Department Sanitation, Water and Solid Waste for Development

Waste Flow Diagram – Plastic leakage into the environment

Mismanaged waste leads to plastic leakage into rivers, lakes, and oceans. This is a global and growing problem leading to significant environmental harm, emerging risks to human health, and economic burdens. To tackle the issue, a first step is to understand why these plastics leak into the environment and what their fates in the environment are.

In collaboration with GIZ, the University of Leeds and Wasteaware, Eawag developed the Waste Flow Diagram (WFD). This is a rapid, observation-based assessment tool that maps how municipal solid waste moves through a city and identifies where plastics leak into the environment. Using a Material Flow Analysis (MFA) approach, it visualises waste flows from generation to collection, transport, treatment and disposal, while pinpointing leakage sources and their fate in the environment.

The WFD is especially valuable in cities—particularly in low- and middle-income contexts—to strengthen waste management systems and monitor progress toward SDG 11.6.1. It produces clear numerical estimates (e.g., tonnes per year) and visual diagrams that help authorities and organisations prioritise interventions, compare scenarios, and design actions to reduce pollution and plastic leakage.

Through the AWARE project, in collaboration with Phenikaa University, Hanoi, Vietnam, we rigorously applied the WFD to Tuy Hoa City and explored methodologies to also use the tool regionally, at Phu Yen province level.

Furthermore, we developed training materials for practitioners on how to apply the WFD in their contexts. Training videos can be used alongside the WFD user manual which is also available online.

 

Further resources:

Latest WFD developments on the online platform

Training videos and user manual

Publications

Tosi Robinson, D.; Zurbrügg, C.; Nguyen, T. H. T. (2025). Applying the Waste Flow Diagram Regionally. Technical Brief. Eawag-Sandec

Regional land-based plastic leakage into the aquatic environment – Waste Flow Diagram applied to the Phu Yen province, Vietnam

Land-based plastic waste is the primary source of ocean plastic pollution, but data regarding its origins and pathways remain limited. This study adapted the Waste Flow Diagram (WFD) tool, initially developed for city-level plastic leakage assessment, for regional application in Phu Yen province, Vietnam. This adaptation aims to capture plastic leakage dynamics across a broader spatial scale to account for all significant sources contributing to ocean plastic pollution. The results show that, excluding Tuy Hoa City, Phu Yen contributes 9.4 kg per capita per year to aquatic environments. Most leakage (88.6 %) originated from uncollected waste in areas lacking collection services. Additional leakage arises from waste collection and transport (7.9 %), disposal sites (2.8 %), and informal activities (0.6 %). Leakage varies widely across districts, ranging from 1 to 55.7 kg/cap/year. The findings offer valuable insights for targeted interventions and policies aimed to enhance waste collection coverage and mitigate regional marine plastic pollution.
Tosi Robinson, D.; Le, T. T.; Ngo, H. T. T.; Hoang, T. H. T.; Zurbrügg, C.; Nguyen, T. H. T. (2025) Regional land-based plastic leakage into the aquatic environment – Waste Flow Diagram applied to the Phu Yen province, Vietnam, Marine Pollution Bulletin, 217, 118058 (10 pp.), doi:10.1016/j.marpolbul.2025.118058, Institutional Repository

Land-based plastic leakage into the aquatic environment from municipal solid waste – Waste flow diagram applied to Tuy Hoa City, Phu Yen, Vietnam

Plastic mismanagement and its subsequent pollution by rapid economic development and urbanisation pose significant challenges for modern world society. Notwithstanding one of the main sources for macro plastic leakage into the ocean from land, precise assessment of plastic pollution origins from Southeast Asia is yet to be clearly examined. In order to make informed decisions and prioritise areas of improvement it is required to better understand the waste leakage dynamics at the local level. In this work, the Waste Flow Diagram (WFD) was applied to understand the sources and fates of plastics leaking from the solid waste management system for the case of Tuy Hoa City, Phu Yen, Vietnam. The study shows scenarios of leakage into the aquatic environment ranging from 0.8 to 2.7 kg/cap/year, which originates mainly from the collection system. Targeted improvements to this stage of the service could reduce leakages and the overall environmental impacts of mismanaged plastic waste. The results of this study show the necessity and importance of having up to date and reliable data to better inform stakeholders and service planning, facilitating efficient action against plastic pollution. As the first peer-reviewed scientific article critically applying the WFD, this work highlights the steps and challenges of the methodology and critically analyses different methodological pathways.
Tosi Robinson, D.; Thao Vu, P.; Le, T. T.; Thi Hoang, T. H.; Viet Ly, Q.; Thi Thuy Ngo, H.; Zurbrügg, C.; Hanh Tien Nguyen, T. (2024) Land-based plastic leakage into the aquatic environment from municipal solid waste – Waste flow diagram applied to Tuy Hoa City, Phu Yen, Vietnam, Waste Management, 186, 226-235, doi:10.1016/j.wasman.2024.06.014, Institutional Repository