The Resource Recovery and Reuse (RRR) Series originated in 2014 under the CGIAR Research Program on Water, Land and Ecosystems (WLE), and continues since 2021 under the CGIAR Initiatives on Resilient Cities and Nature-Positive Solutions. The aim of the RRR series is to present applied research on the safe recovery of water, nutrients and energy from domestic and agro-industrial waste streams. IWMI’s research on RRR aims to create impact through different lines of action research, including (i) developing and testing scalable RRR business models, (ii) assessing and mitigating risks from RRR for public health and the environment, (iii) supporting public and private entities with innovative approaches for the safe reuse of wastewater and organic waste, and (iv) improving rural urban linkages and resource allocations while minimizing the negative urban footprint on the peri-urban environment. IWMI works closely with the World Health Organization (WHO), Food and Agriculture Organization of the United Nations (FAO), United Nations Environment Programme (UNEP), United Nations University (UNU), and many national and international partners across the globe. The RRR series of documents present summaries and reviews of the research and resulting application guidelines, targeting development experts and others in the research for development continuum. All titles in the IWMI Resource Recovery and Reuse Series are under Creative Commons Attribution CC BY.