Anecdata: a dentist mentioned flouridated bottled water as an option since the parents didn't realize their kids were missing out with "regular" bottled water.

To me it's interesting to consider the long-term impact of all products that are consumed/applied frequently (both manufactured and natural ones, though somehow natural usually seems less worrisome). I believe it is best to introduce fairly dramatic variety just to give the body a chance to dodge any long term accumulating effects/deficiencies... but this hasn't translated into a soap-switching schedule yet! (a very low personal priority thanks to mass-market manufacturing similarities).

Water supply selection seems to be one of the most critical choices in this department; I appreciate this chance to learn from what other HN users have researched and implemented as best.