How does backflow occur?
Backflow happens when water from a property is drawn back into our water system.
It can occur when:
- There is a burst on the water main suppling your property.
- Water is being pumped from our water main for firefighting.
- You’re using water at a high pressure.
- There is a cross connection from the drinking water supply at your property (i.e. bore water supply).
Why is it a problem?
Backflow can result in a public health risk. It allows pollutants into our water supply that contaminate the drinking water for other customers.
Assessing the risk
We’ll assess the risk of backflow at you property when you apply for a property connection. If you need a backflow prevention device, then we’ll let you know what kind of device you’ll need.
Installing a backflow prevention device
It’s up to you to arrange a licensed plumber to install your device. The plumber must be accredited in backflow prevention.
The following tables show what types of backflow prevention devices are required.
The following types of backflow prevention are required for the premises listed below:
High Hazard Rating
| Type of Premises | Type of device |
|---|---|
| Abattoirs | RBT, RPZD |
| Bidet and similar devices | RAG, RPZD |
| Car and plant washing facilities | RBT, RPZD |
| Caravan parks with dump point | RAG, RPZD |
| Chemical laboratories | RBT, RPZD |
| Chemical plants | RBT, RPZD |
| Commercial laundries | RAG, RPZD |
| Drinking nipples and troughs | RAG, RBT, RPZD |
| Factories using processing or manufacturing toxic chemicals | RBT, RPZD |
| Hospitals, mortuaries, clinics and similar | RBT, RPZD |
| Industrial and teaching laboratories | RAG, RPZD |
| Irrigation systems injected with fertilizers, herbicides, nematicides and insecticides (Type D) | RBT, RPZD |
| Metal finishing plants | RBT, RPZD |
| Petroleum processing or storage plant | RBT, RPZD |
| Piers, docks and other waterfront facilities | RBT, RPZD |
| Premises where inspection of devices is restricted | RBT, RPZD |
| Premises with alternative water supply e.g Bore | RBT, RPZD |
| Premises with recirculating water for heating, cooling, processing | RAG, RPZD |
| Sanitary depots | RBT, RPZD |
| Sanitary dump points | RAG, RPZD |
| Secondary school | RAG, RPZD |
| Sewerage treatment plants and sewerage lift stations | RBT, RPZD |
| Standpipes used for water carting or temporary supplies | RBT, RPZD |
| Public swimming pools | RAG, RPZD |
| Universities | RBT, RPZD |
| Water tanker trucks (cartage) | RPZD |
Medium Hazard Rating
| Type of Premises | Type of device |
|---|---|
| Aircraft facilities | Testable Device |
| Drinking fountains | Testable Device |
| Food and beverage processing plants | Testable Device |
| Irrigation Systems (Type C) | Testable Device |
| Premises with grey water reuse systems | Testable Device |
| Premises with rainwater tanks plumbed into domestic supply | Testable Device |
| Premises with reticulated and disinfected reclaimed water systems | Testable Device |
| Public amenities | Testable Device |
Low Hazard Rating
| Type of Premises | Type of device |
|---|---|
| Fire services unless otherwise determined | SCV |
- The backflow device at containment must match the highest internal hazard rating.
- Wannon Water does not permit RPZD to be installed in pits.
- The premises table shows a representative sample of premises and facilities listed in the NCC and AS3500 where Wannon Water requirements take precedent.
- Where a residential property has an alternative water source such as grey water, recycled water or water tank, a dual check valve with an atmospheric port is required to be installed after the water meter.
- Despite the above, where a backflow accredited plumber deems the hazard can be managed via an alternative device, a recommendation is to be provided in writing and assessed prior to approval.
Abbreviations, standards and codes
- RAG means Registered Air Gap
- RBT means Registered Break Tank
- RPZD means Reduced Pressure Zone Device
- SCV means Single Check Valve
Testing and maintenance requirements
After installation, your plumber needs to test your backflow prevention device. Test results must be sent to us within 10 days of testing.
You’ll also need to arrange your plumber to test the device on an annual basis. Again, results must be sent to us within 10 days of testing.
Need more information
Call us, or download our information sheet for more details.
