I have switched from soda to water as my main drink during the day. Mafetone Recommended 3-4 Liters (minimum) per day: http://www.pccoach.com/products/books/book_fit_e4e.htm

I now carry a 1 liter nalgene bottle. Added 5 beads on the 550 Cord to count the number of fills each day. Easy to track my consumption.

If urine is not clear you are dehidrated.

Be sure not to drink "too much" water:
http://www.cyclingsite.com/collected_wisdom/touring_info/concerns/electrolytes.htm