I filter my tap water with a Brita filter. I was buying gallon jugs. After hearing something about people in Wisconsin fighting a Perrier plant I realized there were issues about water as a commodity. That on top of questionable health standards, I decided it would be better to filter the tap water. One place to find out more about water issues is:
Save America's Water.

I don't like soda so I do seem to end up buying plenty of bottled water when I'm out & want something to drink. It keeps me stocked with bottles to fill with my filtered water. I just don't ever seem to have a bottle with me when I want it.