The economic, social, and environmental limits of supplying water to metropolitan areas through conventional means (reservoirs, water transfers, etc.) have resulted in growing consideration of demand management actions as well as in the use of non-conventional sources of supply. In terms of demand management, economic instruments (pricing and taxes), domestic water-saving technologies, and educational campaigns to encourage water saving during periods of drought have received special attention. While demand management policies have an effect on conserving water and therefore should be welcome, they present problems and uncertainties as well. Using the example of the metropolitan region of Barcelona, in this article I argue that water demand management policies may be insufficient for reaching their ultimate goal of controlled water consumption when confronted with structural changes in urban development such as the expansion of low-density growth, the multiplication of the number of households, or gains in income, all of which lead to a potentially greater demand for water. This calls for more integration of water policies with land use and urban development policies.