Backflow Prevention Devices

Backflow prevention devices are used to protect the community and ensure that reverse flow of contaminants into the town drinking water supply cannot occur through either;

  • Siphoning of contaminated liquid into a water main when there is negative pressure due to a burst water main.
  • A cross-connection of wastewater in a system (or other system) having a higher pressure than the water main.

A video explaining owner responsibilities for backflow prevention devices is below.

Watch the video or read the text version.

  • Backflow is any unwanted flow of potentially contaminated water into the potable (drinking water) distribution system.

    This can occur when water flows backwards, or opposite to its normal and intended direction of flow, which can result when water pressure to a property is not maintained or if a pump is connected to a property’s water plumbing system.

    Backflow can occur when for example:

    • the water delivery main (reticulation system) is at a lower pressure than a property’s plumbing system. This can occur when there is a burst in the supply main or during fire-fighting operations;
    • if a pump is connected to a property’s internal water plumbing system; a property is using water at a pressure higher than the pressure in a water main;
    • if a pump is connected to a non-potable supply and there is a town water top-up or interconnection. Many rainwater tank installations are fitted with a pressure pump on the delivery side of the tank;
    • high water usage downstream causes a pressure reduction upstream;
    • the water outlet on a property is significantly higher in elevation than the water utility’s main with a constant back pressure; or
    • if an alternate water supply (e.g. bore water) is connected to a property’s water supply system.
  • A backflow prevention device prevents this reverse flow of water from a potentially polluted source into the regional drinking water supply system.

    You may have a backflow prevention device fitted on your property if you have any of the following:

    • an irrigation system;
    • fire hose reels or hydrants;
    • a commercial or industrial activity or machinery connected to the mains;
    • water outlets in proximity to pollutants, grease traps or chemicals;
    • an underground rainwater tank that has mains water backup; or
    • a black or greywater dump point.
  • If you have a testable backflow prevention device on your property it must be tested annually by a private, fully licensed plumber and the test results forwarded to Council.

    It is a requirement under the Plumbing and Drainage Regulation 2019 that owners of installed testable backflow prevention devices must:

    • register the device with the local government; and
    • at least once each year, have the device inspected or tested by a person who is licensed to do the work.

    Please ensure that the plumber you engage to carry out the test has the correct license endorsement as not all plumbers are licensed to carry out testing of backflow prevention devices.

    Details of suitable plumbers within the Region can be found in the Yellow Pages and other business search facilities.

    Testable backflow prevention devices include reduced pressure zone, double check and some single check valves.

    It is the responsibility of the plumber to forward the test results to Council within 10 business days after testing the device.

    Non-testable devices like dual check valves and some single check valves do not need to be tested annually.

  • Council has a responsibility under state government legislation to maintain a program for the registration, maintenance and testing of testable backflow prevention devices installed in its area.

    The information supplied to Council from test reports is recorded in a register.

    Council charges an annual administration fee per device which is used to maintain the register and for any correspondence that may need to be sent to owners.

  • The majority of new backflow prevention devices will require a plumbing application and an inspection by Council’s plumbing inspectors.

    Some devices may be installed under the notifiable work category.

    It is the responsibility of the licensed plumbing contractor to submit a Form 4 to the Queensland Building and Construction Commission and forward a copy of the completed Form 9 to Council.

Contact us

For further information, please contact Council's Customer Service Centre on 1300 79 49 29 or email