Facts for All


Water Resources  
Estimates of global water resources based on several different calculation methods have produced varied estimates. Shiklomanov in Gleick (1993) estimated that:
  • The total volume of water on Earth is ~1.4 billion km3.
  • The volume of freshwater resources is ~35 million km3, or about 2.5% of the total volume.
  • Of these freshwater resources, ~24 million km3 or 68.9% is in the form of ice and permanent snow cover in mountainous regions, the Antarctic and Arctic regions.
  • Some 8 million km3 or 30.8% is stored underground in the form of groundwater (shallow and deep groundwater basins up to 2 000 metres, soil moisture, swamp water and permafrost). This constitutes about 97% of all the freshwater that is potentially available for human use.
  • Freshwater lakes and rivers contain an estimated 105 000 km3 or ~0.3% of the world's freshwater.
  • The total usable freshwater supply for ecosystems and humans is ~200 000 km3 of water, which is < 1% of all freshwater resources, and only 0.01% of all the water on Earth.


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Water Withdrawal and Consumption
Freshwater use by continents is partly based on several socio-economic development factors, including population, physiography, and climatic characteristics.
  • Annual global freshwater withdrawal has grown from 3 790 km3 (of which consumption accounted for 2 070 km3 or 61%) in 1995, to ~4 430 km3 (of which consumption accounted for 2 304 km3 or 52%) in 2000 (Shiklomanov, 1999).
  • In 2000, about 57% of the world's freshwater withdrawal, and 70% of its consumption, took place in Asia, where the world's major irrigated lands are located (UNESCO, 1999).
  • In the future, annual global water withdrawal is expected to grow by about 10-12% every 10 years, reaching approximately 5 240 km3 (or an increase of 1.38 times since 1995) by 2025. Water consumption is expected to grow at a slower rate of 1.33 times (UNESCO, 1999).
  • In the coming decades, the most intensive growth of water withdrawal is expected to occur in Africa and South America (increasing by 1.5-1.6 times), while the smallest growth will take place in Europe and North America (1.2 times) (Harrison and Pearce, 2001; Shiklomanov, 1999; UNESCO, 1999).

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Water Scarcity
  • About one-third of the world's population lives in countries suffering from moderate-to-high water stress - where water consumption is more than 10 per cent of renewable freshwater resources. 
  • Some 80 countries, constituting 40 percent of the world's population, were suffering from serious water shortages by the mid-1990s (CSD 1997a) and it is estimated that in less than 25 years two-thirds of the world's people will be living in water-stressed countries (CSD 1997b). 
  • By 2020, water use is expected to increase by 40 percent, and 17 percent more water will be required for food production to meet the needs of the growing population (World Water Council 2000a).
  • The three major factors causing increasing water demand over the past century are population growth, industrial development and the expansion of irrigated agriculture.

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Definitions of Water Stress and Scarcity

An area is experiencing water stress when annual water supplies drop below 1 700 m3 per person. When annual water supplies drop below 1 000 m3 per person, the population faces water scarcity.

Sources: UNPD, UNEP, World Bank, and WRI, 2000.


