California C-36 Plumbing Contractor License: Scope, Verification, and Workers' Comp

The C-36 classification covers plumbing systems: water supply, drainage and waste, vent piping, gas piping, water heaters, backflow-prevention devices, and the installation of water-conditioning equipment (which overlaps the C-55 water-conditioning classification).

Sewer and sewer-line work can fall under C-36, the C-42 sanitation-system classification, or the C-34 pipeline classification depending on the job, so for a main sewer replacement, confirm the contractor's classification actually covers it.

Any project where labor, materials, and all other items total $1,000 or more must be performed by a CSLB-licensed contractor. The threshold rose from $500 to $1,000 on January 1, 2025 under Assembly Bill 2622 (Business & Professions Code §7048). Below $1,000, a narrow minor-work exemption can apply only if the job is casual, minor, and standalone (not part of a larger project), requires no building permit of any kind, no one is employed on the job, and any advertising discloses that the person is not licensed.

Water-heater changeouts, repipes, and sewer work typically also require a building permit, which a licensed contractor pulls in their own name. For anything beyond a minor repair, look specifically for an Active C-36 (or a B General Building license where the project spans at least two unrelated trades).

No. CSLB licenses the contracting business, not each worker: an employee plumber working for a licensed company does not need a personal license. The license is held through the company's qualifying individual (an RMO or RME).

So verify the business you're hiring, not the person who shows up: confirm the company holds an Active C-36 in the name on your contract and bid.

Confirm the license is Active and the C-36 classification is listed, either on the CSLB "Check a License" tool or on the contractor's profile in this directory. Match the license to the business you're hiring. Check that the $25,000 contractor bond is on file (Business & Professions Code §7071.6) and that workers' compensation coverage, or a valid exemption, is shown.

You can browse Active C-36 plumbers by city in the California plumbing directory and see each one's dated CSLB status before you hire.

A plumbing contractor must carry workers' compensation insurance for any employees. A contractor that genuinely works alone can currently file a no-employee exemption, so the CSLB record may show an exemption rather than a policy: confirm one or the other before you hire. Since January 1, 2026 (SB 291), a licensee caught employing workers without coverage faces minimum penalties of $10,000 per violation for a sole owner and $20,000 per violation for a partnership, corporation, or LLC, and cannot renew without current coverage.

Senate Bill 1455 will extend that requirement to every CSLB licensee, regardless of employees, on January 1, 2028, with CSLB's exemption-verification process due by January 1, 2027. Five high-risk classifications already carry no exemption at all, C-8 (concrete), C-20 (HVAC), C-22 (asbestos abatement), C-39 (roofing), and C-61/D-49 (tree service), and must hold coverage regardless of employees.