Who may do plumbing work in Minnesota
Short version: a business that offers plumbing work needs a state plumbing contractor license, and a licensed master plumber must be in charge of the work. This page summarizes the state law and Department of Labor and Industry (DLI) guidance. It is not legal advice.
The license ladder: who needs what
1. A plumbing contractor license (the business)
Minnesota Statutes section 326B.46 says that, apart from listed exemptions, no person may perform or offer to perform plumbing work, with or without pay, unless they hold a contractor's license. A contractor's license does not by itself qualify its holder to do the plumbing work that a master or journeyworker plumber license allows.
2. A licensed master plumber in charge
Anyone in the business of planning, superintending or installing plumbing must always have a licensed master plumber in charge of the plumbing work. In cities and towns with fewer than 5,000 people, a restricted master plumber can fill that role.
3. People who do the work
Licensed plumbers, plus registered unlicensed plumbers and apprentices. DLI says registered unlicensed plumbers and apprentices may work without a license only within the scope of what their employer is authorized to do, and while directly supervised at all times by a licensed journeyworker or master plumber.
The homeowner exception
The statute says a person who is not licensed may do plumbing work that meets the minimum standards on premises they own and actually live in as their residence, unless a local ordinance forbids it.
What DLI says about who can do the work
DLI says a person may perform plumbing work in Minnesota if they are at least 18 and one of these applies:
What this means when you hire
Ask for the license number
Ask for the company's plumbing contractor license number. In the DLI file this site uses, plumbing contractor numbers begin with PC.
Ask who the master plumber in charge is
A licensed master plumber must be in charge of the plumbing work.
Check it before you agree to a price
Check the license in DLI's lookup. DLI says no account is needed.
Next: replacing a water heater, or find a licensed contractor by city.
Sources
Statute and DLI page read November 5, 2026. Laws and pages change; check the sources for the current text.