How much fluid you need on any given day varies greatly based on your age, sex, weight – and other factors like how much you exercise, and how hot or cold it is. Basically, the more the active you are and the more you are exposed to heat or extreme cold, the more fluids you require.

According to the Institute of Medicine, men should consume, on average, 16 cups of fluids each day, and women should consume 12. Children and adolescents need slightly less, about 9-14 cups per day. Active individuals and the elderly should consume more fluids than the guidelines for the general population. But this does not mean you need to drink that much fluid. Fluid can also come from the water that is naturally found in foods. For example many fruits and vegetables are made up of more than half water.

Getting 12 or 16 cups of fluid every day may sound like a lot, but the food you eat provides about 20 percent of your total daily needs. The remaining 80 percent needs to come from water or other beverages like juices, milk, coffee, tea, sports drinks and soft drinks.

Consuming caffeine causes your body to lose a very small amount of water. However, the hydration benefits of coffee, tea and other beverages containing caffeine far outweigh this small effect. According to a report published by the Institute of Medicine of the National Academy of Sciences (IOM), all beverages, including those with caffeine, contribute to hydration. Since regular soft drinks are 90 percent water and diet soft drinks with zero calories are 99 percent water, their findings make common sense.

Unfortunately, the 'thirst sensation' in humans is not a perfect indicator for the need for drinking. In fact, you are already beginning to be dehydrated when you feel thirsty. Therefore, it is recommended to drink before you’re thirsty and throughout the day to maintain proper hydration