Water makes up more than two-thirds of the weight of the human body. An average adult loses about 10 cups of water a day. This needs to be replaced, so the typical recommendation is to drink 8-10 cups of fluid each day.
One way to determine fluid need is to take your weight, multiply by 30, then divide by 240 to get the amount of water you should drink daily.
Some of the water in our body is obtained through foods we eat (those that are 85-95 percent water) and some is the byproduct of metabolism. But drinking water is our main -- and best -- source of water.
We also obtain water through liquid foods and beverages, such as soup, milk and juices. Alcoholic beverages and beverages containing caffeine (coffee, tea and colas) are not the best choices, because they have a diuretic (water-excreting) effect.
If an inadequate amount of water is consumed, the body fluids become imbalanced, causing dehydration, which can be life-threatening when severe. Water is a lubricant within the body, and is the basis of saliva and the fluids surrounding the joints. Water regulates body temperature through perspiration. It also helps prevent and alleviate constipation by moving food through the intestinal tract.