Backflow Containment

What is backflow?
Backflow is the term used to describe when water within a plumbing system on a property flows in the reverse direction. Backflow can be caused by a combination of factors such as water or other contaminated liquids entering the reticulated water supply,  this can happen when the water supply is turned off to conduct repairs and a reverse pressure occurs allowing contaminated water to enter. Another example is back pressure which can result in contaminated liquid reversing its flow.

How is backflow prevented?
An authorised plumber can fit a backflow prevention device to internal plumbing to rectify backflow issues. All water meters have backflow prevention valves installed however other preventative measures may need to be installed. These are determined by whether the backflow prevention device is needed at a fixture (tap), connection within the property or at the property boundary.

These are described as:

Measures   Description
Individual Protection

Backflow prevention at individual fixtures.


Zone Protection

Backflow prevention provided at the connection to specific sections of the water supply system within a building.


Containment Protection                 

Backflow protection provided at the property boundary to protect TasWater’s reticulation supply from contamination.


The type of prevention device required is determined at the time a property owner wishes to undertake building or plumbing works that affect TasWater's interests.  They will have to obtain a certificate for certifiable work from TasWater and a condition of that certificate may be the installation by the property owner of a backflow prevention device.  Property owners are required to test the prevention device on a regular basis.

Who is responsible for installing and maintaining prevention devices?
All properties connected to either the reticulation or bulk water supply require an appropriate backflow prevention containment device at the property boundary. Ownership of the backflow prevention device, (with exception of water meters) and the associated costs for installing, maintenance, annual testing and administration costs shall be the responsibility of the customer. The device required will be identified by the hazard rating of the processes conducted onsite as as specified below:

Assessment Description
Unknown Hazard Rating Where the hazards are unknown for a new commercial and industrial development at time of building/connection application, the hazard rating will default to HIGH.
Fire Service If the boundary site hazard is HIGH or MEDIUM a fire service with testable double detector check assembly with testable metered low flow bypass will be required or else a testable single detector check assembly with metered low flow bypass is required.

(Refer: defined by AS/NZS 3500:1 Section 4, table 4.1 and table F3)

Who can I talk to about my specific requirements?
Please contact our Development team on 13 6992.  They will only be too happy to provide assistance and advice about your particular requirements.

New build plumbing

Hazard Rating System (AS/NZS 3500.1)

Hazard Rating Description


Any condition, device or practice that, in connection with the drinking water supply system, has the potential to cause death.
Medium Any condition, device or practice that, in connection with the drinking water supply system, has the potential to endanger health
Low Any condition, device or practice that, in connection with the drinking water supply system, constitutes a nuisance but does not endanger health.

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