Backflow Prevention

Backflow Prevention

A Backflow Prevention Device is critical for the protection of the potable water supply from contamination due to the unplanned reverse flow (backflow) of water or mixtures of water and contaminants into Central Highland Water’s (CHW) reticulated water supply system.

Normal business activities on your property may involve substances that, if unknowingly consumed, may result in illness, injury or death.

Click here to view/download a Backflow Prevention Device Inspection/Test Report.


What are the risks?

There are three levels of backflow risk (low, medium and high) associated with cross connection and contamination of the reticulated supply.

The boundary hazard rating is determined by the potential for cross-connection based on the likely activity at the site in accordance with AS/NZS 3500.1.

  • Low Hazard Rating: Any condition, device, or practice, which in connection with the system, is a nuisance but does not endanger health or cause injury.
  • Medium Hazard Rating: Any condition, device, or practice, which in connection with the system, could endanger health.
  • High Hazard rating: Any condition, device, or practice, which in connection with the system, has the potential to cause death.


How can backflow occur?

Backflow can be caused by a sudden drop in pressure in the supply main (back siphonage), or when the internal pressure becomes higher than the pressure supplied in the main (back pressure).

For example, backflow can occur when:

  • there is a break in the water main which supplies your property
  • water is being pumped from the main by the CFA during a fire
  • you are using water at a higher pressure than the pressure supplied by CHW
  • high water demand reducing water pressure to your property.


What does a backflow prevention device do?

A backflow prevention device allows water from the main to enter the property through the water meter assembly but will prevent the water and/or contaminants from flowing back into the reticulated water supply network.

The type of device fitted will depend on the level of potential risk. For example, businesses that produce highly contaminated water as a by-product of their activities will require a more complex testable device compared to a residential house where (generally) a simple, non-testable device would be appropriate.


What are the property owner’s responsibilities?

Property owners are responsible for ensuring that activities carried out on their property do not lead to contamination of the water supply.

All property owners, when requested by CHW, must engage a suitably qualified person to assess the onsite hazards and install, test and maintain a containment backflow prevention device in accordance with the requirements of AS/NZS 3500.1, AS/NZS 2845, the Plumbing Code of Australia (also known as the National Construction Code Series – Volume Three) and the Water (Estimation, Supply and Sewerage) Regulations 2014.

The installed device(s) must be tested annually and the test reports forwarded to CHW within 20 days of the test date.

Note: The property owner has a legal obligation to maintain the reticulated water supply system inside their property and depending upon the plumbing system and hazard ratings of the internal processes, to install additional individual/zone protection backflow prevention devices

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