Dominic Lawson: Bottled or tap, we drink far too much water

There is a new commandment in the land: "Thou shalt not drink bottled water." The Environment minister, Phil Woolas, says that it is "morally unacceptable to spend hundreds of millions of pounds on bottled water when we have pure drinking water, and at the same time one of the crises that is facing the world is the supply of water."

I'm not sure that adds up, any more than it makes sense to argue that it's morally unacceptable to buy packaged supermarket food rather than grow our own, just because many people in another part of the world are hungry. Drinking tapwater, rather than Evian, in Surrey will not assist a single parched desert nomad in Somalia.

Mr Woolas is on less dodgy ground when he stigmatises as irrational the purchase of vast numbers of plastic bottles of H20 in preference to drinking equally clean water from the mains – which is approximately 2,000 times less expensive; and there is something faintly repellent about the sight of people who are unable to leave their home without being attached to some form of plastic bottle, like so many big babies with comforters. However, if pure reason and good taste lay behind consumer demand then there would be no such thing as a chewing gum industry – or professional football, for that matter.

Besides, not all forms of bottled mineral water are as indistinguishable from tapwater as Dasani, the Coca-Cola brand of "mineral water" humiliatingly withdrawn from the UK when it was revealed (by this newspaper) to be nothing more than Kent tapwater with added bromate. I, for example, have a weakness for St Yorre mineral water, which according to its label "obtains its specific mineral composition from its journey through the earth under the Auvergne volcano". I just like the taste – which is absolutely distinctive, and much saltier than anything which would be allowed to flow from our taps.

Over the past few days many commentators – not to mention spokesmen for the Conservatives and the Liberal Democrats – have endorsed Mr Woolas's remarks. Yet none of them have addressed the fundamental modern idiocy – which is not whether the water we drink comes from plastic bottles rather than our own taps, but the fact that we have allowed ourselves to be persuaded that we should be drinking so much of the stuff in any form.

It is taken as an indisputable truth that anyone who has a proper regard for his or her health will drink eight glasses of water a day. Given that the average glass will hold about eight ounces of water, this is frequently described as the "rule of 8x8". As Rose Shapiro notes in her new book, Suckers, the bottled drink industry has warmly endorsed the ludicrous pseudo-medical fad which suggests that we are at great risk of dangerous levels of dehydration unless we spend much of our day glugging down water.

One of the health-through-water fanatics quoted by Shapiro claims – by no means untypically – that as soon as we become "thirsty", we're already starting to become dehydrated and that "by the time we decide it's time to stop and get a bottle of water we're already approaching a level of dehydration that would be physiologically compromising". This organised panic about dehydration seems to stem from a misreading – quite possibly deliberate – of guidelines from the US Food and Nutrition Board in 1945. These stated that "a suitable allowance of water for adults is 2.5 litres daily in most instances. An ordinary standard for diverse persons is one millilitre for each calorie of food. Most of this quantity is contained in prepared foods." As Shapiro notes, the last sentence of that advice is always left out, leading to the idea that we need an extra eight glasses of water over and above our actual requirements.

The truth is that if you have a normal diet incorporating fruit and vegetables – not to mention plenty of tea or coffee – then you don't actually need to drink any water at all, bottled or otherwise. I have this on the best authority-from my own doctor. Dr Peter Wheeler tells me that "I hardly ever have a drink of water. What would be the point? I get all the hydration I need from what I eat".

Dr Wheeler is one of a number of doctors who have witnessed the dire medical consequences of fashionably excessive water consumption. One of his patients, the actor Anthony Andrews, almost died a few years ago as a direct result of drinking five or six litres of water a day – which Andrews had felt he needed to refresh his vocal cords while playing the part of Henry Higgins in a West End production of My Fair Lady. The actor slowly developed the condition known as hyponatraemia – more frequently associated with marathon runners who have drunk too much water in the mistaken belief that they are suffering from heat exhaustion.

In extreme cases, the excess water is sucked into the brain cells, which causes them to swell, eventually resulting in coma and death. This, for example, is what killed Leah Betts. She is frequently described as "the teenager who died after taking a single Ecstasy tablet"; but, according to the doctors who treated her, the cause of death was "water intoxication". She had mistakenly thought that drinking huge quantities of water would make her feel better.

As Dr Wheeler pointed out to the press when credited with helping to save Mr Andrews's life by spotting his condition: "The body's ability to assess its hydration is very poor. Over a long time, the more you drink, the thirstier you become."

My sister, Nigella, seems to suffer from this condition. She is a self-confessed "aquaholic", drinking up to three litres of water before retiring for the night. Ever since she admitted the fact, "alternative" health writers have claimed that her bladder-testing nightcap is the secret of her lustrous complexion – a typically far-fetched claim by the advocates of "8x8". Nigella is much too sensible to believe this nonsense, attributing her skin-tone instead to a mixture of genetic good fortune and a high dietary fat intake.

An extreme example of the opposite inclination was the late Monsignor Alfred Gilbey. He was appalled when, as his guest at the Travellers Club, I asked if I could have some water with the food we had ordered. He thought this a barbaric suggestion, adding – rather in the style of WC Fields – that he had never stooped to drinking water: we should have wine, and wine alone. I might have regarded his regime as medically eccentric – except that he was already well into his nineties at the time.

So if Mr Woolas really wants to set us a good example in the matter of water consumption, perhaps he should declare that he will abstain from the stuff altogether. In that way he will not only confound his foes in the plastic bottle business, but an entire health conspiracy.

d.lawson@independent.co.uk