Some 1.2 billion people—almost one fifth of the world—live in areas of physical water scarcity, while another 1.6 billion face what can be called economic water shortage. The situation is only expected to worsen as population growth, climate change, investment and management shortfalls, and inefficient use of existing resources restrict the amount of water available to people. It is estimated that by 2025 fully 1.8 billion people will live in countries or regions with absolute water scarcity, with almost half of the world living in conditions of water stress.