Backflow is the unwanted flow of potentially contaminated water into the potable (drinking) water supply. Our water distribution system is designed to ensure that water flows to a property under pressure, if this pressure is not maintained there is a chance that water could transfer from a property back into the main water supply.
Backflow can occur in two ways:
- Back Siphonage is a condition that can occur when a negative pressure occurs in the main and contaminated liquids enter the potable water supply by siphonage.
- Backpressure is a condition where the pressure downstream becomes greater than the pressure upstream of the cross connection thus allowing water or other contaminated liquids to enter the potable supply.
What is a Cross Connection?
Cross connections are actual or potential physical connections between potable and non-potable water. There is a risk to public health if there is a cross connection between a water supply and a contaminated source.
The most common situation involving cross connection is with unmetered fire services and internal plumbing of water tanks. Other examples of where potential cross connections are likely to occur are – market gardens, dairy farms, commercial kitchens, clubs & hotels, dental surgeries, funeral parlours, hospitals, and mechanical workshops.
Cross connections without proper backflow prevention can cause health issues for water supply customers. By protecting our water supplies from contamination, we can better protect our community from harmful hazards.