Higher-quality water will cost Duntroon residents about three times as much a year once the Waitaki District Council upgrades the town's scheme to meet legal requirements.
The supply is drawn from a spring between the town and the Waitaki River, but is subject to frequent and sometimes lengthy ''boil water'' notices because it becomes contaminated.
Yesterday, the council's assets committee recommended $110,000 be spent installing filter and ultraviolet units to meet drinking water standards for 106 residents, which will result in the unit water rate increasing from $188 to an estimated $560 a year per connected property.
Depending upon final approval from the council at its August 6 meeting, design work is expected to start promptly, with the higher rate being paid from the 2015-16 financial year after upgrading work is finished.
Cr Jim Hopkins emphasised that, as with other water schemes throughout the district, the council was passing on costs imposed by ''Parliament passing a law we have to comply with''.
Alternatives were examined, including finding a higher-quality source, but treating the existing one was the cheapest.
Other options ranged in price from $280,000 to $330,000, including connecting the township to the Tokarahi water supply.
However, doing that would have put the Tokarahi supply, at present designated agricultural, into the community supply category, requiring further upgrading.
Looking for other sources of better quality and right quantity water would add to the costs, especially if none was found.
A report for the council said the existing supply provided sufficient water, but recorded persistent bacterial count.
This could be treated by ultraviolet and filtration units installed within the existing shed which, apart from the capital cost, would add an estimated $24,000 a year to operating costs.
Using ultraviolet bacteria treatment would avoid the use of chlorine, which the community did not want.
The council had resource consent until 2033 to take water from the existing source.
The upgrade had been discussed with the Duntroon water subcommittee, which favoured retaining and treating the existing source.
