The water is cracked in the process, but it is also recombined, with the net result that one water molecule remains, and the other is combined with the carbon atom from the CO2 molecule, to become part of a carbohydrate.
Thus, one water molecule remains a water molecule, the other becomes part of a carbohydrate, the CO2 molecule is cracked so that the carbon becomes part of the carbohydrate and the O2 is released as gas.
What you are talking about are intermediate steps. Photosynthesis won't work without these intermediate steps, but to the world outside the plant, the net effect is that CO2 is split, the carbon retained, and the O2 released.
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