That would be cool. You can log water in your food tab, if you like as a free member though I don't know of a way to see it in a report.
On the other hand, if you're a Premium member, you can create a custom report to track it so you can see a daily graph, which is pretty cool.
PS Good for you tracking your water--it's so important. I try to do at least 1 gallon a day if circumstances allow (sometimes you just can't head to the bathroom every 15 minutes!).
47 M 5'8"
May 4, 2010...... 440? lbs. (Start FitDay Size 60 Jeans)
June 19, 2010.... 393 lbs. (First Weigh-in)
June 19, 2011.... 229 lbs. (164 lbs. gone in one year :-)
Current Weight... 185 lbs. (Size 36 Jeans)
Next Goal 169 lbs. (07/04/12)
Ultimate Goal 165 lbs. (12/31/12)
The best exercises for weight loss are Fork Putdowns and Table Pushaways.