# Commercial Plumbing Contractors in St. Louis, MO | Legacy > Union commercial plumbing contractor serving St. Louis since 1996: new construction, tenant finish, medical gas and service. Request a bid. Canonical: https://legacyplumbingmo.com/commercial Last updated: 2026-10-29 Commercial Plumbing 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. [Request a Project Bid](https://legacyplumbingmo.com/contact-us) [Call 636-978-0120](tel:+16369780120) - Serving St. Louis since 1996 - UA Local 562 Signatory - Licensed & Bonded - Bids answered in 1 business day - [Read our Google reviews](https://www.google.com/maps/place/?q=place_id:ChIJVZ_RvFh0PEQRENfYXJfxiv0) ## 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. Construction Capabilities ## 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 details ### Tenant 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 details ### Industrial & Specialty Systems Compressed air, industrial waste, equipment connections, and specialty systems for demanding facilities. Equipment connections and industrial waste systems. View Industrial & Specialty Systems details ### Design-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 details ### Plan & 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 details ### Underground & 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 details ## Why 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.” Senior Superintendent, General Contractor ## Request a Commercial Quote Tell us about your project — we respond within one business day. Self-Performing Contractor ## 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 Industries We Serve ## Commercial Plumbing Across Every Sector [Restaurants & QSR](https://legacyplumbingmo.com/industries/restaurants-food-service) [Multi-Unit Residential](https://legacyplumbingmo.com/industries/multifamily) Retail & Mixed-Use [Medical & Dental](https://legacyplumbingmo.com/industries/healthcare) Car Washes [Industrial & Warehouse](https://legacyplumbingmo.com/industries/industrial-manufacturing) Office & Tenant Build-Outs Specialty Facilities ## 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 [Request Commercial Service](https://legacyplumbingmo.com/contact-us) ## For Property Managers Property management plumbing works best on a schedule instead of a string of service calls. Our [planned commercial plumbing maintenance](https://legacyplumbingmo.com/facility-services/preventive-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](https://legacyplumbingmo.com/facility-services/grease-trap-cleaning) . ## 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](https://legacyplumbingmo.com/services/medical-gas) 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](https://legacyplumbingmo.com/services/service-repair) . How We Build ## 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 - [Bid-Spec (Plan & Spec) Projects](https://legacyplumbingmo.com/commercial/bid-spec) - [Ground-Up New Construction](https://legacyplumbingmo.com/services/new-construction) - [Design/Build & Preconstruction](https://legacyplumbingmo.com/commercial/design-build) - [Underground & Site Utilities](https://legacyplumbingmo.com/commercial/underground-site-utilities) - [Industrial Plumbing](https://legacyplumbingmo.com/commercial/industrial-plumbing) - [Backflow Prevention & Testing](https://legacyplumbingmo.com/commercial/backflow-prevention) - [Commercial Hydro Jetting](https://legacyplumbingmo.com/facility-services/hydro-jetting) - [Commercial Leak Detection](https://legacyplumbingmo.com/facility-services/commercial-leak-detection) - [Sewer Camera Inspection](https://legacyplumbingmo.com/facility-services/sewer-camera-inspection) - [Grease Trap & Interceptor Service](https://legacyplumbingmo.com/facility-services/grease-trap-cleaning) - [Commercial Water Heaters](https://legacyplumbingmo.com/facility-services/commercial-water-heaters) ### Next Steps - [Request Service](https://legacyplumbingmo.com/request-service) - [View All Commercial Services](https://legacyplumbingmo.com/commercial) - [Request a Free Estimate](https://legacyplumbingmo.com/contact-us) ## 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. [Get Free Estimate](https://legacyplumbingmo.com/contact-us) [636-978-0120](tel:+16369780120) ## Related - [Contact Legacy Plumbing](https://legacyplumbingmo.com/contact-us) - [Company facts](https://legacyplumbingmo.com/company-facts) - [All pages (llms.txt)](https://legacyplumbingmo.com/llms.txt)