Water Sources

Aquifer: underground porous rock which will hold groundwater and let it through.

Ground water: all water found under the surface of the ground which is not chemically combined with any minerals present, but not including underground streams.

Irrigation: the supply of water to the land by means of channels, streams and sprinklers in order to permit the growth of crops.

Surface water:

  • Rivers, lakes and reservoirs provide large amounts of surface water for a wide variety of uses.
  • Half of all the world’s dams are in China, the USA, India and Japan, and their reservoirs account for a quarter of the global freshwater supply.
  • Construction of reservoirs brings short-term economic gains in terms of water supply, HEP and flood control, but these must be measured against their longer-term environmental and social impacts.


Underground supplies from aquifers are the sole source of drinking water for about a quarter of the world’s population.

  • ¾ of Europe’s drinking water comes from groundwater.
  • Bangladesh and India use most of their ground water for irrigation.
  • In many countries, for example the USA, China and India, as well in much of the middle east, water is being abstracted from aquifers faster than it is being replaced.
  • Long-term cost of over-abstraction – dwindling supplies, falling water tables and seawater contamination.
  • In the UK 2/3 of supply is from surface and 1/3 from groundwater, with regional variations.
  • Freshwater is effectively a finite resource since only about 1% of freshwater is easily available for human use.
  • The water footprint indicates how much is required by consumers- and in an increasingly globalized world, the footprint of someone in a country like the UK will not be just local as so many products using water will have been produced elsewhere!