The "Clean" episode [1] of PBS's "How We got to now" explored how in one particular case drinking beer was preferred over drinking water. If I recall correctly (the video is no longer available for streaming) drinking water became contaminated and it was observed that regulars to a bar fared better health-wise, leading to the assumption that beer/alcohol was safer.
Whether that story fed the myth discussed in the above article or not, I don't know, but maybe it wasn't entirely baseless as it suggests.
Whether that story fed the myth discussed in the above article or not, I don't know, but maybe it wasn't entirely baseless as it suggests.
[1] http://video.pbs.org/video/2365323193/