Council staff have been visiting commercial properties around the district as part of work around backflow prevention rules set by the Water Services Authority, Taumata Arowai.

The rules require drinking water suppliers like Ashburton District Council to assess the risk of backflow in their supply networks and ensure appropriate backflow prevention devices are installed.

Following the staff visits, the first batch of letters will be sent this month to around 130 property owners that need to install backflow prevention devices to their drinking water connections.

This includes dental clinics, food preparation facilities, hairdressers and residential properties with swimming pools. More letters will be sent as the investigation work progresses.

Group Manager of Infrastructure Neil McCann said Council was legally required to check the risk posed by backflow on its public drinking water schemes.

“Backflow happens when contaminated or dirty water is sucked back into the drinking water network from pipes, taps, tanks or outlets. When the pressure drops in the watermains nearby, it can suck liquid back into the network from connections to houses or businesses contaminating the water supplier network in the process.

“This could be through a hose sitting in a tank of chemicals or even in a swimming pool. If the hose is connected to the mains, it is vulnerable to backflow, unless a backflow prevention device is installed.”

Backflow risk assessment is a requirement of the Drinking Water Quality Assurance rules and Council has examined its property records and identified about 200 properties with a potential risk.

Council staff have been surveying those properties, with around 30 identified as high risk and about 100 as medium risk. The letters being sent will recommend the type of backflow prevention device needed and it is up to Council to test those devices annually from a register it will create.

As per Council’s Backflow Prevention Policy, all property owners will have to pay for their backflow devices and installation costs.

Mr McCann said residential properties with swimming pools and spas would most likely require some backflow prevention and council staff would start investigations of properties with pools in the coming months.

“It’s a big project overall, but one we have to do to eliminate risks to the safety of our drinking water networks.”

Property owners receiving letters will be asked to install backflow devices at the property boundary by Friday 12 December, and there’ll be follow-up visits to make sure that is done.

Mr McCann said council was also sending copies of Council’s backflow prevention policy as guidance.

“People will no doubt have questions or need more information and we have staff able to help.”

Property owners can contact council on 03 3077700, or email the project’s technical support officer ian.pringle@adc.govt.nz.