Backflow Testing in Michigan: A Plain-English Guide for Homeowners and Property Owners

A letter arrives from your city's water department. It mentions a backflow preventer, a deadline, and a certified tester. Most people have never given that device a thought, and now it has a due date.

Here is what it is, who can test it, and what to do before the deadline passes.

What Backflow Is, and Why It Matters

Water in your pipes is supposed to move one direction: from the city main into your building. Backflow is what happens when that reverses, usually because of a pressure drop in the main or a spike in your own plumbing. Whatever is on your side of the line can then be pulled back toward the public supply.

That might be fertilizer in an irrigation system, boiler chemicals, or standing water from a fixture. A backflow preventer is the valve assembly that stops it. Because it has moving parts, it can wear out or fail, which is why testable models need to be checked on a schedule.

Who Needs Backflow Testing

Commercial and multi-family properties. If your building has a testable backflow preventer on the main service, a fire line, a boiler, a commercial kitchen, or an irrigation system, expect annual testing. The Michigan Plumbing Code calls for yearly checks by a certified tester.

Homes with irrigation systems. An in-ground sprinkler system is usually protected by a testable assembly. How often a residence is asked to submit results depends on the municipality. Some cities ask every year, others every few years, and many send a notice when your test is due. Your water department's letter is the best source for your schedule.

If you aren't sure what is installed at your property, a plumber can identify it in a short visit.

Who Is Allowed to Do the Testing

This part surprises people. In Michigan, a tester needs a current ASSE 5110 certification, and under a state interpretation issued in recent years, the person performing the test must also be a licensed plumber (master, journeyman, or an apprentice working under direct supervision). Many cities also want results submitted on their own form, and some require the contractor to be licensed locally.

When you hire a tester, ask for their credentials and make sure they appear on your completed report. A test done by someone who doesn't meet the requirements can be rejected by your water department, and then you're paying for it twice.

What Happens During a Test

A technician attaches a calibrated gauge to the assembly, runs it through a series of pressure checks, and records the readings. For most properties it takes a short visit, and the water is shut off briefly while it is done.

There are two outcomes:

• It passes. The tester completes the form and it gets submitted to your water department. You're done until next cycle.

• It fails. The device needs repair or replacement, which must be handled by a licensed plumber. Once fixed, it is tested again and the passing result is what gets submitted.

What Happens if You Miss the Deadline

It depends on your municipality, but notices of violation are common, and some water departments can escalate to fees or, for repeated non-compliance, shut-off. More practically, an untested device is one you don't know works.

How to Stay Ahead of It

• Keep your last report on file, and note the date. Most are due on a yearly cycle.

• Book early. Testers get busy as notice deadlines approach, particularly in spring when irrigation systems come back online.

• Schedule a retest right after any repair or replacement.

• If you get a notice you don't understand, call your water department and ask which assembly it refers to.

Backflow Testing and Certification with Mitten State Plumbing

Mitten State Plumbing Co. provides backflow testing and certification for commercial and residential properties across Southeast Michigan. We're a licensed, insured, veteran-owned team based in Troy, and we can handle the testing, any repairs that come out of it, and the paperwork your water department needs.

Our office hours are 8 a.m. to 6 p.m., Monday through Friday.

[Insert phone number / "Schedule a Backflow Test" button linking to your contact page]

Quick Questions

How often does a backflow preventer need to be tested? Commercial properties are generally tested annually. Residential irrigation schedules vary by city, so check the notice from your water department.

Can any plumber test my backflow preventer? No. The tester needs an ASSE 5110 certification and, under current state guidance, a Michigan plumbing license.

What if my device fails? It gets repaired or replaced by a licensed plumber, then retested. The passing report is what's submitted.

I got a notice, but I don't know what I have. Where do I start? Call us. We can identify the assembly, tell you what your notice is asking for, and schedule the work.

Requirements vary by municipality, so confirm the specifics with your local water department.