Tensions on water is now widely recognized as both a threat and a challenge to human well-being. Although acting on enhancing water availability to some users has been the main option up to now in many situations, attention is more and more given to reducing the demand. Recent events at national and international scales have proven how actual the question is, and initiatives toward sobriety are increasingly gaining ground, even if somewhat disputably. I will describe the situation of water scarcity in France nowadays and under climate warming pressure. Then I will present the Strateau tool, which is currently under deployment at the CEREMA, and its potential for describing in a territorialized manner the main water consumers. Contrary to most of existing tools, it calculates all water usages from non-water related information from various data sources, instead of relying on less accurate, sectorially limited, water-related data. This allows to explore vulnerability and development options by acting on the real levers for decision making.