Awhile ago I read an interesting article (and another one ) about bottled water popularity. According to its authors, selling mineral water is a genius business idea, but the product has very little to offer to an average consumer in the Western world, especially where tap water is good.
It connects, actually, to a not so recent scandal in the UK, when Coca-Cola was caught red-handed pouring tap water into plastic bottles and selling it with a very nice profit (estimations around 3 pence per bottle were quoted, with retail price around 50p at least).
So I had this great idea - it would be nice to start selling really clean water - meaning distilled one. It should explicitly say, that the source is the public water supply systems, but it has been purified to the highest standards and contains no alien chemicals whatsoever - only H20!
If you start selling the stuff, don't forget my 5% from your profits for the idea :-)