Design has begun for chlorinating Blenheim’s water supply.

National water regulator Taumata Arowai requires a residual disinfectant, typically provided by chlorine, to be added to water supplies by 31 December this year. That deadline won’t be met, but systems should be in place by mid-2025.

Council’s Planning and Development Engineer Stuart Donaldson said Taumata Arowai had reinforced the need for Blenheim’s water supply to be chlorinated to ensure it met the Water Services Act and the Drinking Water Quality Assurance Rules.

While Blenheim’s water, which delivers water to 10,700 households, is currently treated for protozoa and bacteria, there is no chlorine dosing.

Taumata Arowai has outlined that the Water Services Act 2021 requires suppliers to use a multi-barrier approach to managing risks to protect drinking water from contamination.

Mr Donaldson said a permanent chlorination plant would be built, for which design was already underway.

Chlorine is a safe, simple and inexpensive way to disinfect drinking water, capable of killing most common bacteria including campylobacter and norovirus. It’s generally used alongside other processes such as protozoa barriers which remove or inactivate single-celled parasites such as cryptosporidium and giardia. Supplies in Renwick, Picton, Havelock, Wairau Valley, Seddon and Rural Awatere are chlorinated.

Budget has been set aside in the Council’s Long Term Plan for chlorinating the supply.

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