Getting back to tap water, or "municipal pop" as some of us called it; I lived in England for 30 years from 1944-74, mostly in South Cheshire, but also at various times in Essex, Sussex and Southampton. "Bottled water" would have been a strange concept, back then; for all purposes we used it straight from the tap, and thought nothing of it. I emigrated to Canada in'74, and lived in and around Vancouver, B.C. for about 15 years, then Saltspring Island, again for about 15 years, then the Kelowna area, in the Okanagan Valley (allegedly the home of Ogopogo, Canada's answer to Nessie); In all those places, again, I would drink tap water. My wife runs hers through a charcoal filter - she's diabetic, and has quite a few allergies, so just as a precaution - and some of our friends do drink bottled water - as do we, if we're away from home and thirsty, such as on a long drive. We occasionally get a "Boil water advisory" from the municipality after a long dry period.
Since I retired, we spend a few months of each winter in Mexico, a tiny fishing village on the Pacific coast, called La Manzanilla, about 4 hours south of Puerto Vallarta (not to be confused with ManzanillO, a big port city about an hour further south). In Mexico, you don't drink the tap water, or even brush your teeth with it, though it seems to be perfectly fine when boiled for tea, coffee or soup. Drinking water is delivered by pickup truck in 20-litre plastic containers called garrafons; the drill is, you put your empty garrafon out on the sidewalk, and sometime during the day someone will come tapping on your door with a shout of "Hola! Agua?", and with a full one over his, or her, shoulder. It costs 15-20 pesos, equivalent to about $1.00 or $1.20. In my more cynical moments I sometimes suspect it's simply water from someone else's tap, but we haven't had any major problems - yet. They probably run it through activated charcoal, but it doesn't seem to be chlorinated.
I'll be turning 77 next month, and I still have all my own teeth - minus one, which I had to have pulled when I was about 22 (I found it kind of strange that, over a period of about 18 months, the other teeth gradually migrated to fill the gap), and a few fillings. I also have most of my hair, and even a bit of colour (reddish blond; my nickname at school was Ginger or Red). If I let my beard grow it would be grey, though.
So what does all this prove? Nothing much, probably. Luck of the draw, I guess.