I love plain water but it has to be bottled and ice cold. Tap water... YUCK. So I'm sure I will be spending even more of a fortune on bottled water now! I discovered when I was doing the Slimfast thing, leading up to the Exante, that I felt pretty good when I was in the first part of the day (doing the shakes) but then when I'd eat a meal I would get a horrible headache. I think maybe because I was drinking a regular fizzy drink with my meal... maybe the caffeine was hitting me hard? I don't know. I will see how I feel having coke zero with my soup. If I get a headache from that then I'll know it's caffeine.