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Example of how backflow can occurBackflow is the reverse flow of a liquid into the drinking water supply.

Backflow from an industrial or commercial property that uses harmful substances could pollute the local water supply.

For example, a hose left running in a container of toxic chemicals could result in harmful backflow. A sudden drop in water pressure could cause the liquid to be siphoned back through the hose and into the water supply.

The installation of a backflow prevention device protects the water supply from this very serious situation.

For more information visit the Backflow Prevention Association of Australia website at

Commercial and trade waste customers

If you’re a commercial or trade waste customer you must provide a backflow prevention device immediately downstream of your water meter.

Without a backflow prevention device, you risk:

  • causing serious illness or death
  • prosecution under the Water Act 1989
  • substantial financial losses and litigation (such as Workcover, and Occupation Health and Safety claims)
  • being disconnected from the water supply.

Installing a device

It's the property owner's responsibility to make sure that a suitable backflow device is properly installed and tested. Only plumbers with a Water Supply license are qualified to install a device.

Here's what you need to do:

1. Get a risk assessment

Arrange for an accredited plumber to assess the potential onsite hazards of your property.

The hazard ratings are:

  • High hazard - potential to cause death.
  • Medium hazard - potential to endanger health.
  • Low hazard - constitute a nuisance but not endanger health.

2. Choose and install a device

Your accredited plumber will recommend and install a suitable device based on your property's hazard rating. If installing a device in a medium or high hazard area, your plumber must be licensed in Backflow Prevention.

3. Test your device

Medium and high hazard devices need testing annually by a plumber licensed in Backflow Prevention. Results must be lodged within 20 days to either Coliban Water at or Coliban Water's agent:

CIS Services Pty Ltd or


4. Backflow Prevention Containment Policy

As the aim of the Backflow Prevention Containment Policy is the protection of the system and public health, it is vital that all parties comply with the relevant Acts, Regulations and Standards.

In the event of a property owner refusing to rectify a potential backflow or cross‐connection hazard, the water corporation has the authority to disconnect the reticulated water supply system to the relevant property, in order to protect the system and public health as per Section 141 of the Water Act 1989.

Examples where the system may be disconnected include:

  • Failure to install a backflow prevention containment device following request from the water corporation.
  • Failure to carry out tests or maintain a backflow prevention containment device in accordance with AS/NZS 3500 and AS/NZS 2845.
  • Failure to replace or repair a backflow prevention containment device.
  • Removal or bypassing of a backflow prevention containment device without the authority of the water corporation.

The water corporation reserves the right to install the appropriate containment device at the relevant property and to take necessary action to recover all associated costs.


Last updated on 16 Jul 2024
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