This publication describes guidance intended to assist pharmaceutical manufacturers in assessing, mitigating and managing the potential environmental impacts of active pharmaceutical ingredients (APIs) in wastewater from manufacturing operations, including those from external suppliers. The tools in this publication are not a substitute for compliance with local regulatory requirements, but rather are intended to help manufacturers achieve the general standard of “no discharge of APIs in toxic amounts.” The approaches detailed herein identify practices for assessing potential environmental risks from APIs in manufacturing effluent and outline measures that can be used to reduce the risk including selective application of available treatment technologies. These measures are either commonly employed within the industry or have been implemented to a more limited extent based on local circumstances. Much of the material is based on company experience and case studies discussed at an industry workshop held on this topic; as such, much of the text of this manuscript does not cite published literature.