In the Field · Part 4
Commercial basics: grease interceptors, the backflow program, and the tester certification that opens a second line of work
A C-36 who wants steadier work than residential service adds two commercial products: grease interceptors, which every restaurant and commercial kitchen must have and maintain, and backflow prevention, which every public water system must enforce at commercial service connections and which is tested annually by certified testers. This lesson gives the interceptor rule and sizing logic from the plumbing code, the structure of California's cross-connection program under the State Water Board's 2024 policy handbook, what a backflow assembly tester certification is and why it turns a plumber into a recurring-revenue business, and the parts of commercial work that are not in the plumbing code at all: the contract, the confined space, and the health inspector.
What the full lesson covers
- Grease interceptors are required where the authority having jurisdiction determines pretreatment is needed, which in practice is every food-service kitchen; they are listed to the standards in CPC 1014.1, sized by the code's method, and connected only to grease-producing fixtures (never to toilets or floor drains from restrooms).
- The sewer agency's FOG (fats, oils, grease) program sets the maintenance schedule, the inspection, and the fine; a restaurant's plumber is the one who sizes, installs, and often maintains the interceptor to that program.
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More lessons in The Field: Method, Code, and Cases
- 1The diagnostic method: verify, isolate, cheapest test first, cause not symptom, the options ladder, document
- 2Permits: when one is required, what is exempt, pulling it online, the inspection sequence, what inspectors look for, and handling corrections
- 3Daily-use code: drainage slope, venting, water sizing, cleanouts, trap arms, and fixture units, with the section for each
- 4Gas piping in practice: sizing, CSST bonding, the pressure test, appliance connectors and shutoffs, sediment traps, and seismic shutoff valves