Water is the most abundant element of the body and comprises 50-70% of total body weight. This percentage decreases with age and also varies inversely with the percentage of body fat. Not only is water one of the most abundant nutrients available, but it's also the most important. Water helps regulate and maintain your body temperature, transports nutrients and oxygen, removes waste products, and moistens your mouth, eyes, nose, hair, skin, joints, and digestive tract. Limiting your water intake can result in dehydration, elevated body temperature, fatigue, decreased performance, and increased risk of heat-related illness. The intake of slightly more water is highly recommended to facilitate the normal function of the GIT and kidney. Consume at least eight 8-ounce glasses (commonly known as "8 x 8") of water per day.

The above paragraph, represent the importance or advantages or requirements of plenty water intake. But a lot of harmful effects have been identified associated with excess water intake. There are strong evidence now indicates that not all of the prescribed fluid need be in the form of water. As a result, we are currently drinking enough and possibly even more than enough.

Some disadvantages of a high water intake:

1. Sometimes modest increases in fluid intake can result in "water intoxication" if one's kidneys are unable to excrete enough water (urine). Such instances are not unheard of, and they have led to mental confusion and even death in athletes, in teenagers after ingesting the recreational drug Ecstasy, and in ordinary patients.
2. Possible exposure to pollutants, especially if sustained over many years;
3. Frequent urination, which can be both inconvenient and embarrassing;
4. Expense, for those who satisfy the 8 x 8 requirements with bottled water; and
5. Feelings of guilt for not achieving 8 x 8. 
   

Advice:

Don't start drinking an extra gallon of water a day - that can kill you, especially if you are fasting or eating very little. Water taken in must be in balance with body salt - electrolytes. The body needs to maintain salt balance or risk hyponatremia with heart attack and even death. Drinking too much water dilutes the salt in your blood and tissues - and can kill you. Healthy athletes have died from drinking too much plain water and not replacing salt. Dieters should not plunge into drinking gallons of water a day in hopes of burning a few more calories. Drink an extra few glasses, yes. But a gallon is too much.

Factors that influence water needs:

It is generally the case that if you drink enough fluid so that you rarely feel thirsty and produce between one and two liters 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: More water is needed during exercise and in hot weather. A rough guideline—for every hour of exercise, drink an extra quart of water. During long bouts of intense exercise, it's best to use oral rehydration solution(ORS), as this will help replace sodium lost in sweat.
• 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.
• Injured/Disease conditions: Signs of illnesses, such as fever, vomiting and diarrhea, cause your body to lose additional fluids. In these cases you should drink more water and may even need ORS. Certain conditions, including bladder infections or urinary tract stones, also require increased water intake. On the other hand, certain conditions such as heart failure and some types of kidney, liver and adrenal diseases may impair excretion of water and even require that you limit your fluid intake.
• Pregnancy or breast-feeding: Women who are expecting or breast-feeding need additional fluids to stay hydrated. Normally, a pregnant woman needs 2.4 liters of fluids daily and women who breast-feed needs 3.0 liters of fluids a day.

Standard Procedure:

1. Following Intake Guidelines

It is widely accepted that1 milliliter of water for each calorie of food. So according to this guideline, a person who eats 2,000 calories should be drinking 2,000 mL. Other suggestions:

• Fruit juice, soda, ice tea all have calories that add up.
• Caffeinated beverages, such as coffee, tea, and green tea, count for ½.

Drinking at night may result in waking up during the night to urinate and sleeping disturbance. Avoid drinking at least two hours before bedtime.

2. Filtered Water is best

The contaminated agents of drinking water are chlorine, fluoride, heavy metals, microorganisms, and other impurities.

• The latest filtering methods of drinking water are reverse osmosis system, charcoal or ceramic filter.
• Check bottled water—some types are not spring water but actually purified water from the same source as tap water.
• Glass made water containers are more friendly with your body than other materials.
• As the distilled water can deplete the needed minerals of your body, frequent drinking of distilled water should be avoided.

3. Drink normal Temperature Water   

You wouldn’t water your plants with freezing cold water or put icy water into your pet’s water bowl, would you? In Traditional Chinese Medicine, cold drinks disrupt the proper flow of energy in the body and “shock” the body. Stick to warm or room temperature fluids.

So, take the optimum amount of water, but don’t overdo it.