Backflow Prevention in WA: Do You Need Annual Testing?
Backflow prevention is one of those plumbing requirements that catches people by surprise, usually when a letter arrives saying a device on their property is due for testing. If you've received one, or you run a business or property with certain water connections, this guide explains what backflow is, who needs annual testing in WA, and how to stay compliant.
The short version: if your property has a testable backflow prevention device installed, WA requirements mean it generally must be tested every year by a licensed plumber with the right endorsement, and the results reported. Here's the detail.
What is backflow?
Normally, water flows one way: from the mains, into your property, and out through your taps and fixtures. Backflow is when that flow reverses and water flows backwards into the drinking water supply. It sounds unlikely, but it can happen when there's a sudden drop in mains pressure (from a burst main or heavy demand, for example) or a rise in pressure on your side of the meter.
The danger is contamination. If water flows backwards, it can drag whatever it's been in contact with back into the pipes, potentially into the shared drinking water supply. Think garden chemicals from a hose left in a bucket, water from an irrigation system, or contaminants from an industrial process. Backflow prevention devices are one-way valves that stop this reversal, protecting both your water and everyone else's on the network.
Why WA takes this seriously
Protecting the public drinking water supply is a genuine health matter, which is why backflow prevention is regulated. In Western Australia, plumbing work including backflow devices falls under the state's plumbing regulations administered by Building and Energy, and water supply protection is overseen alongside the water authority. Properties assessed as posing a contamination risk are required to have appropriate backflow prevention installed, and where testable devices are fitted, they must be tested to confirm they're still working.
Who needs annual backflow testing?
Not every home has a testable device, but many properties do, particularly where there's a higher contamination risk. You're more likely to require testable backflow prevention and annual testing if your property has:
- An irrigation or reticulation system connected to scheme water
- A fire sprinkler or hydrant system
- Commercial or industrial water use (workshops, medical, dental, food, manufacturing)
- A rainwater or bore supply connected alongside scheme water
- Certain higher-hazard fixtures or equipment
The key distinction is testable versus non-testable devices. Some backflow prevention (like certain low-hazard fittings) isn't testable and doesn't require annual testing, just correct installation. Testable devices, such as reduced pressure zone (RPZ) devices and double check valves, have test points built in precisely so they can be verified each year. If your property has a testable device, that's what triggers the annual testing obligation.
| Device type | Testable? | Typical requirement |
|---|---|---|
| Reduced pressure zone (RPZ) device | Yes | Annual testing by a licensed plumber with backflow endorsement |
| Double check valve (testable) | Yes | Annual testing and reporting |
| Low-hazard non-testable devices | No | Correct installation, no annual test |
How the annual testing works
Testing has to be done by a licensed plumber who holds the appropriate backflow prevention endorsement, using calibrated test equipment. The process typically involves:
- The plumber isolates and tests the device to confirm the valves hold pressure correctly and the device is functioning.
- If it passes, results are recorded and the test report is submitted to the relevant water authority to keep your compliance up to date.
- If it fails, the device is repaired or replaced, then retested until it passes.
You'll usually receive a reminder when your annual test is due. Keeping on top of it matters, because failing to test a required device can, in some cases, lead to the water authority taking action over the non-compliant connection. Our backflow prevention service handles installation, testing and reporting so you don't have to chase the paperwork.
What if my device fails the test?
Devices can fail as internal seals and springs wear over time, which is exactly why annual testing exists. A failed device isn't a disaster, but it does need to be repaired or replaced promptly, since a faulty device isn't protecting your water. A licensed plumber can service the device on the spot in many cases, or fit a replacement, then retest to confirm it passes.
Do I need a plumber, or can I test it myself?
Backflow testing is not a DIY job. It requires specific licensing, an endorsement to work on backflow devices, calibrated equipment, and the results must be lodged with the water authority to count. This is part of the broader rule that plumbing work in WA must be carried out by licensed professionals, which we cover in our guide on whether you need a licensed plumber in WA.
How often, and who's responsible?
Testable devices are generally tested at installation and then once a year after that. Responsibility for arranging and paying for the testing usually sits with the property owner, whether that's a homeowner, a business, or a landlord. If you own a rental or commercial premises with a testable device, it's your job to keep the testing current, so it's worth building the annual test into your property maintenance schedule rather than waiting for a reminder.
The test itself is quick, often taking well under an hour for a single device, and a licensed plumber can usually service a minor fault on the spot so you don't need a second visit. Keeping a record of your test reports also helps if you ever sell the property or need to demonstrate compliance.
Staying compliant, the easy way
The simplest approach is to work with a licensed plumber who tracks your test due date, carries out the annual test, and lodges the report for you. That way your protection stays valid, your compliance is maintained, and you're not scrambling when a reminder or notice arrives. If you're unsure whether your property even has a testable device, a plumber can inspect and tell you 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
Do I need annual backflow testing on my property in WA?
If your property has a testable backflow prevention device installed, such as an RPZ or testable double check valve, it generally must be tested every year by a licensed plumber with a backflow endorsement, and the results reported to the water authority.
What kinds of properties usually need backflow prevention?
Properties with a higher contamination risk, such as those with irrigation or reticulation connected to scheme water, fire sprinkler systems, commercial or industrial water use, or a bore or rainwater supply alongside scheme water, commonly require testable backflow devices.
Can I test my own backflow device?
No. Backflow testing requires a licensed plumber with a specific backflow endorsement, calibrated test equipment, and the results must be lodged with the water authority to be valid. It isn't a DIY task.
What happens if my backflow device fails the annual test?
A failed device needs to be repaired or replaced promptly, since it's no longer protecting your water supply. A licensed plumber can often service it on the spot or fit a replacement, then retest it to confirm it passes before reporting compliance.