- Last updated:
- 21 Feb 2020
Backflow prevention devices play an important role in protecting our drinking water supply from contamination.
All backflow prevention devices must be registered with the local government and the valves tested at least every 12 months to ensure they are working correctly.
We do this by ensuring the check valves within the backflow prevention device are closing tightly against the valve seat. Because we cannot normally see inside the valve we use a differential pressure test gauge to ensure the check valves are not leaking.
Before you commence any work or testing procedure it is important to notify the owner for permission to be in the area. It is also important to ensure the area you are working in is safe.
Water supplies are often used to earth electrical supplies, so bonding straps be used to prevent any danger of electrocution. Next, inspect the valve to check for any damaged or broken components. It is also important to ensure the installation complies with Australian standards and local authority requirements.
Test gauges are a precision instrument and must be calibrated every 12 months to ensure their accuracy. They must be treated with care and maintained in good working order.
It's important to know how the differential pressure gauge works, and that you know what the different valves and hoses do.
A differential pressure gauge always has two ports. A high pressure port – red, and a low pressure port – blue.
The gauge shows the difference in pressure. The vent line, which is yellow, allows you to bleed the air from both the high and low pressure sides of the gauge to ensure you get a correct reading.
The balance valve must be in the closed position to read the differential pressure.Guidelines for backflow prevention are available on council’s website.