Four pints is good for you. Water, that is

We are all aware that our bodies need water. An adult's daily intake should exceed 1.8 litres, or eight glasses. But do we actually drink enough? Apparently not. Research suggests that only one in ten adults is drinking the optimum amount. The rest of us leave ourselves prone to mood swings, headaches, poor concentration and digestive problems that would take little more than a few glasses of water to solve.

We are all aware that our bodies need water. An adult's daily intake should exceed 1.8 litres, or eight glasses. But do we actually drink enough? Apparently not. Research suggests that only one in ten adults is drinking the optimum amount. The rest of us leave ourselves prone to mood swings, headaches, poor concentration and digestive problems that would take little more than a few glasses of water to solve.

So why aren't we compulsively downing the source of life? In this day of free-range and organic food and juice bars, why aren't we going down to the public house for a few pints of H2O? Perhaps the answer lies in the fact that it's virtually a free commodity, which renders it a worthless substance. The result is that water becomes overlooked.

Modern lifestyles are partly to blame. Air conditioning can make offices as dry as deserts, and quenching your thirst on caffeine drinks is counter-productive as it will only make dehydration worse.

The human body is made up of approximately 75 per cent water, and it is believed that brain tissue consists of up to 85 per cent water. If we neglect to maintain the concentrations of water in our bodies, the results are both physically and mentally detrimental. Ailments include indigestion, constipation and irritability. Water is essential for every physical and chemical process that occurs in the body, it also helps to fight illness, regulates our temperature and moisturises our skin. Refined foods, tea, coffee and soft drinks create a build-up of toxins in our bodies, which water helps to eliminate.

Jo Jacobius, director of the Natural Mineral Water Information Service, says, "Whatever kind of water people choose, whether it be tap or bottled, they should be drinking more. Just because water is clear and tasteless, it doesn't mean that it doesn't contain elements that are beneficial." Ms Jacobius, not surprisingly, recommends drinking natural mineral water, because it is "water as nature intended, and has had nothing added and nothing removed". She states that although tap water is safe to drink, it contains added sodium and fluoride which some people may wish to avoid.

Without sufficient water, Gudrun Jonsson, author of Gut Reaction, warns that "waste stays in the system longer and deposits may remain clinging resolutely to the walls of the digestive tract to create a disturbance of one sort or another", which can lead to kidney problems and even gallstones. She claims that "chronic dehydration can be a contributory factor in asthma, high blood pressure, heartburn, indigestion, fatigue, constipation, backache and pains in the joints".

One of the problems, says Dr John Leiper, a research fellow in exercise physiology at Aberdeen University, is that thirst is a poor indicator of how hydrated an individual is. "The danger of water is that it is immediately thirst-quenching and therefore the effects of a dry mouth are instantly refreshed." Dr Leiper warns that this can lead to people not drinking enough water. For example, in an average gym,the plastic cups available are large enough to contain 25 millilitres of water, which is enough to satisfy post-exercise thirst, but wouldneed to be refilled a couple of times in order to rehydrate the bodyafter exercise.

Dr Leiper suggests that the elderly and the young are the most at risk of suffering from dehydration. "Elderly people are often suffering from some form of illness, or living in over-heated buildings, and on both counts should therefore be drinking more water.

"Children are very energetic and therefore need to drink more water, but unfortunately the situation at schools doesn't provide them with the time or opportunity to drink enough fluids. Parents should insist on giving their children a bottle of water to take to school, as research shows that the attention span of a child is increased after drinking more fluids." Dr Leiper maintains that a child's intake of fluids needn't be only water and that a glass of low-calorie squash is just as beneficial. "You have to pander to a child's tastes and many children find the lack of flavour in water renders it boring and tasteless. A study carried out in Canada, where children were given the choice of grape juice or water at break time, concluded that children were more likely to drink the juice because it was a novelty and colourful.

"Even if you drink a lot of water, you don't actually absorb a huge amount of minerals - you receive more from eating fruit and vegetables - so any form of fluid is beneficial." Dr Leiper stresses that losing even two per cent of our body's total water content - one litre - can restrict physical and mental ability to a small extent. Obviously the more you lose, the more detrimental are the effects.

Despite all the fears, Dr Leiper claims that in Britain it is very hard to become seriously dehydrated, unless you become very ill or there is a sudden heatwave, which we all know is completely out of the question this summer.