Yea, it was extremely unclear what the author meant by &quot;age&quot;.  If the author is defining the age of the water by the time the hydrogen bonded to the oxygen, and the age of the sun by when it started fusing, then I presume you&#x27;re right.<p>Do you have a source for the claim that the majority of the Earth&#x27;s liquid water has been through a photosynthesis cycle? Seems plausible but not obvious.