This document is a letter from the year 2093 to the generation of 2015 regarding water and sustainable development. It summarizes the challenges facing water management and urges action to achieve the UN Sustainable Development Goals. It warns that past inaction on environmental issues has led to problems like water stress, pollution, and exclusion of the poor from water access. The letter calls for public ownership and management of water as a universal human right. It encourages the 2015 generation to participate in building sustainable water policies at local, national, and global levels through a transdisciplinary global citizenship movement.