How to Choose a Commercial Plumbing Company in St. Louis

Short answer: Hire a commercial plumbing company that holds master plumbing licenses in the jurisdictions where your buildings are, has trained (ideally union) plumbers, can handle both construction and ongoing service, documents its work, and prices clearly. Residential and commercial plumbers are not interchangeable — commercial systems, codes and stakes are different.

Commercial vs. residential plumbers

Commercial work involves larger pipe sizes, multi-story drainage, backflow assemblies, grease interceptors, medical gas in healthcare settings, booster pumps and code inspections that residential shops rarely see. It also means working around tenants, schedules and safety programs. Ask any company you are considering what share of its work is commercial.

1. Licensing where your buildings are

St. Louis County, St. Louis City, St. Charles County and many municipalities each license plumbers separately. Confirm the company's master plumber is licensed in every jurisdiction you need, and that it pulls permits in its own name.

2. Who does the work

Ask whether the plumbers are employees, how they are trained, and whether the company is a union signatory. Union plumbers complete multi-year apprenticeships and continuing training — valuable on complex commercial systems and on projects with prevailing-wage or labor requirements. Read more on what union signatory means for owners.

3. Construction and service under one roof

The best long-term partner can build out a space and then maintain it. Ask whether the company handles: tenant finish and renovation plumbing; service and repair for occupied buildings; backflow testing and certification; water heaters, drain cleaning and hydro jetting; preventive maintenance programs.

4. Responsiveness and scheduling

For occupied buildings, ask how service calls are scheduled, whether work can be done after hours to avoid disrupting tenants, and how you will get updates.

5. Safety and insurance

Request the company's EMR, certificate of insurance and safety program. GCs and property managers should confirm coverage limits match their contracts.

6. Documentation

Good commercial plumbers provide photos, test reports, backflow certifications and clear invoices tied to the work done — the paper trail matters for audits, insurance and the next contractor.

7. Clear pricing

For projects, expect a detailed proposal with inclusions and exclusions. For service, ask about rates, trip charges and how quotes are approved before work starts.

Quick checklist

• Master plumbing licenses in your jurisdictions
• Mostly commercial work
• Employee or union plumbers
• Construction and service capability
• Backflow testing certification
• Insurance and safety record that fit your contract
• Clear proposals and documented work

Frequently asked questions

What does a commercial plumber do?

Installs, maintains and repairs plumbing in commercial, institutional and industrial buildings — water supply, drainage, venting, fixtures, water heaters, backflow assemblies and related systems.

Do I need a licensed plumber in St. Louis County for commercial work?

Yes. Plumbing work generally requires a licensed plumber and a permit from the governing jurisdiction.

Is a union plumbing contractor more expensive?

Not necessarily on total cost. Trained crews often finish faster with fewer callbacks, and some projects require union or prevailing-wage labor.

Looking for a commercial plumbing partner? Learn about Legacy Plumbing in St. Louis or contact our team for a proposal.