While the links between population and freshwater resources are complex, there is no doubt that population growth increases the demand for freshwater (110). While new approaches to managing water supply and demand can help in the short term, reducing population growth is necessary to avoid catastrophe in the long term. There is an urgent need, therefore, to slow developing world. At current fertility rates, populations in sub-Saharan Africa, the Near East, and parts of South Asia would double in another 20 to 40 years (77, 182). At projected growth rates population growth and to stabilize population size as soon as possible (64).
While water scarcity affects countries in all regions of the world, it is particularly a problem in developing countries. Nearly three-quarters of the world's population of 6 billion live in developing countries. Moreover, close to 95% of population growth is taking place in the, by the year 2050 the global population is expected to be 9.4 billion, of whom 8 billion will live in developing countries (182).
How can population growth be slowed? Providing widespread access to family planning has already helped millions of couples who want to space and limit births. Family planning programs have helped lower fertility rates worldwide over the past 30 years, particularly in developing countries (159). Nevertheless, in the developing countries alone there are at least 100 million married women, and probably millions more unmarried people, who want to avoid pregnancy but are not using any contraception, according to surveys (158). Meeting this unmet need for family planning would avoid about one-third of the projected population increase in developing countries over the next half century (117).
Also, family planning and reproductive health services need to be extended and improved to serve the millions more people who are coming of reproductive age. As the world's population grows by 80 million each year, these young people's future decisions about family size and resource use will have a powerful impact on world conditions (133). About half of the projected population increase over the next 50 years will result from the fact that some 3 billion people will enter their reproductive years over the next 25 years. This number equals the entire world population in 1960.