Service · Clayton, MO
Office Building Water Heater Replacement
Replaced twin commercial water heaters over a weekend shutdown.
Commercial Plumbing Contractor · St. Louis Metro Area
St. Louis Commercial Plumbing, Built on Legacy
Legacy Plumbing engineers and installs complex commercial plumbing systems — from early design-assist through final inspection — for general contractors, developers, and facility owners across the St. Louis metro.
Contact Us
Name, phone, email, and a quick note — we respond same business day.
- Since 1996
- Licensed Master Plumbers
- 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.
- BIM / VDC Coordination
- Off-Site Prefab Skids
- Leica Total Station Layout
- Smart Leak Monitoring
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 ProjectsWhat 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 detailsNew Construction Plumbing
Underground rough-in, top-out, trim-out, and final inspection coordination with your GC schedule.
View New Construction Plumbing detailsUnderground & Site Utilities
Sanitary, storm, water service, and grease waste underground for commercial sites and pads.
View Underground & Site Utilities detailsMedical Gas Piping
Brazed med gas and lab gas installed, certified, and tested to NFPA 99.
View Medical Gas Piping detailsBackflow Install & Testing
RPZ and DCVA assemblies installed, repaired, and annually certified for code compliance.
View Backflow Install & Testing detailsCommercial Water Heaters
High-efficiency tank, tankless, and recirculation systems sized for industrial, medium commercial, and medical facilities.
View Commercial Water Heaters detailsService Division (7am–4pm)
Scheduled service Mon–Fri, plus select residential repairs, water heaters, and drain cleaning.
View Service Division (7am–4pm) details 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
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.
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
Industries We Serve
Plumbing Built for Your Facility
Property Management
One plumbing partner for every building in your portfolio.
Learn moreRestaurants & Food Service
Grease interceptors, gas and hot water that keep the kitchen running.
Learn moreHealthcare
Medical gas, dental suites and code-critical systems done right.
Learn moreEducation
Summer-break schedules and restrooms built for heavy use.
Learn moreIndustrial & Manufacturing
Industrial plumbing, trench drains and plant shutdown work.
Learn moreMultifamily
Stacked rough-in and repeatable units for apartment builds.
Learn moreFeatured Projects
Recent Work Across the St. Louis Metro
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.
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.
FAQSee all commercial plumbing FAQs
Frequently Asked Questions
Answers about scheduling, service area, pricing, and qualifications across the St. Louis metro.
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.