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What is Backflow Prevention?

A backflow prevention device is used to protect Sydney's water supply from contamination by backflow from properties connected to the water supply system (from customers premises or standpipes). You can find Sydney Waters Backflow Prevention Page here.

How Does Backflow Occur?

The water supply system is designed to ensure that water flows to your property under pressure. If this pressure is not maintained, there is a chance that water could be drawn backwards into the water main.

Water pressure can be affected when:

  • there is a break in the water main

  • water is being pumped from the main water supply during a fire

  • a customer is using water at a higher pressure than the pressure supplied by Sydney Water

  • heavy water use downstream reduces water pressure upstream

  • the water outlet at the property is higher than the water main, causing constant back pressure.

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Properties That Require Backflow Prevention Devices

A number of different property types pose a particular risk to public health if backflow occurs. These include:

  • Restaurants

  • Laundries

  • Mechanics

  • Medical Centres

  • Chemical Plants

  • Golf Courses/Sporting Oval (any property with alternative water supply)

  • Car Washing Facilities

  • Abattoirs

  • Sydney Backflow Prevention provide backflow testing or repair services at all of the above property types.

Contact Sydney Backflow Prevention For Your Backflow Containment Device Testing:

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Types of Backflow Prevention Device

Reduced Pressure Zone Device (RPZ)

A reduced pressure zone device (RPZ valve) is the most commonly used form of backflow prevention. It provides the highest level of protection from backflow occuring.

The device consists of two independent check valves with a pressure monitored chamber and relief valve in between. The chamber is maintained at a pressure that is lower than the water supply pressure, but high enough to be useful downstream. The relief valve automatically relieves excess pressure in the chamber by discharging to a drain.Discharge from the relief port is an indication that either of the two check valves is 'passing' (leaking past their shutoff seats) or the relief valve itself is faulty. Some normal water use conditions may cause short episodes of discharge.

Sydney Backflow Prevention are experienced in testing and repairing all makes of RPZ valves.

Reduced Pressure Zone Device (RPZ Valve)

Reduced Pressure Zone Device (RPZ)

Double Check Valve

A double check valve (DCV) is a backflow prevention device designed to protect water supplies from contamination from properties that have a medium hazard rating.

It consists of two check valves in series. One check valve will still act, even if the other fails. Secondly the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and preventing backflow occurring.

The double check valve is suitable for prevention of back pressure and back siphonage, but is not suitable for high hazard applications. It is commonly used on lawn irrigation, fire sprinkler systems fire hose reels.

Sydney Backflow Prevention are experienced in testing and repairing all makes of DCv on the market.

Double Check Valve (DCV)

Double Check Valve (DCV)

Double Check Detector Assembly

The Double Check Detector Assembly (DCDA) consists of two independently acting check valves, internally force loaded to a normally closed position. It also include a bypass line which includes a water meter to indicate any leaks or unauthorised use of water.

Sydney Backflow Prevention are experienced in testing and repairing all makes of DCDA valves.

Double Check Detector Assembly (DCDA)

Double Check Detector Assembly (DCDA)

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