The United Nations Environment Programme (UNEP) and the Coordinating Body on the Seas of East Asia (COBSEA) partnered with UN-Habitat under the SEA circular project to apply the Waste Wise CitiesTool (WaCT) and Waste Flow Diagram (WFD) in South-East Asia. WaCT guides cities and local governments through the steps to assess the environmental performance of a Municipal Solid Waste Management system, food waste generation and resource recovery systems in cities. By doing so, it provides critical information for cities and countries to establish better waste and resource management strategies. This report presents findings of the application of these tools in 6 cities in Cambodia, Viet Nam, Malaysia and Thailand with a focus on plastic waste streams and leakage at city level. Recommendations to address waste leakage and management in this report are based on field observations, interviews with local stakeholders as well as international best practices.