Backflow Prevention – Protecting Our Drinking Water

Why backflow prevention matters

Backflow defined

Backflow is an unintended reversal of normal piped flow direction within a water supply system. It can allow contaminants to enter the drinking water supply and may pose serious risks to public health.

There are two primary mechanisms of backflow:

• Back siphonage: Occurs when pressure within the water supply system falls below that of a connected property’s internal plumbing, creating a vacuum that draws water and contaminants back into the potable supply.
• Back pressure: Occurs when pressure within a property’s internal plumbing exceeds the supplied water pressure, forcing water or other substances back into the potable water supply.

Backflow is often caused by:

• A burst or ruptured water main
• Excessive demand during fire-fighting operations
• Other periods of high water demand
• Faulty or poorly maintained backflow prevention devices
• Hoses submerged in buckets, tanks, pools, or stock troughs
• Direct connections between a potable water supply and an alternative water source (for example bore water, rainwater, or dam water)

The installation, maintenance, and ongoing testing of appropriate backflow prevention devices at all properties connected to AlburyCity’s reticulated water supply system is essential to meeting legislative obligations, managing risk, and supporting the Community Strategic Plan.

These devices help to:

• Protect the public drinking water supply from contamination and associated health hazards
• Ensure compliance with statutory and regulatory obligations
• Safeguard AlburyCity’s water supply and infrastructure
• Maintain public confidence in the safety and reliability of the potable water supply

Hazard risks

While the likelihood of risks associated with inadequate backflow prevention is low, the potential consequences for the delivery of clean, safe drinking water are extremely high. Adequate controls are therefore essential to manage identified water supply risks.

Backflow hazards are classified as low, medium, or high risk. These classifications apply to individual items of equipment, specific areas within a property, and the overall containment of risks on site.

• Low risk: Situations where any backflow would be a nuisance rather than a health hazard.
  Example: Rainwater tanks
• Medium risk: Situations with the potential to endanger health.
  Examples: Caravan parks, public swimming pools
• High risk: Situations where backflow could cause serious illness or death.
  Examples: Hospitals, abattoirs, sewage treatment plants

Where uncertainty exists regarding the appropriate hazard classification, the highest hazard rating must be applied.

For example, a caravan park that includes a portable toilet dump point must be classified as high risk rather than medium.

Devices installed to manage medium and high risks must be inspected and assessed periodically in accordance with Australian Standards.

Backflow prevention principles

The following principles guide AlburyCity’s management of backflow prevention:

• Installation of backflow prevention devices: All properties connected to AlburyCity’s potable water supply must install backflow prevention devices in accordance with the Plumbing Code of Australia, AS/NZS 3500.1, and AlburyCity connection requirements.
• Hazard rating determination: Hazard ratings must be assessed by a licensed plumber with appropriate backflow accreditation in accordance with AS/NZS 3500.1.
• Qualified testers and training: All testers must be registered within AlburyCity’s database. AlburyCity Water and Wastewater staff provide training on the digital management system.
• Multiple activities or processes on site: Where more than one activity occurs on a property, the default hazard rating is high, requiring a device suitable for high hazard containment.
• Unknown hazards: Commercial, industrial, or mixed-use developments with unknown hazards default to a high hazard rating.
• Change of use: If a property’s use changes and the hazard rating increases, an appropriate backflow prevention device must be installed.
• Medium and high hazard properties: These properties must install and maintain a Reduced Pressure Zone Device (RPZD) at the property boundary, with no bypass connections permitted.
• Registered air gaps and registered break tanks must comply with AS 2845.2.
• Low hazard meter installations: Low hazard 20mm and 25mm connections must be protected by an AlburyCity-supplied water meter incorporating a backflow prevention device.
• No bypass connections: All water entering a property must pass through the installed backflow prevention device.
• Compliance with standards: All relevant Acts, regulations, and standards must be strictly adhered to in order to safeguard public health and the water supply.

Management of inspections and compliance

AlburyCity oversees inspections, maintenance, repairs, and reporting of backflow prevention devices using a QR code system endorsed by the Backflow Prevention Association of Australia (BPAA).

All inspections and test reports are recorded in a secure, cloud-based system accessible via mobile devices. QR tags streamline registration, inspection, and maintenance, and assist with identifying unregistered devices.

Standpipes and fire services

Standpipes—whether portable or fixed—used for tankers, water carting, or temporary supply are classified as high hazard when connected to AlburyCity’s water supply system.

Fire services connected to potable water require, at minimum, a single testable check valve. Where alternative water sources are interconnected, a higher hazard rating applies.

Where two fire appliances are present in a high-hazard area, backflow prevention devices appropriate to the hazard level must be installed.

How to apply

To ensure all backflow devices are registered and installed in accordance with relevant standards, an application to install a backflow prevention device must be completed and approved prior to installation.

Why compliance matters

Backflow prevention is not optional. It is a critical safeguard for public health and the integrity of the water supply. Compliance helps ensure clean, safe drinking water for the entire community.

Need more information?

Contact the AlburyCity Water and Wastewater team at info@alburycity.nsw.gov.au