Water Use by Sector
The agricultural sector is by far the biggest user of freshwater:
  • Agriculture accounts for more than 70 percent of freshwater drawn from lakes, rivers and underground sources.  Most is used for irrigation which provides about 40 percent of the world food production (CSD 1997a).
  • Over the past 30 years, the area of land under irrigation has increased from less than 200 million ha to more than 270 million ha (FAO 2001).
  • During the same period global water withdrawals rose from about 2500 km3 to more than 3500 km3. (Shiklomanov 1999).
  • Poor management has resulted in the salinisation of about 20 percent of the world's irrigated land, with an additional 1.5 million ha affected annually (CSD 1997a).
  • In the industrial sector, the biggest share of freshwater is stored in reservoirs and dams for electrical power generation and irrigation. However, the volume of water evaporated from reservoirs is estimated to exceed the combined freshwater needs of industry and domestic consumption. This greatly contributes to water losses around the world, especially in the hot tropical regions (UNESCO, 1999).
  • Industrial uses account for about 20% of global freshwater withdrawals. Of this, 57-69% is used for hydropower and nuclear power generation, 30-40% for industrial processes, and 0.5-3% for thermal power generation (Shiklomanov, 1999).
    Domestic water use is related to the quantity of water available to populations in cities and towns.
  • By 2025, agriculture is expected to increase its water requirements by 1.2 times, industry by 1.5 times, and domestic consumption by 1.8 times (Shiklomanov, 1999).
  • People in developed countries on average consume about 10 times more water daily than those in developing countries. It is estimated that the average person in developed countries uses 500-800 litres per day (300 m3 per year), compared to 60-150 litres per day (20 m3 per year) in developing countries (UNESCO, 2000).
  • In large cities with a centralised water supply and an efficient canalisation system, domestic consumption does not usually represent more than 5-10% of the total water withdrawal (intake) (UNESCO, 2000).
  • Water withdrawal in large cities is estimated at 300-600 litres per person per day, while small cities have a water withdrawal of ~100-150 litres, and consumption can reach 40-60% of the total water intake (UNESCO, 2000).
  • In developing countries in Asia, Africa and Latin America, public water withdrawal represents just 50-100 litres per person per day. In regions with insufficient water resources, this figure may be as low as 20-60 litres per day (UNESCO, 2000).

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Water and Sanitation
  • For many of the world's poorer populations, one of the greatest environmental threats to health remains the continued use of untreated water. 
  • While the percentage of people served with improved water supplies increased from 79 percent in 1990 to 82 percent in 2000, 1.1 billion people still lack access to safe drinking water and 2.4 billion lack access to improved sanitation (WHO and UNICEF 2000).  Most of these people are in Africa and Asia.
  • Lack of access to safe water supply and sanitation results in hundreds of millions of cases of water-related diseases, and more than 5 million deaths, ever year.  There are also large, but poorly quantified adverse impacts on economic productivity in many developing countries.

Water Quality
Water quality problems can often be as severe as those of availability but less attention has been paid to them, particularly in developing regions.  Sources of pollution include untreated sewage, chemical discharges, petroleum leaks and spills, dumping in old mines and pits, and agricultural chemicals that are washed off or seep downward from farm fields.  More than half of the world's major rivers are 'seriously depleted and polluted, degrading and poisoning the surrounding ecosystems, threatening the health and livelihood of people who depend on them' (World Commission on Water 1999).

About 2 billion people, approximately one-third of the world's population, depend on groundwater supplies, withdrawing about 20 percent of global water annually - much of it from shallow aquifers (UNDP and others 2000).  Many rural dwellers depend entirely on groundwater.


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Policies and Institutions for Water Management
The Commission for Sustainable Development (CSD) has reported that many countries lack adequate legislation and policies for efficient and equitable allocation and use of water resources.  Progress is, however, being made with the review of national legislation and enactment of new laws and regulations.

Concern has also been expressed about the growing incapacity of national hydrological services and agencies, particularly in developing countries, to assess their respective water resources.  Many agencies have experienced reductions in observation networks and staff despite increases in water demand.  A number of response measures have been undertaken, including the World Hydrological Cycle Observing System (WHYCOS), which has been implemented in several regions. Its main objective is to contribute to the improvement of national and regional water resource assessment capabilities (CSD 1997b).

Many different kinds of organisations play a role in water policy decisions, from national governments to local community groups.  Over the past decades, however, there has been growing emphasis on increasing the participation and responsibility of small, local groups and an acknowledgement that communities have an important role to play in water policy.

The Ministerial declaration at The Hague in March 2000 called for 'Governing water wisely: to ensure good governance, so that the involvement of the public and the interests of all stakeholders are included in the management of water resources' (World Water Forum 2000).

The private sector has recently begun to expand its role in water management.  The 1990s saw a rapid increase in the rate and extent of privatisation of previously publicly managed water systems.  Private water companies are increasingly serving the needs of growing cities by taking over contracts from public agencies to build, own and operate some or even all of the municipal system.  At the same time, concerns have been growing about ho best to ensure equitable access to water for the poor, finance projects and share risks.

IGES 2003