Water covers 71% of our world and is essential for life, although worldwide around 2.5 billion people still lack access to safe drinking water. It is an increasingly rare natural resource, with many areas already experiencing water shortages and demand expected to further outstrip supply in the future.
It makes up around 65% of our body mass, though this varies slightly depending on age and amount of fatty tissue (lean tissue holds more water apparently).
In Chinese, Japanese and Korean water is associated with Wednesday and with the planet for Wednesday Mercury.
Infographic from the Irish Times