When a building is connected to the main water supply line, a pressure difference in the supply lines may force water from the building to start flowing back to the main line. This should not be a problem if the water is clean. However, some people have poorly designed and serviced plumbing systems, so you may find contaminated water flowing back to the main line. The best way to avoid this is to install a backflow prevention valve. This will ensure that no water that has already entered a building’s water supply system returns to the main line. The testing of backflow Sydney water supply systems normally undergo are meant to enhance public safety.
Every property needs to have their backflow valve serviced on a regular basis. This is a legal requirement. The test and service must be done by a qualified plumber.