What percent of the Earths water is utilized by man on a yearly basis?
Water does not get depleted like oil. There is the water cycle of condensation, evaporation and transpiration (rain) which ensures that what gets used is given back to us some point later. There is an infinitessimally small percentage of water molecules that are converted to energy, not enough to affect the water cycle! This link (http://www.ec.gc.ca/Water/en/info/pubs/NSKit/e_chap2.htm) states that there is about a billion cubic kilometres of water on the earth, and 1 cubic kilometer = 1 000 000 000 000 litres – so that makes about 1 000 000 000 000 000 000 litres of water on earth – which is 1 million million million! If you take modern man and assume that each person uses about 1 kilolitre of water per day, with 7 billion people on earth this is usage of let’s say rounded to 10 billion kilolitres which is 0.0001%, most of which is recycled anyway. Hope I got the calculations right!
