Taste and Convenience
In blind taste tests most people can’t discern between bottled and tap water. If you find the taste of chlorine offensive, filter your water with a simple countertop pitcher or let it stand overnight in the fridge. If other contaminants concern you (have your water tested if you’re on a private well or if you want information beyond that supplied by your annual report), get a good on-tap or under-the-sink filter and an easy-to-clean, chemically safe bottle. Remember to bring your bottle when you leave home, and refill it from fountains and spigots. Sure, you’ll spend more money up front on these purchases, but you’ll save in the long run.

I buy a few cases of bottled water every year. I don't drink it at home, but if I'm going for a walk, to a ballgame, canoeing or kayaking, various other activities, it's nice to have a bottle of water to take. So, between my girlfriend and I, maybe use three, four cases a year, costs me $15. That's well worth it.