Commercial Plumbing Contractor in St. Louis, MO & Surrounding Areas
Legacy Plumbing builds complete commercial plumbing systems for general contractors, developers, and facility owners across the St. Louis metro. We deliver ground-up construction, tenant finish, and industrial work through both design-build and plan-and-spec contracts.
- Serving St. Louis since 1996
- UA Local 562 Signatory
- Licensed & Bonded
- Bids answered in 1 business day
- Read our Google reviews
Commercial Plumbing Contractors in St. Louis
Legacy Plumbing is a union commercial plumbing contractor based in O'Fallon, MO. Since 1996 we have served the St. Louis metro and roughly a 2-hour radius, and our work ranges from $500 service calls to $5,000,000 builds. When general contractors compare plumbing contractors in St. Louis, they want a sub that prices clearly, shows up and finishes the scope.
We take work as design-build, design-assist or plan & spec. On every delivery method we self-perform the plumbing from underground through rough-in, trim and startup, with site work referred to Kuesel Excavating, an independent site contractor we refer to. That keeps commercial plumbing St. Louis projects off a chain of separate subs and on one schedule.
Unlike many St. Louis plumbing companies that split construction and service, we give general contractors, developers and facility owners one point of contact from the first budget to closeout — and the same team is there for service after the building opens.
That includes commercial plumbing services after turnover: commercial plumbing repair, backflow testing, water heaters and drain work, scheduled Monday–Friday, 7am–4pm. Property teams looking for plumbers for commercial buildings get the same union crews that build them.
One Plumbing Contractor from Preconstruction to Final Inspection
Choose the project type or delivery method that fits your job. Our team carries the plumbing scope from early pricing through closeout.
Ground-Up Plumbing Systems
Complete plumbing installations from underground utilities and underslab rough-in through trim, testing, and final inspection.
Self-performed from underground through trim and startup.
View Ground-Up Plumbing Systems detailsTenant Finish & Build-Out
Commercial tenant improvements, renovations, and occupied-building build-outs coordinated around the opening schedule.
Scheduled around the tenant's opening date.
View Tenant Finish & Build-Out detailsIndustrial & Specialty Systems
Compressed air, industrial waste, equipment connections, and specialty systems for demanding facilities.
Equipment connections and industrial waste systems.
View Industrial & Specialty Systems detailsDesign-Build & Design-Assist
Early budgeting, constructability review, coordination, and value engineering before the plumbing design is locked.
Pricing and constructability input before drawings lock.
View Design-Build & Design-Assist detailsPlan & Spec
Detailed takeoffs, scope-clear hard bids, installation to the engineer's drawings, and complete closeout documentation.
Installed to the engineer's drawings with full closeout.
View Plan & Spec detailsUnderground & Site Utilities
Self-performed sanitary, storm, water service, and grease waste with our own excavation equipment.
Site work referred to Kuesel Excavating.
View Underground & Site Utilities detailsWhy General Contractors Choose Legacy
- On schedule from ground rough to fixture set.
- One point of contact from preconstruction to closeout.
- Union-trained crews (UA Local 562).
- Closeout package with O&M manuals, as-builts and warranty handoff.
“Legacy kept the plumbing on schedule from underground to fixture set. Their foreman coordinated directly with our super, so we never lost a day waiting on rough-in inspections.”
Request a Commercial Quote
Tell us about your project — we respond within one business day.
Underground & Site Utilities — In-House Across St. Louis
We own and operate our own excavators, skid steers, and mini-excavators so we can self-perform underground sanitary, storm, water service, and grease waste. One trade, one schedule, one point of accountability.
- Underground sanitary & vent
- Storm & roof drain
- Domestic water service
- Grease waste & interceptors
- Site utility tie-ins
- Backflow & meter pits
Commercial Plumbing Across Every Sector
Commercial Service & Maintenance — St. Louis Metro
When a backed-up line or failed water heater threatens revenue, our service division dispatches a stocked truck as scheduled. We support the buildings we build — and the ones we didn't.
- Scheduled service from 7am–4pm Mon–Fri
- Planned preventative maintenance
- Backflow testing & certification
- Water heater & boiler service
- Drain cleaning
- Repipe & leak repair
For Property Managers
Property management plumbing works best on a schedule instead of a string of service calls. Our planned commercial plumbing maintenance program puts backflow testing, water heaters, grease interceptors, drains and pumps on one documented annual schedule across your buildings. For restaurant and food-service tenants we also handle grease trap cleaning in St. Louis.
Commercial Plumbing FAQ
- Who is a good commercial plumbing contractor in St. Louis?
- Legacy Plumbing is a union commercial plumbing contractor based in O'Fallon, MO, serving the St. Louis metro since 1996 with UA Local 562 crews. We handle design-build, design-assist and plan & spec projects, from $500 service calls to $5,000,000 builds, and return bids within one business day.
- Are you a union plumbing contractor?
- Yes, Legacy Plumbing is a UA Local 562 signatory contractor.
- What areas do you serve?
- The St. Louis metro, St. Charles County, Jefferson County and roughly a 2-hour radius of O'Fallon, MO.
- Do you do design-build and plan & spec work?
- Yes, both, plus design-assist on GC-led projects.
- Do you install medical gas?
- Yes, medical gas piping is part of our commercial scope.
- How fast do you turn around a bid?
- We respond to bid requests within 1 business day.
- Do you also handle service and maintenance?
- Yes, from $500 service calls to planned facility maintenance.
Our Process
- 01
Preconstruction
Review drawings, site conditions and schedule with your team.
- 02
Design / Estimating
Size systems, value-engineer and deliver a clear, written number.
- 03
Submittals
Fixture, equipment and material submittals approved before ordering.
- 04
Rough-In
Underground and above-ground piping installed, tested and inspected.
- 05
Trim & Startup
Fixtures and equipment set, water heaters started and balanced.
- 06
Closeout
Final inspection, O&M manuals, as-builts and warranty handoff.
Related Services
Bidding a Project in St. Louis?
Get a bid from a self-performing commercial plumbing contractor headquartered in O'Fallon, MO, serving the greater St. Louis region.