Best to love living off just water... but I don't. I have an almost Dickensian obsession with drinks.
I have ginger beer plant, which is like kefir grains, but for making soda. That's what I use to make the various sodas I like: ginger beer, rosemary-lemon-honey soda, herbal tea soda (try Tension Tamer and Red Zinger), green-tea-honey soda, etc. Only one it doesn't work for is root beer. For that I use brewer's yeast.
I make the brew, bottle in 20-oz PET bottles, keep on the counter until hard, then refrigerate to slow down the yeast. PET bottles are strong.. way better than glass for homebrew soda. Also way easier to clean than a keg.
For a generic not-quite-water drink during the day, I make Rooibos unsweet tea. Quite refreshing and nice when it's hot out, plus no caffeine and lots of Buzzwords for Health.
I also do soda-style kombucha, which is like vinegar soda. :)
Jimmy