It's that time of year again; the weather has turned overnight from an Indian summer to full-on autumn, shops are reminding us that Christmas is a-coming; oh, and children are back at school. Autumn officially begins this Sunday, 22 September, meaning that it's currently summer and although the weather has taken a dip we all still need to keep hydrated; men, women and children. With children there are only two types of drink that are strongly recommended for them by health professionals: water and milk. Water is perfect as it's a great way to hydrate because it's calorie-free, tooth-kind and can help avoid the huge cost to the NHS (an estimated ?50 billion a year by 2050) of treating obesity in later life*. Unfortunately 60 per cent of children are thought to arrive at school in a dehydrated state. Perhaps, just as striking is that a one per cent drop in body mass due to hydration can impair physical and academic performance. But knowing when you are thirsty doesn_t come naturally; children have to learn this behaviour. Their higher total body water content and elevated respiratory and metabolic rate makes them more vulnerable to the risk of dehydration than adults, which is why children need to be taught to drink frequently and healthily for optimum performance. Research has shown that children drink more if they keep water on their desks. Healthy children should have around six to eight drinks a day (mostly water or milk) with the size of the drink depending on the age of the child. Schools need to get the message across that water is a "cool" drink in every sense. Drinking more of it, of whatever kind, benefits most people; but especially children. Add to this the convenience and good taste of bottled or a mains-fed cooler water and you have a drink that goes straight to the top of the class! *?Help stop childhood obesity before it starts