Backflow Prevention in WA: Do You Need Annual Testing?

You get this letter in the mail about some valve out back you never knew existed — most people's first encounter with backflow is exactly like that, to be honest. Maybe that's how you ended up here, or maybe you're just trying to get on top of things for a business or a rental before it becomes a problem. Either way, we're going to cover what backflow actually is, who needs annual testing in WA, and how the compliance side of things works.

What is backflow?

Water only flows one way under normal conditions — comes from the mains, pushes onto your property, runs out your taps. Pretty straightforward. Backflow is when the whole thing reverses and dirty water heads the wrong direction back into the drinking supply. Might sound unlikely but it actually happens, like when mains pressure suddenly drops — could be a burst main, could be half the street running sprinklers on a 40-degree day — or pressure on your side of the meter jumps up above what's coming from the mains.

Contamination's the real concern here. Water reversing its path can drag whatever it's been sitting around near back through the pipes, potentially into the shared supply that your neighbours are drinking. Garden chemicals left soaking in a bucket with a hose draped in it, irrigation water, stuff from industrial setups. Backflow prevention devices are essentially one-way valves made to stop that reversal dead, keeping your water safe and everyone else's supply on the network protected too.

Why WA takes this seriously

The public drinking water supply staying clean is a health thing, which is why backflow prevention has actual laws and regs behind it. In Western Australia, plumbing work — backflow devices included — falls under the state's plumbing regulations administered by Building and Energy, and water supply protection is managed alongside the water authority. When your property gets assessed as carrying a contamination risk, fitting the right backflow prevention becomes mandatory, and any testable devices need regular testing to confirm they're still actually doing their job.

Who needs annual backflow testing?

Plenty of properties have a testable device fitted but not every house does. The ones more likely to need one — and the yearly testing that goes with it — tend to have:

• Irrigation or reticulation systems connected to scheme water

• Fire sprinkler or hydrant systems

• Commercial or industrial water use — think workshops, medical, dental, food production, manufacturing

• Rainwater or bore supply running alongside scheme water

• Certain higher-hazard fixtures or equipment

The important thing to understand is the testable versus non-testable devices difference. Some backflow prevention, certain low-hazard fittings for example, is non-testable and doesn't require annual testing — just needs correct installation. Testable devices on the other hand, things like reduced pressure zone (RPZ) devices and double check valves, they come with test points built in specifically so they can be checked each year. So if your property has got a testable device installed, that's what triggers the annual testing obligation.

How the annual testing works

Only a licensed plumber carrying the right backflow prevention endorsement can perform this work, and they'll need calibrated test equipment to do it properly. The process generally goes something like:

• The plumber isolates the device and runs tests on it, making sure the valves hold pressure properly and everything works the way it's supposed to.

• Assuming it passes, they record the results and submit a test report to the relevant water authority so your compliance stays current.

• If the device fails though, it'll need to be repaired or swapped out, then retested until it passes.

Usually you'll get a reminder when your test comes due. Staying current on this one matters — if you let a required device go untested, the water authority can potentially take action over that non-compliant connection. Our backflow prevention service handles installation, testing, and reporting so you don't have to chase paperwork around yourself.

What if my device fails the test?

Internal seals and springs wear out over time, that's just what happens with mechanical parts, and it's exactly why the annual testing exists in the first place. A failed device isn't the end of the world but you need to get it repaired or replaced pretty quickly because while it's faulty it's not actually protecting your water. In a lot of cases a licensed plumber can service it right there and then, or fit a replacement if needed, then retest to make sure it passes before they pack up and leave.

Do I need a plumber, or can I test it myself?

You can't test this yourself. The job requires specific licensing, a backflow endorsement on top of that, calibrated equipment, and the results have to be formally lodged with the water authority for them to count. It falls under the same rule that says plumbing work in WA has to be done by licensed professionals — we've gone into more detail on that in our guide about whether you need a licensed plumber in WA.

How often, and who's responsible?

Testable devices get tested at installation, and then generally once every twelve months after that. Booking and paying for it typically falls on the property owner — whether that's you as a homeowner, a business operator, or a landlord. So if you own a rental or a commercial place that's got a testable device, keeping the testing current is on you. Probably smarter to build it into your regular property maintenance schedule rather than sitting around waiting for a reminder letter to show up.

The test itself doesn't take long either, often well under an hour for a single device, and a licensed plumber can usually sort out a minor fault while they're there so you won't need them to come back. Keeping copies of your test reports tucked away is also handy if you ever sell the place or need to show someone you've been doing the right thing.

Staying compliant, the easy way

The simplest thing honestly is just working with a licensed plumber who keeps track of when your test is due, does the annual test, and lodges the report on your behalf. That way your protection stays valid, your compliance doesn't lapse, and you're not scrambling around when a reminder or official notice turns up. Not even sure if your property's got a testable device? A plumber can come out, have a look, and tell you exactly where you stand.

Backflow test due, or not sure if you need one? Call our licensed Canning Vale plumbers to test, service and report on your backflow devices and keep your property compliant.

Frequently asked questions