Owners of low hazard properties with meters larger than 25 mm must get a non-testable backflow prevention containment device installed. Our 20 mm and 25 mm meters have an integral backflow prevention device built in. These are suitable for low hazard connections.
If your property connects to our water or recycled water pipes, you must install the right backflow containment device.
What is backflow?
Backflow occurs when used water from a customer's property flows backward into our pipes. It may carry contaminants like chemicals, oil, bacteria, mud and debris that can harm people's health. Contaminated water can pose serious risks.
Preventing backflow is important to protect our water quality and people's health.
How backflow occurs
Backflow is more likely to occur:
- if there's a drop in pressure in the main, for example, during a water main break
- if water pressure at the property is higher than at the main, such as if a pump is operating on the site.
Contaminants may enter the drinking water system through a cross connection caused by:
- faulty plumbing
- hoses submerged in buckets, tanks or pools.
Cross connections are unauthorised plumbing connections between 2 water sources that should be separate, such as a drinking water system and a recycled water or wastewater system.
What backflow devices are
Backflow prevention containment devices stop potentially contaminated water flowing back into our pipes. They have one of the following elements to stop water flowing backward:
- a valve that only lets water go in one direction
- an air gap
- a break tank.
A typical backflow prevention containment device.
What you must do
You must have the correct backflow prevention device installed and keep it in good working order.
You must hire an accredited backflow plumber to:
- assess your site's hazard rating
- install, test and register the device
- test the device every year
- send us the results within 2 days.
Backflow prevention must comply with the Plumbing Code of Australia.
Owners of medium hazard properties must install a testable double check valve for drinking water connections and a double check detector assembly for fire service connections.
Owners of high hazard properties must get a registered break tank, reduced pressure zone device or registered air gap installed.
If we've given you permission to use a metered standpipe on our pipes, your standpipe must have a testable double check valve incorporated into its design.
You need a backflow prevention device on water main connections you use for construction and renovation. If you're building more than a single standalone house, we consider it to be a high backflow hazard.
- If your property has a sprinkler or fire hydrant service, it must have a testable double check detector assembly on each connection. The double check detector assemblies must be installed close to where the water service enters your property and upstream of any booster assembly or off-take from the fire service. You must not use galvanised pipes and fittings on the upstream side of the connection.
- If your property has a window or wall drencher system, you must install a non-testable low hazard device.
If you don't know your site's hazard rating or don't get it assessed, we'll assume it's a high hazard. Owners of properties with unknown hazard ratings must get a registered break tank, reduced pressure zone device or registered air gap installed.
Who can install and test your device
You must use accredited backflow plumbers and licensed plumbers.
- An accredited backflow plumber must assess your site's hazard rating and test your backflow device.
- A licensed plumber must install your device.
To find an accredited plumber near you, use our backflow plumber search.
What we will do
We keep a register of all installed testable backflow prevention containment devices, and will remind you when it's time to get your backflow device tested each year.
We audit a sample of installations to make sure they comply with Australian Standards AS/NZS 3500:1 and AS/NZS 2845, and our connection requirements.
If you don't comply with our backflow requirements or notices, we could:
- test the device and charge you for the service
- restrict your water supply
- disconnect you
- charge you any costs we incur to make your connection satisfy our requirements.
If your installation doesn't comply with the standards, we'll send a notice asking you to repair, maintain, test or replace the device.