Zee, the water with lemon or lime juice added is good. Also, what about taking a fruit juice like and dilluting. You could start with a 50/50 mix, then 40/60, 30/70, 20/80, you know to wean yourself from needing that sweetness.

Also I have seen diet ideas where they mix 8 oz 100% Cran juice with 56oz water, for an antioxidant flush, but that would give your water a little flavor as well.