Here's an interesting snippet from Nourishing Traditions.

I thought why not a thread on water? And having thought to post this now notice that there's another thread on magnesium, which plays in interesting part in this story along with iodine and other trace minerals.

A comparative study of the water in Deaf Smith County, Texas, with that of Dallas produced an interesting profile of drinking water's ideal components. Deaf Smith County residents are famous for their good teeth and bone structure; they have few fractures even in advanced age. X-rays of both people and cattle show unusual bone size and density; cross-sections of long bones are approximnately 50 percent greater in thickness than those of people living in other regions. By contrast bones of Dallas County residents break easily and heal slowly. Analysis of the water in both countries reveals the surprising fact that the calcium content of Dallas County water is six times higher than that of Deaf Smith County. But the Deaf Smith County water is eight times richer in iodine, two times higher in magnesium and contains numerous trace minerals that are absent from Dallas County water. It seems that the magnesium and trace minerals, especially iodine, contribute to enzymatic processes that go into creating strong and healthy bones; and magnesium is incorporated into the bone itself, contributing to its strength.
Apparently, many of the Miss America winners have come from Deaf Smith County. They simply tend to have denser and better-proportioned bone-structure.

It's also been mooted that the long-life and relatively good health claimed for some mountain-dwelling people - The Viicambambans, Hunzakuts, and Georgians - may be, in part, down to their water. They drink water straight off the mountains, so full of mineral-rich silt that it's sometimes cloudy.