Children who start to become dehydrated can have stomach and leg cramps, fatigue, and confusion. With severe dehydration, they are more at risk for heat stroke and shock. The question is: In order to maintain hydration when your child exercises in hot weather, how much water should she drink and how frequently? The exact amount will vary depending on the size of the child, the air temperature and humidity (amount of moisture in the air), and the intensity of the exercise. For instance, continuous running for 30 minutes will cause a child to lose more fluid than playing a baseball game for 30 minutes.
Current recommendations for an average-sized 10- or 11-year-old are that she should drink at least 4 ounces (a half-cup) of water every 20 minutes when exercising outdoors in hot weather. Assuming a gym class is a typical 40-minute period, this would mean that the children should drink at least twice during each class.
Medical guidelines clearly dictate the need for water during exercise, and a physical education teacher should be aware of this. Is the teacher's prohibition due to problems with horseplay by kids who go to the fountain? I doubt she really wants to allow the children to become dehydrated. The teacher needs to change the drinking policy right away. If you do not get a response, you should talk with the school nurse or principal and enlist her support.