One of the big headaches for school nurse Sarah Jewitt was the stream of children knocking on her door complaining of headaches. Over the past six months, however, the stream has reduced to a trickle, and the reason can be found in the dining room of Sheffield's Abbeydale Grange secondary school.
As a surge of teenagers joins the morning break queue at the school tuck shop, dozens more gather around the water cooler.
"I used to have to go to see Mrs Jewitt every break, more or less," says 12-year-old Samuel O'Malley. "I get migraines, so my doctor told me I had to drink water while I was at school. Now I have three cups a day. This is a lot better."
"Water is a natural resource that should be available to children during the day," says Jewitt. "There's water available in the toilet blocks, but no one wanted to drink it because they don't associate clean healthy water with toilets."
The same is true,she says, of the old drinking fountains still lurking in the hidden corners of many British school playgrounds.
"Adolescents have a clear idea of what they will and won't do these days," says Mrs Jewitt, " and many of them have told me that one of the things they won't do is to put their mouths on a drinking fountain, where someone else's mouth has been."
Mrs Jewitt began investigating the issue of water in schools a year ago, and soon found that the lack of drinking water for schoolchildren was a national problem.
Surveys have revealed that even in those schools which do have drinking water, facilities are most likely to be taps in the school toilets, and 10 per cent of schools have no drinking water available for children at all.
Lack of water, she discovered, can lead to headaches, tiredness, and poor concentration, as well as more serious health problems such as urinary infections, kidney stones and bed-wetting.
Abbeydale Grange headteacher Chris Mallaband suggested that Mrs Jewitt costed water systems for pupils and teachers, and after opting for a filtered mains water system - rather than more costly refillable bottles - two units supplying cooled, filtered mains water were installed in October.
The units were placed in the pupils' dining area and the staff room at a cost of just under pound;600 a year, met from general school funds. The Abbeydale Grange water is supplied by Aquaid, which supports the work of Christian Aid to supply safe water to people around the world affected by drought, famine and water-borne diseases.
The children like the idea of their water supply including a donation to charity, and after the first few months, the scheme seems to be going down well.
A trial to allow Year 8 pupils to keep free water bottles from Aquaid on their desks during lessons will soon begin - other year groups are already clamouring to drink water during lessons, too. At present, pupils can use the cooler at breaks, lunch times or, when possible, between lessons.
Initially, plastic cups were supplied. Clean cups were on one side of the machine, and used ones on the other, or you could clean out a cup using the cooler's second non-filtered tap, Jewitt explains. Now pupils are being encouraged to bring their own bottles to refill every day - not least to save on washing up.
"Any bottle will do," she says. "We just suggest they wash their bottle at home every evening, and leave it to drain overnight."
The pupils are in no doubt about the benefits of cool water on demand. They say they are getting fewer headaches and feeling less exhausted after PE, and they are saving money, since they no longer have to buy bottles of water locally at 70p a time.
Fourteen-year-old Qadeer Rabaque is on the school council: "If you've done something energetic like PE or drama you always feel thirsty and you start dehydrating, and if you're dehydrating, you can't concentrate on your work.
"If you have water, you feel a lot more energetic and you can get on with your work. It's made a difference to a lot of us, particularly after PE. I think I've started working better."
Blue Mountain Water