WATER

Water principal characteristics:

Water is a chemical substance that is composed of oxigen and hydrogen and is vital for all known forms of life.

In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseus state, water vapor or steam.

Clean, fresh drinking water is essencial to human and other life forms. Access to save drinking water has inproved steadly and substancially over the last decades in almost avery psrt of the world.

Earth's water percentage:

1.6% of water below grund in aquifers.
0.001% in the air.
97% in oceans.
2.4% in glaciers and polar ice caps.
0.6% rivers, lakes and ponds.
2.75% fresh water.
0.04% In the atmosphere.

Fresh and non-fresh water

Only 2.7% of the water on eath is fresh water, about 2/3 of its frozen in glaciers, a quarter is groundwater and only 0.005 percent of it is surface water. Fresh water lakes, most notably lake baikal in russia and the great lakes in north america, contain 7/8 of this fresh surface water. Swaps have most of the balance with only a small amount in rivers, most notably the amazon river.

Clean, fresh drinking water is essential to human and other life forms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. A recent report (November 2009) suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70% of freshwater is consumed by agriculture.