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What is backflow?

Backflow means any unwanted flow of used or non-potable water or substance from any domestic, industrial or institutional piping system into the pure, potable water distribution system. Backflow occurs when the contaminated source enters the water supply through cross connection of that source with the drinking water supply.
Common installations within domestic or residential premises can be underground sprinkler systems and/or underground water tanks which require backflow control if connected to the domestic water supply.
Tweed Shire Council is the local water authority and regulatory authority for plumbing and drainage work in the Shire. This means that Council has a role to ensure that all plumbing and drainage is carried out in accordance with the relevant standards. Generally Council accepts responsibility for the shires water supply, its maintenance, repair or renewal of water service pipe work from the water main to the meter comnnected to a property. The property owner is responsible for all maintenance within the property from the water meter.

How Does Backflow Occur?

Council’s water supply system is designed to ensure that water flows to your property under pressure. If pressure is not maintained, there is a chance that water could be drawn backwards and into the water supply. Water pressure can be affected when:
  • there is a break in the water main
  • water is being pumped from a water main during a fire
  • a customer is using water at a higher pressure than that supplied
  • heavy water use downstream reduces the water pressure upstream
  • the water outlet at the property is higher than the water main which causes a constant backpressure
If there is a cross connection between your water and a contaminated source there is a potential health risk. If there is a pressure drop in the main, a vacuum could be created in the water supply system which, under certain conditions, creates a siphoning effect and draws liquid from a contaminated source back into the drinking water supply. This contaminant may then remain in the water supply system until such time as pressure is restored. If this water is used for drinking, showering, household or business purposes the occupants could be seriously of even fatally injured.

Prevention of Backflow

A backflow incident can cause health concerns for people using the water supply system. A backflow prevention device ensures that where there is cross connection the drinking water cannot be contaminated. There are different types of backflow devices which can be installed depending on the hazard rating of the property. These hazard ratings are identified under AS/NZSS3500:1 and broken up into three categories being high, medium and low. Some devices are fitted as part of a connection to Councils water supply and others may be required to be fitted to an internal supply system to protect the occupants of a particular property. It should be noted that many of these backflow devices need to be tested annually. These testable devices once installed will be entered onto Councils backflow register.

Annual Testing

Customers that have a testable backflow device/s installed are required to have the device tested for operational function at intervals not exceeding 12 months. Council will advise you in writing when the annual test date is due. Maintenance of all backflow devices is the responsibility of the property owner.

The annual testing of a backflow device is a condition of connection to Councils water supply. Annual testing provides an assurance to both yourself and Council that the device is properly maintained and is operating effectively and safely. The annual test will ensure the drinking water supply is protected from backflow. If a device is defective or faulty, it may:
  • not prevent a contaminated source entering the drinking the water supply
  • cause water to be wasted through leaking devices
  • impact on the water pressure supplying your property

How to Have Your Device Tested

Only licensed plumbers with backflow prevention accreditation issued by a registered training organisation can inspect commission and test backflow devices. When arranging your annual inspection simply ask the plumber if they hold accreditation for backflow device testing and certification as this is issued separately to their plumbing license.

After testing your device your licensed plumber will give you a Backflow Prevention Device Inspection and Maintenance Report. A copy of this report must be sent to Council within 2 days of testing together with the prescribed registration and archiving fee to ensure customer compliance with Tweed Shires backflow prevention requirements. Given the potentially serious nature of backflow contamination failure to comply with this requirement may lead to the disconnection of your property from Councils water supply.
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