Given the importance of water for overall physical and mental health and performance, dehydration is something to be avoided. However, a study involving 10-12 year old boys showed that dehydration is something we voluntarily enter into more often than not. The experiment involved having the boys work in the heat and leaving them free to hydrate themselves as they desired. Another set of boys were made to drink at various intervals so as to replenish fluid loss. The results showed that kids who hydrate themselves only when they feel thirsty, in fact, progressively dehydrate themselves. They are relying on thirst signals rather than intelligently and proactively meeting their body’s needs. Can the same be true of adults? How often do you take water breaks? Do your own study and investigate your hydration habits.
 

Bar-Or O, Dotan R, Inbar O, Rotshtein A, Zonder H. Voluntary hypohydration in 10- to 12-year-old boys. J Appl Physiol Respir Environ Exerc Physiol. 1980 Jan;48(1):104-8. PubMed PMID: 7353962. – http://www.ncbi.nlm.nih.gov/pubmed/7353962