# Legacy Plumbing | Commercial Plumbing Contractor O'Fallon MO > Commercial plumber in O'Fallon, MO serving St. Louis & St. Charles County since 1996: new construction, tenant finish, service, backflow and med gas. Canonical: https://legacyplumbingmo.com/ Last updated: 2026-10-29 Built on Legacy · O'Fallon, MO · Since 1996 Legacy Plumbing is a commercial plumbing contractor based in O'Fallon, MO, providing [commercial plumbing in St. Louis](https://legacyplumbingmo.com/locations/st-louis) and across the metro. We engineer and install complex commercial plumbing systems — from early design-assist through final inspection — for general contractors, developers, and facility owners across the St. Louis metro. As plumbers for commercial buildings — offices, schools, medical and dental clinics, restaurants, warehouses and multi-family — our crews build new systems and keep existing ones running. [Request a Project Bid](https://legacyplumbingmo.com/contact-us) [Call 636-978-0120](tel:+16369780120) ## Contact Us Name, phone, email, and a quick note — we respond same business day. - Since 1996 - Master Plumbers on Staff - Licensed to Pull Permits Throughout the St. Louis Area - UA Local 562 Union Workforce - Scheduled Service 7am–4pm - Fully Insured 30 Years in Business 500+ Projects Completed 40+ Jurisdictions Licensed 1 Day Response Time Any Size, Any Scope ## From $500 Service Calls to $5,000,000 Builds A scheduled faucet repair during business hours or a ground-up healthcare campus — the same Legacy crew shows up with the same standards, the same tools, and the same accountability. Service & Repairs Tenant Build-Outs Industrial & Warehouse Medium Commercial & Office Healthcare & Medical Underground & Site Utilities Multi-Unit Residential Design/Build Mega-Projects Modern Plumbing, Built on Legacy ## State-of-the-Art Techniques on Every Project BIM/VDC preconstruction, off-site prefabrication, ProPress, Leica total station layout, hydro-excavation, and IoT leak monitoring — modern tools in the hands of union-trained Local 562 craftsmen. Learn how our [commercial plumbing contractors in St. Louis](https://legacyplumbingmo.com/commercial) run a project. - BIM / VDC Coordination - Off-Site Prefab Skids - Leica Total Station Layout - Smart Leak Monitoring [Explore Our Technology](https://legacyplumbingmo.com/innovation) Construction Capabilities ## Bid-Spec, Design/Build & Industrial Plumbing Construction Whether the drawings are already stamped, the design is still on a napkin, or the system has to survive a production floor, Legacy Plumbing delivers the same self-performed installation — priced honestly, built to spec, and sequenced to your schedule. ### Bid-Spec Projects You have plans and specs from your engineer. We take off the drawings, return a scope-clear hard bid, and install the system exactly as designed. Explore Bid-Spec Projects ### Design/Build Projects Bring us in at concept. We budget early, model the system in BIM/VDC, value engineer with your design team, then prefab and install it. Explore Design/Build Projects ### Industrial Projects Compressed air, industrial waste and neutralization, trench drains, and plant shutdown work for demanding facilities. Explore Industrial Projects What We Do ## Commercial Plumbing Services in St. Louis, MO & Surrounding Areas Self-performing commercial plumbing for general contractors, developers, and facility owners — plus a service division that handles everything after the ribbon-cutting. ### Design/Build Commercial Plumbing Full design/build delivery for ground-up commercial construction across the St. Louis metro. View Design/Build Commercial Plumbing details ### New Construction Plumbing Underground rough-in, top-out, trim-out, and final inspection coordination with your GC schedule. View New Construction Plumbing details ### Underground & Site Utilities Sanitary, storm, water service, and grease waste underground for commercial sites and pads. View Underground & Site Utilities details ### Medical Gas Piping Brazed med gas and lab gas installed, certified, and tested to NFPA 99. View Medical Gas Piping details ### Backflow Install & Testing RPZ and DCVA assemblies installed, repaired, and annually certified for code compliance. View Backflow Install & Testing details ### Commercial Water Heaters High-efficiency tank, tankless, and recirculation systems sized for industrial, medium commercial, and medical facilities. View Commercial Water Heaters details ### Service Division (7am–4pm) Scheduled service Mon–Fri, plus select