Commercial Backflow Testing & Certification in St. Louis
RPZ, DCVA, and PVB install, repair, and annual certification for St. Louis commercial buildings — with the paperwork filed to your local water authority so you stay in compliance.
Schedule a Test or Install
Tell us about your project — we respond within one business day.
Stay certified and inspection-ready.
We provide annual backflow testing, repair, and replacement by certified testers, and we file your results with the water authority. We also handle grease interceptor maintenance to keep you compliant with MSD FOG requirements.
Schedule TestingIncludes
- Annual backflow testing
- Backflow repair and replacement
- Results filed with the water authority
- Grease interceptor maintenance (MSD FOG)
Backflow Testing and Certification in St. Louis
Backflow testing confirms that the backflow preventer on a building's water service, fire line or irrigation connection still keeps used water from flowing back into the public supply. Commercial assemblies, including reduced-pressure zone (RPZ), double-check valve (DCVA) and pressure-vacuum breaker (PVB) assemblies, are typically tested every year on the schedule your water provider sets. Certified testers use calibrated gauges, and the certified test report is filed with the local water authority on your behalf.
Backflow preventer testing is required across restaurants and quick-service kitchens, healthcare and dental offices, multifamily buildings, schools and universities, industrial and warehouse facilities, retail, hotels and car washes. Property managers can put a whole portfolio on one annual program with one schedule, one invoice and every report filed.
Legacy Plumbing serves St. Louis City, St. Louis County, St. Charles County and Jefferson County from our O'Fallon, MO shop, and has since 1996, with UA Local 562 crews. Testing is typically $250–$500 per assembly per year (estimate; final price depends on device size, number of devices and access), scheduled Monday–Friday, 7am–4pm.
Related: Backflow Compliance Checker · Preventive Maintenance Plans · Commercial Water Heaters · commercial plumbing contractors in St. Louis
Service areas: St. Louis · St. Charles County · Jefferson County
Backflow Services for St. Louis Commercial Buildings
From new install to annual certification — one certified team, one paperwork trail.
RPZ Install & Replacement
Reduced-pressure zone assemblies sized, installed, and certified for high-hazard commercial connections.
View RPZ Install & Replacement detailsDCVA & PVB Install
Double-check valve and pressure-vacuum breaker assemblies for fire mains and irrigation.
View DCVA & PVB Install detailsRepair & Rebuild
Rubber-goods kits, check repairs, and full rebuilds — same-day service so you stay in compliance.
View Repair & Rebuild detailsAnnual Certification Testing
Certified testers, calibrated gauges, and reports filed with the local water authority on your behalf.
View Annual Certification Testing detailsFailed Test Response
If an assembly fails, we repair and retest fast — no shut-off notice from the water utility.
View Failed Test Response detailsCross-Connection Surveys
Walkthroughs and risk assessments to identify unprotected cross-connections before the utility does.
View Cross-Connection Surveys detailsRPZ, DCVA and PVB Assemblies
We test reduced-pressure zone (RPZ), double-check valve (DCVA) and pressure-vacuum breaker (PVB) assemblies on the three lines where commercial buildings carry them:
- Domestic water services
- Fire sprinkler lines, coordinated with your fire sprinkler contractor
- Irrigation systems
When an Assembly Fails
- 1
Diagnose
The tester identifies which check or relief valve failed and why.
- 2
Repair or Rebuild
Common rebuild parts ride on the truck, so most repairs happen on the same visit.
- 3
Replace if Needed
Assemblies that can't be rebuilt are replaced with a properly sized unit.
- 4
Retest & Report
We retest the assembly and handle the test report with your water provider.
Certified Backflow Testers Across the St. Louis Metro
Missouri-licensed backflow testers with calibrated gauges, parts on the truck, and direct working relationships with St. Louis–area water authorities. No back-and-forth, no missed annuals.
- Missouri-licensed testers
- Calibrated gauges on file
- RPZ/DCVA parts in stock
- Reports filed for you
- Portfolio program management
- Same-day repair & retest
St. Louis Facilities We Keep Compliant
How It Works
Once you're on the program, we track the annual due date, schedule the test, file the paperwork, and only call you if something fails.
- 1
Onboarding & Inventory
We map every assembly across your portfolio with size, location, and current due dates.
- 2
Scheduled Annual Test
Certified test in line with your local St. Louis water authority's renewal date.
- 3
Repair if Needed
If anything fails, we repair on the same visit when possible and retest on the spot.
- 4
Filed Documentation
Certified test report submitted to the water authority and copied to your facilities team.
St. Louis Commercial Backflow — FAQs
- What is backflow testing?
- Backflow testing checks that a backflow preventer, such as an RPZ, double-check valve or pressure-vacuum breaker, still stops used water from flowing back into the public supply. A certified tester uses calibrated gauges, records the results and files the test report with the local water authority.
- How often does a commercial backflow preventer need to be tested?
- Most commercial assemblies are tested annually, and your water provider sets the schedule and due date. Fire-line backflows also need annual testing, which we coordinate with your fire sprinkler contractor. Our free backflow compliance checker helps you see what applies to your building.
- Who files the backflow certification with the water utility?
- We do. After each annual test, Legacy Plumbing files the certified test report directly with your local water authority and copies your facilities team, so you don't receive a delinquency notice. Property managers can keep every building on one schedule with one paperwork trail.
- What happens if a backflow preventer fails its test?
- We repair or rebuild the assembly with rubber-goods kits, check repairs or a full rebuild, then retest, usually on the same visit when parts are on the truck. Once it passes, the certified report is filed so the building stays in compliance with the water utility.
- How much does commercial backflow testing cost?
- Annual backflow testing is typically $250–$500 per assembly per year (estimate; final price depends on device size, number of devices and access). Repairs, rebuilds or replacement assemblies are quoted separately if an assembly fails its test. Call 636-978-0120 Monday–Friday, 7am–4pm to schedule certified testing anywhere in St. Louis, St. Charles County or Jefferson County.
Get an Annual Backflow Test Reminder
We'll email you about a month before your next test is due. No spam — just the reminder.
Backflow Prevention & Testing Across the St. Louis Metro
Every municipality in the St. Louis area — from St. Louis City and Florissant to St. Peters, Wentzville, and Ballwin — requires annual backflow testing on RPZ and DCV assemblies, and most water districts will shut off service if the report doesn't land on time.
Our state-licensed backflow technicians install, repair, certify, and file the paperwork directly with Missouri American Water and the city water districts across the metro — so your assemblies stay compliant and your water stays on.
Don't see your city below? We work the entire metro and a 2-hour radius from O'Fallon, MO. View full service area →
St. Charles County
Warren County
For examples of this work, see Facility Water Heater & Backflow Program (Regional Portfolio). For planning guidance, read Before the First Hard Freeze: A Plumbing Walk-Through for St. Louis Commercial Buildings.
Need a Backflow Test in St. Louis?
Get a certified tester from a self-performing commercial plumbing contractor based in O'Fallon, MO.
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