The growing demand for water, energy, and critical minerals has encouraged governments and private companies to explore resources beyond Earth. Recent advances in lunar exploration, asteroid prospecting, and space resource technologies have transformed outer space from a domain of scientific exploration into a potential source of strategic resources. Among these resources, water occupies a uniquely important position. Lunar water ice can support human habitation, sustain industrial activities, and be converted into hydrogen and oxygen for rocket fuel. At the same time, asteroids and celestial bodies may contain minerals essential for renewable energy technologies and future industrial development. This article examines the emerging relationship between space resource extraction, water security, and energy transitions. It analyses the role of in-situ resource utilization (ISRU), the strategic significance of lunar water, the prospects of helium-3 and asteroid mining, and the implications of extraterrestrial resources for terrestrial sustainability. The article argues that water will likely become the foundational resource of the future space economy and that developments in space resource utilization may reshape long-term energy systems, industrial supply chains, and global approaches to sustainable development.