Spring Water vs. Faucet water?? Please give me?

I drink lots of water. At home we keep a pitcher full in the fridge and I fill it from the sink. I think my chances of dying from bad water in the USA are pretty slim and I have other things to worry about. At work we also have a pitcher in the fridge but we do have a filter on the faucet. I only buy bottled water when I'm out at a game or something and I have been known to keep the bottle and just refill it and keep it in the fridge and take that with me.