Water is essential to good health, yet needs vary by individual. These guidelines can help ensure you drink enough fluids.
Basically your water needs depend on many factors, including your health, how active you are and where you live. Though no single formula fits everyone, knowing more about your body's need for fluids will help you estimate how much water to drink each day. Water is your body's principal chemical component making up about 60 percent of your body weight. Every system in your body depends on water. It flushes toxins out of vital organs, carries nutrients to your cells and provides a moist environment for ear, nose and throat tissues. Obviously lack of water can lead to dehydration and even mild dehydration can drain your energy and make you tired. Every day you lose water through your breath, perspiration, urine / bowel movements. For your body to function properly, you must replenish the water supply by consuming beverages and foods that contain water.
THE 8 CUP APPROACH.
The average urine output for adults is about 1.5 liters a day. You lose close to an additional liter of water a day through breathing, sweating and bowel movements. Food usually accounts for 20 percent of your total fluid intake, so if you consume 2 liters of water or other beverages a day (a little more than 8 cups) along with your normal diet, you will typically replace the lost fluids.
8 x 8
A second approach for water intake is the "8 x 8 rule" — drink eight 8-ounce glasses of water a day (about 1.9 liters) or drink eight 8-ounce glasses of fluid a day, as all fluids count toward the daily total. Not quite supported by scientific evidence, many people use this basic rule as a guideline for how much water and other fluids to drink.
The Institute of Medicine advises that men consume roughly 3 liters of total beverages a day and women consume 2.2 liters of total beverages a day.
Even apart from the above approaches, if you drink enough fluid so that you rarely feel thirsty and produce 1.5 liters or more of colorless or slightly yellow urine a day, your fluid intake is probably adequate.
You may need to modify your total fluid intake depending on how active you are, the climate you live in, your health status, and if you're pregnant or breast-feeding.
Exercise. If you exercise or engage in any activity that makes you sweat, you need to drink extra water to compensate for the fluid loss. An extra 400 to 600 milliliters of water for short bouts of exercise, but intense exercise lasting more than an hour requires more fluid intake. During long bouts of intense exercise, it's best to use a sports drink that contains sodium, as this will help replace sodium lost in sweat. Continue to replace fluids after you're finished exercising!
Environment. Hot or humid weather can make you sweat and requires additional intake of fluid. Heated indoor air also can cause your skin to lose moisture during wintertime. Altitudes greater than 8,200 feet may trigger increased urination and more rapid breathing, which use up more of your fluid reserves.
Health conditions. Signs of illnesses, such as fever, vomiting and diarrhea, cause your body to lose additional fluids. Defintely drink more water and you may even need rehydration solutions, such as Gatorade, Powerade or CeraLyte. Bladder infections or urinary tract issues also require increased fluid intake.
Pregnancy. Women who are expecting or breast-feeding require additional fluids to stay hydrated. Large amounts of fluid are used especially when nursing.
It's generally not a good idea to use thirst alone as a guide for when to drink. By the time you become thirsty, it's possible to already be slightly dehydrated. As you get older your body is less able to sense dehydration and send your brain signals of thirst.
Though uncommon, it is possible to drink too much water. When your kidneys are unable to excrete the excess water, the electrolyte content of the blood is diluted, resulting in low sodium levels in the blood, called hyponatremia. Endurance athletes, such as marathon runners, who drink large amounts of water are at higher risk of hyponatremia. In general, though, drinking too much water is rare in healthy adults who consume an average American diet. So drink up!