It appears that in an increasing number of regions, land and water could be the main factors limiting food production. The objective of this paper is to examine present and future water availability for food production at a time of increasing demands for water from other users, e.g. for sanitation and drinking-water in mega-cities and for industry. Farmers not only have to compete for water with urban residents and industries, but increasingly also with the environment as its services in sustaining good-quality water supplies through wetlands and groundwater aquifers become more widely recognized. The latter demand has not yet been quantified accurately. Decision-makers should know more clearly the consequences of the choices they make in order to balance water supply and demand.