Would you like to live to a healthy, ripe old age without suffering from headaches, migraine, arthritis, asthma, allergies, diabetes, osteoporosis, stomach pains - or any other modern ill?

If the answer is yes, then just turn on the tap. You should drink up to eight glasses of water every day to keep all body systems in good working order.

And that, says Dr Fereydoon Batmanghelidj, could be all the medicine you will ever need. 'Most people believe thirst is signified by a dry mouth. But I'm certain that the dry mouth is the last, not the first, signal of a profound and chronic thirst,' he says.

The doctor, who works from his own clinic in Falls Church, Virginia, in the United States, even believes that many, if not most, of today's serious illnesses are caused by chronic dehydration of the body.

We have, he says in a new and highly controversial book, Your Body's Many Cries for Water, completely forgotten how to respond to our numerous thirst signals. But if, instead of taking painkillers and medication, we just drank lots of ordinary water, we would probably find that not only the pain, but also the condition would go away for ever.

That is the theory. Even obesity, he believes, may be at least partly caused by wrongly interpreting our body's cries for water as cries for hunger. Dr Batmanghelidj, whose clinic is dedicated to promoting simple cures in medicine, is even more controversial when he talks about the kind of water we should drink. Ideally, it should not be bottled, but come straight out of the tap.

He says: 'The problem with drinking bottled water is that if we run out, we may consider we have no water in the house. The availability of bottled water has made people forget that there is perfectly drinkable water on tap, freely available.

'Also, tap water contains chlorine, which is an anti-bacterial agent. If you develop a taste for bottled water, you may go without when there is none available. The calcium in tap water acts as good protection against osteoporosis, the brittle-bone disease.'

Iranian-born Dr Batmanghelidj, who claims to have cured more than 3,000 people of peptic ulcers with plain, simple water, says most of us are suffering from severe internal drought.

Lack of water affects the body and the brain. It can cause depression, stress and anxiety as well as physical diseases. 'The human body is composed of 25 per cent solid matter and 75 per cent water. Brain tissue is 85 per cent water. When we starve body cells of water, they start to complain - and set up many adverse reactions,' he says.

'Blood vessels constrict and joints become dry and painful. I believe that stomach pains are almost always a signal that the body is suffering from severe thirst.

'Fifty million Americans suffer from rheumatoid arthritis, and another 30 million from low back pain. I have become convinced that dehydration eventually causes severe damage to joint surfaces.'

He has developed this idea. 'Spinal joints are dependent on the hydraulic properties of water which are stored in the disc core. Water acts as a lubricating agent to all joints, and when they are dehydrated pain sets in. But it's not just joints that are affected. Migraines are, I am sure, largely brought on by long-term dehydration.'

High blood pressure, which affects the majority of older men in Western countries, could also be a sign of gross water deficiency. He argues that high blood pressure is a mechanism for trying to keep cells hydrated - but the attempt fails because there is not enough water available.

'When we take medication to bring down blood pressure or cholesterol levels we ensure that the body's mechanisms are never put right.'

Babies in the womb, says Dr Batmanghelidj, are surrounded by water. Babies recognise thirst signals readily and cry out when they need liquid. But as people grow up, they become unused to drinking water and, gradually, the thirst signals are misinterpreted or over-ridden.

As they grow up, children learn to drink sodas, colas and juices instead of satisfying their thirst with simple water. Adults respond to the body's thirst signals with tea, coffee and alcohol - all of which dehydrate the body even more as they act as diuretics, leaching water out of the body through the kidneys.

'We have made the mistake of assuming that because water is freely available and costs nothing, the body cannot possibly fall short of it. I believe that most physical pains are signals that the body needs rehydrating - and that we ignore these signals at our peril,' he says.

So how do we best protect our health with water? The doctor advises drinking an 8oz glass of water half an hour before each meal - not with, as this dilutes the gastric juices - and two hours after each meal. Six to eight glasses a day are the absolute minimum needed. Substitutes are not allowed. 'It is simply not possible to drink manufactured products in full replacement of the water needs of the body,' he said. So, on this plan, alcohol, tea, coffee, sodas and fruit and vegetable juices do not count. Hangover headaches, dyspeptic pain and rheumatoid arthritis should not be treated with painkillers or antacids, but 2 1/2 quarts of water every 24 hours. This will increase urine output - a good sign that the kidneys are active.

Dr Batmanghelidj does not advise seriously ill people to stop taking their medication instantly and start drinking plain water instead. But if they start drinking water as well, pains will gradually disappear and joints will rehydrate themselves. And you will never suffer from bad headaches or migraines, allergies or asthma ever again.

The doctor's advice is: try the water cure before you fall victim to a serious or chronic complaint.

'Your Body's Many Cries for Water,' by F Batmanghelidj, MD, is published by Global Health Solutions Ltd, PO Box 3189, Falls Church, VA 22043. It is not yet available in the UK, but can be obtained by mail order from the above address for dollars 17.95, including postage & packing.

(Photograph omitted)