Backflow Prevention & Annual Testing
Backflow prevention is one of those plumbing requirements that catches a lot of business owners and property managers by surprise — usually with a compliance letter from Water Corporation landing in the mail. In Western Australia, many commercial, irrigation and higher-risk connections must have a testable backflow prevention device installed, and that device must be tested every year by a licensed, endorsed plumber. Our Canning Vale team handles the whole thing: installation, annual testing, and lodging the paperwork so you stay on the right side of the rules.
What backflow actually is
Normally, water flows one way — from the Water Corporation main into your property. Backflow is when that flow reverses and potentially pulls contaminated water back into the drinking supply. It can happen through back-siphonage (a sudden drop in mains pressure, like a burst main nearby) or back-pressure (a system on your property pushing back against the mains). A backflow prevention device is a one-way barrier that stops that from happening.
The risk is real: think of an irrigation system dosing fertiliser, a commercial kitchen, a medical practice, a car wash, or a fire service. If contaminated water were siphoned back into the main, it wouldn't just affect that property — it could reach neighbours on the same line. That's exactly why WA takes it so seriously, and why the rules apply to more properties than most people expect.
Who needs a backflow device in WA
Not every home needs a testable device, but a broad range of properties and connections do. You likely need one if you have:
- An irrigation or reticulation system connected to scheme water, especially with fertiliser or chemical injection
- A commercial or industrial property — offices, retail, hospitality, workshops
- A fire service connection
- Medical, dental or veterinary premises
- A property with a bore, rainwater tank or alternative water source cross-connected to mains
- Certain multi-storey or strata developments
Reticulation is extremely common across Canning Vale, Southern River and Harrisdale, and many bore and reticulation setups fall under these rules. If you're not sure whether yours does, we can assess it and give you a straight answer. Our guide to backflow testing in WA explains the requirements in plain English.
Annual testing and compliance
Here's the part people miss: installing the device isn't a one-and-done job. Testable backflow prevention devices contain valves and seals that wear over time, so WA requires them to be tested every year to confirm they're still working. The test must be carried out by a plumber holding the correct backflow endorsement, and the results are lodged with Water Corporation.
If your device fails the test or the testing is overdue, you can face compliance action — and more importantly, your barrier against contamination might not be working when it's needed. We keep track of when your test is due, carry out the annual test, and handle the reporting so you stay compliant without having to think about it or diarise it yourself.
What the annual test involves
- Isolating and inspecting the device
- Testing the valves and seals with calibrated gauges
- Servicing or repairing the device if it fails
- Completing and lodging the compliance paperwork with Water Corporation
- Setting a reminder for next year's test
Installation done properly
If you're setting up a new connection, fitting a reticulation system, or a compliance letter says you need a device, we install the right type for your risk level and connection. The device has to be the correct rating for the hazard, installed in an accessible position for testing, and registered properly. Getting this right from the start saves headaches at every future test — a device buried in an awkward spot is a nuisance to test for years to come.
Types of backflow device
Not all backflow devices are the same, and the one you need depends on the hazard rating of your connection. Lower-risk situations might only require a simple non-testable device, while higher-hazard connections — chemical injection, medical premises, fire services — call for a testable device like a reduced pressure zone valve or double check valve assembly. Matching the device to the actual risk matters: fit too little protection and you're non-compliant and exposed; over-specify and you've paid for more than the connection needs. Part of our job is assessing the hazard correctly and recommending the right device the first time, so you're properly protected without over-capitalising.
Sorted for commercial and irrigation
Backflow compliance sits alongside other requirements many commercial properties have, like tempering valves and grease traps — all part of our commercial plumbing service. If you manage a strata, run a business, or maintain a large irrigated property, we can bundle your backflow testing into a regular maintenance schedule so nothing lapses. For irrigation, it pairs naturally with keeping your reticulation and general plumbing in good order year-round.
Every device is installed and tested by a licensed plumber with the correct backflow endorsement, and pricing is upfront so there are no surprises on the invoice. Staying compliant is far cheaper and less stressful than dealing with a failed audit or, worse, a contamination incident that puts your neighbours' water at risk as well as your own.
We look after backflow compliance for properties across Canning Vale, Thornlie, Willetton, Riverton, Southern River, Harrisdale, Gosnells and Huntingdale. Being local means we can fit your annual test in without a long wait, and we keep your records so the next reminder comes from us rather than a Water Corporation letter. If you've received a compliance notice and aren't sure what it's asking for, bring it to us — decoding those letters and sorting out exactly what your property needs is a big part of what we do.
Need a backflow device installed or your annual test done? Request a quote or call our licensed Canning Vale plumbers to stay compliant.
Frequently asked questions
Do I legally need a backflow prevention device in WA?
Many properties do. Water Corporation requires testable backflow prevention devices on a broad range of commercial, irrigation, fire, medical and higher-risk connections. Reticulation systems on scheme water often need one too. If you're unsure, we can assess your property and tell you whether it applies to you.
How often does a backflow device need testing?
In WA, testable backflow prevention devices must be tested every year by a plumber holding the correct backflow endorsement. The results are lodged with Water Corporation. The annual test confirms the internal valves and seals are still working — they wear over time, so it's not a set-and-forget device.
What happens if my backflow testing is overdue?
An overdue or failed test can lead to compliance action from Water Corporation, and more importantly your protection against contamination may not be working. We track your due dates, carry out the test, service the device if needed, and lodge the paperwork so you stay compliant.
My reticulation is on scheme water — does it need a device?
Quite possibly. Reticulation connected to mains water, particularly with fertiliser or chemical injection, is a common reason a backflow device is required. Reticulation is widespread in Canning Vale and surrounds, so it's worth checking. We can inspect your setup and advise.