Water - how much should we drink?
Water comprises, on average, 60 percent of our weight. Every system in our body depends on water, as it flushes toxins out of vital organs and carries nutrients to our cells.
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So how much water is needed each day for our bodies to stay hydrated? The answer is - nobody is sure.
Experts disagree, with some claiming you should drink in excess of two litres of water a day. But both the Food Standards Agency and the British Nutrition Foundation (BNF) advise that the average person requires a daily intake of about 1.5 litres of water, or six to eight glasses. The precise amount depends on climatic conditions as well as your age, size, weight and level of activity.
The main point is that we should drink enough to replace what is lost, through, for example, sweat and urine. Failing to take in more water than our bodies use can lead to dehydration - sapping energy and making us tired.
The BNF warn that the sensation of thirst is not triggered until there is already a water deficit, so it is important to drink before you get thirsty. Particular attention should be paid to children and the elderly who do not recognise the signals of thirst so readily.
And while tap water is an ideal - and cheap - beverage to support our body's need for hydration, many other drinks - and foods - support hydration while providing other useful nutrients. Even drinks like coffee, tea and alcoholic beverages, like lagers and wine spritzers, contribute to fluid intakes (though the amounts should be limited due to other health concerns).
While about two thirds of our daily water intake comes from liquid, the rest comes from food. Good sources are lettuce, cucumbers, watermelon, broccoli, grapefruit, carrots and apples.
Though it is possible to overdose on water: in extreme cases, drinking too much water, in too short a time, results in water intoxication (hyponatraemia) as the body no longer has the vital minerals it needs. So it's better to sip water continuously throughout the day rather than gulping down several glasses at once.
The BNF also say there are few nutritional differences between bottled and tap water in the UK, and regulations are often tighter for tap than bottled water. As for filtered water, the filtering process helps reduce limescale build-up, chlorine and impurities in the water - that may affect the taste - but filtered water offers no special benefits in terms of nutrition.
So, if you're green-minded, help reduce the amount of plastic bottles that end up in landfill sites - while keeping hydrated at the same time - by turning on the tap.
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