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Information

Information and advice for

a safer tomorrow

What can cause backflow?

Mixing Water with drums of chemicals with no backflow prevention device in place in a sure way of playing Russian Roulette with the drinking water

High Hazard

Any condition, or potential of a condition, device, or practice, which in connection with the water supply system has the potential to cause death.

Medium Hazard

Any condition, or potential of a condition, device, or practice, which in connection with the water supply could endanger health.

Low Hazard

Any condition or potential of a condition, device, or practice, which in connection with the water supply system would constitute a nuisance but not endanger health or cause injury.

Three hazard ratings identified AS/NZS 3500:1 Section 4 are:

Does my property require a Backflow Prevention device?

Most industrial, commercial and some residential properties will require a backflow prevention device.

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If a property requires a backflow prevention device at a minimum this will be installed at the water meters and at the fire services. These are called a containment backflow prevention device.

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Additional backflow preventions devices may be necessary inside the premises. These devices are called either a zone backflow prevention device or an individual backflow prevention device.

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Contact your BPAA member, who is a licensed accredited backflow plumber for more information and help. Go to our testers page in your state to contact them.

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All backflow prevention devices (containment, zone and individual) must be tested every year by your licensed accredited backflow plumber to ensure that they are working correctly.

 

Failure to have these devices tested annual may effect your public liability and building insurances.

There are multiple conditions which can cause water backflow

There are multiple conditions which can cause water backflow such as –

  • Cross Connection Backflow – It is a connection between a drinkable water supply and any source of contamination. A cross connection can lead to a dangerous situation where the contaminated or waste water may enter the supply water pipelines thus contaminating an entire city’s water supply. Some classic examples of cross connection that can occur in any household are: 

  • Bidets cross connection 

  • Commercial grease arrestors

  • Chemical dispensers

  • Cooling Towers

  • Mixing of Chemicals

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Cross Connection Backflow has the potential of allowing contaminants into the drinking water system.

  • Back Siphonage Backflow – Back siphonage may be caused by atmospheric pressure exerted on a pollutant liquid, forcing it towards a drinking water supply i.e. instead of water entering the tank of a house, the entire content of the tank which might contain insecticides were drawn into opposite direction into the potable water supply. For example, it can occur when the pressure in a tank or water trough is lower than the water system’s pressure. This could allow the influx, or pulling, of contaminated water into the system. 

Why are Backflow Prevention devices necessary?

A backflow incident can cause health concerns for people using water. A Backflow Prevention Containment Device ensures that when there is a cross connection the drinking water supply cannot be contaminated.

Backflow Protection is also required where there is the possibility of a Cross Connection.

 

There are different types of devices which can be installed depending on the hazard rating of the property. The three hazard ratings identified AS/NZS 3500:1 Section 4 are:

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