This paper presents a methodology for improved understanding of options for managing urban water demands under the uncertainties associated with climate change. It combines a sensitivity analysis of water supply with forecasts of water demand and examines how, conservation efforts may offset deficits which result from climate change. It presents a case study of Nassau County, New York State, USA, that concludes that deficits projected for warmer climate scenarios can probably be alleviated by increased conservation. For scenarios of decreased precipitation, more extreme measures (eg rationing) may be necessary, illustrating the prudence of considering climate change in planning studies for communities which already experience water supply problems.