We are already in an era of water scarcity – a quarter of the world's population has no safe water, 46 percent have no proper sanitation, and each year 4 million children die of water-borne diseases. The prospect of large-scale conflict over water supplies becomes more and more likely. Yet the technology for effective water husbandry does exist, and investing in water efficiency, recycling and conservation can go a long way to meet rising demands.