GEMS/Water Programme is part of the United Nations Division of Early Warning and Assessment (DEWA) in the Environment Programme. It provides scientifically sound data and information on the state of and trends in global inland water quality.

Working with a global network of partners in 106 countries, GEMS/Water develops and maintains a global freshwater quality information system and facilitates the formulation and implementation of programs to build the capacity of developing countries for the acquisition and management of water quality information.

National monitoring programs are essential for water resources planning and economic and environmental decision making. GEMS/Water's monitoring and assessment function works toward a consistent international database that can produce a variety of global and regional assessments by water-related agencies.

In March 2005, GEMS/Water introduced a new scientific resource called GEMStat, a database designed to share surface-water and groundwater quality data sets collected from the GEMS/Water Global Network, including more than 1,500 stations, two million records, and more than 100 parameters. Users start by selecting a country, then a station within that country, if there is more than one, and then other parameters. Although the site is still being developed, it will allow users to create maps, graphs, and data tables, or download the data in different formats.