Mexico City is experiencing a deep water crisis. It ranks 3rd on the Nature Conservancy’s list of places most likely to run out. Of 2.6 million homes, 36% experience regular water shortages, and total cuts in supply are increasingly common. Isla Urbana develops Rainwater Harvesting (RWH) technology designed to increase water supply for the most affected residents. Rain is captured from the houses’ roofs, cleaned, and stored for use, providing an abundant, autonomous, water source where it’s most needed. Its mission is not to simply install RWH systems, but to transfer the know-how and work with communities to teach them to harvest their own water in the most effective ways. Isla Urbana designs physical components, communication and teaching strategies, implementation models, and user support, to allow large-scale adoption of RWH in Mexico City. To date, it has designed city-wide programs, and has directly installed over 20,000 systems in houses and schools throughout Mexico.