Sustainable development requires suitable supplies of clean water for drinking and cleaning. The main world-wide use of water (70-80%) is for irrigation schemes which provide water to allow crops to be grown in dry areas. A great deal of water is lost in these schemes through evaporation, and so countries which are downstream often have very little water to use, which can lead to disputes. Other uses of inland water include hydroelectric schemes and recreational activities.
Groundwater is just that – fresh water beneath the ground. In many countries it is used for industrial and drinking water supplies. When groundwater is over-exploited it can become contaminated with salt water which makes it unsuitable for use.
The water that is available in rivers and lakes is sometimes polluted, making it harmful to plants, animals and people. The cost of providing treatment works is usually much cheaper than the cost of dealing with disease and illness. This should make water treatment a more sustainable option, especially in the developing world where up to 80% of all diseases and a third of deaths are caused by drinking contaminated water.
Proper sanitation requires a good quality water supply – a lot of pollution in water comes from human waste. The rapid growth in the populations of towns and cities in the developing world is putting pressure on governments to set up sustainable sanitation schemes to cope with large numbers of people.
The United Nations claims that the sustainable use of the worlds water resources will be achieved through co-operation between countries which share a source of water, efficient water use, and a reduction in pollution and contamination.