Fair fresh water distribution among humans and nature and among all sectors will be one of the main challenges of the 21st century. There is a complex interplay between the different water users, and clear systematics are needed for efficient decision making. Water uses can be divided into four sectors, (i) water for people, services and industries, (ii) water for agriculture, (iii) water for nature, and (iv) water for energy production. A number of water related issues are relevant for each sector, though not all with the same importance. The issues relate either to water quality, water quantity, (urban) water infrastructure and integrated water management, and socio-economics and institutional aspects. Depending on the sector and the issues, there is an appropriate level for actions. Responsibilities for providing water for people, services, and industries must be taken at the local level (communities, cities, districts). Water for nature and the provision of ecosystem services ask for a more regional, national, or even multinational decision-making structure. The demographic development of the coming 25 years will be a challenge for agriculture to satisfy the food needs of all humans. The adequate and just access to agricultural products needs to be internationally guaranteed. Decisions for all sectors and on all levels imply formidable economic challenges, which will accompany human societies for the next decennia.