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Backflow Prevention

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There are certain appliances which require additional layers of protection, to prevent chemicals from entering the potable water supply. These devices are referred to as Backflow Prevention Devices.

This is not just a plumbing rule with little or no foundation. These devices are extremely important to our water quality and safety of the general population.

Backflow Prevention Hazard Ratings

Some situations present more dangers than others, which is why backflow prevention devices have different zone ratings. These devices fall into High, Medium, and Low hazard categories.

  • “High Rating Backflow prevention devices are used where cross-connections are made with water supply and the contaminants. These actions have the potential to cause death”
  • “Medium Rating Backflow prevention devices are used where cross-connections are made with water supply and the contaminants. These actions have the potential to endanger health”
  • “Low Rating Backflow prevention devices are used where cross-connections are made with water supply and the contaminants. This would constitute a nuisance but neither endanger health nor cause an injury”

AS/NZS 3500.1:2015.4.3

What types of installations require a testable backflow prevention device?

You may need to install a testable backflow prevention device on your premises if you have any of the following.

  • an irrigation system.
  • fire hose reels or fire hydrants.
  • commercial cooking equipment or industrial equipment.
  • water outlets in proximity to a grease trap, grey water tank, or septic tank.
  • water outlets in proximity to pollutants or chemicals.
  • an alternate water supply.

Common Commercial Appliances which Require Backflow Protection

The list below shows the most common commercial appliances which require a backflow prevention device. It also indicates their most commonly identified hazard ratings. Please note that every local council has different installation requirements for backflow prevention.

The Brisbane and surrounding councils are generally quite fair but strict on their backflow requirements.  They quite often require more than the national standard.

If the appliance below has a low rating, then a non-testable device in most cases will be adequate.

  • Chemically Injected Combi Oven (Medium, High).
  • Chemically Injected Glass Wash (Medium, High).
  • Chemically Injected Dishwasher (Medium, High).
  • Post mix (Low).
  • Coffee Machine (Low).
  • Ice Machine (Low).
  • Jug rinse (Low).
  • Hot Water Unit (Low).
  • Hose reel (Medium).
  • Beer Lines (Medium)
  • Chemical Dispensers with low toxicity (Low).
  • Hair Salon Basins, massage chairs (Low).

Contact the manufacturer or read your appliance manual if you require more information.

Types of Backflow Prevention Devices

Backflow devices generally fall into two different categories and are rated in High – (H), Medium – (M), Low – (L) categories;

  • Testable Backflow prevention devices
    • RPZD (H, M, L)

  • Double Check Valve assembly (DCV), (M, L).
  • Double Check Detector assembly (DCDA), (M, L)
  • Spill-Resistant Type Vacuum Breaker (SPVB), (H, M, L).
  • Pressure Type Vacuum Breaker (PVB), (M, L).
  • Registered Beak Tank (RBT), (H, M, L).
  • Registered Air Gap (RAG), (H, M, L).

  • Non-Testable Backflow prevention devices
    • Non-Testable Dual Check Valve (DUAL CV), (L).
    • Non-Return Duo Valve, (DUAL CV), (L).
    • Atmospheric Vacuum Breaker, (AVB), (L).
    • Air Gap (AG), (L).
    • Break Tank (BT), (L).
    • Dual Check Valve with Atmospheric Port, (DCAP), (L).

The list could be far more extensive than this. These valves are the main backflow prevention devices you are likely to come across.

Requirements for Testable Backflow Prevention Devices

At the installation stage, the backflow prevention device will need to be installed and commissioned by a licensed person and then registered with the local authority. These devices will then require an annual inspection to make sure they are still providing a level of protection to the water supply.

Testable devices will require water and drainage feeds.

Requirements for Non-Testable Backflow Prevention Devices

The only requirement here is that these watermarked devices are installed by a qualified plumber. There are no annual inspections for these devices. Charges are only applicable if they require maintenance. The council will check to see whether they are installed during the inspection phase for new installations.

General Costing

All the prices below are based on basic scenarios for the supply and installation of these backflow prevention devices. Use these figures to get quotes as a guide only.

RZPD$600 – $800 – 15/20mm Only. High rating (Testable).

DCV$500 – $700 – 15/ 20mm Only. Medium/Low Rating (Testable).

Dual Check Valve$175 – $250 – 15/20/25mm only. Low Rating (Non-Testable).

Atmospheric Vacuum Breaker$120 – $175 – 15/20mm only. Low Rating (non-Testable Device).

Our pricing calculator can be used to help you price your job today.

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