The Importance of Drinking Water

Water is the most important substance in all living systems. Although humans can survive for weeks without food, without drinking water we die in a matter of days. The majority of the body’s chemical reactions occur in the presence of water. It is the one substance found in the greatest quantity in the body.

couple-drinking-water-after-fitnessThe human body is made up of approximately 60% water in men and 50-55% in women. Percentages vary due to the different makeup of the genders. Men in general carry less body fat. Fat cells are made up of less water about 20%, unlike other cells in the body such as muscle. Muscle and brain tissue are about 75% water, blood and kidneys over 80%, Liver over 70% and even them dry bones are 22% water.

It has many functions in the body from regulating body temperature, cushioning the brain, and lubricating skeletal joints. It is our most important utility helping to nourish the body and remove waste products.

One-third of the body’s water is found in the areas around body cells as interstitial fluid and blood plasma but the remaining two-thirds is found within the cells themselves.

The balance between intake and excretion is controlled by a system called homeostasis – a very clever mechanism working throughout the body. It monitors every slight chemical imbalance, temperature change, and the signals from the nervous system and then sends messages to the brain to stimulate thirst or sweating.

Without drinking water we cannot survive or function properly – but how much do we need, and where do we get it from in our diet?

There are guidelines for age and gender see later but these will also vary according to your levels of exercise and the weather. You will need more in hotter climates so when you are on holiday in the sun or when you are participating in a sports activity, even skiing. Depending on our diet, between 1/4 to 1/3 of our water intake comes from food and the rest is sourced solely through what we drink.

woman-drinking-water-from-bottleAs we age past 60 our signals for thirst reduce and the elderly are susceptible to dehydration symptoms including constipation. As a result we often don’t drink enough at this time of our lives, we should get into the habit of drinking on a regular basis with meals and between.

Certain drinks are better than others water itself of course is the best. There is an argument that the variation available to us is as important as quantity. We are more likely to drink more if what we are drinking is interesting in both taste and appearance. Puritans would say water is the only way to hydration as anything added to it makes the body process it as food. Others and I include myself here, that caffeine should be avoided. Sparkling drinks in moderation occasionally is ok but should not be the main constituent of daily fluid intake. Juices, milk, and milk products such as milkshakes contribute too and also have additional vitamins, minerals, antioxidants, and electrolytes that are all important contributors to good health. Fruit and vegetable juices so long as they are pure also contribute to our all-important 5 a day.

Try to avoid artificial sweeteners. In my opinion natural sugar in small quantities is best. But that is a subject for another installment.

Remember, water is essential!

Main reference for this article:


0-6 months 680 mL/day or 100-190 mL/kg/day. From human milk
6-12 months 0.8-1.0 L/day. From human milk and complementary foods and beverages
1-2 years 1.1-1.2 L/day
2-3 years 1.3 L/day
4-8 years 1.6 L/day
9-13 years – Males 2.1 L/day
9-13 years – Females 1.9 L/day
14-18 years – Males 2.5 L/day
14-18 years – Females 2.0 L/day
19-70 years – Males 2.5 L/day
19-70 years – Females 2.0 L/day
Special cases
Pregnant women 2.3 L/day
Lactating women 2.7 L/day
Adapted from: EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Dietary reference values for water. EFSA Journal 2010; 8(3):1459. [48 pp.]. doi:10.2903/j.efsa.2010.1459. Available

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