Water is essential for growing children and they must drink at least six to eight glasses of fluid every day. Milk contains a good quantity of water molecules and is considered the best fluid for rehydration, outside of drinking actual water. Water makes up more than 80% of our body mass, and the balance of fluids in our body is essential for every single process in our body. That is why dehydration is such a major and dangerous problem, as it threatens all of our metabolic functions. So, if you can’t find any water, grab a glass of milk!