Irish Water has no plans to develop a second reservoir in the Killarney area.
Independent Alliance councillor Michael Gleeson had sought for Kerry County Council to ask the national utility to develop a reservoir at Sheheree, Muckross.
He says this would ensure adequate and secure water supply to the catchment area at all times.
In response, the council says the existing reservoir - which has a capacity of 30,000 cubic metres - provides storage of more than 18 hours for the extremities of the scheme.
Council engineer Colm Mangan says this scheme extends as far as Abbeydorney.