Water information and data bases are used for addressing environmental, physical, social, political, economic, and ecological issues of water supply, consumption, availability, and accessibility. Different disciplines of water resources management, such as flood risk assessment, water supply management, reservoir operation, and water sanitation require incorporation of different types of water information for efficient planning and decision making. Therefore, this chapter aims to investigate the main features of water information, data sources, water data challenges, water data processing, analysis and dissemination which also play a key role in integrated and sustainable water resources management. This chapter begins with an introduction to the importance of data and information in various water disciplines as well as indication of data life cycle. Thereafter, different types of water data and sources (measurements, models, remote sensing, and administrative institutes) are proposed. Additionally, the challenges and limitation of water data, such as poor data quality, lack of integrated water portals, limited funds, and big data problems are discussed. This section is followed by indication of water data processing key points and steps of water data dissemination. Additionally, the World Hydrological Cyclone Observing System (WHYCOS), Global Runoff Data Centre (GRDC), and Bureau of Meteorology (BOM) are introduced as examples of important water data systems which improve development in delivery and use of water data, and evaluation of environmental impacts and risks. Finally, the chapter revealed recommendations to improve water data information and portals for the purpose of efficient water resources planning and management.