residential repairs, water heaters, and drain cleaning. View Service Division (7am–4pm) details Restaurants and kitchens: we also provide [grease trap cleaning in St. Louis](https://legacyplumbingmo.com/facility-services/grease-trap-cleaning) , plus interceptor repair and installation. Our Priority ### Commercial Construction & Site Work Ground-up new construction, underground site utilities, design/build, med gas, and tenant build-outs for St. Louis developers and GCs. Explore commercial work → Service Division ### Service, Repair & Residential Scheduled commercial service Mon–Fri 7am–4pm, plus select residential repairs — water heaters, drain cleaning, and leak repair across the metro. See service options → Why GCs & Owners Choose Legacy Legacy Plumbing — commercial plumbing contractor in O'Fallon & St. Louis, MO since 1996 ## A St. Louis Commercial Plumbing Partner That Hits the Schedule In commercial construction, plumbing drives the schedule. Our crews show up staffed, sequenced, and ready to keep your GC timeline on track. - ### Self-Performing Underground In-house excavation, skid steers, and mini-excavators for sanitary, storm, and water service. - ### Design/Build & Preconstruction Early-stage budgeting, value engineering, and constructability review with your design team. - ### Code & Inspection Experts Deep knowledge of MO plumbing code, backflow, med gas certification, and municipal permitting. - ### Service Division That Backs the Build When the punch list closes, our scheduled service division keeps your facility running. [About Legacy Plumbing](https://legacyplumbingmo.com/about-us) Service Area ## Local Plumbers Across the St. Louis Metro & 2-Hour Radius Headquartered in O'Fallon, MO and serving homeowners, property managers, and businesses across the St. Louis metro and a 2-hour radius. ### St. Charles County - • O'Fallon - • St. Charles - • St. Peters - • Wentzville - • Lake St. Louis - • Dardenne Prairie - • Cottleville - • Weldon Spring ### St. Louis County - • Chesterfield - • Clayton - • Ladue - • Kirkwood - • Webster Groves - • Creve Coeur - • Ballwin - • Maryland Heights ### St. Louis City - • Central West End - • Lafayette Square - • Soulard - • The Hill - • Tower Grove - • Downtown - • Midtown - • South City [View Full Service Area](https://legacyplumbingmo.com/service-areas) [636-978-0120](tel:+16369780120) Industries We Serve ## Plumbing Built for Your Facility ### Property Management One plumbing partner for every building in your portfolio. Explore property management plumbing ### Restaurants & Food Service Grease interceptors, gas and hot water that keep the kitchen running. Explore restaurants & food service plumbing ### Healthcare Medical gas, dental suites and code-critical systems done right. Explore healthcare plumbing ### Education Summer-break schedules and restrooms built for heavy use. Explore education plumbing ### Industrial & Manufacturing Industrial plumbing, trench drains and plant shutdown work. Explore industrial & manufacturing plumbing ### Multifamily Stacked rough-in and repeatable units for apartment builds. Explore multifamily plumbing Featured Projects ## Recent Work Across the St. Louis Metro Service · Clayton, MO ### Office Building Water Heater Replacement Replaced twin commercial water heaters over a weekend shutdown. Design-Build · Chesterfield, MO ### Dental Office Build Designed and installed dental vacuum, air and domestic water. Plan & Spec · Wentzville, MO ### Distribution Warehouse Bid and installed underground, restrooms and trench drains to spec. Service · St. Charles, MO ### Backflow Testing Program Annual testing and repairs across a multi-building portfolio. Design-Build · O'Fallon, MO ### Manufacturing Plumbing Engineered water and waste systems and equipment tie-ins. Plan & Spec · St. Louis, MO ### School Restroom Renovation Summer-break restroom and fixture replacement per engineer's plans. [View all projects](https://legacyplumbingmo.com/projects) ## What Clients Say “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 Trusted Industry Partnerships ## Union-trained. Industry-backed. Proud signatory and member — bringing certified craftsmanship and industry standards to every Legacy Plumbing project. [UA Local 562 Union-trained craftsmanship and apprenticeship pipeline.](https://local562.org/en) [MCA of Eastern Missouri Mechanical Contractors Association member — industry advocacy and standards leadership.](https://www.mca-emo.com/) [BOMA St. Louis Building Owners and Managers Association of