Backflow Prevention Management
Backflow Prevention Management prevents water from ‘backfeeding’ into the water supply. This can contaminate the supply and can potentially affect the health of consumers. The back flow prevention device you need would depend on the risk that your property poses to the water supply. The higher the risk the premise poses to the water supply the stricter the controls. Our Backflow Prevention Officer will be checking these control types during her inspections.
How to prevent backflow
To protect our water supply, property owners have a responsibility to install devices and implement measures to stop the backflow of water into the public water supply. It is the owner’s responsibility to pay for backflow protection.
To provide adequate protection, there are four levels of protection that should be provided according to the potential risk at the property.
Please also refer to Hurunui District Council's Backflow Prevention Policy and Backflow Guidance document.
One of the biggest risks to our water supply is backflow. This is caused when water pressure drops in the water supply causing water to flow in the opposite direction - from residential or commercial premises - back into the public water supply network. Contaminants could be back-siphoned or injected by back-pressure into the public water supply.
A back-siphon occurs due to a loss of pressure in the public water distribution system. This can occur:
- when large volumes of water are being drawn for fire protection
- during a water main or plumbing system break or
- during a shut-down of a water main or plumbing system for repair.
During a back-siphon, a reduction of pressure creates a vacuum in the piping and the water flows in the opposite direction. For example, if a hose tap is open when the end of the hose is submerged in a contaminated container of water, the contaminated water in the container can be siphoned into the properties plumbing.
Back-pressure occurs when water is being pumped at a pressure higher than the town mains or the pressure within the building. When back-pressure occurs, water flows in the reverse direction to normal flow. It is important to understand that with a reduction in mains water pressure, the water source only needs to be slightly higher than the public water supply pipe pressure, to push the water back through the property into the water mains.
Because homes and businesses use chemicals and other potential contaminants, backflow can be a major threat to the health and wellbeing of our consumers. At its worst, backflow contamination of the water supply could cause death or serious injury, so we all have a responsibility to help reduce this risk.