Water infrastructures are long-lived systems that evolve over time through successive interventions and partial renewals. Individual assets are indeed designed for specific service lives depending on their type and context; however, as integrated systems, these infrastructures endure far beyond the lifespan of their components. This systemic piecemeal renewal approach ^[1], guided by capital maintenance strategies, allows infrastructures to adapt to new requirements while preserving the value embedded in existing assets. Because water infrastructures comprise numerous interdependent assets with different lifespans, their long duration and high cost reinforce the need for system-based approaches that maintain overall service continuity while guiding the renewal of individual assets through lifecycle management principles. Such adaptive approaches are essential in high-uncertainty environments where linear planning assumptions are no longer sufficient. Large components such as dams, maritime structures, treatment plants, pipelines, and reservoirs represent significant public investments that cannot simply be discarded. Instead, their ongoing management must focus on extending functionality, upgrading performance, and ensuring resilience. In this sense, the challenge is not only to operate and maintain current systems, but also to manage their transition toward the infrastructures we aspire to have in the future.

This perspective reframes infrastructure as a living system—one that must continuously adapt to shifting societal expectations, technological innovations, and environmental pressures. The central task, therefore, is to guide the evolution of water infrastructures in ways that preserve existing value while steering them toward long-term sustainability and resilience.

This applies to water infrastructures for water resources management, water services (urban, agricultural, and industrial), maritime systems (coasts, ports, and harbors), and inland navigation, encompassing grey, blue, and green infrastructures such as Nature-based Solutions (NbS). The focus of this entry, however, is on water resources, urban water services, and maritime systems, without addressing the specificities of inland navigation.