The Water Harvesting Assessment Toolbox is a prototype decision aid designed to help communities in the Southwest US understand the role water harvesting can play in meeting water resource challenges while providing multiple additional benefits. It also introduces water harvesting techniques and suggests ways to implement locally appropriate water harvesting efforts. The Toolbox is intended for a wide range of users. In order to make most effective use of the Toolbox, a local facilitator should convene a varied group of community personnel (water supply management, stormwater management, transportation, planning, engineering, etc.) to go through the water harvesting assessment process together. A separate Facilitator’s Instructions document presents the five tools in the Toolbox and step-by-step instructions for using them.