TL;DR: In California, a licensed plumber holds a C-36 Plumbing Contractor license issued by the Contractors State License Board (CSLB). Any plumbing job valued over $500 in labor and materials requires a licensed contractor. You can verify any plumber’s license number on the CSLB website in about 60 seconds. Hiring unlicensed means no bond protection, no workers’ comp coverage, and potential liability if something goes wrong on your property.
You found a plumber on a neighborhood app, got a quote that seemed fair, and now you’re wondering: is this person actually licensed? It’s a smart question, and California makes it easy to answer. The CSLB maintains a public license lookup that shows license status, expiration date, bond status, and any disciplinary actions. This post walks you through the lookup step by step, explains what a C-36 actually covers, and tells you which common plumbing jobs require a permit on top of a license.
What Is a C-36 Plumbing Contractor License?
A C-36 is a specialty contractor license issued by the California Contractors State License Board that authorizes a contractor to install, alter, and repair plumbing systems in residential and commercial buildings. It covers water supply lines, drain and waste systems, gas piping, water heaters, and related fixtures. Without a C-36 (or a General Building contractor license that includes plumbing), a contractor cannot legally perform plumbing work valued over $500 in California.
The C-36 is not a journeyman plumber card. It is a business license for the contracting entity. To qualify, the applicant must pass a trade exam and a law-and-business exam, document four years of journey-level experience, and carry a $25,000 contractor’s bond. The CSLB also requires workers’ compensation insurance if the contractor has employees. That combination of testing, experience, and financial accountability is what separates a licensed contractor from someone who learned the trade informally.
California’s C-36 does not automatically include HVAC work. A heating and air conditioning contractor holds a separate C-20 license. If a company offers both plumbing and HVAC, look for both license classifications, or a B General Building contractor license that covers both trades.
How to Verify a Plumber’s License in 60 Seconds
Go to the CSLB license check page and enter the contractor’s license number or business name. The result shows the license classification, current status (Active, Inactive, Suspended, or Expired), expiration date, bond information, and any workers’ comp filings.
Here is the step-by-step:
- Open cslb.ca.gov/OnlineServices/CheckLicenseII/CheckLicense.aspx on your phone or computer.
- Enter the license number the contractor gave you, or search by business name.
- Confirm the status reads Active. Expired or Suspended means the contractor cannot legally work.
- Check the classifications listed. You want to see C-36 for plumbing work.
- Confirm the bond is in place. No bond means no financial backstop if the contractor walks off the job.
- Check for any disciplinary actions listed at the bottom of the result.
The whole process takes under a minute. If a contractor hesitates when you ask for their license number, that hesitation is your answer.
RT Olson Plumbing, Heating and Air Conditioning holds California license 997337. You can look that number up right now on the CSLB site to confirm it is active, bonded, and in good standing. That is the kind of transparency every licensed contractor should offer without being asked.
Which Plumbing Jobs Require a Permit?
A license and a permit are two different things. A license authorizes the contractor to do the work. A permit authorizes the specific job at a specific address, and it triggers an inspection by the local building department.
In Riverside County and the cities it encompasses, the following plumbing jobs typically require a permit:
- Water heater replacement: Any water heater swap, tank or tankless, requires a permit. The inspector checks the T&P relief valve, the discharge line routing, seismic straps, and gas connections. Skipping the permit means an uninspected gas connection and a potential insurance issue if the unit ever floods or fails.
- Whole-house repipe: Replacing copper or galvanized pipe with PEX or new copper is a significant structural alteration. A permit is required, and inspections happen at rough-in (before walls close) and final.
- Gas line work: New gas lines, extended runs, and pressure tests all require permits. Gas work also requires the contractor to perform a pressure test witnessed by the inspector.
- Sewer line replacement or relining: Any work on the building sewer from the house to the property line requires a permit. Trenchless relining is included.
- New fixture rough-ins: Adding a bathroom, relocating a sink, or adding a laundry connection requires a permit because it changes the drain-waste-vent system.
