i'll buy a bottle of water if i'm out somewhere and thirsty and already drank the water i bought with me- or more likely if my bf drank it all when i wan't looking *sigh* which happens too often, lol -i almost always bring a bottle of water with me from home if i go somewhere.
our tap water is icky too, but we have a big water jug with a replacable (every 3 months or so) charcoal based (i think) brita filter in it, that we fill from the tap, then keep in the fridge for nice cool unyucky water on demand
if i do buy a little bottle of water, i try and go with the most local one i can find, and i try and avoid water packaged by big brands like nestle and coke- if i can find more local small scale produced water, great.
currently i use plastic bottles for refilling, and haven't died yet from any possible leaching of chemicals, but if i add it to all the other carcanogens i'm no doubt in contact with on a daily basis, i probably will. if i come across a nice glass bottle, i'll definately consider swapping to it, lol.
I've also heard that bottled water isn't held to the same standards as the confusingly more icky tasting municipal water, so that steers me towards using filtered tap water- as well as the whole processing and plastic issue- but when i filter my water, i'm creating waste/using resources due to the charcoal filters and plastic casings in the filters too...ughhhh... the complexities of it all.