This study identified situations when flushing is advisable and explored the best practices for flushing premise plumbing and service lines. The project also provided examples of effective messaging for audiences consisting of homeowners, building managers, and others with control over premise plumbing. This report provided a guidance for premise plumbing flushing based on expert input, as well as a communications strategy for delivering the guidance based on analysis of past flushing guidance documents and water communication best practices. The guidance and communications strategies are first steps toward development of evidence-based flushing guidance materials and communications strategies. The report also explores the properties of contaminants and how those properties influence whether or how a particular contaminant can be flushed; the make-up and properties of premise plumbing and the impacts of premise plumbing configuration on flushing efficacy; and data gaps in our understanding of premise plumbing flushing and communication with water customers regarding flushing. Published in 2018.