Minor repairs, like replacing a faucet, swapping a toilet, or clearing a clogged drain, generally do not require a permit. When in doubt, ask your contractor. A licensed contractor will know the local requirements and pull the permit on your behalf. The permit fee is typically included in a reputable contractor’s quote. If a contractor tells you a permit is unnecessary for a water heater swap or a repipe, that is a red flag.
For more detail on what the CSLB expects from licensed contractors and what homeowners can do to protect themselves, see the CSLB’s Hire a Contractor guide.
What Are the Risks of Hiring an Unlicensed Plumber?
Hiring an unlicensed plumber exposes you to several concrete risks beyond just shoddy work.
No bond protection. A licensed contractor’s $25,000 CSLB bond exists to compensate you if the contractor abandons the job or causes damage. An unlicensed contractor has no bond. If they disappear after taking a deposit, your recourse is small claims court, not the CSLB.
No workers’ comp coverage. If an unlicensed worker is injured on your property, you may be liable for their medical bills and lost wages. Licensed contractors with employees are required to carry workers’ compensation insurance. That coverage protects them and protects you.
Permit problems. Unpermitted work can surface when you sell the house. A buyer’s inspector or the title company may flag it, and you may be required to open walls, bring the work up to code, and pay for the inspection retroactively. Unpermitted gas or water heater work can also void your homeowner’s insurance coverage for related claims.
Code violations. The California Plumbing Code (based on the Uniform Plumbing Code, or UPC) sets minimum standards for pipe sizing, venting, water pressure, and fixture installation. A licensed contractor knows these standards and is accountable to them through the permit process. An unlicensed one is not.
If you want a broader framework for evaluating any plumber before you hire, the post How to Pick the Best Plumber Near Me covers the full checklist, including what questions to ask before anyone touches your pipes.
Does a Plumber Also Need to Be Bonded and Insured?
Yes, and the CSLB lookup shows you both. A licensed California plumbing contractor must carry a $25,000 contractor’s license bond, which the CSLB verifies and displays in the license record. Contractors with employees must also carry workers’ compensation insurance.
General liability insurance is separate from the bond and is not tracked by the CSLB. Ask the contractor for a certificate of insurance showing general liability coverage. A reputable contractor provides this without hesitation. The certificate names the insurance company, policy number, coverage limits, and expiration date. For a water heater installation or a repipe, you want to see at least $1 million in general liability coverage.
What To Do Before Scheduling Any Major Plumbing Job
Before you book a water heater installation, a repipe, or any gas line work, take three minutes to do the following:
- Ask for the contractor’s CSLB license number before they arrive.
- Look it up at cslb.ca.gov. Confirm Active status, C-36 classification, and bond.
- Ask for a certificate of general liability insurance.
- Confirm the contractor will pull the permit. If they say the job doesn’t need one and you’re not sure, call your city’s building department to verify.
- Get a written scope of work and price before any work starts. The written quote should list materials, labor, permit fees, and the estimated inspection timeline.
For a water heater swap specifically, the water heater installation page covers what a complete job looks like, including permit, seismic straps, and T&P valve testing. For a repipe, the services overview lists what RT Olson’s repiping work includes.
If you want to schedule an estimate or have questions about a specific job, contact the team directly. RT Olson Plumbing, Heating and Air Conditioning is available around the clock and will provide the license number, insurance certificate, and written quote before any work begins.
About RT Olson Plumbing, Heating and Air Conditioning
RT Olson Plumbing, Heating and Air Conditioning is a licensed and insured plumbing and HVAC contractor serving Corona, CA and the surrounding Inland Empire and Orange County region since 2014 (CSLB license 997337). Their technicians handle water heater installation and repair, whole-house repiping, gas line services, drain cleaning, leak detection, and heating and air conditioning across dozens of cities in Riverside, San Bernardino, and Orange Counties. Available 24/7 for emergencies.