How much water we need depends on many factors, including our health status, how active we are, and where we live. Although there is no single answer for this question, there are a few guidelines that will help us estimate how much water we should drink every day.
Water is essential to our health; it makes up approximately sixty percent of our body weight. Insufficient intake of water may lead to dehydration, a condition that occurs when we do not have enough water in our body to carry on normal functions. Even mild dehydration, as little as a one to two percent loss of our body weight, decreases our energy and make us feel tired and sluggish. Dehydration is a particular health risk for the very young and the very old.
The signs and symptoms of dehydration are thirst, dry mouth, fatigue, headaches, dizziness, diminished or absent urination, and weakness. How much water do we need to drink? We lose water every minute of our life through sweating, breathing, urinating and with bowel movements. For our body to function properly, we must replace the water we lose by consuming beverages and foods that contain it.
Daily water needs for healthy adults vary widely; most people drink fluids to quench thirst, to satisfy perceived water needs and also out of habit. It is estimated that total water needs for healthy adults living in a temperate climate vary widely, depending mostly on physical activity. For sedentary adults, drinking approximately half to one gallon of water a day, might be sufficient. We have to consider that food intake accounts for about twenty percent of this amount, and that we make up for the rest by drinking water or other beverages. One gallon may seem like a lot of fluids, but in reality it is not. It is the equivalent of about eight, 8-ounce glasses of water throughout the day.
Some studies estimate that adults should consume an average of three quarter gallons of fluid a day. However, we should know that if we have enough energy to go through our daily activities and do not feel excessive thirst, we are actually consuming enough fluids. Fluid intake needs depend on factors such as physical activity, climate, general health, pregnancy, breast-feeding, etc. If we exercise or engage in any activity that makes us sweat, we will need to drink extra water to compensate for that fluid loss.
Drinking one or two 8-once glasses of water about one hour before working out would compensate for losses through sweating and increased breathing. Of course, if the physical activity is more intense, we will need more fluids. It is a good idea to replenish fluids during intense physical activity. However, it should be done by drinking a few sips of water at a time, not drinking a lot a water, because this may lead to stomach aches and other physical problems. Excessive fluid intake during exercise may lead to a dangerous metabolic imbalance, causing serious neurological problems, starting with dizziness and fainting, coma and possibly death, due to marked swelling of brain tissues. Consuming the so called sports drinks in limited amounts may prevent some of these complications, because of their salt contents.
In hot and humid weather, we lose an increased amount of water through sweat and breathing and may need an extra amount of water to compensate this loss. Paradoxically, we may need more water in cold weather because of increased sweating while wearing insulated clothing. Excessive indoor heating may also increase the need for fluids intake.
Altitudes greater than eight thousand feet increase breathing frequency due to the air’s lower oxygen concentration; this, in turn, leads to loss of fluids.
Fever, vomiting, and diarrhea cause our body to lose extra fluids. We need to drink more water or oral rehydration solutions such as Gatorade, Powerade, CeraLyte, etc. to compensate for this loss. If the water loss is severe and cannot be replaced by mouth, intravenous water and electrolytes may be necessary. Increased water intake is advisable with the presence of stones in the urinary tract; limited intake of fluids may be recommended in the presence of heart failure, renal insufficiency and also with some hormonal imbalances. Pregnancy and breast-feeding require additional water to stay hydrated and to replenish the fluids lost, especially when nursing. It is recommended that water intake may be increased up to about three quarters to one gallon a day.
