When it comes to safety, knowledge is everything, and fortunately there is a wealth of information about RPZD's (Reduced Pressure Zone Device), AKA backflow prevention devices, available at our fingertips.
Similar to a component of a Fire Protection System in a commercial or multi-story building, an RPZD has the potential to save lives or, at least, minimise serious harm to people. It is understandable that regional and local water authorities have made it mandatory to have them installed into new build buildings with water meters larger than 25mm (medium to high hazard). Some authorities have taken the step to serve owners with a 'notice to comply' to install backflow devices retrospectively at their cost.
A backflow prevention device eliminates the potential of a cross-connection within a property between potable water and any source of contamination that can cause harm or even fatal injuries. This can occur when the water mains is at a lower pressure than the internal plumbing system causing back siphonage. Examples of where this may occur are during a burst water main, excessive water demand, and sometimes during firefighting operations.
Owners are responsible for organising a Licenced Plumber (RPZD accredited) to assess, install, and maintain their backflow prevention devices. Plumbers are also responsible for advising property owners of their backflow requirements and for installing correctly rated backflow prevention device in-line with their needs, and in accordance with the current 3500 AS/NZS Standards. All RPZD's are required to be registered, tested yearly and test results submitted to their local water authority using an online lodgement system.
Water Corporations/Authorities may inspect properties to ensure ongoing compliance with Backflow Prevention obligations are met. Failure to maintain a backflow device will result in the serving of a non-compliance notice to the property owner or occupier.
For lower hazardous situations, Vacuum Breakers or Dual Check Valves are suitable backflow prevention devices that attach to hose taps to prevent back siphonage in contaminated areas. These devices may be used on hose connections in pool areas, garbage/waste rooms, grease trap enclosures, laboratory sinks, etc.
If you are unsure of your obligations, it is always better to be safe and ask you plumber to assess your properties backflow prevention requirements. I have seen many developments with existing RPZD's that have been forgotten about, so it is also worth asking your plumber to investigate if there are existing devices that need to be put back onto your maintenance program.