A temporary ultraviolet (UV) water treatment unit from Selwyn District will be installed at the Ranfurly water treatment plant, following a decision by Central Otago District Council (CODC) on Wednesday (July 30).

The move aims to shorten the duration of the current boil water notice affecting Ranfurly residents, while the full upgrade of the Ranfurly and Patearoa water supplies is completed by December.

The stop-gap measure, costing an estimated $200,000, includes transporting and installing the temporary protozoa barrier and continuing the supply of tankered drinking water during the transition.

CODC mayor Tamah Alley said the decision to install the temporary UV unit factored in more than just cost.

“I’m factoring in visitor image,” she said during the meeting, adding that relying on select taps - whether from a tanker or a point-of-use filter - was not an acceptable look for the township and appeared “third world in the Maniototo”.

Council staff had explored point-of-use treatment options, including for the Maniototo Hospital and various food outlets, but these alternatives raised concerns around practicality and public access. 

Two tankers had already been positioned at Ranfurly’s schools, but issues arose with members of the public entering school grounds to fill containers.

Water services manager Julie Muir said the Selwyn-supplied UV unit offered the most significant improvement for the community in the interim.

“You get a big lift in the level of service…having that temporary barrier,” she told the meeting.

In her report to councillors, Julie said the interim solution would allow the boil water advisory to be lifted several months earlier than otherwise possible.

“The container will be available after 5 August, and could be decommissioned on the existing site, transported, installed and commissioned by early September,” she said.

“This would enable the boil water advisory on Ranfurly to be lifted three to four months earlier (than planned).”

Ranfurly and Patearoa’s water treatment systems, built in the 1980s, currently do not meet modern standards for protozoa - or, at times, bacterial compliance - particularly after rain events that increase turbidity.

A long-term boil water notice was implemented in mid-July after the council was advised by water regulator Taumata Arowai that a boil notice was the only acceptable mitigation until UV treatment was in place.

The installation will be funded through a mix of operational and capital budgets already allocated for the $4.2 million upgrade project.

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