What should a manager do to prevent backflow?

Backflow prevention refers to the control of potentially harmful contaminants entering into our drinking water supply from cross connections in a customer’s premises or backflow of contaminants into the water supply system.

Backflow prevention devices are required under our Site Containment Backflow Prevention Standard, Australian Standards AS/NZS 2845: Water Supply – Backflow Prevention and AS/NZS 3500: Plumbing and Drainage for any property or operations that pose a risk to the public drinking water supply.

All properties connected to our water supply system are required to be risk assessed and have an applicable site containment backflow prevention device installed. The risk assessment should address the requirements of our Site Containment Backflow Prevention Standard to determine if the property is a high, medium or low hazard risk to the drinking water supply.

If the property operations are outside the scope of the Standard contact our Technical Services team.

Learn more about hazard ratings, required devices, and a customer's right to appeal the rating.

The three 'cross connection' hazard ratings identified by Australian Standard AS/NZS 3500 Plumbing & Drainage are:
- 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.
- 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.
The hazard rating of the site's operations and processes determines which type of device you are required to install. If the hazard rating varies due to multiple processes, you must apply the highest hazard rating.
- Low hazard – All 20mm and 25mm Hunter Water issued water meters incorporate internal low hazard devices therefore no additional device is required in this instance. We manage the replacement of these devices through our meter exchange program. For water meter sizes greater than 25mm, an independent site containment testable device is required to be installed immediately downstream of the property’s water meter.
- Medium hazard – An independent testable back flow prevention device is required for all service sizes. We recognise a testable Double Check Valve (DCV) for this category. The device is to be installed immediately downstream of the property’s water meter.
- High hazard – An independent testable back flow prevention device is required for all service sizes. We recognises a testable Reduced Pressure Zone Device (RPZD) for this category. The device is to be installed immediately downstream of the property’s water meter.
Backflow risk can be classed as low, medium or high as provided in our Site Containment Backflow Prevention Standard and Australian Standard AS/NZS 3500 Plumbing & Drainage.
- Low risk – any condition, device or practice in connection with the drinking water supply system that constitutes a nuisance but does not endanger health or cause injury.
- Medium risk – any condition, device or practice in connection with the drinking water supply system that could endanger health.
- High risk – any condition, device or practice in connection with the drinking water supply system that could cause death.
The hazard rating of the site's operations and processes determines which type of device you are required to install. If the hazard rating varies due to multiple processes, you must apply the highest hazard rating.
Yes. If the property owner considers the risk rating assigned to the property is higher than the risk of site-specific activities being carried out, then they may appeal this rating.

The appeal must include:
- reason for proposed risk downgrade from a licensed plumber (include supporting evidence)
- You licence number, name and contact number
A formal appeal can be submitted to our Technical Services Section via email

Avocet Place - 1, 2, 3, 4, 5, 6, 8, 9Barker Road - 10, 15, 20, 25, 30, 35, 45, 55, 60, 65, 70, 75, 80, 85, 95, 105, 115, 125, 130, 135, 145, 150, 155, 160Carroll Road - 6, 11, 20, 25, 28, 30, 36,Corella Avenue - 15, 19, 20, 25, 30, 34, 38, 40, 45, 50, 60, 65, 70, 75, 80, 81, 85, 90, 95, 99, 105, 109, 110, 115, 120, 125, 129, 130, 135, 140, 145,Currawong Drive - 5, 9, 10, 20, 27, 30, 31, 35, 39, 40, 45, 50, 51, 55, 59, 60, 65, 66, 70, 80, 81, 84, 85, 90, 91, 95, 100, 104, 105, 108, 110, 115, 120, 121, 125, 126, 130, 140,Deborah Road - 5, 10, 14, 15, 21, 24, 34, 36, 50,Dougall Court - 5, 10, 15, 20, 25, 30, 35, 40, 45, 50,Heron Court - 5, 15, 25, 30,Hicks Road - 470, 483, 499,Hillier Road - 150, 155, 160, 170, 180, 190, 200, 210, 220, 240, 250, 260, 270, 280, 290, 295, 300, 310, 320,Jason Road - 6, 16, 25, 30, 31, 36, 37, 43, 44, 50, 51, 53, 55, 56, 57,Lacey Road - 20, 30, 50,Macleod Road - 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105,110, 115, 120, 125, 130, 135, 140, 145, 150, 160,Ninnis Court - 6, 12, 15, 20, 25, 30, 35, 36, 40, 45, 50, 52, 55,Sandpiper Grove - 10, 15, 20, 25, 30, 35, 44, 45, 50, 55, 60, 65, 70, 80, 85, 95, 100, 105, 109, 110,Schirmer Court - 5, 15, 19, 20,Sittella Road - 5, 10, 12, 15, 20, 25, 30, 35, 45, 46, 56, 60, 64, 70, 76, 80, 85, 90, 95, 100,115, 130, 140, 150,Smyth Road - 65, 105, 125,Stanley Road - 10, 25, 65, 70, 80, 90, 100, 105, 109, 110, 115, 120, 125, 130, 135, 140,SunbiRoad Court - 1, 2, 3, 4, 5, 6,Tattler Court - 2, 3, 4, 5, 6,Thornbill Cres - 1, 7, 10, 13, 14, 19, 20, 24, 25, 30, 31, 37, 43, 49, 50, 55, 60, 61, 64, 67,73, 79, 80, 81, 85, 90,Tobin Road - 10, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120,Whistler Court - 5, 15, 19, 20, 24, 25,

Whitewood Road - 420, 425, 430, 435, 440, 445, 465, 475, 485, 494, 495, 502, 505,

Backflow is water that flows backwards into our pipes after a property has used it. It may carry contaminants that can harm people's health. That's why all connections to our water and recycled water pipes – including fire service connections – must be protected with devices for backflow prevention containment. Property owners are responsible for getting the right kind of backflow device installed.

What backflow devices are

What type of backflow device you need

Backflow occurs when water from a customer's property flows backwards into our pipes. This may carry contaminants that can harm people's health. 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.

Backflow prevention devices stop water flowing back into our pipes. They 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.

These devices are important as they protect our water quality, and the health of people using it.

Property owners are responsible for getting the right kind of backflow device installed. If you're 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. They need to assess the hazard rating every time site activities change. Tell them if your property has more than one connection to our water main. This may affect your hazard rating and the type of device the plumber must install.

Install the device

You must get a licensed plumber to install the right kind of device. You're responsible for ensuring your plumber sends us a certificate of compliance when they install high and medium hazard devices.

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 sends us the results within 2 days of the test.

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 the Australian Standard, AS/NZS 3500:1.

Low hazard properties

Owners of low hazard properties must get a non-testable backflow prevention containment device installed. Our 20mm and 25mm meters have a simple backflow prevention device in them. These are suitable for low hazard connections.

You must get a separate device installed if you have:

a larger meter
an unmetered water connection
a high or medium hazard rating.

Medium hazard properties

Owners of medium hazard properties must get a testable double check valve assembly installed.

High hazard properties

Owners of high hazard properties must get a registered break tank, reduced pressure zone 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 separate sprinkler and fire services, you must get a testable double check detector assembly. It must be installed near where the water service enters your property or upstream of any booster assembly or off-take from the fire service. 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 or registered air gap installed.

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. NSW Fair Trading licenses plumbers in NSW.

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 Standard AS/NZS 3500:1. If your installation doesn't comply with the standard, 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: