Backflow is the unplanned reversal of liquid/contamination from your property into the Council's potable water supply system.

Backflow devices have the fundamental function of preventing contamination of our potable water supply networks. All metered properties have a level of backflow protection with a dual check device maintained by the Council.

However, properties that have activities that are considered as a major risk to the health, safety and wellbeing of our consumers need a higher degree of protection.

High and Medium risk activities

  • The Building Act 2004 requires all buildings to have a safe and adequate water supply. The Health Act 1956, and the Health (Drinking Water) Amendment Act 2007, section 69ZZZ “Protecting water supplies from risk of backflow”, authorises the Council to enforce backflow prevention, whether the hazard is new or historic, and recover all reasonable costs incurred for testing, survey, and retrofitting devices. The Backflow Prevention Policy (W213, page 79 Council Policies) [PDF, 4338 KB] sets out the backflow prevention requirements for new and existing properties in the district depending on the types of activities that are undertaken.
  • Properties are classified into three degrees of risk. This determines the type of backflow device you need to install.
  • RiskActivityExamplesDeviceTesting
    High Uses or produces toxic or bacterial matter that may cause death or serious illness if leaked into the main water supply Hospitals, mortuaries, chemical plants, laboratories, cooling towers, hairdressing salons, food processing and other manufacturing plants. Reduced pressure zone (RPZ) Annual
    Medium Produces backflow that can endanger health Public and private swimming pools, spa baths, garden irrigation systems (pop-up sprinklers), drink dispensers with carbonators, commercial laundries and rainwater tanks connected to household plumbing.Testable Double-check valve Annual
    Low Could cause a nuisance from colour, smell or taste but does not endanger health
    A residential home with only domestic water use
    Air gap separation or hose vacuum break valve Not required

    Examples of activities which may require backflow prevention with a Reduced Pressure Zone Device (RPZ) are:

    • You use water for washing equipment that has been exposed to chemicals or pathogens.
    • You mix water with other substances on your property.
    • You have a secondary water supply on your property.

    Our responsibility

    We assess the requirement to install a backflow preventer at the time of any:

    • Building consent application: a building consent is required for most backflow preventers, but if you have already applied for a building consent for other work you can include your backflow device(s) in this application.
    • New water connection approval: all new water connection to our network must be supervised by our maintenance contractor Sicon Ltd).
    • Property/building change of use: property owners must notify the Council when changing the use of a building.
    • Building Warrant of Fitness certificate renewal: to maintain a current building warrant of fitness all backflow devices must be inspected and tested annually, by an Independently Qualified Person (IQP).
    • Application for a temporary bulk water extraction permit

    Your responsibility

    • It is the cost of the property owner to supply and install the appropriate backflow prevention device where required.
    • The cost of installation will depend on the diameter of the water main required within the site.
    • New backflow devices are required to be installed just inside the property boundaries in Rolleston IZone area and must be added to the Property's Compliance Schedule.
    • For new commercial connection, a water meter must be installed in the berm side of the property boundary to enable access to it for reading and maintenance at any given time. This should not be installed within the same housing box as the backflow device. Plantings must be kept clear a minimum of 0.5 metres from the new water meter. It is the responsibility of the applicant/property owner to advise Council of all as-built information (including the new meter serial number, installation date & start reading) through the new connection approval process.

    For all other enquiries regarding Backflow prevention requirements please contact us.