Urbanizing river deltas are highly susceptible to sea level rise and extreme weather events such as floods and droughts. Water-related disasters are already happening more often due to climate change, rapid urbanization, unsustainable land use and aging infrastructure threatening a large fraction of human and natural environments in these low lying and sinking areas around the globe. As stress levels of climate change are accelerating, societal and physical transformations are essential for adapting our deltas to climate change. In the Netherlands, imagination and evidence by design in the form of a long-term spatial vision, played a pivotal role in the past century to set, share and accomplish a new direction to overcome flood disasters by altering the coastlines and riverbeds of the Rhine–Meuse–Scheldt delta. The unprecedented rainfall in July 2021 and the storm in December 2021 which hit Western Europe revealed the effectiveness of this new direction. We therefore plea for a prominent role of design in climate science and delta management to imagine, analyse and communicate future perspectives for climate adaptation in urbanizing deltas.

Freshwater scarcity has increased in the cities of the global South due to rapid urban agglomeration and changing climate. Alternative water resources such as treated wastewater can play a significant role to reduce the water supply-demand gap. In the recent past, wastewater has been used solely for irrigation and other allied agriculture purposes, with limited focus on reuse for other purposes within the cities. Despite the progress in wastewater treatment technology and various policy frameworks, in low income and lower-middle-income countries, limited progress has been made. Through this article, we compare three aspects, representing the wastewater paradigms in India and the Netherlands. The three elements are 1) framing, 2) policy goals, and 3) technical and financial instruments. Using policy document analysis and interviews, we compare water and related policies prepared in India and the Netherlands. We found that the wastewater paradigms have evolved in the two countries. In India, the wastewater paradigms have realized paradigm changes from ‘water resource to meet a basic human need’ to ‘water as an engine of economic growth’ and then to ‘water scarcity and beautification of cities’. In the case of the Netherlands, the wastewater paradigms have changed from an emphasis on ‘public health and environmental concerns’ to the ‘circular economy of wastewater’. Although the Netherlands has to still meet the water quality targets of the European Water Directive Framework with regards to micropollutants, the country has made significant progress towards wastewater treatment and reuse in the last four decades. On the contrary, the Indian wastewater policy domain has room for improvement in terms of designing appropriate financial instruments and governance strategies to increase the urban wastewater treatment capacity and reuse. This article concludes that the use of the concept of wastewater paradigm is useful to show the progress and challenges in the two countries.