Backflow prevention

Important changes

Our backflow prevention application has been upgraded and is now available. To use the system, you'll first need to Register for backflow prevention using your email address.

For more details, please read:



Information for plumbers

All fire services, fire hydrant and sprinkler services require the installation of a Double Check Detector Assembly (DCDA).

The materials used on the upstream side of the Double Check Detector Assembly (DCDA) and including the outlet control valve must be WaterMark approved for plumbing and drainage installations.

No galvanised pipe and fittings on the upstream/inlet side of the containment device.

  • All rising spindle valves must be WaterMark approved
  • All butterfly valves must be WaterMark approved and gear operated
If you require further information, email us at backflow@sydneywater.com.au
We no longer accept reports for zone and individual backflow devices.

Contact  NSW 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. Find out more about meters and metered standpipes.

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 medium and high hazard 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.

Soon, all plumbers will be able to tell us about the installation of low hazard devices via Sydney Water Tap in™.

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 backflow@sydneywater.com.au or call us on 13 20 92.

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

We now audit lodgements.

As part of our audit, we may ask you to provide two (2) photographs for any backflow containment device test you've registered with us. The photos need to show the:

  • backflow device you tested with the serial number clearly visible
  • test kit you used.

You don't need to attach photographs to your test reports when you upload them using the new backflow prevention application. However, your uploaded test reports may be subject to an audit. If we audit your lodgement, we'll send you an email asking you to email the photographic evidence to us as proof. 

Note: We won't audit the first test report you upload using the new backflow prevention application. However, we will be auditing second and future test reports.  


For more details about the photographic evidence we may ask for, please read:

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

To access the system for the first time, you'll need to Register for backflow prevention using your personal email address.



If you can't access the system, email us at backflow@sydneywater.com.au
Backflow prevention containment device on site

Backflow prevention containment devices must meet our connection requirements.