Commercial and Industrial Plumbing in Union, MO

Union runs its own permits, inspections and water department, and a few of its rules can catch a schedule off guard. Here's what to know before you plan a Union job.

Who you'll deal with in Union

The city's commercial booklet asks that every commercial project be reported to Building & Engineering, and the fire district reviews plans under its own separate permit. Every contractor and subcontractor needs a City of Union business license before starting work. Union has adopted the 2021 International Plumbing Code, along with the 2021 IBC, IMC, IFGC and IECC and the 2020 NEC.

Inspections: pressure tests and timing

Union requires an air or water pressure test at the under-floor plumbing inspection and again at rough-in. Inspections need 24 hours' notice. If you call before 8:30 a.m., the city will try for a same-day inspection. Re-inspections carry a fee, so we test our own work before calling for one. On slab-on-grade buildings, we sequence under-floor rough-in with the slab pour, which is the same approach in our underground-before-the-slab checklist.

Water and sewer taps: size decides the schedule

This is the part of a Union job most likely to set the schedule:

• Meters. The city stocks water meters up to 2". A larger meter has to be ordered through the city, so the Water Department asks that you call early.
• Taps. The city doesn't make taps larger than 1". A larger service, such as a plant's domestic line or a combined fire service, needs a contractor-arranged tap.
• Water tap excavation. It needs to be ready by 2:00 p.m. with 24 hours' notice, at least 36" wide, at least 4" below and behind the main, with at least 18" of main exposed and cleaned. The line is pressure tested.
• Sewer connection. The city provides the saddle and tap, and the contractor does the rest. The connection is concreted and inspected.
• Inspection before backfill. The Water Department inspects water and sewer hookups before backfill. An excavation that doesn't meet the rules can be failed.
• Street cuts. Hard surfaces are saw-cut, then backfilled with Type 1 aggregate in 6" lifts compacted to 95% standard Proctor, or with flowable fill, and restored within two weeks.
• Fire lines. The city's own booklet warns that not every main is big enough for a fire line, and that gas isn't available everywhere. Check both before buying a site.

For a new building in Union, we settle the service size, meter size and who makes the tap during design. Otherwise they can turn into a long-lead item at the end. This is everyday work for our underground and site utilities crews. Our sister company Kuesel can handle larger site water and sewer mains when a project needs them.

Backflow containment for Union's plants

Union's water system falls under Missouri's backflow rule, 10 CSR 60-11.010. The rule sorts customers by hazard, and Union's mix of industry puts many buildings in the top class:

• Class I (reduced-pressure assembly or air gap). The state list includes metal or plastic manufacturing and fabrication; packing houses; beverage, dairy and bottling plants; pharmaceutical plants; laboratories, including those at schools and colleges; medical and dental offices; car washes; buildings with boilers or pumped heating and cooling systems; and fire sprinkler systems with chemical additives.
• Class II (double check valve assembly at minimum). This includes fire sprinkler systems without additives (new or modified) and irrigation systems without chemical injection.
• Installation. The containment assembly goes as close to the service connection as practical, ahead of any branch. Bypasses aren't allowed unless they're equally protected. An RP's relief port must sit at least 12" above the floor and can't be plugged, which matters when a mechanical room is tight.
• Testing and reporting. Each assembly is tested when installed and then every year, no later than 30 days past its anniversary date. Test reports go to the water supplier within 30 days. If a report isn't received within 60 days after the anniversary, the supplier must notify the customer, the local government and DNR. The supplier can shut off service to an unprotected cross-connection.

Union also requires annual inspection of irrigation backflow devices by a licensed inspector, with the paperwork filed at City Hall.

Plant expansions and process changes are the usual trigger. When a Class I facility modifies its water system, it's a good time to confirm the containment assembly is the right type and still accessible. We install, test and rebuild RP, double check and PVB assemblies. See backflow testing and compliance or try our backflow compliance tool.

What's growing in Union

• Union Corporate Center. The city's industrial park has U.S. 50 access, all utilities and fiber. Its tenants include Volpi Foods, Silgan, Pharma Tech, Heat and Control and EMJ Metals, and the city is still marketing open sites there.
• Parkside Business Center. This is a planned six-lot, roughly 21-acre commercial development on Progress Parkway. In late October 2026 it received a Planning and Zoning recommendation on its preliminary plat, and site preparation began.
• East Central College. The college brings lab, classroom and food-service plumbing to town.

These are listed as local context. Legacy Plumbing isn't claiming work on them.

How Legacy Plumbing helps in Union

• New construction plumbing for industrial, retail and institutional buildings
• Industrial plumbing: equipment hookups; trench drains; eyewash and safety showers; planned shutdown tie-ins.
• Tenant finish for new retail and office suites
• Backflow installation, annual testing and reporting
• Preventive maintenance and commercial water heaters for plants and schools
• Education and manufacturing facility experience

Scheduled work runs Monday through Friday, 7 a.m. to 4 p.m. Night, weekend and shutdown work can be scheduled ahead of time at premium rates.

Similar work

• Manufacturing facility, St. Peters: a new domestic service with backflow prevention, sanitary and trench drains laid out for the production floor, and underground sequenced with the slab.
• Cold storage facility, Foristell: ground-up plumbing and site utilities for a 100,000+ sq ft distribution building.
• Facility water heater and backflow program: RPZ installs and annual certification with municipal reporting across a multi-site portfolio.