This special issue explores the interconnected water–energy–environment nexus as a foundation for sustainable development, bringing together advances in desalination, membrane technology, renewable energy integration, and pollution control. Contributions are invited on solar-driven and hybrid desalination systems, membrane distillation and nanocomposite membrane materials, renewable-energy-coupled water treatment processes, resource recovery and circular economy approaches, and the mitigation of industrial, marine, and wastewater pollution. The issue aims to present technically rigorous, application-oriented research and reviews addressing the global challenge of securing clean water while minimizing energy consumption and environmental impact. By connecting engineering innovation with sustainability goals, this collection seeks to advance techno-economically viable solutions for water scarcity, energy efficiency, and pollution control across academic, industrial, and policy communities worldwide.