Your obligations regarding backflow prevention
In most circumstances backflow devices are installed at the boundary of the property at the water meter. This is done to protect the potable water supply and is referred to as containment. Where a backflow protection device is installed the backflow protection device must be registered with the relevant water authority.
The backflow device is typically required to be tested on commissioning, after any maintenance and every 12 months thereafter by a licensed plumber.
Our local water authority will send a letter annually to the property owner regarding maintenance of a backflow device, with penalties applying if the backflow protection device is not tested.
We are happy to place you on a backflow protection device testing schedule if needed. These services are commonly used by facilities such as building, body corporates, hospitals and schools.
What is the purpose of a backflow protection device?
Generally the purpose is to stop contaminates from entering the drinking water where a risk exists. In commercial plumbing situations this may be where chemicals could siphon back into the drinking water. While the chances are lower similar risks exist in domestic plumbing situations.
Siphoning back via a hose pipe is a common cause and therefore the law states you must have back flow prevention in place. A hose connection vacuum breaker (HCVB) can be installed at the outlet of your hose tap, this will protect your mains water supply from the siphon of contaminated water back into your drinking supply. To use a domestic plumbing example if you used your hose to fill the weed killer spray bottle and leave the hose in the bottle while attending to something urgent a siphon may set itself up and contaminate your drinking water. A backflow prevention device stops this.
Types of backflow protection
In Australia, water authorities require containment protection on our water or fire services in order to protect the community’s water supply.
There are 3 types of backflow protection installation methods:
Containment protection – where the device is installed at the property boundary, just downstream of the meter assembly serving the property, including all fire services located at the boundary.
Zone protection- where the device isolates an area or building within the property boundary.
Individual protection – where the device Device installed at point of potential contamination within the property.
Some properties may have more than one device as is common with commercial plumbing situations or larger domestic properties and farms.
Loss of water pressure
Installation of a backflow protection device will reduce water pressure and flow rate downstream of the device. The Plumbing and Gas Guys can resolve loss of water pressure for you if needed. We discuss any potential loss of water pressure with you when installing a backflow protection device should we believe that a loss of pressure or water flow will occur.
Common backflow devices
Break tank backflow protection device:
A break tank is an approved air gap that disconnects the incoming water supply from the downstream water system. It has an air gap on the water inlet to the tank and an overflow that is below the level of the air gap.
A registered break tank means the device is recorded in a backflow prevention management system and is suitable for use in high risk situations. Registered break tanks must be tested at commissioning, after any maintenance and every 12 months by a licensed plumbing contractor, qualified to test the devices.
Reduced pressure zone backflow protection device:
Reduced pressure zone devices have two independently acting non‐return valves. Flow through the device will only occur when there is sufficient pressure to overcome the valve springs. A relief valve is located between the non‐return valves and opens to atmosphere under conditions of backflow.
Double check backflow protection device:
Double check valves have 2 independently operated spring loaded, non‐return valves in series. Flow through the device will only occur when there is sufficient pressure to overcome the valve springs.