[thedoc (OP)]

John  asked the Naked Scientists:
   So this may be a little difficult to explain the question but here goes"  Since water never gets destroyed (molecularly). We can deduce that every drop of water is eventually going to evaporate and be brought back into clouds to continue the cycle of water drops ie humidity, condensation rain etc.  If this assumption is generally true, we can deduce that every drop of water we encounter has been used before (different combinations of H2O).    So thinking of every time we use water for bathing, growing plant life, drinking, swimming etc each of these drops of water must have had quite a few uses before today.  Could we say for example each drop of water we encounter could have been used to cultivate life before us?  How many times on average would we think a drop of rain has been created and consumed, eventually evaporated?    

 
What do you think?