Plumbing Contractor License Requirements in California

Overview — plumbing licensing in California

California requires a state-level plumbing contractor license, issued by the Contractors State License Board (CSLB). The license verifies competence and consumer protection, and is required to legally bid and perform plumbing work in the state. Working without one when required is typically a misdemeanor and exposes the contractor to civil penalties — and the contract becomes unenforceable in court.

License classes available

California offers 2 plumbing license classes — pick based on the largest project you plan to bid:

• C-36 Plumbing Contractor. Installs, alters, repairs, and services plumbing systems — water supply, drains, vents, fixtures, water heaters, gas piping. Standard CA plumbing license.
• B General Building Contractor. Allowed to plumb as part of a multi-trade project. Cannot bid plumbing-only jobs.

Experience required

4 years of journey-level plumbing experience in the past 10 years.

Exam — what you're tested on

California requires a written examination administered by PSI Services (CSLB-administered). Topics covered:

• California Plumbing Code
• Water supply / drain-waste-vent systems
• Cal/OSHA safety
• Business and law (separate exam)

Passing score: 73% on each section. Up to 4 attempts per year are allowed.

Fees

• Application fee: $450
• Initial license fee: $200
• Renewal fee: $450 ( biennial)

Bond & insurance

Bond: Required — typically $25,000. Standard CSLB contractor bond.

General liability insurance: Minimum $1,000,000.

Workers' compensation: Required for any contractor with 1+ employees. Sole-prop plumbers exempt without employees.

Reciprocity with other states

California has reciprocity agreements with: AZ, NV, UT, LA. Reciprocity typically waives the trade exam if you hold an equivalent license in good standing in the reciprocal state for at least one year. Each state still requires its own application and business/law exam.

Local permits and requirements

Every CA city requires plumbing permits per job. Many require backflow prevention test certifications for irrigation/landscape connections.

Common gotchas

Things that catch most applicants on their first license cycle in California:

• Gas piping is covered under C-36 in California — no separate gas fitter license required.
• California's water-conservation ordinances (e.g., low-flow fixture mandates) require specific product compliance.
• Backflow tester certification (separate from C-36) required to install/test backflow preventers — common gap.
• Title 24 plumbing requires hot-water recirculation efficiency on most new construction.

Frequently asked questions

Does California's C-36 cover gas piping?

Yes — gas piping for natural gas and propane is covered under the C-36 Plumbing Contractor license. Some other states require a separate gas fitter license.

Do I need a separate license to install backflow preventers in California?

Yes. Beyond the C-36, you need to be a Certified Backflow Tester (issued by AWWA or USC accredited programs). Required for testing/installing reduced-pressure assemblies on irrigation and commercial connections.

How long does C-36 licensing take in California?

4–6 months from application to active license, including exam scheduling.

Can a C-36 install solar water heating in California?

Yes — solar thermal (water heating) is covered under C-36. Solar electric (PV) requires separate C-46.

What's California's continuing education for C-36?

None required at state level. Some local backflow programs require CE for certified testers.