# How plumber licensing works by state

Check the business licence and the qualification of the person who will do the work.

Updated 2026-11-10. Also on the [web page](https://plumberpros.fyi/guides/plumber-licensing-by-state).

A business name is not enough to check a plumber. Ask for the exact licence number, issuing agency and legal business name. Ask who will supervise your job. Then compare those details with the issuing agency's record.

## Start with the right register

This is a starting map, not a complete rule book for every state. The sources below were checked on 2026-11-10.

| Place | Public source | What to check |
| --- | --- | --- |
| California | Contractors State License Board (CSLB) | The contractor record and the C-36 plumbing classification |
| Texas | Texas State Board of Plumbing Examiners | The licence record and licence class for the person named by the business |
| Washington | Department of Labor & Industries | The plumber certificate and the scope of the certificate |
| Ontario | Skilled Trades Ontario | The public trade record and the status of the individual plumber |

California's CSLB describes C-36 as the plumbing contractor classification. Washington's Labor & Industries page says plumbing work within its stated scope needs plumber certification. It separates journey level work from specialty work. Ontario's trade page describes plumber as a compulsory trade and lists the credentials that allow a person to practise. These statements come from the linked agency pages, checked 2026-11-10. They are not interchangeable rules.

## Read the record carefully

Match the spelling, business name and licence class. Read any status or restriction shown. If the name on the quote differs, ask the contractor to explain the link. Save the register URL and the date you checked it. A screenshot can help you compare later, but check the live record again before signing.

## Ask about the actual job

Describe whether the work includes a water heater, a sewer connection or a gas line. Ask the agency whether the named licence covers that scope at your address. A trade association entry can help you find a business. It does not replace a licence check. A paid directory badge does not replace it either.

## For other states and provinces

Start at the government licensing agency for your location. Ask the permit office who regulates the trade if you cannot find a register. Do not use a rule from a neighbouring state as proof. Keep your notes with the written quote and permit record.

## Sources

Checked 2026-11-10. These pages can change.

- [California CSLB: C-36 plumbing contractor](https://www.cslb.ca.gov/About_Us/Library/Licensing_Classifications/Licensing_Classifications_Detail.aspx?Class=C36), accessed 2026-11-10.
- [California CSLB: Hire a Licensed Contractor](https://www.cslb.ca.gov/Consumers/Hire_A_Contractor/), accessed 2026-11-10.
- [Texas State Board of Plumbing Examiners](https://tsbpe.texas.gov/), accessed 2026-11-10.
- [Washington L&I: Plumber Certification](https://lni.wa.gov/licensing-permits/plumbing/plumber-certification/), accessed 2026-11-10.
- [Skilled Trades Ontario: Plumber](https://www.skilledtradesontario.ca/trade-information/plumber/), accessed 2026-11-10.

## Questions

### Does a business listing prove a licence is current?

No. Match the licence number and business name against the issuing agency record before hiring.