Water is a chemical substance with the chemical formulaH2O. Its molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is often co-exists on Earth with its solid state ice, and gaseous state, water vapor or steam. According to researcher’s, water covers 70.9% of the Earth's surface, and is vital for all known forms of life. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Research also claims that oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Water on Earth moves continually through a cycle of evaporation or transpiration(evapotranspiration), precipitation, and runoff, usually reaching the sea. Over land, evaporation and transpiration contribute to the precipitation over land.

      Human consumption of water:

    •  Drinking water
    •  Washing
    •  Chemical uses
    •   Recreation
    •   Industrial uses
    •   Food processing