St. Louis.](https://bomastl.org/) FAQ ## Frequently Asked Questions Answers about scheduling, service area, pricing, and qualifications across the St. Louis metro. [See all commercial plumbing FAQs](https://legacyplumbingmo.com/faq) ## Schedule Your Free Estimate Four quick fields — we respond same business day. Office Hours Mon–Fri 7:00 AM – 4:00 PM, Sat–Sun Closed 811 N Main St, O'Fallon, MO 63366 ## Need a Plumber in St. Louis or the Surrounding Area? Written bids within one business day, scheduled service Monday–Friday 7am–4pm, and union-trained crews since 1996 across the St. Louis metro and a 2-hour radius. [Get Free Estimate](https://legacyplumbingmo.com/contact-us) [636-978-0120](tel:+16369780120) ## Frequently Asked Questions ### Do you only work on commercial buildings? Mostly. Legacy Plumbing is primarily a commercial plumbing contractor, building and servicing plumbing for commercial, institutional and industrial buildings across the St. Louis metro since 1996. Our service division also handles select residential service — repairs, water heaters, drains, and gas lines. ### 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. ### Who is the best commercial plumber near me in St. Louis? Legacy Plumbing is primarily a commercial plumbing contractor, and our service division also handles select residential service — repairs, water heaters, drains, and gas lines. We serve St. Louis City, St. Louis County, St. Charles County, and Jefferson County from our O'Fallon, MO shop. We have built commercial and industrial plumbing systems since 1996, and every job runs under master-licensed supervision with UA Local 562 crews. The best way to compare us is to send drawings or a scope — we return a written bid within one business day. ### Do you offer after-hours or emergency commercial plumbing? No — we do not staff an overnight on-call crew, and we would rather tell you that than leave you waiting on a phone tree. Legacy Plumbing schedules commercial service across the St. Louis metro from 7am–4pm Mon–Fri. Call 636-978-0120 and we will get you on the board for the earliest window we have. ### How fast can you respond to a commercial plumbing emergency? For urgent commercial calls in St. Louis, St. Charles, and Jefferson County we aim for same-day response during our 7am–4pm service hours. Our service trucks are stocked for the common failures — burst lines, sewer backups, water heater failures, and gas leaks — so the first visit is usually the repair visit. Buildings on a maintenance agreement get priority scheduling. ### What areas do you serve? Legacy Plumbing serves the entire St. Louis metro from our O'Fallon, MO office — St. Louis City and County, St. Charles County, Jefferson County, plus Lincoln and Warren counties. That includes O'Fallon, St. Charles, St. Peters, Wentzville, Chesterfield, Arnold, and the surrounding communities within about a two-hour radius. If your building is near that line, call and we will tell you honestly whether we can cover it. ### Are your plumbers licensed in St. Louis City and County? Yes. Legacy Plumbing has master plumbers on staff and holds the licensing to pull plumbing permits in the City of St. Louis, St. Louis County and its municipalities, and every other St. Louis–area jurisdiction we serve, including St. Charles County and Jefferson County. We file the permits ourselves, and we are bonded and insured for commercial and industrial scopes. ### Do you handle medical gas plumbing installation? Yes. We install, repair, and test medical gas systems for hospitals, surgical centers, dental offices, and veterinary clinics throughout the St. Louis metro. Our brazers are ASSE 6010 certified, the piping is installed under nitrogen purge to NFPA 99, and we coordinate the third-party ASSE 6030 verifier and hand over the documentation your compliance file needs. ### Do you self-perform underground and site utilities? Yes. Sanitary, storm, domestic water service, and grease waste underground are self-performed with our own excavation equipment on commercial sites across St. Louis and St. Charles County. Keeping that scope in-house means the underground is coordinated with the slab schedule instead of subbed out and hoped for. ### Do you provide free estimates for commercial plumbing in St. Louis? Yes. Bid requests and commercial estimates in the St. Louis metro are free and carry no obligation. If you would rather skip the estimate and get moving, we can also begin work on a time-and-material basis. ## 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)