In its simplest form, Backflow usually occur when water flows in the opposite direction to what it is expected to flow. The water is intended to flow in one direction and for what ever reason it flows in a different direction.
A sudden and unexpected drop in pressure normally causes issues. Some of the causes for this can be main bursts, pipes freeze or unexpectedly high demand on the system. This automatically creates a negative pressure in the supply system in your home. When a backflow occurs, reduced pressure may allow contaminated water from the ground, storage or other sources to enter the system. One of the biggest issues is that this allows drinking water to be contaminated via a cross-connection.
A properly installed and maintained device unit will ensure water flows safely by automatically trapping it as it begins to flow in the wrong direction. This prevents water from a property being drawn back into the main drinking supply and dangerously causing cross-connection.
The risk ratings of a home or building will determine what type of backflow device will need to be installed to prevent back flow. Homes and buildings are classed as low risk, medium risk or high risk. A professional plumber from Melbourne 24 Hour Plumbing or Mr. Plumber Sydney who are accredited plumbers can confirm the risk rating of your property. A typical back flow assembly unit will have test cocks and shut off valves for prevention. Back flow device units must be thoroughly tested when they are installed, relocated or repaired. Back flow devices must also be tested annually to ensure they are in proper working order for safety.
Sydney Water States the following about backflow:
Each backflow prevention containment device must be tested on an annual basis. This is a condition of connection to the supply. It means that the device is maintained and continues to operate effectively. The annual test will ensure the drinking water supply is protected from backflow. If a device is defective or faulty, it may:
A backflow prevention accredited licensed plumber will need to test all of your devices. After testing your devices your licensed plumber will submit his report within 2 days on the Sydney water website stating if the device is installed correctly and if it has passed or failed the test. The plumber will give you a copy of the Backflow Prevention Device Inspection and Maintenance Report. If a valve fails the test and is not repaired or replaced Sydney water can disconnect you from the main supply.
This shows the seriousness of water backflow issues. Please be sure you follow the rules and advice given by Sydney Water.