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Keeping water free of contaminants
Connections to our water and recycled water pipes, including fire service connections, need backflow prevention containment devices. Property owners must make sure the right one is installed.
How backflow occurs
Backflow occurs when used water from a customer's property flows backward into our pipes. It may carry contaminants like chemicals, oil, bacteria, mud and debris that can harm people's health. Contaminated water can pose serious risks.
Backflow is more likely to occur:
- if there's a drop in pressure in the main, for example, during a main break
- if water pressure at the property is higher than at the main, for example, if a pump is operating on the site.
Contaminants may enter the drinking water system through a cross connection caused by:
- faulty plumbing
- hoses submerged in buckets, tanks or pools.
Cross connections are unauthorised plumbing connections between 2 water sources that should be separate, for example, a drinking water system and a recycled water or wastewater system.
Backflow prevention containment devices stop potentially contaminated water from flowing back into our water pipes.
What backflow devices are
Backflow containment prevention devices stop water flowing back into our pipes. They have one of the following elements to stop water flowing backward:
- a valve that only lets water go in one direction
- an air gap
- a break tank.
These devices are important. They protect our water quality and the health of people using it.
What you must do
Property owners are responsible for getting the right kind of backflow device installed. As the property owner, you need to ensure:
- you have the right kind of backflow prevention device installed at your property
- the device is properly maintained.
Assess the hazard rating
You must engage an accredited backflow plumber (a licensed plumber with a backflow accreditation) to assess your site's hazard rating. The hazard rating must be reassessed when site activities change. If the property has more than one connection to our water main, multiple backflow containment devices will be required.
Install a device
You're responsible for ensuring your plumber installs, tests and registers the correct backflow containment device on the water connection servicing your property.
Test the device
Your accredited backflow plumber must test high and medium hazard devices when they're installed and every year afterwards.
Send us the results
Ensure your accredited backflow plumber lodges the test results within 2 days of the test. Ask your plumber for a copy of the report.
What type of backflow device you need
Your backflow device must be suitable for your property's hazard rating. A hazard rating measures whether your property is a high, medium or low hazard to our water supply system. Your accredited backflow plumber will assess your rating. Examples of hazard ratings for different businesses are shown in Australian Standard AS/NZS 3500:1.
Low hazard properties
Owners of low hazard properties with meters larger than 25 mm must get a non-testable backflow prevention containment device installed. Our 20 mm and 25 mm meters have an integral backflow prevention device in them. These are suitable for low hazard connections.
Medium hazard properties
Owners of medium hazard properties must install a testable double check valve for drinking water connections and a double check detector assembly for fire service connections.
High hazard properties
Owners of high hazard properties must get a registered break tank, reduced pressure zone device or registered air gap installed.
Metered standpipes
If we've given you permission to use a metered standpipe on our pipes, your standpipe must have a testable double check valve incorporated into its design.
Construction sites
You need a backflow prevention device on water main connections you use for construction and renovation. If you're building more than a single standalone house, we consider it to be a high backflow hazard.
Sprinkler and fire services
If your property has a sprinkler or fire hydrant service, it must have a testable double check detector assembly on each connection. The double check detector assemblies must be installed close to where the water service enters your property and upstream of any booster assembly or off-take from the fire service. You must not use galvanised pipes and fittings on the upstream side of the connection.
If your property has a window or wall drencher system, you must install a non-testable low hazard device.
Unknown hazard rating
If you don't know your site's hazard rating or don't get it assessed, we'll assume it's a high hazard. Owners of properties with unknown hazard ratings must get a registered break tank, reduced pressure zone device or registered air gap installed.
Who can fit your device
You must use accredited backflow plumbers and licensed plumbers.
- An accredited backflow plumber must assess your site's hazard rating and test your backflow device. Search for an accredited backflow plumber.
- A licensed plumber must install your device. Building Commission NSW licenses plumbers in NSW.
What we will do
We keep a register of all installed testable backflow prevention containment devices. We'll remind you when it's time to get your backflow device tested each year.
We audit a sample of installations to make sure they comply with Australian Standards AS/NZS 3500:1 and AS/NZS 2845, and our connection requirements. If your installation doesn't comply with these standards, we'll send a notice asking you to repair, maintain, test or replace the device.
If you don't comply with our backflow requirements or notices, we may:
- test the device and charge you for the service
- restrict your water supply
- disconnect you
- charge you any costs we incur to make your connection satisfy our requirements.