California Plumbing Code

Adopted Code

Local jurisdictions may amend the state code further. Always confirm with the authority having jurisdiction before submitting for permit.

How the California Code Is Organised

The plumbing provisions live in Title 24 Part 5 of the California Code of Regulations, which is the California Plumbing Code. Because it is a regulation rather than a standalone code book, it is cited by Title 24 section number, and the residential provisions for one- and two-family dwellings sit in Part 2.5 (the California Residential Code) rather than in Part 5. A designer checking a fixture requirement therefore needs to know the occupancy first, because the two parts do not carry identical language.

What It Changes About Sizing

California amends the UPC base heavily on water conservation. Maximum fixture flow rates are lower than the model code, which changes the fixture-unit arithmetic feeding water supply sizing: a design that meets UPC demand tables can still fail California because the permitted flow per fixture is capped tighter. Seismic bracing requirements for piping also add support and anchorage provisions with no UPC equivalent.

Licensing in California

Plumbing contractors hold a C-36 licence from the Contractors State License Board. There is no separate state journeyman plumber licence: the licence attaches to the contracting business, and individual workers are regulated instead through apprenticeship and, on public works, through prevailing-wage and certified-payroll rules. This catches contractors from journeyman-licence states, who expect to register an individual credential and find there is nothing to register.

Cities That Do Something Different

Los Angeles enforces its own amendments through the LA Plumbing Code, and San Francisco likewise amends the state code. Any California city or county may adopt amendments more restrictive than Title 24, but must file them with the Building Standards Commission to be enforceable — so an unfiled local rule is not binding, which is worth knowing when an inspector cites one.

What Out-of-State Contractors Get Wrong in California

1. 1Citing the UPC directly instead of Title 24 Part 5. Plan reviewers want the California section number, and the two are not interchangeable because of the state amendments.
2. 2Assuming the three-year cycle. California runs an intervening intermediate adoption cycle, so provisions can change between full Title 24 editions.
3. 3Sizing water supply from UPC flow rates. California's conservation caps are lower and they propagate through the whole demand calculation.
4. 4Expecting an individual journeyman licence to exist. It does not; the C-36 is a contractor licence.

California in Practice

Our sizing calculators state the edition and table they use: pipe sizing, drainage slope, gas line sizing. Check them against the CA edition in force before relying on a result.