Thirsty learning at one in five schools
Mr Robson stated in a parliamentary answer that 22 per cent of schools had not yet met the Scottish Executive's target. Recent estimates suggest that up to 10 per cent of UK schools do not lay on drinking water.
Mr Robson warned that it would be 2006 before every education authority complied fully with the Healthy Schools initiative.
Research by the Schools Health Education Unit (SHEU) found students who drink water are more likely to be diligent about their work and have better overall health. The Executive's flagship policy to tackle childhood obesity cites water as an aid to weight loss because properly hydrated people do not crave food.
Charles Saunders, chairman of the public health committee of the British Medical Association in Scotland, said he found it difficult to understand why there was a lack of water in schools when unsuitable drinks were freely available.
"It seems daft for pupils to drink fizzy drinks high in sugar and caffeine that will make them fat and rot their teeth when there is a perfectly safe and healthy public water supply throughout Scotland," Dr Saunders said.
"There is good evidence that drinking water avoids deterioration in performance and helps pupils to concentrate. I can't understand why we are in this situation." Brian Monteith, Scottish Tory local government spokesman, blamed the slow progress on too much central direction.
"If schools were given greater control over their own budgets, headteachers would choose to spend money on water coolers to help improve pupil performance," Mr Monteith said.
Martin Schweiger, a health protection consultant, said that providing water in schools could bring about a "huge difference" in health and performance.
"Dehydration in schoolchildren is far more common than you might think. Headaches, tiredness, poor concentration and irritability are common signs that the body is drying out," Mr Schweiger said.
"And long-term problems of infection, kidney disease and high blood pressure are the price many people pay for drinking too little as a child."
According to the World Health Organisation, children should drink at least six to eight glasses (1.5-2 litres) of water a day, three to four of them while at school.
Joe Harvey, director of the Health Education Trust, condemned as "very bad practice" the fact that 22 per cent of schools in Scotland deny children appropriate access to a basic human right.