Is there such a thing as TOO much water?

Dr Peter Berridge, a consultant anaesthetist at the Royal Oldham Hospital who has treated Ecstasy users, said powerful stimulants such as Ecstasy triggered release of ADH, a hormone that slows the action of the kidneys, even when excess water is in the body. "Water intoxication can occur after drinking as little as three litres. Under these circumstances, it causes headache, nausea and vomiting," he said.

Dr Berridge said the advice from drug agencies to young people to drink plain water could have fatal consequences, as in Leah's case. They should drink water or soft drinks with salt added at the rate of two teaspoons per litre or isotonic sports drinks. If taken in excessive amounts these could lead to swelling in the body tissues but would not cause swelling of the brain because the would maintain plasma sodium levels.