Backflow Prevention: Protecting Our Water Supply

Backflow is defined as the un-intended flow of water from a potentially polluted source into a potable water supply or flow in direction contrary to the normal direction. This can happen when water moves "backwards" through pipes, which could lead to contamination of the drinking water. Backflow is a serious concern that can lead to harmful chemicals, waste, or other contaminants entering the water supply.

Backflow prevention involves using special devices that stop the reverse flow of water, ensuring that our water remains clean and safe for drinking and use. These devices are installed in properties where there is a risk of contamination, protecting the public water supply from pollutants.

Backflow can occur when the pressure in the water supply system is lower than the pressure at the property, causing water to flow backward. Some common situations where backflow may occur include:

• A break in the water main, either within the property or outside in the Council’s network
• Water being pumped from the main water supply during a fire
• Water usage on the property at a higher pressure than the supply pressure
• Heavy water use at the property reducing water pressure in the supply network
• The water outlet on the property being much higher than the water main

Contaminants that can enter the water supply through backflow depend on the type of activity or business at the property. Some examples include:

• Chemical pollutants from industries using chemicals (e.g., vehicle repair shops or businesses with chemical waste)
• Grease and oils from food establishments with grease traps or oil separators
• Pesticides or fertilisers from agricultural operations (e.g., farmers filling spray tanks)
• Wastewater from laundromats or cleaning facilities

Plumbers with backflow accreditation are trained to assess the risks of contamination and advise on the appropriate prevention measures.

Certain properties are at higher risk for backflow contamination and are required to have testable backflow prevention devices. These properties include:

• Hotels, motels, and caravan parks
• Vehicle repair workshops
• Restaurants and food establishments
• Medical and dental surgeries
• Car washing and plant washing facilities
• Laundries and dry cleaners
• Hospitals and funeral parlors
• Schools, daycares, and kindergartens
• Pest control businesses
• Water-carrying vehicles
• Banana packing sheds
• Properties with a fire hose reel

Domestic homes are usually considered low-risk, but some homes may still require backflow devices, especially if they have non-testable devices that prevent contamination.

There are different backflow prevention devices which can be installed depending on the hazard(s) within the premises and their hazard rating. Australian Standard AS 3500 defines three degrees of hazard associated with cross-connection and backflow, namely:

High Hazard: “Any condition, device or practice that, in connection with the water supply system, has the potential to cause death.”

Medium Hazard: “Any condition, device or practice that, in connection with the water supply system, has the potential to endanger health.”

Low Hazard: “Any condition, device or practice that, in connection with the water supply system, constitutes a nuisance but does not endanger health or cause injury.”

AS 3500.1 Appendix F outlines the hazard rating for individual facilities within a premises and the hazard rating of different uses within a premises or the hazard rating of different types of premises. Based on the type of facility or premises type, the standard prescribes different forms of backflow prevention device.

Backflow prevention devices have one of the following elements to stop water flowing backwards:

• a valve that only lets water go in one direction
•  an air gap
•  a break tank.

To register and test your backflow prevention devices, contact a licensed plumber with backflow accreditation. The plumber will inspect and test your device, send the registration details to Council, and advise on any maintenance or repairs if necessary.

Your plumber will provide a quote for the inspection, testing, and any repairs required. The cost of repairs depends on the size and complexity of the valve, but spare parts are generally available for most devices.

Yes. There is a $50 backflow device register maintenance (administration) fee. This fee covers the costs of managing the testing and registration program, including issuing notices and reminders, maintaining records, processing test results, and carrying out audits or investigations.

Backflow prevention devices are necessary as long as there is a risk of contamination. If you think the device is no longer required, you can contact a licensed plumber to assess your property and determine whether the device can be removed.

Failure to register your testable backflow prevention device and comply with state legislation (Plumbing and Drainage Regulation 2019 Section 102) can result in significant fines. Cassowary Coast Regional Council is obligated to ensure all water consumers comply with regulations to protect public health and water safety.