Apparently the writers of the hit CW TV series “The Flash” favor the heavy water origin story. In the second episode of the second season, entitled “Flash of Two Worlds,” which aired on October 13, 2015, the Flash of Earth 2 makes his first appearance on the show. As Jay Garrick explained it, when asked how he gained his speed: “I was trying to purify heavy water without any residual radiation when there was a blinding light. I fell into a coma … when I woke up, I could run almost as fast as the speed of light.”
Although all superhero origin stories require a healthy dose of imagination, some are more scientifically plausible than others. Hence the writers of the show, who really seem to be doing their homework into The Flash mythology, and who are creating a highly entertaining show (some are calling it the best action-adventure series on television), have opted for the heavy water origin story.
Radiation can cause cellular changes and mutations, and can alter DNA. Advantageous mutations are what drives evolution, and it provides at least a plausible basis for the acquisition of enhanced functional capabilities or “super-human” powers. Inhaling the “fumes from hard water” would not have this physiological effect. Moreover, hard water does not release fumes, it releases steam when it is boiled, and the water vapor would not contain any dissolved minerals (this is how distillation works).
However, the heavy water explanation is also flawed, because contrary to popular belief, heavy water is not radioactive, so there is no “residual radiation” associated with it. Nevertheless, the fact that radiation is mentioned in connection with Jay Garrick’s origin story, indicates at least a general scientific awareness that radiation is capable of causing cellular changes and mutations.
Whether the “fumes of hard water” in the 1940 origin story of The Flash was simply a misprint, or whether the writer, Gardner Fox, was scientifically misinformed, may never be known with certainty, but the writers of “The Flash” television series wisely chose to stay as true to the original Flash origin story as possible, while choosing the more scientifically plausible explanation for the Flash’s super speed.