This paper addresses a gap in the literature on the effects of water supplementation on visual attention and motor performance in schoolchildren. There has been extensive research showing that dehydration in adults is associated with detrimental effects on cognitive performance. Furthermore, studies of schoolchildren found that those that arrived at school with a hydration deficit performed worse in cognitive tasks than those children who were better hydrated. This is a concern because a recent study of 452 UK schoolchildren, aged between 9 and 11 years old, suggested that 60% of children arrive at school insufficiently hydrated (Barker et al, 2012). These results are consistent with similar studies from France and Israel in which two thirds of the children, of the same age, were insufficiently hydrated at the beginning of the school day (Bonnet et al, 2012; Edmonds, 2012).