Backflow prevention

Whether you’re planning to build, extend, purchase or lease, if your property connects to Barwon Water’s water supply system you need to know about backflow and your role in its prevention and containment.

Information for property owners

What is backflow?

Backflow occurs when water within a property is drawn back into the water mains, compromising the integrity of our reticulated water supply system and possibly contaminating our drinking water. This can happen when:

  • pressure within the main drops
  • there is a cross connection between your water supply and a contaminated source, or
  • a nearby property working with chemicals or other contaminants uses the water supply.

Contaminants in our drinking water endanger people’s health and can be deadly. By minimising the risk of this occurring, backflow prevention protects and preserves the quality of our water supply, and safeguards the health and wellbeing of our community.

Preventing backflow

Under our backflow prevention containment policy, new and existing commercial, industrial and residential properties rated as medium or high risk of contaminating the water supply are required to have appropriate backflow prevention device/s installed at the main water meter.

Each device must be tested annually by an accredited backflow prevention plumber to ensure it continues to work efficiently to stop backflow from entering the water supply.

Do I need a backflow prevention device?

As part of connecting your property to the water supply, your plumber may advise that you need to install backflow prevention. This will then require an assessment of the property’s hazard rating by an accredited backflow prevention plumber.

If your property is assessed as medium or high risk, you will need a device. The assessment will also determine the number and type of device/s to be installed.

Installing a backflow prevention device

You will need to register with us for a backflow prevention agreement and arrange for a backflow prevention device appropriate to your risk level to be installed at the main water meter on your property. If you have more than one main meter, you will need more than one device.

A licensed plumber can install the device/s, which will then need to be tested by an accredited backflow prevention plumber and the results submitted back to us.

Under your agreement, you will be required to arrange for your device/s to be tested once every year, again by an accredited backflow prevention plumber, with the results to be submitted to us online. We will remind you when your annual test is due.

Properties fitted with backflow prevention

As a property owner, you need to register with us for a backflow prevention agreement to enable us to help you meet your obligations. We will, for example, let you know when your annual test is due.

We recommend you check the date your device was last tested, so you can arrange a test if needed and/or include this information with your registration form. If you can’t find the last test date, please email our Backflow Prevention Officer or call 1300 656 007 .

Costs associated with backflow prevention

Generally, the property owner is responsible for all costs associated with purchasing, installing, testing and maintaining any backflow prevention device/s installed on the property.

If the property is leased, it is up to the owner to negotiate with the tenant about who pays for installation and all ongoing maintenance.

Our current pricing schedule sets out all our fees and charges, including those applying to backflow prevention.

What happens if I don’t comply?

Failing to install, maintain and test your device as directed by us, and to submit your test results may result in Barwon Water:

  • arranging for our licensed contractor to undertake your annual backflow prevention test and to charge all associated costs to you, and/or
  • removing or disconnecting the water supply to your property.

Furthermore, a failure to prevent or contain backflow within your property that results in contamination of the water supply may expose you and/or your business to:

  • injury claims
  • illness or death of occupants
  • contamination of products and subsequent exposure to product liability claims
  • litigation and possibly penalties, as the result of actions brought under Occupational Health and Safety legislation
  • liability for damages caused to others at adjoining premises serviced by the same main water supply as your property.

Help and information

If you need to get in touch with us, please contact us.

Information for plumbers

Backflow prevention regulatory framework

If you’re a licensed plumber who installs backflow prevention devices and/or an accredited backflow prevention plumber, refer to our backflow prevention containment policy for details about the operating principles and requirements pertaining to preventing and containing backflow across our region.

The latest versions (as amended) of the following legislation, regulations and standards also apply:

  • Water Act 1989
  • Safe Drinking Water Act 2003
  • Water (Estimation, Supply and Sewerage) Regulations 2014
  • Victorian Plumbing Regulations 2008
  • Plumbing Code of Australia
  • AS/NZS 2845 Water Supply – Backflow Prevention Devices
  • AS/NZS 3500 Part 1 – Water Services and Part 5 – Housing Installations

Defining your responsibilities

As detailed in our backflow prevention containment policy, property owners/agents must arrange for a suitably qualified person to assess potential onsite hazards, install and maintain an appropriate backflow prevention device at boundary/main water meter, and conduct ongoing annual servicing and testing of backflow prevention devices.

A suitably qualified person is defined as:

  • a licensed plumber for the purpose of fitting water service connections (eg general, fire, recycled water) with appropriate backflow prevention devices, and/or
  • an accredited backflow prevention plumber to assess potential onsite hazards, install and test a backflow prevention device (on a first and ongoing annual basis), and complete all necessary documentation (eg compliance certificate, annual test reports).

Bidets and sanitary sprays

A high-hazard backflow prevention device is required at the point of installation of any bidet or sanitary spray, as per Victorian Building Authority (VBA) requirements. Barwon Water does not require this to be repeated at the meter.


We have developed online forms for you to use for testing and reporting purposes. These are quick and easy to use on your smartphone or other digital device and provide a useful checklist for your backflow prevention jobs.

The forms also enable us to gather more consistent and complete information that supports better monitoring of backflow prevention across the region.

Please use the link we email to you (or your customer) to access the form and to complete and submit the annual test report online. Device testing will remain incomplete until the correct documentation is received.

Help and information

If you need to get in touch with us, please contact us.