The board received a report from 3 Waters manager Gerry Essenberg, proposing the board approve and recommend an extension to the area serviced by the Wanaka wastewater scheme, Project Pure, which is at Wanaka Airport.
Following Mr Geddes' warning, the board deleted Mr Essenberg's recommendation and added a new one of its own drafting, requesting the Wanaka airport management committee present a feasibility study on extending the scheme before any new connections are approved.
Several airport businesses are on septic tanks and want to connect to the scheme, as do the owners of two blocks of land near the airport.
The Pittaway family has made a resource-consent application to build hangars near the airport.
Because Project Pure lines go through their property, they have an existing agreement with the council to connect, subject to paying developer contributions.
The Rhodes family, which owns and is extending the Wanaka Toy and Transport Museum, also wants to connect.
Mr Essenberg's report was prompted by the Wanaka airport committee, through the Queenstown Airport Corporation.
His report notes all financial costs of extending the scheme would have to be met by the applicants, including the full costs of providing the reticulation and connections.
Additional properties could then make use of part of the works in the future, subject to approval.
Mr Geddes said the board needed to ascertain the number and location of other potential connectors and the risk of future resource consent applications in the area before proceeding.
Scheme extensions through rural areas around Queenstown had encouraged more development of rural lifestyle areas, which in turn had imposed high infrastructure costs on the community, particularly around Lake Hayes, he said.
A scheme extension could also encourage inappropriate strip development along the pipeline, which follows State Highway 6 between Wanaka and the airport.
"The next thing that will happen is you will have all adjacent landowners along Ballantyne Rd saying "connect us, too" . . . Do the feasibility first, understand the costs, the implications for development contributions. Get feedback from tenants [whether] this cost is acceptable, then go back to the utilities committee with an extension proposal," Mr Geddes said.
He agreed with board member Carrick Jones, who noted there was "tons of capacity" in the system for growth.
But having capacity was not a rationale for approving extensions, "because there are a lot of planning issues that arise from that", Mr Geddes said.
