The issue of the presence of water on Mars (and its
biological implications) has been around for hundreds of years. However,
it is only in the past 40 years that martian water was unambiguously
detected, and only in the last 25 years that the current water amount has
been quantified. In this talk I will trace the history of our knowledge
of martian water during the 'old days' (pre-1960), during the initial
spacecraft exploration phase (through the mid-90's), and currently. Based
upon the spectacular results derived from Mars Global Surveyor and Mars
Odyssey orbiter observations, we are now developing a clear picture of the
current reservoirs of water and the cycle which transfers water between
them. The implications of this understanding with regard to future
exploration, and to revealing what past conditions might have been like,
will be addressed.