Most Freshwater resources data were provided by AQUASTAT, a global database of water statistics maintained by the Food and Agriculture Organization of the United Nations (FAO).

AQUASTAT collects its information from a number of sources--

• national water resources and irrigation master plans;
• national yearbooks, statistics and reports;
• FAO reports and project documents;
• international surveys; and,
• results from surveys done by national or international research centers.

In most cases, a critical analysis of the information was necessary to ensure consistency among the different data collected for a given country.