What is Backflow Prevention?
A backflow prevention device is used to protect water supplies from contamination by backflow from connections to the water supply system (from customers premises or standpipes).
How does backflow occur?
The water supply system is designed to ensure that water flows to your property under pressure. If this pressure is not maintained, there is a chance that water could be drawn backwards into the water main.
Water pressure can be affected when:
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there is a break in the water main
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water is being pumped from the main water supply during a fire
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a customer is using water at a higher pressure than the pressure supplied by Sydney Water
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heavy water use downstream reduces water pressure upstream
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the water outlet at the property is higher than the water main, causing constant back pressure.
There is a risk to public health if there is a cross connection between your water supply and a contaminated source. If there is a pressure drop in the water main, a vacume could be created in the water supply system. Under certain conditions this creates a siphoning effect and draws liquid from a contaminated source back into the drinking water supply.
A number of different property types pose a particular risk to public health through cross connections.
These include:
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chemical plants
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pest controllers
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market gardeners
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golf courses/sporting ovals
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caravan parks
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greywater treatment systems
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metal processing plants
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paint manufacturers
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laundries
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nurseries
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residential properties with rainwater storage