huge: they will continue to have many millions of poorly educated workers unable to contribute their full potential to development. This will only cease when faeco-oral disease in infancy is effectively controlled to the point where its incidence is minimal.
The macro-economic toll of water- and excreta- related disease is almost incredibly high. Data for 197911 (and there seem to be no more recent data) show that, in that year, some 360 – 400 billion working days were lost in developing countries due to water- and excreta-related diseases that kept people from work. Valuing these days lost at only US$ 0.50, developing countries lost some US$ 180 – 200 billion. Their GNP was around US$ 370 billion in 1979, so output was below potential production by as much as 33–35%. The cholera epidemic in Peru in 1991 provides another good economic example: 350,000 people became infected, and the total cost of the epidemic (due to lost tourism, lost agricultural exports and absences from work) has been estimated at US$ 500 million12—more than had been invested in the country in water supply and sanitation improvements during the previous 10 years, which were ironically the years of the International Drinking Water Supply and Sanitation Decade.
Improved water supplies and sanitation
The types of water supply and sanitation technologies that we have developed in the UK and other industrialized countries are inappropriate for the 2.9 billion people needing adequate water supplies and the 4.2 billion people needing adequate sanitation by the end of 2025. They are inappropriate because they are too expensive to use in poor communities in developing countries, and because the water they need is not available to poor communities, and even if it were, they could not afford it.
The technologies to be used in peri-urban and rural areas have to be suitable for poor people—2.8 billion people (nearly half the world’s population) live on less than US$ 1/day.13 So above all, these technologies must be both low cost and affordable. They must also be socioculturally acceptable to their users. In rural areas, community participation in planning, design, implementation and operation is essential for a water supply and sanitation project to succeed. Both women and men need to participate in this process. In fact, operation and maintenance (O & M) are best completely devolved to the local level; generally