What is backflow?
The term backflow refers to the reverse flow of water that makes its way into the main water supply from either a residential or commercial system. This water will contaminate the main supply of the Altogether network if contact between the two is made.
How does backflow occur?
Backflow occurs when there is a sudden pressure drop in the water main outside of your property (e.g., there is a break in the network). The effect of this may result in water within the fixtures (bidets, toilets, hoses, irrigation systems etc.) in your home being syphoned back into the Altogether network. This can potentially pollute your (and your neighbours') water system – and no one wants to use water from their neighbour's bidet!
Backflow prevention stops potentially harmful contaminants entering our drinking and recycled water systems from cross connections in customer premises or backflow of contaminants.
The main backflow prevention methods are as follows:
- Air gaps
- Break tanks
- Double-check valves
- Reduced pressure zone device
- Pressure vacuum breaker
- Single check valve
Yes, there are a few different legislative and regulatory documents to consider when it comes to backflow prevention in NSW:
- Plumbing and Drainage Act 2011 (NSW).
- Plumbing and Drainage Regulation 2017 (NSW).
- Plumbing Code of Australia [PCA].
- AS/NZS 3500.
All properties connected to our water infrastructure must comply with the site containment backflow requirements of AS/NZS 3500 (Australia and New Zealand Standard for Plumbing and Drainage Part 1) and the Plumbing Code of Australia.
The required backflow device is determined by identifying the individual hazard(s) within the property. There are three hazard ratings identified in AS/NZS 3500 for cross connections:
- Low Hazard: Any condition, device, or practice that, in connection with the water supply systems, constitutes a nuisance but does not endanger health or cause injury.
- Medium Hazard: Any condition, device, or practice that, in connection with the water supply system, has the potential to endanger health.
- High Hazard: Any condition, device, or practice that, in connection with the water supply system, has the potential to cause death.
If unsure, check with Altogether regarding your hazard rating.
- Low Hazard: All 20mm and 25mm Altogether Group issued water meters have internal low hazard backflow prevention devices. No further device is required.
- Medium Hazard: An independent, testable backflow prevention device is required for any service size and must comply with the site containment backflow requirements of AS/NZS 3500. This could be in the form of a double-check valve assembly or reduced pressure zone device (RPZD) installed downstream of the property’s meter.
- High Hazard: An independent, testable backflow prevention device is required for any service size and must comply with the site containment backflow requirements of AS/NZS 3500. This must be in the form of an RPZD installed downstream of the property’s meter.
An appropriately qualified and licenced plumber is the only person who can install a backflow prevention device.
Yes. Your accredited backflow plumber must test high and medium hazard devices:
- At installation
- Every year after the device is installed
A report must be submitted to Altogether Group each time the device is tested.
Yes. A toilet seat douche or bidet installation must comply with AS/NZS 3500, which includes requirements for backflow prevention based on the hazard rating.
Toilet bidets are becoming more and more popular as time goes on in Australia, with various options now available on the market. Utilise an appropriately qualified plumber to ensure you are meeting the requirements of AS/NZS 3500 when it comes to your bidet installation. This is incredibly important for ensuring the safety of our water supply - and maybe something that you haven’t considered before now.
It is worth noting that in all situations, the connection point for a bidet outlet shall be taken from a drinking water supply. Recycled water supply cannot be used for this purpose.