Does the CSLB require general liability insurance for plumbing contractors?

Only if your license is held by a limited liability company. California does not require a sole proprietor, partnership or corporation to carry general liability insurance as a condition of holding a CSLB license. For those licensees, general liability is driven by customers, general contractors, property managers and the contracts you sign, not by the license.

For an LLC licensee, Business and Professions Code §7071.19 requires general liability insurance with a cumulative limit of at least $1,000,000 if the LLC has five or fewer personnel of record, plus $100,000 for each additional person of record, and the requirement does not go above $5,000,000. The policy must be written by a California-licensed insurer or an eligible surplus lines insurer. An LLC also files a separate $100,000 surety bond for the benefit of its employees and workers (B&P §7071.6.5), on top of the $25,000 contractor's bond every licensee carries.

Two practical points. First, the LLC limit is tied to the number of people listed on the license, so re-check the required limit whenever you add members or officers. Second, the CSLB minimum is a floor, not a recommendation: general contractors and commercial property owners commonly ask every plumbing subcontractor, LLC or not, for at least $1,000,000 per occurrence by contract.

If you are not an LLC and sign no contracts that require coverage, nothing in California law compels you to buy general liability. One failed supply line in an occupied home is the reason most working plumbers carry it anyway.