The securing of an adequate water supply has become one of the most critical problems facing many societies today. Fresh water, needed by human beings to sustain life, health and productive activities, constitutes only 0.8% of the world's total water supply, and it is not known just what portion of this amount is contaminated. Lack of water and ensuing poor sanitation are responsible for disability, disease and death, especially among infants and young children. Women, traditionally the world's water-bearers, suffer particular hardships. The time and energy they consume in fetching water from long distances might otherwise be devoted to caring for their families – or to educational or income earning pursuits of benefit to the entire community.
Of all environmental ills, contaminated drinking water the most devastating in its consequences. Each year 10 million deaths are directly attributable to waterborne intestinal diseases. One-third of humanity labours in a perpetual state of illness or debility as a result of impure water; another third is threatened by the release into water of chemical substances whose long-term effects are unknown.
The challenge of addressing global water scarcity is in understanding that it is both a natural and a human-made phenomenon. Although much of the world's biggest groundwater systems are already in distress, there is enough freshwater for 7 billion people; however, it is unevenly distributed and a significant portion is wasted, polluted and unsustainably managed.
Water is essential for life. The adult human body is about 75% water, with up to 85% of brain cells liquid; even teeth are 10% moisture. The body needs a constant supply of clean water to remain healthy. Around 71% of the planet is covered in H2O, but 97.5% of it is salt water and of the remainder, some 70% is frozen in the polar icecaps. All the water in lakes and rivers, all the moisture in the atmosphere, the soil and vegetation, and all the water underground amounts to only one percent of the total water of the planet; and of this one percent of liquid freshwater, 98% is groundwater and one percent is in rivers and lakes.
Rapid population growth combined with industrialization, urbanization, agricultural intensification and water-intensive lifestyles is resulting in a global water crisis. About 20 per cent of the population currently lacks access to safe drinking water, while 50 per cent lacks access to a safe sanitation system. Falling water tables are widespread and cause serious problems, both because they lead to water shortages and, in coastal areas, to salt intrusion. Contamination of drinking water is mostly felt in megacities, while nitrate pollution and increasing loads of heavy metals affect water quality nearly everywhere. The world supply of freshwater cannot be increased; more and more people depend on this fixed supply; and more and more of it is polluted. Water security, like food security, will become a major national and regional priority in many areas of the world in the decades to come.
The shortage of fresh water affects every continent. In the last century, global water use has been growing at more than twice the rate of population increase. Over one-fifth of the world's population (2 billion people) already live in countries experiencing high water stress (UN 2018). Pressures on water resources will greatly intensify as climate change disrupts water systems, industrial agriculture increases, and as people flock to rapidly growing urban areas.
According to a UN Report: "The world could suffer a 40 percent shortfall in water in just 15 years unless countries dramatically change their use of the resource. Many underground water reserves are already running low, while rainfall patterns are predicted to become more erratic with climate change. As the world's population grows to an expected 9 billion by 2050, more groundwater will be needed for farming, industry and personal consumption.The report predicts global water demand will increase 55 percent by 2050, while reserves dwindle. If current usage trends don't change, the world will have only 60 percent of the water it needs in 2030" (The United Nations World Water Development Report 2015)
Barely 70% of the urban population in developing countries has access to a water supply: that is, to running water, tube wells, etc. The figure is significantly lower in rural areas, where only 12% of the population has reasonable access to a water supply. Some of the serious communicable and parasitic diseases in the developing countries, affecting millions of people, can be directly related to the water conditions prevailing in their immediate environment; according to a WHO report, about 80% of all known diseases are related to water misuse. A lack of basic sanitation, nutrition, water supply and sewage facilities provokes great centres of infection, which are characteristic of the developing countries.
Chemical pollutants, including pesticides and herbicides also produce water shortage by rendering water unpotable. Some chemicals are highly persistent in water and, unlike 'conventional' contaminants, are not amenable to natural purification. This situation is worse in arid zones, where there is little chance of dilution.
Throughout Africa, water is unevenly distributed by nature and unfairly allocated by man. Many African countries experience water stress or scarcity conditions. Over 4000 million Africans in at least 17 water-scarce countries face severe constraints on food production, ecosystems protection and economic development due to water shortage. The poor majority will likely continue to pay the highest price. They already spend a considerable part of their limited income, calories and time to get inadequate amounts of water. Over half the population still lacks reasonable access to safe water. Even more lack adequate sanitation.
Many parts of the European Region are well endowed with freshwater resources, but shortage of water may be the most urgent environmental problem some countries face. Throughout the 1990s, the CCEE and NIS were especially severely affected, suffering from a significant period of reduced investment in water supply in addition to organizational disruption.
Global freshwater consumption rose sixfold between 1900 and 1995 – at more than twice the rate of population growth. About one-third of the world's population already lives in countries with moderate to high water stress – that is, where water consumption is more than 10 per cent of the renewable freshwater supply. The problems are most acute in Africa and West Asia but lack of water is already a major constraint to industrial and socio-economic growth in many other areas, including China, India and Indonesia (Roger 1998). In Africa, 14 countries are already subject to water stress or water scarcity, and a further 11 countries will join them in the next 25 years (Johns Hopkins 1998). If present consumption patterns continue, two out of every three persons on Earth will live in water-stressed conditions by the year 2025 (WMO and others 1997). The declining state of the world's freshwater resources, in terms of quantity and quality, may prove to be the dominant issue on the environment and development agenda of the coming century.
It has been estimated that by 2025 up to 16 per cent of Africa's population (230 million people) will be living in countries facing water scarcity, and 32 per cent (another 460 million) in water-stressed countries (Johns Hopkins 1998). Africa's share of water on a per capita basis is estimated to have declined by as much as 50 per cent since 1950 (Bryant 1994).