A commercial plumber installs, services, and repairs the plumbing in large buildings — offices, schools, hospitals, hotels, retail, and industrial facilities — where the piping serves hundreds of people instead of one household.
The systems are bigger, more of the work runs from engineered plans, and the code and inspection regime is heavier than on a house.
Here is the job, the systems, the skills, the licensing, and the pay.
What does a commercial plumber do?
A commercial plumber is a plumber whose job site is the non-residential building: offices, schools, hospitals, hotels, retail space, and industrial facilities.
The federal definition of the trade already covers the setting — BLS describes plumbers as installing and repairing water, gas, and other piping systems in homes, businesses, and factories, along with the fixtures such as bathtubs and toilets and the appliances such as dishwashers and water heaters connected to them.
Commercial plumbing is the business-and-factory end of that definition, at building scale.
Day to day, that changes the texture of the work more than the trade itself.
The water supply, drain-waste-vent, and fixture work is the same plumbing a house needs — there is just more of it, the pipe runs are longer, and hundreds of people depend on it working.
You spend more of the day building from plans and specifications instead of improvising, coordinating with other trades in shared ceilings and shafts, and passing staged inspections before walls close.
Big pipe and big buildings also take more hands, so commercial work runs in crews rather than as one plumber and a van.
If you are starting from zero, the plumber career guide covers the trade as a whole — the license ladder, the full job-title map, and every work setting including this one.
This page stays on the commercial lane.
Commercial systems: large DWV, booster pumps, grease interceptors, med gas
The systems are where commercial work stops feeling like big residential plumbing.
Four of them define the lane.
Large drain-waste-vent.
A whole building's drains, waste lines, and vents get sized for its fixture count, so pipe diameters grow well beyond anything in a house — and the slope rules change with size.
Under the 2024 International Plumbing Code, Table 704.1 sets the minimum slope for horizontal drainage pipe at 1/4 inch per foot for pipe 2-1/2 inches or smaller, 1/8 inch per foot for 3- to 6-inch pipe, and 1/16 inch per foot for 8-inch and larger.
The 1/4-inch-per-foot rule you learn as an apprentice is the small-pipe minimum, not a universal.
Grease interceptors.
Restaurants and institutional kitchens send grease-laden waste through its own interceptor before it reaches the sewer, and the code treats the piping feeding it specially: IPC 704.1 requires at least 1/4 inch per foot (a 2-percent slope) for drainage piping upstream of a grease interceptor, regardless of pipe size.
Booster pumps.
In taller commercial buildings, booster pump systems raise the pressure of the water supply so it reaches the upper floors.
Medical gas.
Hospitals and clinics pipe medical gases to patient rooms and operating suites, and the standards work is specialized: the ASSE/IAPMO/ANSI Series 6000-2024 standards define separate roles for 6010 Installers, 6020 Inspectors, 6030 Verifiers, 6035 Bulk Medical Gas/Cryogenic Fluid Central Supply Verifiers, 6040 Maintenance Personnel, 6060 Designers, and 6070 Design Instructors, and the 2024 series is aligned with the medical gas requirements of NFPA 99-2024.
States layer credential requirements on top of the plumbing license — Iowa, for example, requires a separate board-approved certification to install or repair medical gas piping, and applicants need a valid NITC (or equivalent) certification.
Model-code numbers are minimums — your local code governs
Typical commercial jobs: new construction vs service
Commercial plumbing jobs split into two calendars, and most plumbers develop a feel for one or the other.
New construction is the build-it side: you rough in drains, water lines, and vents while the building is open framing, set equipment, tie the new system into the water and sewer mains, and trim out fixtures as the building finishes.
The work comes from engineered drawings and specifications, inspections happen at fixed stages, and your schedule rides the construction cycle — sequence with concrete, steel, and the other trades, not with who called in a leak this morning.
Commercial service is the keep-it-running side: repairs, maintenance contracts, retrofits, and tenant improvements in buildings that are open for business.
A hospital floor, a school wing, or an office tower cannot simply shut its water off while you figure it out, so the job is diagnosis, planning around the building's operations, and making the repair with the least disruption.
Service work rewards troubleshooting speed and clear communication with building engineers and managers.
The two sides share the systems from the section above, and plenty of plumbers cross between them over a career — construction when the local build cycle is busy, service when it is not, or a foot in each at a contractor that runs both divisions.
Skills and licensing commercial work requires
The skill set is the residential one, extended.
Reading construction drawings and specifications matters more, because the engineer's plans drive the install.
The pipe itself gets bigger, and the commercial material mix — copper, cast iron, and plastic — is core, tested skill territory rather than an extra: Indiana's plumbing apprenticeship schools, for instance, must give a practical exam with copper, cast iron, and plastic pipe assembly projects, scored 70% on each, before a 4-year apprenticeship counts as complete.
