Backflow prevention devices reduce the risk of contaminating our water supply.

All connections to our water mains must have suitable backflow containment. 

What plumbers must do

Licensed plumbers must assess each site to work out its specific backflow containment needs.

If you've determined the site's hazard rating as low, our 20 mm and 25 mm water meters already have a simple backflow prevention device in them. If the property's water meter is larger than 25 mm, you'll need a separate backflow device. 

You must advise the property owner of the backflow requirements and install a backflow prevention device appropriate to the property's hazard rating. You must also tell the owner if the device needs to be tested each year. 

Only licensed plumbers with backflow prevention accreditation issued by a registered training organisation (backflow plumbers) can inspect, commission and test backflow devices.

Once backflow devices have been installed, only backflow plumbers can test them. Once a test has been done, backflow plumbers must submit the test report using our online lodgement system.

The hazard rating of the site's processes determines which type of device you need to install. If the hazard rating varies due to multiple processes, you must apply the highest hazard rating.

Backflow device types

Reduced pressure zone device (hazard rating - high)

This device has two independent action, non-return valves that are force-loaded to the closed position. A relief valve is positioned between the non-return valves and is arranged to be force-loaded to open to the atmosphere.

Break tank/air gap (hazard rating - high)

This device has an air break (physical gap) between the lowest water service pipe outlet and any upstream tank, fitting or container.

Testable double check valve (hazard rating - medium)

This device has two independent action, non-return valves that are force-loaded to the closed position. It is fitted with three test taps for yearly testing.