It would be cool if MFP could calculate your water goal to hit by your weight and how many minutes you work out so you know how many glasses of water you need to consume to stay hydrated.
the amount of water a person needs in ounces is calculated by taking your weight in lbs and dividing it in half.
ex: person weighting 150 lbs would need to consume 75 ounces of water.
for exercise you need on average 8 ounces for every 15 minutes working out.
for caffeine and alcohol drinks its 8 ounces approx of water for every 8 ounces of caffeinated and alcohol drinks