Hiring a plumber in L.A.: check the C-36 first
A C-36 plumbing license is the California classification for plumbing work, issued by CSLB, the Contractors State License Board. Check the license online before you sign, keep any down payment within the legal limit and get the contract in writing.
From the Plumbing Across L.A. desk. Updated .
This paper doesn't recommend contractors, takes no leads and has no list of favorites. What it can do is show you the checks that the state itself suggests, in the order you'd use them.
What does a C-36 license cover?
The C-36 classification covers supplying safe water and disposing of fluid waste. That includes water and gas piping from the owner's side of the utility meter to the structure, gas appliances and their flues and connections, and equipment to heat water. It also covers the upkeep and replacement of health and safety devices, including gas earthquake valves, backflow preventers and regulating valves.
Other classifications overlap on some jobs. For a sewer line, for example, A, C-36, C-42 and C-34 contractors may install or repair building sewers. Water softener specialists may hold a C-55. If a contractor has a different license from the one you expected, ask how it applies to your job.
| Job | Classification to look for |
|---|---|
| Repipe, water heater, gas piping | C-36 |
| Seismic gas valve | C-36 lists gas earthquake valves |
| Building sewer | A, C-36, C-42 or C-34 |
| Water softener | C-36 or C-55; ask |
How do you check a C-36 plumbing license?
Use CSLB's free license check, and do it before you sign or pay.
- Get the license number in writing. Advertisements and contracts should show it.
- Look it up on CSLB's site. Check that the name and address match the person you're dealing with.
- Confirm the status is active and the classification fits your job.
- Read what the record says about bonds, workers' compensation and any complaints or discipline.
- If a salesperson is signing you up, check their Home Improvement Salesperson registration too.
The record only tells you what's on file. It isn't a judgment on quality, so still ask for details of similar jobs in houses like yours.
How much can a plumber ask for as a down payment?
No more than $1,000 or 10 percent of the contract price, whichever is less, on a home improvement job. CSLB says there are no exceptions for special-order materials. A narrow exception applies to contractors with a qualifying blanket bond, which you can ask about and verify.
Beyond the down payment, payments cannot exceed the value of the work performed. Example: on a $6,000 contract, 10 percent is $600, so the limit is $600. On a $20,000 contract, 10 percent is $2,000, so the limit is $1,000. These are illustrations of the arithmetic, not job prices.
Be wary of a request for most of the money up front. Slow down and read the contract.
What should a plumbing contract include?
CSLB says California requires a written contract for all home improvement projects over $500. It must be legible and easy to understand, and it must tell you about your rights to cancel or rescind. A verbal promise should go in the contract.
- A detailed written payment schedule.
- Written direction on who gets the permits, and a completion date.
- Materials and scope, including what's being left in place. Our repipe page has a question list.
- Any change in writing, as a change order signed by you and the contractor before the change happens.
When is a handyperson legal for plumbing work?
Only for small jobs. Since January 1, 2025, under AB 2622, an unlicensed person's limit is $1,000 in total on a job, and only for work that needs no permit and with no workers. Fixing a leaky faucet may fall under it. A water heater change or anything on a gas line is another matter, and you should hire a licensed plumber.
What this means by age of house
- Before 1930Ask how much old-house work they've done: plaster, partial repipes and galvanized pipe. See before 1930.
- 1930s–1940sAsk about crawlspace access and clay or cast iron drains, and how they'd handle a surprise behind a wall. See the 1930s and 1940s.
- 1950s–1960sMany houses here are on slabs. Ask how they'd find and route around a slab leak before agreeing to break concrete.
- 1970s and newerThe problem may be a single failed part. Ask for the diagnosis in writing before agreeing to a whole-house repipe.
Questions that come up
Is a city business license the same as a plumbing license?
No. City business paperwork is different from a CSLB contractor's license. Look up the CSLB number.
Can a general contractor do my plumbing?
It depends on the job and how the contract is set up. Ask how the plumbing fits within their license, then check it at CSLB.
The plumber wants cash and no contract because the job is small. Is that allowed?
Over $500, CSLB says a written contract is required. Under that, a written agreement still protects you.
Does this paper keep a list of good plumbers?
No. We don't take leads or recommend named contractors. Use the license check and compare written bids.
The bid is for materials bought up front. Can they ask for more than the limit?
CSLB says there are no exceptions for special-order materials under the down payment limit.
Who handles this
What this was checked against
- C-36 Plumbing Contractor: CSLB
- Licensing classifications: CSLB
- Hire a licensed contractor pages: CSLB consumer section
- Down payments, written contracts and change orders: CSLB contract pages
- AB 2622 press release: CSLB
Sources read in November 2026. Rules and prices change: check the agency before you act.