If this water vapor did exist in the past, then it would have effectively shielded the atmosphere from much of the cosmic radiation.This shielding would have drastically reduced the amount of Carbon-14 produced.
This bombardment causes a nuclear reaction to take place.
The Carbon-14 produced by this process is then converted into carbon dioxide, just as normal Carbon-12 becomes carbon dioxide.
For some reason, which I have not yet figured out, at least one person per week has been asking me about the Carbon-14 Radiometric Dating Technique.
They want to know if it is accurate or if it works at all.
There are more than 80 such technologies that are claimed to work.