Making waves: Harnessing stormwater for resilient water supply - A blueprint for vulnerable continental coasts and oceanic islands

At the forefront of climate change and natural disasters, small islands like Puerto Rico confront immense challenges in sustaining an adaptive water supply. The challenges are further exacerbated when the islands’ constraints, such as geographic isolation, limited resources, aging infrastructure, constrained capacity, and environmental fragility, are compounded. As these issues increasingly impact low-lying continental coasts, home to approximately 40 % of the global population, similar water supply crises have already emerged or are anticipated in these regions. To surmount these widespread challenges, harnessing stormwater as a non-conventional water source presents a promising solution. A stormwater-enabled water supply system, collectively characterized by water source diversification, decentralization, and modularity, can enhance the resilience of water supply in these vulnerable regions, both in routine situations and during emergencies. This article identifies barriers to the implementation of stormwater-to-drinking water (STDW) practices in Puerto Rico and advocates for engineering solutions to utilize stormwater at both community and household scales in vulnerable continental coasts and small oceanic islands. The primary barriers in Puerto Rico include uncertainty in water quality, insufficient data on local stormwater availability and domestic water demand, economic constraints, and the lack of an adaptive power supply. To overcome these obstacles, we emphasize engineering strategies focused on modular system design, assessments of local stormwater capture and demand dynamics, advancements in treatment technologies, and the enhancement of energy resilience. By analyzing the Puerto Rican context, we propose a conceptual framework that outlines pathways to adaptive STDW strategies for other oceanic islands and larger, more complex continental coasts in the face of similar challenges. These pathways encompass enhancing system modularity, understanding the dynamics of local stormwater supply and water consumption, applying tailored treatment technologies, and strengthening the resilience of supporting infrastructures. The insights gained from Puerto Rico's experience can guide current and future efforts for resilient water supply solutions in increasingly vulnerable coastal, island, and other regions.