Backflow prevention

Important changes

Our Backflow Prevention application is being upgraded and will be unavailable from 4 pm on Friday 27 November until 9 am on Monday 7 December.

We apologise for any inconvenience.

For more details, please read:
Need help?
Watch these short videos to see how to use the current backflow online system.

How to replace a device
How to create a manifold set up
How to create a fire service connection
How to submit an annual test

Coming soon: We'll be updating these training videos when the new Backflow system launches on Monday 7 December.

Information for plumbers

We no longer accept reports for zone and individual backflow devices.

Contact the Department of Fair Trading if you have any questions about these type of devices.

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. 

Contact NSW Fair Trading about property (zone or individual) backflow containment.

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.

Who has backflow plumber accreditation?
We maintain a list of backflow plumbers.

If you're already accredited and want to be on our list, email a copy of your Certificate of Attainment to or call us on 13 20 92.

If you want to become an accredited backflow plumber, visit  TAFE and search for 'plumbing' or 'backflow'.

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.

Use our  online lodgement system to submit your backflow test report.

If you can't access the system, call us on 13 20 92.

If you're having problems using the current lodgement system, read our  Backflow online Frequently asked questions. If you're still having problems, email us at  

Please note that when the new system launches on Monday 7 December, you'll need to register again using your personal email address.
Backflow prevention containment device on site

Backflow prevention containment devices must meet our connection requirements.