1.1 BACKGROUND

The cornerstone of any healthy population is access to safe drinking water. The goal of the United Nations International Drinking Water Supply and Sanitation Decade from 1981 to 1990 was safe drinking water for all. A substantial effort was made by the United Nations to provide drinking water and sanitation services to populations lacking those services. Unfortunately, the population growth in developing countries almost entirely wiped out the gains. In fact, nearly as many people lack those services today as they did at the beginning of the 1980s (Gleick, 1993). Table 1.1 lists the developing countries needs for urban and rural water supplies and sanitation. Four-fifths of the world s population and approximately 100 percent of the population of developing countries are covered by this table. Also refer to Gleick (1998).