Explanation: Per CPC trap requirements, each fixture trap must have a water seal of not less than 2 inches and not more than 4 inches. The 2-inch minimum prevents sewer gases from passing through under normal conditions.

5According to the CPC as enforced in California, at what intervals must cleanouts be installed on horizontal drainage piping 4 inches and smaller?

A.Every 50 feet

B.Every 75 feet

C.Every 100 feet

D.Every 150 feet

Explanation: Per CPC cleanout requirements, cleanouts must be installed at intervals not exceeding 100 feet for pipes 4 inches and smaller. Additional cleanouts are required at each change of direction greater than 45 degrees.

6Under the CPC as adopted in California, what is the maximum number of DFUs that can be connected to a 3-inch horizontal branch?

A.12 DFU

B.20 DFU

C.36 DFU

D.42 DFU

Explanation: Per CPC drain sizing tables, a 3-inch horizontal branch can serve a maximum of approximately 20 DFU. Exceeding this limit risks drainage backup and surcharging.

7Per the CPC as enforced in California, what is the required slope for a 2-inch horizontal drainage pipe?

A.1/16 inch per foot

B.1/8 inch per foot

C.1/4 inch per foot

D.1/2 inch per foot

Explanation: Per CPC slope requirements, pipes smaller than 3 inches require a minimum slope of 1/4 inch per foot. The steeper slope is necessary for smaller pipes to maintain self-scouring velocity.

8According to the CPC as adopted in California, what is the minimum size building sewer when serving more than one water closet?

A.3 inches

B.4 inches

C.6 inches

D.2 inches

Explanation: Per CPC building sewer requirements, a building sewer serving more than one water closet must be at least 4 inches. A single water closet may use a 3-inch sewer in some configurations.

9Under the CPC as enforced in California, what is the maximum tailpiece length from a fixture outlet to the trap weir?

A.12 inches

B.18 inches

C.24 inches

D.36 inches

Explanation: Per CPC trap requirements, the vertical distance from the fixture outlet to the trap weir must not exceed 24 inches. Longer tailpieces risk siphonage and waste buildup.

10Per the CPC as adopted in California, what is the DFU value for a residential bathtub with shower?

A.1 DFU

B.2 DFU

C.3 DFU

D.4 DFU

Explanation: Per CPC fixture unit tables, a residential bathtub with or without a shower is assigned 2 DFU. The shower head does not add fixture units since it shares the same drain and trap.

About the CA Plumber Exam

The California journeyman plumber exam is administered by PSI on behalf of the Contractors State License Board (CSLB). The C-36 Plumbing Contractor exam is closed-book and uses scaled scoring rather than a fixed percentage. It tests knowledge of the CPC, drainage systems, water supply, venting, gas piping, and California-specific amendments.

Questions

100 scored questions

Time Limit

3.5 hours

Passing Score

Scaled scoring

Exam Fee

$450+ (Contractors State License Board (CSLB))

CA Plumber Exam Content Outline

25%

Drainage, Waste & Vent Systems

CPC drain sizing, fixture units, slope requirements, cleanouts, trap seals, and DWV installation per California amendments

25%

Water Supply & Distribution

Pipe sizing, backflow prevention, cross-connection control, water heaters, pressure regulation, and T&P relief requirements

20%

Venting Systems

Vent sizing, wet venting, circuit venting, air admittance valves, vent termination per the CPC

15%

Gas Piping & Appliances

Gas pipe sizing, BTU calculations, pressure testing, appliance venting, and combustion air requirements

15%

Code Administration & Materials

Permits, inspections, approved materials, joint methods, pipe supports, and California-specific rules

How to Pass the CA Plumber Exam

What You Need to Know

Passing score: Scaled scoring
Exam length: 100 questions
Time limit: 3.5 hours
Exam fee: $450+

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CA Plumber Study Tips from Top Performers

1Master CPC drain sizing tables and fixture unit calculations — heavily tested on the California exam

2Study backflow prevention device selection for different hazard levels per CPC cross-connection requirements

3Memorize minimum pipe sizes, trap sizes, and vent sizes for common residential fixtures

4Practice gas pipe sizing using fuel gas code tables including BTU demand calculations

5Review water heater installation requirements including T&P relief, expansion tanks, and pan requirements

Frequently Asked Questions

What plumbing code does California use?

California uses the California Plumbing Code (CPC), which is based on the UPC with extensive state amendments. The Contractors State License Board (CSLB) oversees all licensing requirements. The exam is based on the current adopted CPC edition.

How many questions are on the California plumber exam?

The California C-36 plumbing contractor exam has approximately 100 multiple-choice questions with a time limit of 3.5 hours. California uses scaled scoring rather than a fixed percentage — your score is adjusted based on question difficulty.

Who administers the California plumber exam?

The exam is administered by PSI on behalf of the Contractors State License Board (CSLB). You must apply through the agency and schedule your exam through PSI's testing system.

What experience is required for the California journeyman plumber exam?

At least 4 years of journeyman-level experience within the last 10 years as a plumber. Contact the Contractors State License Board (CSLB) for specific requirements and application procedures.