Most healthy people need 2 to 2½ liters of fluid per day. Many people don’t get enough. Some surveys suggest a portion of the population may be frequently dehydrated. Factors that increase likelihood of dehydration include dissatisfaction with the taste of water, over consumption of natural diuretics like caffeine and alcohol, participation in exercise and environmental conditions. Losing as little as 2% body weight from dehydration can result in impaired physiological performance and response. A good rule of thumb is to try to drink eight 8oz. glasses of water every day to be adequately hydrated. Fruits and vegetables also contain considerable amounts of water. People who are dieting find that drinking plenty of water helps curb appetite.

Additional Resources:

http://www.mayoclinic.com/health/water/NU00283