Why do people say that water is necessary for life?
Why have we never found any living organism that can flourish in a completely dry environment?
How is it that something odorless, colorless, tasteless and relatively nonreactive makes up 60% of our body mass?
Why could another liquid not be used?
Why water? 

 Water has several properties that make it unique among compounds and make it possible for all forms of known life to function.