Cromwell residents will be down to just one bore this week as a vital treatment upgrade takes place for meeting drinking water standards.

The Central Otago District Council has asked residents in Bannockburn, Ripponvale, Lowburn and Pisa communities to reduce their water usage from Tuesday until Friday, while the testing phase took place.

The upgrade would be completed by the end of 2025 and the water services team would be carrying out further bore testing this week to help scope out the final design towards creating an improved treatment plant.

“During this time, the Cromwell water supply will be operating from one bore rather than the normal two, which will impact on the rate at which water can be produced,” a statement from council said.

In early October the council also received direction from Taumata Arowai regarding compliance deadlines for protozoa barriers across all water systems. The move came after a cryptosporidium outbreak in Queenstown, which left many people sick and prompted a boil water notice.

Some of the new technology inside the LDWS treatment plant. PHOTO: Supplied

For water systems that used bore water as their source, installation and operation of a protozoa barrier must be in place by December 31, 2025.

Capital projects programme manager Patrick Keenan said it has always been the council’s intention to upgrade the Cromwell treatment plant as part of the Long-Term Plan (LTP) projects, by the end of 2025.

“Obviously, the council is going to be working hard to meet drinking water standards, however the upgrade is part of the bigger picture around Cromwell water.

“The fact that there are those deadlines (Taumata Arowai compliance) is not directly related to the scheduling of the work on the bore as this had been planned ahead of time.

“The protozoa barrier is one part of the drinking water assurance rules, but the upgrade goes wider. While meeting the aims of the LTP, we’re also future-proofing the water supply for growth and Central Otago, in particular Cromwell, is growing fast.”

To ensure that the council continued to provide safe water in the Cromwell community, people were asked to think carefully about their water usage, and reduce during the four-day period.

During the works, the team would be monitoring the water supply levels closely and may issue a conserve water notice if required.

To help with the water reduction efforts, the council would not be irrigating some greenways and open spaces over this period.

The latest developments involved the Three Waters team investigating the yield and quality of water at two possible new bore sites adjacent to Lake Dunstan.

The drilling works would be carried out in such a way that there would  be no adverse environmental effects, and when the investigation was completed, the drill holes would be backfilled.

Another project awarded by the council this week was to HEB Construction Ltd for the installation of a dedicated rising main to the existing Cromwell reservoir, a $5.7 million contract. 

In the Maniototo, the Ranfurly wastewater pipe renewals project contract was awarded to SouthRoads Limited this week.

The project was estimated to cost just under $1.4million which would cover approximately 750 metres of new wastewater piping. 

Works would get under way in January and the main scope of work would be in the Ranfurly township. 

One of the key benefits to this work was to mitigate infiltration from the variable ground water table and stormwater, which negatively impacted the effectiveness of the Ranfurly wastewater treatment plant.