Health, Water

Water security through effective wastewater management: Lessons from Japan’s public–private partnerships

Wastewater management is crucial for water security due to its inherent correlation with institutional development, resilience, and welfare (World Health Organization 2020). But despite this, many countries will fail to achieve Sustainable Development Goal (SDG) 6 of clean water and sanitation for all by 2030 (UNGA 2015; UN ESCAP 2020; Messerli et al. 2019). Globally, success in addressing wastewater management has not been uniform and has depended on environmental and social factors, such as population density, economic prosperity, pre-existing infrastructure, and institutional and legal frameworks. However, the Metro Manila Wastewater Management Project in the Philippines and ongoing pilot studies in the People’s Republic of China have specifically cited Japan as a source of inspiration when deciding on how wastewater management measures for human waste and miscellaneous wastewater should be implemented (Fan, Li, and Wang 2022a, 2022b).

The Japanese innovative approach

Japan offers a profound case study within wastewater management due to its pioneering way of utilizing public–private partnerships (PPPs) to enact coordination between mixed-method decentralized and centralized systems. Predominantly, this concept takes the form of Johkasou, decentralized wastewater treatment systems commonly used in Japan designed to treat and purify domestic sewage and wastewater from individual households or small communities. These can be installed at low cost in areas that are better suited to decentralized purification tanks than connection to a centralized system (Urakami 2023). By viewing Johkasou as an important part of the global long-term solution instead of as a stepping stone for developing countries to achieve a base system, Japan has legitimized the value of PPP decentralized measures as an exportable wastewater management approach.

One way Japan arrived at this solution was to expand the notion of wastewater management under public policy by grouping together all the stakeholders involved in the creation of a sound material-cycle society. This approach aims to bring together various parties rather than retroactively attempting to coordinate efforts through numerous separate systems. Specifically, the sound material-cycle society involves the inclusion of both upstream (extraction of raw materials) and downstream (waste emissions) waste together, improving effectiveness by addressing the three key issues of resource productivity, circulation, and final disposal (Namiki 2008). Understanding the link between wastewater management and a sound material-cycle society can encourage sustainable innovation, leading to policies that provide incentives for manufacturers to create more recyclable products in exchange for reduced final disposal costs, thereby addressing resource productivity. (Yabar et al. 2009). Decoupling certain aspects of economic growth from environmental pressures can not only enhance the sustainability of measures but also extend the environmental benefits and longevity.

Another way involved improving understanding among stakeholders of how proactive engagement with decentralization and centralization measures can bring trickle-down benefits (Hara and Yabar 2012). Overall, PPPs benefit national governments by expanding domestic markets and increasing internal competitiveness. For local governments, market monetary benefits are combined with improved civil regulatory capacities as a result of a more adaptable and facilitated network. For private businesses, a superior market and legislative impetuses enable venture stability. Meanwhile, for citizens, there are improved standards of health, access to information, and education.

Export barriers

Despite the related stakeholder benefits, cost-effectiveness, and ease of implementation, the exportability of the Japanese strategy should not require an elaborate marketing scheme or investment for similar engagement internationally. Nonetheless, during the global drive for SDG 6 progress, many economies are instead relying on alternative methods.

Ultimately, the approach assumes that PPPs can take a similar position within coordination measures, which is simply not the reality for many countries. In some developing countries, domestic PPPs are limited because governments predominantly instead engage with developing partners who maintain significant stakeholder interest and power in projects (Weththasinghe et al. 2016).

The approach also supposes that domestic demand exists for such a solution. The value users place on inputting sanitation may distinctly contrast with presumptions, whether due to cost-benefit analysis or social factors, or because perceptions of needs differ.

Perceptions that solutions exist solely for developing countries rather than developed countries also persist. As a ramification of this misconstrued idea, developed nations may perceive a sense of completion that is incongruous with reality (Wood 1985) and in turn postpones the implementation of beneficial alternative frameworks.

The future of wastewater management

When moving forward, demystification over which actors could benefit from the Japanese approach, a reassertion of waste management advantages, and careful management of labelling will embolden further projects to utilize the mixed-method approach. As explained by Francis Fukuyama (ADBI 2022), theory of change, as a means for mapping out stakeholder interests during problem identification, can generate the information necessary for formulating an effective domestic plan and guiding future coordination efforts.


Asian Development Bank Institute. 2022. ADBI-Stanford University Training Program on Public Policy for Infrastructure. 24-28 October 2022.

Fan, B., A. Li, and Z. Wang. 2022a. Challenges and Solutions for On-Site Wastewater Treatment in Rural Areas: Case Study of Chongming, Shanghai, People’s Republic of China. ADBI Development Case Study No. 2022-2. Tokyo: ADBI.

Fan, B., Li, A. and Wang, Z., 2022b. Public–Private Partnerships for Wastewater Treatment in Rural Areas: Case Study of Changshu, People’s Republic of China. ADBI Development Case Study No. 2022-1. Tokyo: ADBI.

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Lauranne Finney

About the Author

Lauranne Finney is a former ADBI intern and a recent graduate of the University of Tokyo's Graduate School of Public Policy
Santi Setiawati

About the Author

Santi Setiawati is a program officer at the Asian Productivity Organization.
KE Seetha Ram

About the Author

KE Seetha Ram is a senior consulting specialist for capacity building and training projects at ADBI.

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