The International Water Association (IWA) is a self-governing nonprofit organization and knowledge hub for the water sector, connecting water professionals and companies to find solutions to the world's water challenges. It has permanent staff housed in its headquarters and global secretariat in central London, the United Kingdom, to support the activities, and has a regional office in Chennai, India. The aim of the IWA is to function as an international network for water experts and promote standards and optimal approaches in sustainable water management. Its membership is a global mosaic comprising 313 technology companies, water and wastewater utilities, 54 universities, and wider stakeholders in the fields of water services, infrastructure engineering and consulting as well as 7,791 individuals including scientists and researchers, with 53 governing members (2021). IWA is an affiliated member of the International Science Council (ISC). IWA features regional associations, approximately 50 specialist groups covering key topics in urban water management, specialized task forces, and web-based knowledge networks.

Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. 97% of the water on Earth is salt water and only three percent is fresh water; slightly over two-thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air. Natural sources of fresh water include surface water, under river flow, groundwater and frozen water. Non-natural or human-made sources of fresh water can include wastewater that has been treated for reuse options, and desalinated seawater. People use water resources for agricultural, industrial and household activities.