Studies have found that children who are dehydrated do not work as well in the classroom as those who have drunk the recommended eight glasses of water a day.

Yorkshire Water has run a pilot project in Leeds in which water coolers were put in three schools.

The time has come to take the tap water out of the toilets

Kevin White Yorkshire Water

There was a significant increase in the amount of water the children drank and the company now plans to put the coolers in every primary school in Yorkshire over the next three years.

One of the schools involved in the pilot was Otley Ashfield Primary in north Leeds.

Head teacher Yvonne Davison said she supported the initiative "wholeheartedly".

Pupils will be given refillable bottles

"All brain activity is neurological and is a chemical activity which doesn't function without water.

"Children who are dehydrated don't learn well."

Dr Martin Schweiger, a consultant at Leeds Health Protection Unit, said dehydration in childhood can cause serious health problems in adults.

"If children don't drink enough water, the delicate enzyme systems their bodies depend on start to get out of kilter.

"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."

Kidney health

Yorkshire Water is teaming up with local companies who lease water coolers.

If they lease three, they are offered a fourth to donate to a local school.

The initiative is welcomed by kidney charities

Kevin White, managing director of Yorkshire Water, said: "The standard of sanitation and provision of drinking water in some schools hasn't improved since schools were built back in Victorian times.

"The time has come to take the tap water out of the toilets."

The project was welcomed by the National Kidney Research Fund.

"It is another way to get across the important message that everyone should drink more water," said spokeswoman Louise Cox.