The Earth’s climate is changing rapidly, affecting the distribution of and increasing the pressures placed on natural resources in entirely new and unpredictable ways. Recognizing that water in the United States is not immune to this fate, environmentally conscious citizens are increasingly turning to rainwater collection as a means of securing a precious resource for their reasonable personal use. Government encouragement of such water conservation activity has developed in the form of financial incentives, rebates, and a push for green building. However, water laws can differ significantly from one state or region to another, which can lead to frustration of these recent eco-friendly movements in parts of the country. These factors form significant obstacles to the efforts of those interested in harvesting rainwater, which at times makes such efforts illegal. This growing tension between landowners’ water rights and existing legal restrictions is made even more prescient in light of what it represents in the abstract. Climate change, population growth, and a comprehensive social focus on sustainability are advancing toward an enemy seemingly ill-equipped to deal with their combined demands: existing water law.