Good on yer Alistair, hope it works out.
As to why people buy the bottled stuff?
Well in this country, I believe that they are the victims of advertising, who think they will look more "Cool" by having the bottled water.
There are however some places in the world, not that few or far away, where if you are not born and bred to the local stuff you are well advised to drink only bottled.
Been there done it and a few times felt sick!
Also if you are buying bottled in one of those places, if you happen to find something from Scotland you do get that "Warm Fuzzy Feeling" of satisfaction.
Jim