Annual Testing · Michigan DEQ Requirement

Backflow Prevention Testing
Metro Detroit & Southeast Michigan

Annual certified backflow preventer testing for commercial properties across Wayne, Oakland, and Macomb counties. Michigan DEQ compliant, test reports filed with your water authority on your behalf.

Annual Testing Required
Michigan DEQ Compliant
Reports Filed on Your Behalf
Serving All of Metro Detroit

Michigan's backflow prevention requirements

Backflow prevention assemblies protect the public water supply from contamination by preventing water from flowing backward from a commercial property's plumbing system into the municipal water supply. Michigan's Safe Drinking Water Act, enforced by the Michigan Department of Environment, Great Lakes, and Energy (EGLE), requires that all backflow prevention assemblies on commercial properties be tested annually by a certified tester.

Most Metro Detroit municipalities — including Detroit, Troy, Southfield, and others — have their own backflow prevention programs that require test results to be filed with the local water authority each year. Missing or overdue tests result in notices of violation and can ultimately result in water service shutoff.

Test reports must be submitted to the appropriate water authority by the deadline specified in each municipality's program. Guardian handles all testing and report filing so nothing slips through the cracks.

Many property managers don't realize they have multiple backflow preventers — one for domestic water, one for irrigation, and one for fire suppression. Guardian inventories all of them.

Which properties need backflow testing?

Any commercial property connected to the public water supply with a potential cross-connection hazard requires annual testing. This includes virtually all commercial buildings:

  • Office buildings and commercial properties
  • Medical and dental offices
  • Restaurants and food service facilities
  • Industrial and manufacturing facilities
  • HOA and condo associations with irrigation
  • Shopping centers and retail properties
  • Properties with fire suppression systems
  • Car washes and automotive properties

All assembly types. All locations.

Guardian inventories and tests all backflow prevention assemblies at your property, covering every connection type and hazard level.

RPZ

Reduced Pressure Zone Assemblies

The highest level of backflow protection, required for high-hazard connections. Tested for relief valve operation, check valve function, and differential pressure.

DC

Double Check Valve Assemblies

Used for moderate-hazard applications. Both check valves tested for proper seating and differential pressure compliance.

PVB/SVB

Pressure & Spill Vacuum Breakers

Common on irrigation systems. Tested for proper operation under both static and flow conditions.

Fire Lines

Fire Suppression Backflow Preventers

Dedicated backflow preventers on fire suppression water supplies, tested in coordination with your fire system requirements.

Test, repair, file — fully managed

Guardian handles the entire backflow testing cycle including report filing with your water authority and any repair or replacement needed.

01

Assembly Inventory

We locate and document all backflow preventers at your property — many owners are unaware of how many they have.

02

Certified Testing

Michigan-certified backflow testers perform all required tests using calibrated equipment.

03

Report Filing

We submit test reports to your local water authority on your behalf, meeting all municipal deadlines.

04

Repair & Replacement

Any failed assemblies are repaired or replaced through our licensed plumbing contractor network.

05

Annual Tracking

We track your annual testing cycle and schedule proactively so deadlines are never missed.

Backflow testing FAQ

Do I need a backflow preventer tested every year in Michigan?
Yes. Michigan requires annual testing of all backflow prevention assemblies on commercial properties. Most Metro Detroit municipalities also have their own backflow prevention programs that require test results to be filed with the local water authority annually. Missing the annual deadline results in a notice of violation and, if not corrected, can lead to water service interruption. See our full article on this topic for more detail.
Who can test backflow preventers in Michigan?
Testing must be performed by a Michigan-certified backflow preventer tester. Certification requires passing a state-approved exam and maintaining current credentials. Guardian works exclusively with certified testers who carry the appropriate credentials for all assembly types and are approved by Metro Detroit water authorities.
What happens if my backflow preventer fails the test?
A failed assembly must be repaired or replaced before a passing test report can be submitted. Guardian coordinates all repairs through licensed plumbing contractors in our network so you don't have to source separate vendors. We re-test after repair and file the passing report with your water authority.
How many backflow preventers does my building have?
Many building owners are surprised to find they have multiple assemblies. A typical commercial property may have a domestic water backflow preventer, a separate one for irrigation, and another for the fire suppression system. Properties with laboratories, medical equipment, or industrial processes may have additional assemblies. Guardian conducts a full inventory as part of the initial assessment.
Backflow prevention testing across Metro Detroit & Southeast Michigan

Ready to get your backflow preventers tested?

We'll inventory your assemblies and get you on a compliant annual schedule — at no cost to assess.

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