If you are looking for a real-life case study of “sell ice to Eskimos” story, it is the bottled water industry (I am talking specifically about the United States alone because I have not had a chance to study water quality elsewhere, though, I suspect that it should be the case for most of the industrialized world). Study after study has shown that we have some of the cleanest water that is technologically and economically feasible but still through aggressive, misleading advertising, bottled water companies (and filter manufacturers) were able to convince millions of Americans that they should drink only bottled water and install filters in their homes.
We already pay a lot for our water. We get bills for our water supply at home and water available at public faucets is paid for by our taxes and/or fees. In other words, our towns are required by law to guarantee safe drinking water according to standards set by various agencies. Could the water be even cleaner? Absolutely, but I don’t think it is needed. Drinking highly filtered water simply lowers your immunity and may even deprive of you of some of the naturally available minerals.
Finally, water bottlers will disclose what some of us have known for years that the water in bottle (which in many cases costs more than gasoline and milk, and definitely many other beverages in the supermarket) for which you paid a fortune is simply the same water that you could have got from your own tap. So just buy a high-quality polycarbonate bottle, fill it up before you head out of the house (I am still reluctant to drink water from a public fountain because I have seen too many men not wash their hands in the restroom and then go touch the fountain outside), and never pay a penny again to a crook who tries to sell you drinking water. Plus, it is an environmentally friendly way. Most of these plastic bottles do not get recycled.