You become a plumber the same way electricians do: apprentice, then journeyman, then master, with a contractor license on top if you run your own business. You log documented field hours as a supervised apprentice, pass an exam built on the plumbing code to earn your journeyman license (the minimum to work independently), then add years and a harder exam for master status. Plumbing carries even more state-to-state variation than electrical, so the exact hours, exams, and whether your state licenses you as an individual or only as a contractor all route to the Contractor License Checker.
What the work actually is
Plumbers install and service the systems that move water, waste, and gas through a building: supply lines, drains, vents, fixtures, water heaters, and gas piping. The main worlds are:
- Service and repair on existing homes and businesses. Steady, high-demand, strong for going solo.
- New construction rough-in and finish, working off prints for a general contractor.
- Commercial and industrial systems, which run larger and more technical.
- Gas work, which in many places needs its own license on top of your plumbing license.
The high-margin niches are backflow testing and medical-gas work, both of which need their own credential.
The licensing ladder (and why plumbing is messier)
The ladder is apprentice, journeyman, master, then contractor, but the state variation is arguably the widest of any trade:
- Some states license you as an individual journeyman and master.
- Some do not license individuals at all and instead license the contracting business (California licenses plumbing contractors rather than individual journeymen, for example).
- Some run two tiers, a local or registered license plus a state-wide certified contractor license.
- Some require state registration at every level, including apprentices.
The standard union apprenticeship (UA/JATC) runs about five years, pairing on-the-job hours with classroom time, but your state sets the exact hour count and exam. Even in states without individual licensing, your city or county may still require local registration. Run your state through the Contractor License Checker so you apply for the right thing.
The code you have to know cold
Most plumbing work lives under the International Plumbing Code (IPC), and gas work under the National Fuel Gas Code (NFPA 54) and the International Fuel Gas Code (IFGC). Which edition your state enforces routes to Working in Your State, but the concepts show up on every exam and every inspection:
- Water heaters carry a stack of code requirements: a temperature-and-pressure relief valve discharged safely near the floor, a dedicated shutoff, and specific service and access clearances. Getting these wrong is a classic failed inspection.
- Gas appliances have ignition-source and clearance rules (a water heater in a garage, for example, has to keep its ignition source elevated off the floor so it cannot ignite fuel vapors).
- A trend to watch: some states are making heat-pump water heaters the prescriptive baseline in their energy code, which pushes gas water-heater installs onto a performance pathway and requires electrical infrastructure to be roughed in for a future heat pump. Whether that applies to you depends on your state's energy code, so route it.
Gas: usually a separate license
In most states a master plumber license covers gas piping up to a defined pressure. But plenty of states and municipalities require a separate gas fitter or gas technician license for work on gas appliances and piping. If gas is part of your plan, do not assume your plumbing license covers it. Check the Contractor License Checker for your state's gas rule.
The certs that unlock the better-paid work
- OSHA 10 or OSHA 30, widely required for commercial site access.
- Backflow prevention tester, required in most states through a separate exam. Backflow testing is recurring, scheduled work that many plumbers build a steady side income on.
- Medical-gas certification (ASSE 6010), the ticket into hospital and healthcare work, which is one of the highest-margin niches in the trade.
One national rule that catches plumbers out
If you open walls or disturb painted surfaces in a home or child-occupied building built before 1978, the federal EPA RRP (Lead-Safe) Rule applies to you. Disturbing more than 6 square feet of interior paint (or 20 exterior) means the job needs an EPA-certified firm and a certified renovator. Plumbers cutting into old walls trigger this constantly, and the penalties are steep, so factor certification in before you take remodel work in older homes.
The startup reality
Going independent as a plumber means the standard kit: license and exam fees, forming your business, general liability, commercial auto, a service van, and workers' comp when you hire. On top of that you carry a heavier tool load than most trades: pipe tools, press-fitting systems, and a drain camera add up fast. The totals vary by state and by how much you buy used, so build yours from real quotes. See Going out on your own and How to price your work.
Common questions
How long does it take to become a licensed plumber?
Typically four to five years of documented apprenticeship hours before you can sit the journeyman exam, then more years at journeyman level before a master exam. The hour requirement is the real clock, and an apprenticeship pays you through it. The exact hours, the exam, and whether classroom time counts toward the total are set by your state, so confirm them in Working in Your State before planning your timeline.
Do I need a separate license to do gas work?
Often, yes. In many states and cities, gas piping and gas appliance work need a separate gas fitter or gas technician license on top of your plumbing license. In other states a master plumber license covers gas up to a defined pressure. Because it splits both ways, never assume, especially across a state or city line. Check your state's gas rule in the Contractor License Checker before you quote gas work.
Does California really not license journeyman plumbers?
Correct. Some states license the plumbing contractor (the business) rather than the individual journeyman. In those states you work under a licensed contractor's license as an employee, and you need your own contractor license to run your own shop. Other states license individuals at every level. This is exactly the kind of thing that varies, so confirm how your state licenses plumbers in the Contractor License Checker rather than assuming.
What is backflow certification and is it worth it?
Backflow certification lets you test and certify backflow prevention assemblies, which most states require to be checked on a schedule. It is a separate exam from your plumbing license. It is worth it because backflow testing is recurring, low-overhead work that comes back every year, so it builds a predictable book of business alongside your service work. Whether your state requires it and who administers the exam route to Working in Your State.
The honest bit
- Every number in your path, the apprenticeship hours, the exams, whether your state licenses individuals or only contractors, the gas rule, and the bond, is set by your state and changes over time. Do not copy a neighboring state. Get your specifics from the Contractor License Checker and confirm against your state board's .gov page.
- We do not publish wage or rate figures. What a plumber earns swings by state, sector, and niche (backflow and medical-gas work pay differently than basic service). For real local numbers, use the pricing tools and Working in Your State.
- Code requirements cited here (IPC water-heater rules, gas clearances, the heat-pump water-heater trend) are described as concepts. Which code and energy-code edition applies to you is a per-state question. Confirm your adopted edition before you rely on any specific rule.
- This is general guidance on becoming a plumber, not legal or licensing advice. Confirm with your state board before you take paid work.
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