Afternoons can be hell in class. Irritable children, tired teacher, stifling atmosphere - stringing coherent thoughts together and keeping tempers on an even keel becomes an uphill struggle. But some of this may have less to do with meeting the national curriculum and more to do with everybody needing a glass of water.

Schools are dry places. Sheer pressure of the job means that many teachers skip breaks or forget to drink as often as they should. Children are given little opportunity to drink and so end up dehydrated by the end of the day.

Stephen Orman is head of the 600-pupil Kings primary in Bournemouth, a school that draws children from the town’s bed and breakfast and bedsit accommodation, as well as refugees placed in the area. When he took over as head 18 months ago, the school was described by Ofsted as having serious weaknesses. He kick-started a series of measures to bring about rapid improvement.

One of these was to introduce a water policy. “We looked at the effect of nutrition on the brain and learning and found that the brain is affected quickly by dehydration.” Now that water is freely available to everybody throughout the school day, Mr Orman says his own and his pupils’ performance is maintained into the afternoon. Water coolers have been placed at strategic points around the school, and all the children bring in a plastic bottle of water which they keep on their desks, are encouraged to drink from and are allowed to refill whenever they need to.

Mr Orman says staff were slightly sceptical at first, wary about the prospect of spillage, water fights and queues of children asking to go to the toilet. But none of these problems has materialised. Indeed, children seem appreciative, say they feel fresh, and understand more in school. Teachers have found that they, and their pupils, are less inclined to flag during the last hour or two, and are less irritable.

Parents have noticed that their children are not as tired at home time, have less of an “attitude” and fewer headaches, and are better able to concentrate on homework.

Most dieticians recommend that adults drink at least six to eight large glasses of water a day - around 1.5 to two litres - and that children drink the same. They require a proportionately higher intake than adults because they become dehydrated more readily. One of the many reasons for this is that the surface area of a child in relation to its volume is about 36 per cent greater than that of an adult.

Nickie Brander, a former French teacher from Hampshire, is a GP’s daughter who learned the importance of drinking plenty of water from an early age. “My father always told me that if my wee was a deep yellow and smelly then I needed to drink more water,” she says. She grew up knowing that water plays a critical role in major functions, such as carrying nutrients and oxygen to cells, removing waste, cushioning joints and protecting organs and tissues.

Our brain is 78 per cent water, two-thirds of our body weight is water, a human embryo is 80 per cent water. Like plants, we wilt when lacking water. Joint pain, stomach pain and ulcers, back pain, low energy, mental confusion and disorientation, urinary tract infection, kidney damage, cardiovascular disease, dry mouth and smelly breath can result from chronic dehydration. More importantly, once we become dehydrated our core temperature rises and our body, particularly our brain, overheats.

Mrs Brander embarked on extensive research into the reasons and effects of dehydration in children after she became concerned that her daughter was coming home from school tired and thirsty. The girl had concentrated yellow urine and complained of headaches. “My daughter goes to a very academic junior school and there seemed to be little opportunity for children to take breaks for a drink. When I asked if she could take in a bottle of water, they opposed it as they do not allow children to take in food and drink for playtime. I was horrified. All they had were two antiquated water fountains in the toilets for 500 children. They didn’t work properly, the water jet was low, and for children to get a drink they would have to put their mouth completely over the nozzle. At best they would probably manage little more than a few sips. The school didn’t want children to need to keep going to the loo. But they should be going to the loo. I was told to produce a scientific paper on the need for children to drink.”

Which is exactly what she did, becoming more horrified that so little research had been carried out into children and hydration. Mrs Brander’s research has been taken up by the Enuresis Resource and Information Centre (ERIC), the national charity that provides information and support on childhood bed-wetting, daytime wetting and soiling. ERIC has launched a “water is cool in school” campaign, and has called on the Government to take urgent action on the supply of good quality drinking water in schools.

The charity is seeking to ensure that every child has three fluid breaks daily; that they drink three to four glasses of pure water every day; that drinking water facilities are in accessible places - no more taps in lavatories. It found that 10 per cent of schools had no drinking facilities. And although most had at least one outlet, it tended to be a water fountain or tap in the toilet area. Less than half of schools allowed children to leave lessons for a drink.

Kim Walters, an environmental health undergraduate at Leeds Metropolitan University, is a mature student with a background in the food industry. As part of her degree, she has surveyed facilities for drinking water for children in North Yorkshire schools. She found, through environmental swabs, that water fountains in toilets were more contaminated than those found elsewhere.

Radha Sethi is a school nurse seconded to the Manchester Health Promotion Unit as part of its government-funded Healthy School Award scheme. Concerned with the effects of dehydration - “I see bed-wetting, constipation, bowel and urinary tract problems, irritability and lethargy all connected to dehydration” - she set out to promote the drinking of water in schools. In her survey of 198 Manchester schools, she found that 62 per cent had no accessible water provision. She also found that most children were drinking no water, only sugary squashes and fizzy drinks, which, she believes, exacerbate dehydration. If children do not drink during the day their bladder capacity is reduced. If they then drink large quantities when they go home, their bladder may not cope and bed-wetting can result.

Dr Trevor Brocklebank is a paediatric consultant who cares for children with kidney damage in Leeds. He believes that many children are 2 per cent dehydrated for much of the time. In a child weighing 30kg, that would mean dehydration by about one pint. He says: “That kind of dehydration cannot be detected medically, but a Navy survey of submariners has shown that dehydration of that order affects cognitive function and memory.” His department of paediatrics at Leeds University plans to look further into the consequences of water deprivation on learning and memory.

Wet your whistle

Concerns about pollutants such as pesticide traces and so-called “gender-bender” hormones in tap water prompt many people to opt for bottled.

But, according to a report published by the Worldwide Fund for Nature in May - Bottled water: understanding a social phenomenon - bottled water, while selling for up to 1,000 times the price of tap water, may be no safer or healthier in many countries. It says there are more standards regulating tap water in Europe and the US than there are governing the bottled water industry.The study also finds that 1.5 million tons of plastic are used to bottle water every year; toxic chemicals can be released into the atmosphere during the manufacture and disposal of bottles, and transport causes the emission of greenhouse gases.

According to the British Dietetic Association, up to 40 per cent of our fluid needs comes from food. In addition:

* a 22kg five- year-old requires 1.5 litres of fluid a day , preferably water or milk;

* a 30kg 10-year-old requires 1.75 litres;

* adults need 1.5 to two litres;

* the human body loses 1.25 to 1.9 litres in urine - a quantity necessary to rid the body of toxins; between 0.6 and 1.2 litres in perspiration; up to 0.3 litres through the breath; and 0.2 litres through faeces * people should avoid taking in more than six litres of water in less than an hour as this can cause water intoxication leading to nausea, confusion and, in extreme cases, convulsions and coma.

BDA: 0121 200 8080

ERIC campaign website: www.wateriscoolinschools.co.uk