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Water quality changes for water supply

Friday 11 November, 2022

New national regulations for the quality of safe drinking water come into effect on Monday 14 November.

The changes are to the threshold for bacteriological treatment, which means Council will make some changes to how the Gisborne City water supply is treated.

“To be compliant with the new changes we will have to increase the concentration of chlorine,” says Drinking Water Team Leader Judith Robertson.

“This will be a temporary measure until the new UV treatment facility at the Waingake water treatment plant is completed.”

Council’s Drinking Water Assessment for the city supply has been 100 per cent compliant.

Ms Robertson says there is a risk of not complying with the new rules if enough water can’t be treated at the Waipaoa plant over summer and all the water for the city has to be supplied from the Waingake treatment plant.

“Although the treated water will be safe, the new rules can’t be fully met when we run very high water flows through the Waingake plant.

“Everything we do in the treatment process is to ensure the water supplied is safe and the proposed chlorine level will be well within the acceptable levels for a water supply,” says Ms Robertson.

“Council will maintain adequate water flow from the Waingake plant to stay within the new treatment threshold and will be operating the Waipaoa treatment plant from mid-November through to April to make up the water demand for the summer months.”

The UV disinfection facility is currently being constructed at Waingake and is due to be commissioned by June 2023, adding another level of treatment for contamination and means we won’t have to rely only on chlorine.

“As we come into summer everyone needs to be making efforts to conserve the water supply and to not waste water as we don’t have an unlimited supply. This includes industry as well as individual households,” says Ms Robertson.

“We will soon be starting our annual water conservation campaign to encourage people to be careful about water use.”

The new Drinking Water Standards are now separate from the Drinking Water Quality Assurance Rules and Operational Monitoring Rules.

The Standards list the maximum allowable limits for contaminants in drinking water and the Rules for water treatment and monitoring must be met to demonstrate safe water is supplied to customers.

In addition to increasing chlorine levels in the water, Council has also recently increased the fluoride levels to meet the optimal range for dental health as recommended by the Ministry of Health.