The Information Tool on Urban Water Systems was developed at the Zofnass Program for Sustainable Infrastructure at the Harvard Graduate School of Design. The tool is the outcome of research on urban water management cases across US, from East to West Coast. It is a data-driven framework designed to be tailored to varying water system challenges: from stormwater management in New England, to water shortage as in California. The tool consists of two distinct parts: the first can be summarized as "learn the system" and the second as "improve the system". The scope of the first part is to develop awareness about the water system for non-expert stakeholders, such as city managers and the community. Through data visualization and system-based storytelling, it provides information about the urban water flows, performance data, and geospatial synergies. The second part - through interactive modeling and scenario evaluation - highlights the opportunities to improve the system. Our algorithm identifies the buildings, streets, and parking areas for potential green infrastructure or water-harvesting interventions, and quantifies their impact to the reduction of runoff and imported water. The opportunities (green roofs, street planters, porous pavement) focus on the needs of the City of Chelsea MA, our first prototype.