Do I have to register my backflow assembly with the City of Phoenix?

Not every building has one. The City requires a backflow assembly where there is a cross-connection hazard, meaning a point where non-drinkable water could flow backward into the public drinking supply. The higher the health risk, the stricter the device.

Common triggers in Phoenix include:

• Irrigation systems, because sprinkler lines sit in soil, fertilizer, and pet waste
• Fire sprinkler lines, which hold stagnant water and sometimes chemical additives
• Commercial buildings with boilers, cooling towers, processing equipment, or chemical feed lines
• Medical, dental, and lab facilities, restaurants, car washes, and similar high-hazard sites

The EPA explains the danger plainly. Its Cross-Connection Control Manual states: "Backflow into a public water system can pollute or contaminate the water in that system." That single sentence is the reason the whole program exists. If your building connects to the City water main and has any of these hazards, expect to need an assembly.

The type of device you need scales with the hazard. A low-hazard connection may take a double-check valve assembly, while a high-hazard or health-hazard connection takes a reduced-pressure principle (RPZ) assembly, the one with a relief valve and the strongest protection. The City and your plumber match the device to the risk; you do not get to pick the cheaper unit if your hazard calls for an RPZ. Either way, once a testable assembly is on your service, it enters the program and the annual cycle starts.

For background on what backflow actually is and how it happens, see our page on what is backflow in plumbing. If your hazard is a lawn or yard irrigation system, our backflow preventer for sprinklers in Arizona page covers that specific case.

People mix these up, so it helps to separate them.

The annual test is the physical check. A licensed, certified backflow tester hooks gauges to the assembly, runs the valves through their motions, and confirms the device still stops reverse flow. That hands-on work is covered in detail on our commercial backflow testing requirements in Arizona page.

Registration and reporting is the paper side. The City has to know the assembly exists, where it sits, what type it is, and that it passed this year. So after the test, the result goes to the City as a test report. The tester usually submits it on your behalf, but the duty to make sure it lands rests with you, the customer. Think of the test as the exam and the report as the grade you have to turn in.

Arizona backs this cycle at the state level too. Arizona Administrative Code R18-4-215 requires assemblies to be tested by a certified person and sets the annual rhythm that local programs follow. Phoenix administers the day-to-day program, but the state rule is why "test it every year" is not optional anywhere in Arizona.

Here is the full loop a property owner runs under Article XII.

Install at your own expense. The City requires the assembly, but the customer buys and installs it. Phoenix City Code 37-144 places the cost and the duty on the water user, not the City. A licensed plumber sizes and sets the correct device for your hazard level and gets the install inspected.

Test it every year. Once installed, the assembly must be tested at startup and then annually by a tester the City accepts as certified. This is the single most-cited number in the program, so put it on a calendar.

Submit the test report. The passing (or failing) result goes to the City. A failed test means repair or replacement, then a retest, before the report can show a pass.

Keep your records. Hold onto your test reports and repair paperwork. The retention window is generally about three years, so a quick audit or a question from the City is easy to answer. Keeping a simple folder, paper or digital, of every annual report is the cleanest way to stay ready.

The City names a program administrator to run all of this. Under the code, the Planning and Development Director oversees the cross-connection control program for Phoenix, including which devices are approved and who counts as a certified tester. Many approved-assembly lists trace back to the USC Foundation for Cross-Connection Control and Hydraulic Research, the national lab that tests and lists acceptable devices. When you buy an assembly, check that the model appears on the City's accepted list so it does not get rejected at install or at the first test.

One more practical note on timing. The clock for the annual test runs from the last passing test, not from the calendar year, so two properties can have due dates months apart. If you take over a building, ask the City for the current test date on that account rather than assuming a January reset. Missing the window by even a few weeks can put you in notice status, so an early test beats a late one.

The property owner carries the responsibility. Even if a tenant runs the business or a landscaper installed the sprinklers, the City looks to the owner of the connection to keep the assembly tested and reported. In a leased commercial space, the lease may push the task to the tenant, but that is a private arrangement; the City still holds the account holder accountable.

Skipping the cycle has real teeth. The City sends a notice when a test is overdue or a report never arrived. Ignore the notice and the City can move toward shutting off water service to the property. Phoenix's broader water rules already allow the Water Services Director to terminate service after written notice when a customer fails to meet requirements, and a missing backflow test falls squarely in that bucket. For a business, a water shutoff is not a minor warning; it can close your doors the same day.

A failed test that goes unrepaired is just as serious as no test at all. The point of the assembly is active protection, and a broken one protects nothing. So the safe path is simple: test on schedule, fix any failure fast, and get the report in.

It also helps to know why the City pushes so hard on this. A single backflow event at one building can pull contaminated water into the shared main and reach neighboring properties, which is why a missed test is treated as a public-safety issue and not just a paperwork lapse. The annual cadence exists so a slow valve failure gets caught before it ever matters. Seen that way, the yearly report is cheap insurance against a much larger problem for you and everyone downstream of your meter.

Because hazard levels and device types vary, your exact requirement depends on your property. Here is how to pin it down.

Start with the City. Phoenix City Code Chapter 37, Article XII is the governing text, and a call to Phoenix Water Services can confirm whether your account already has an assembly on file and when its next test is due. Have your water account number ready.

Next, line up a certified tester. Phoenix only accepts results from testers it recognizes, so confirm the tester is current before you book. A qualified commercial plumber can both test the device and handle the report submission, which keeps the whole annual task in one place.

Finally, a caveat that matters for any rule like this. Code sections, retention periods, fees, and submission methods change, and the City updates its program over time. The figures here, including the annual test schedule and the roughly three-year record-keeping window, reflect Phoenix's cross-connection program as of this writing under sections 37-141 to 37-146. Verify the current requirements directly with the City of Phoenix Water Services before you rely on them, especially the exact deadline tied to your account. If you want help installing, testing, or reporting a backflow assembly on a Phoenix commercial property, HQ Plumbing & Air can walk the whole cycle with you.