Backflow prevention
Safe Protection of Shoalhaven Water
Water Authorities of the Shoalhaven have a responsibility to provide safe drinking water to the residents of the Shoalhaven from the point of treatment to the point of use. It is the property owner's responsibility of any commercial or industrial property to ensure that they do not affect the mains supply with any contaminated water from their property. Shoalhaven Waters aim in the Backflow Prevention Program is to:
- Protect public health
- Protect the environment
Backflow preventers are required by Australian Standards, National Plumbing and Drainage Code (AS 3500.1) for protection and conservation of safe drinking water.
What is Backflow Prevention?
Backflow Prevention is the unwanted reverse flow of contaminants into the potable water supply. As drinking water quality standards are increasing across Australia due to community expectations, a greater focus is now being given to the prevention of contamination of water reticulation systems.
The water supply system is designed to ensure that water flows to your property under pressure. If this pressure is not maintained, there is a chance that water could be drawn from your property back into the Shoalhaven’s main water supply. Backflow can occur in two ways:
- Back Siphonage – a condition that can occur where the water or other contaminated or polluted liquids enter the potable water supply by siphonage, when a negative pressure occurs in the main.
- Backpressure – a condition where the pressure downstream of the cross connection becomes greater than the pressure upstream of the cross connection thus allowing water or other contaminated or polluted liquids to enter the potable supply.
What is Cross Connection Control?
Cross Connection Control is the control of contamination of a reticulation system from potential sources within premises connected to the water reticulation system. Cross connections are direct or indirect physical connections of potable and non-potable water.
There is a risk to public health if there is a cross connection between your water supply and a contaminated source. If there is a pressure drop in the watermain, a vacuum could be created in the water supply system. Under certain conditions this creates a siphonage effect and draws liquid from a contaminated source back into the drinking water supply.
Some examples of where potential cross connections that are likely to occur are:
- Market gardens
- Dairy farms
- Commercial kitchens, Clubs, Hotels
- Dental surgeries
- Funeral Parlours, Mortuaries
- Hospitals, Nursing homes
- Industrial or Commercial Premises eg chemical plants, dry cleaners, photographic developers, laboratories, mechanical workshops
Backflow Prevention Containment Devices
A backflow prevention device helps to ensure that where there is a cross connection to the water supply, the potable (or drinking) water of the Shoalhaven is protected against any possible contaminants from entering into our precious water supply.
Any commercial property that potable water enters is designated to be either a high, medium or low hazard area. These three hazard ratings are identified by AS/NZS 3500.1 are:
- High Hazard – any condition, device or practice which in connection with the water supply system has the potential to cause death
- Medium Hazard – any condition, device or practice which in connection with the water supply could endanger health
- Low Hazard – any condition, device or practice which in connection with the water supply system could constitute a nuisance but not endanger health
Hazard Ratings determine the type of backflow prevention device that is required. A survey from a certified plumber will determine the appropriate hazard rating. For a property that has been determined high risk, the most common device installed is a Reduced Pressure Zone Device (RPZD). For a property determined as a medium risk, the most common device installed is a Double Check Valve (DCV). These are all classified as testable devices.
Shoalhaven Water requires that a backflow prevention containment device be installed at the boundary water meter servicing your property and that all services serving the property be protected by a backflow prevention device. This ensures that if there is a cross connection the drinking water supply is protected from backflow.
The purpose of a CONTAINMENT Backflow Prevention Device is to isolate one consumer’s property from another and the public water supply.
Inspection and Maintenance after Installation
Testable backflow prevention devices must be inspected and tested after installation and a plumbers Test and Maintenance Report must be forwarded to Council to initiate the registration process.
The Initial Registration process involves having one of Shoalhaven Waters Field Officers inspect the device/s for correct installation, and the device/s entered into a specialised backflow prevention database.
The need for annual testing
Each backflow prevention device must be tested on an annual basis. This is a condition of connection to the water supply. It ensures that the device is maintained and continues to operate effectively. The annual test will ensure the drinking water supply is protected from backflow.
WARNING: If a device is faulty or defective it may not prevent a contaminated source entering the drinking water supply.
Worse case scenario:
A nearby property uses the drinking water supply.
A dangerous chemical (or contaminant), which can remain in the watermain for a period of time, will go down the watermains and into a nearby property. When this water is used for drinking, showering, household or business purposes the occupants could be seriously or fatally injured.
How to have your device tested
A backflow prevention accredited licensed plumber will need to test all your devices. Shoalhaven Water has a list of certified plumbers who have volunteered their names, although there may be other plumbers in the yellow pages available for use, they will have to provide their accreditations to Shoalhaven Water for their test reports to be accepted. Please see attached list of accredited plumbers in the Shoalhaven.
Shoalhaven Water has an Annual Registration process in place that involves a Reminder Letter being sent to you approximately four weeks prior to the due test date allowing you adequate time to engage a plumber to test all of your devices.
The plumber will supply you with a Test and Maintenance Report for each of the devices tested. These reports will have to be forwarded to Council along with a signed Annual Agreement Form which is issued to you with the Reminder Letter.
Shoalhaven Water can provide you with information on both the Initial Registration Procedure and the Annual Reminder Procedure at your request.
Backflow Prevention Fees and Charges - 2007 / 2008
Shoalhaven City Council has an adopted policy that requires fees and charges to coincide with your testable backflow prevention device. They are as follows:
0-3 devices |
4-9 devices |
10+ devices |
|
Initial Registration |
$85.00 |
$100.00 |
$120.00 |
Annual Registration |
$30.00 |
$45.00 |
$60.00 |
Overdue Registration (in addition to the above) for every four week period overdue or part thereof |
$60.00 |
$60.00 |
$60.00 |
For further information contact our Regulatory Field Officer, Keith Foley on 4429 3518 or our Assistant Regulatory Officer, Michelle Murden on 4429 3140.
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