That is the option that will be put to the Waitaki District Council's meeting on Wednesday to upgrade the Hampden-Moeraki and Herbert-Waianakarua schemes to Ministry of Health drinking water standards.
Those schemes do not meet the standards now.
In March, the council commissioned a consultant to look at the options for future supplies and the cost of treatment to meet the standards.
That report found the most cost-effective was a pipeline connecting the two schemes to the Oamaru water treatment plant, which had already had a $12 million upgrade to meet new standards.
Kakanui and Weston-Enfield schemes have already been connected to Oamaru.
For Herbert-Waianakarua and Hampden-Moeraki, three options costing between $2.4 million and $5.5 million were identified.
Connecting to Oamaru would cost about $4.9 million, not the cheapest but the best in terms of ensuring enough water for the future while providing cost-effective treatment.
Rates would rise with the upgrading. At present, the Hampden-Moeraki urban rate is $301 a year and rural rate $379. The Herbert-Waianakarua rate is $289.
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.
Initially, the council was told by the two scheme committees their communities were gravely concerned about the cost which they considered was absolutely significant and far too much.
However, after a public meeting, a survey was sent out to all consumers. Of the 192 returned, 125 favoured connecting to Oamaru.
Water and waste water manager Oscar Smit, in a report for Wednesday's meeting, said connecting to Oamaru spread the operating and maintenance costs across a much larger number of ratepayers.
The cost for the new consumers could be reduced by Oamaru ratepayers sharing in the cost of the pipeline, adding about $18 to their rates.
However, Mr Smit recommended that not be done and the pipeline cost be on the Herbert-Waianakarua and Hampden-Moeraki consumers.
That way, there would be no impact on Oamaru ratepayers.
