The purpose of this professional project is to address the practical implications of decentralized greywater usage in the City of Arroyo Grande. This professional project consists of two products: a brief greywater guide for the City and a background report. The greywater guide is intended for city planners to use for general information about greywater systems. The guide addresses Arroyo Grande’s potable water shortage; what greywater is; advantages and concerns about greywater use; plants that are tolerant and intolerant of greywater irrigation; appropriate detergents to use with a greywater system; and a summary of California greywater law. The background report discusses the City of Arroyo Grande’s potable water conditions and how water supply will be affected by growth projections for 2030. It is estimated that by the year 2030, Arroyo Grande’s water demand will outgrow its water supply by 283 acre feet. Future water shortages are a concern at a local level and also on a global level. Three case studies examine how water scarcity has prompted the successful use of greywater. These studies examine the Hashemite Kingdom of Jordan; the Casa del Agua project in Arizona; and a local study in Santa Barbara, California. The report concludes with California greywater law, and how the recent change in August, 2009 has greatly increased the legal accessibility of greywater reuse as an obtainable method of water conservation. In combination with education and outreach among city officials and residents, greywater has potential to play a main role in water conservation in Arroyo Grande.