Add blueprint fluency, coordination with other trades, and comfort working under an inspector's sign-off schedule, and you have the commercial profile.
Licensing is where the residential and commercial tracks can genuinely split.
Colorado licenses plumbers statewide through the State Plumbing Board (Division of Professions and Occupations) at three levels — Residential Plumber, Journeyworker Plumber, and Master Plumber.
Louisiana licenses a Residential Plumber of its own — 3,000 hours of plumbing work under a licensed master (as an indentured apprentice in an LWC-approved program) or 4,000 hours (as an unindentured registered apprentice).
And under Georgia's 2026 statute, Master Plumber Class I may work on single-family homes, townhomes, and multifamily buildings up to three stories plus commercial buildings up to 20,000 square feet, while Class II has no scope limit.
Where a licence is scoped to residential work like Georgia's Class I, the commercial setting belongs to the general licence above it.
The full ladder, and what each state asks, is our plumbing license guide.
The split is also formal at the contractor level: Mississippi licenses plumbing businesses through its State Board of Contractors, whose commercial Plumbing specialty covers sanitary and storm drainage, venting, water supply, septic tanks, and medical gas and related piping — but not fuel gas or boiler systems.
(Our research did not find a statewide individual plumber licence in Mississippi; cities may license plumbers locally.)
And specialties like medical gas carry their own credential requirements on top of the license, as the section above covers.
Licensing is state and local — confirm before you plan
Commercial plumber pay and schedules
Start with what the federal data cannot say: there is no "commercial plumber salary" in BLS statistics.
The Occupational Employment and Wage Statistics program publishes one combined occupation — Plumbers, Pipefitters, and Steamfitters, SOC 47-2152 — and no separate wage for residential versus commercial, service versus new construction, or journeyman versus master.
Any table that prices "commercial plumber" against "residential plumber" from federal data is making the split up.
What the combined occupation does show, from OEWS May 2025: a median wage of $30.67 an hour, or $63,800 a year, with the 10th percentile at $21.22 an hour ($44,150 a year) and the 90th at $52.13 an hour ($108,420 a year).
The closest cut to "type of employer" is industry: at plumbing, heating, and air-conditioning contractors (NAICS 238220), the combined occupation counted 330,570 jobs with a $63,010 median — and that employer industry still mixes commercial and residential firms alike.
For the full tables, national and by state, see our plumber salary page, and our plumber pay scale guide compares apprentice, journeyman, and master pay.
Schedules and pay structure are where commercial work genuinely differs.
On the public side, the Davis-Bacon and Related Acts apply to contractors on federally funded or assisted construction contracts over $2,000, and workers must receive at least locally prevailing wages and fringe benefits; on Davis-Bacon contracts over $100,000, the Contract Work Hours and Safety Standards Act also requires time-and-a-half for hours over 40 in a workweek.
Union presence is part of the same picture: BLS counted union membership at 16.4% among wage-and-salary workers in construction and extraction occupations in 2025 (17.4% represented by unions), against 12.5% in installation, maintenance, and repair occupations — though BLS publishes no union rate for plumbers specifically.
Our plumbers and pipefitters union guide covers how UA membership works.
Outlook is published for the combined trade too: employment is projected to grow 6.8% from 2025 to 2035, with about 42,000 openings a year on average — above the 3.5% all-occupation average.
How to move into commercial plumbing
There is no separate commercial plumbing license to chase — the move is about where you train and which contractors you build your hours with.
The one licence question is scope: where a state issues residential-scoped licences, commercial work sits outside them (see the licensing section above).
Learn the trade
Most plumbers, pipefitters, and steamfitters learn through a 4- or 5-year apprenticeship with about 2,000 hours of paid on-the-job training each year plus technical instruction, per BLS. Our plumbing apprentice guide and how-to-become guide cover the entry routes.Get licensed where your state licenses
The individual ladder — apprentice, journeyman, master — is the same one commercial plumbers ride. Requirements are set by your state board, or the city or county where licensing is local.Pick commercial employers
Apply to mechanical and plumbing contractors that run commercial construction or commercial service divisions. That is where the large DWV, booster pump, interceptor, and plan-reading hours accumulate.Add the specialty credentials as your work demands them
Medical gas is the clearest example — the ASSE 6000-series roles and your state's own endorsement requirements govern who can install it. Let the work you are bidding set which credentials come next.Or cross over mid-career
Residential plumbers move into commercial settings all the time: the systems are the same trade at scale, and the new material — bigger pipe, engineered drawings, staged inspections — is learned on the job with a commercial crew. If your licence is a residential-scoped one, check its scope with your board before you switch.
When you are ready to work, the plumbing job listings are the place to start.
Career and pay information, not legal or licensing advice. Requirements, code rules and wages vary by state, city and employer — confirm what applies to you with your state licensing board, or the city or county where licensing is local, before you make a decision.