Water is humanity’s most valuable resource – every human being on the planet depends on clean water for survival. It is also the key element for economic development: virtually every production process, from agriculture to manufacturing and energy production, relies on vast amounts of water. While many regions on Earth are blessed with plenty of water to provide for life and growth, water scarcity affects over 2.7 billion people for at least one month per year. Regional climate conditions are obviously a key factor behind water scarcity – and climate change may cause even more water security challenges in the future – but in order to understand the complex economy of water consumption, water shortages and pollution, the problem needs to be considered from a global perspective. Arjen Hoekstra, the world’s leading expert on international water management, has addressed this by introducing the concept of the water footprint, a way to measure the amount of water used directly or indirectly in producing goods and services from a cup of coffee to the performance of a nuclear power plant. According to Arjen, “Water problems are often closely tied to the structure of the global economy. Many countries have significantly externalized their water footprint, importing water-intensive goods from elsewhere. This puts pressure on the water resources in the exporting regions, where too often mechanisms for wise water governance and conservation are lacking.” At Falling Walls, he shows why a fair distribution of fresh water among a growing world population is one of the great challenges of the 21st century and what businesses, civil society and consumers can do to support more sustainable policies.