Sustainable Sewage Management

City of Yokohama,
Publié: 21 octobre 2020
Dernière modification: 02 décembre 2020
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The sewage system of Yokohama City almost fully covers its large territory with more than 3.5 million population. The length of sewer pipes is about 11,000 km in total, equivalent to the distance between Yokohama City and New York City, USA. The city’s 11 wastewater treatment plants constructed between 1962 and 1984 daily treat about 1,500,000 m3 of waste water. The sewage system has been addressing sustainability challenges in resource efficiency, reduction of greenhouse gas (GHG) emissions, and reduction of flood risk in the context of an aging society and national resilience. It also adopted advanced treatment technologies in pursuit of improved sanitary conditions and water quality in rivers and streams.


Asie de l'Est
Échelle de la mise en œuvre
Rivière, ruisseau
Zone humide urbain
Écosystème urbain
Écosystèmes d'eau douce
Atténuation du changement climatique
Distribution d'eau et gestion des ressources en eau
Fragmentation et la dégradtion de l'habitat
Traitment des eaux usées
Non classé
Water management
Perte de biodiversité
Perte de l'écosystème
Pollution (y compris eutrophisation et déchets)
Manque d'accès au financement à long terme
Manque d'infrastructures
Objectifs de Développement Durable
ODD 6 - Eau propre et assainissement
ODD 7 - Énergie propre et d'un coût abordable
ODD 11 - Villes et communautés durables
ODD 14 - Vie aquatique
Obectifs d'Aichi
Objectif 2: Valeurs de la biodiversité intégrées
Objectif 4: Production et consommation durables
Objectif 7: Agriculture, aquaculture et sylviculture durable
Objectif 15: Restauration et la résilience des écosystèmes
Objectif 19: Partage de l'information et de la connaissance
Objectif 20: Mobiliser toutes les ressources disponibles


Yokohama, Kanagawa Prefecture, Japan


The sewage system faces several sustainability challenges in terms of its service. Firstly, the city is expected to update a large portion of its sewage infrastructure systems within the next 30 years as most of them were constructed more than 20 years ago. Aging sewage pipes and infrastructure not only directly affect the quality of sewage service but they also expose daily life and socio-economic activities in the city to danger, such as sink holes in roads due to damage to pipes, that need to be prevented. Secondly, the City pursuits environmentally sustainable sewage system. For instance, despite of the system thoroughly covering the city area, eutrophication in enclosed water bodies still remained. Moreover, the large amount of sludge generated everyday in the treatment plants reaches about 20% of total industrial waste.


  • Residents of Yokohama City
  • Private companies in Yokohama City

Comment les blocs constitutifs interagissent-ils entre eux dans la solution?

Sustainable finance is among the biggest challenges the sewage system faces in the context of an aging society. To reduce the total cost, a set of facilities needs to be managed in a systematic manner. Not only does recycling water and processed sludge contributes to environmental conservation, it also helps to recover the costs of maintenance and renewal in sewage system. Application of advanced technologies also enhances quality of treated water, as well as resource recovery and electric power generation.

Les impacts positifs

Economic Impact: The city is trying to reduce the heavy dependence on corporate bonds, and a new target set for the current mid-term plan aims for further improvement of the city's financial situation of sewage management, such as resource recovery measures to reduce the cost of treatment and increase revenue by the sale of recycle materials, private sector involvement in sewage management for cost reduction, and exporting experience and technology of Yokohama’s sewage system (eg. waste water treatment technology to Batam City in Indonesia under a project by the Japan International Cooperation Agency).


Social Impact: The sewage system in Yokohama contributes to the improvement of sanitation in the city. In addition, small streams where ozonized reclaimed water is used provide excellent waterfront and leisure space for citizens. The efforts to pursue sustainability for sewage systems contributes to serve as inundation mitigation during floods.


Environmental Impact: Water quality in rivers, streams and coastal waters in Yokohama has improved due to its sewage system. Improved water quality also resulted in the increase of diversity of fish in the main rivers. Studies showed that fishes such as killifish, salmon and freshwater minnows returned. About 20% of GHG emissions from business and services operated by the City of Yokohama comes from sewage management.

Contribué par

TDLC / DRM Hub Japan World Bank