Three options costing between $2.4 million and $5.5 million are being considered to upgrade two southern community water supplies administered by the Waitaki District Council.
The Hampden-Moeraki and Herbert-Waianakarua schemes, which together have about 1400 consumers, do not meet the Government's drinking water standards.
But before the council makes any decisions, it will put three options -including connecting to Oamaru's water treatment plant - to consumers with costs and the effect on their water rates.
The council's assets committee will decide on Wednesday whether to accept the options, prepare a letter and survey for consumers on the two schemes and hold a public meeting to provide additional information and answer questions.
After that consultation, a final recommendation will go to the committee on October 15.
Technical reports have been prepared for the council looking at sources of water and upgrading options, not just to meet existing demand but also to provide a secure supply in the future.
The options which have come out of those investigations are exploring and testing a ground-water supply from the Papakaio aquifer; building either a single treatment plant or twin treatment plants using existing or augmented water sources; or connecting to the Oamaru water treatment plant, up to 40km to the north.
Oamaru ratepayers paid $12 million to upgrade their treatment plant in 2007, including providing extra capacity.
Weston has already been connected, Kakanui is in the process and the two southern water schemes would stretch the capacity at peak demand of its filtration system, which may need upgrading.
The council had budgeted $1.347 million for upgrading both southern supplies.
The cost of the three options being looked at for the southern schemes are (excluding GST):
• Papakaio aquifer deep ground water: $2.4 million.
• Surface water with either single or twin treatment plants: $4.9 million to $5.5 million.
• Connecting to the Oamaru water treatment plant: $4.9 million.
Rates would also increase with the upgrading. At present, the Hampden-Moeraki urban rate is $301 a year and rural rate $379. The Herbert-Waianakarua rate is $289.
An estimate based on the ground-water option (including loan payments) would increase the rates to $652 for Hampden urban and $821 for rural. The Herbert rate would be $821.
Treating the existing supplies would increase the rate for Hampden urban to $624 and rural $786. Herbert would increase to $786.
Connecting to the Oamaru scheme would, depending on two options, result in a rate as high as $523 for Hampden urban and $659 for rural. Herbert would be $659.
While the ground-water proposal was the cheapest, it carried significant risk including drilling and finding suitable water and the cost of treatment which may be required.
Connecting to Oamaru was the preferred option, but all would be put to consumers for their views.
