Drink water before, during, and after exercise to make up for the fluids you lose when you sweat.
Because sweating more happens when it's hot, you need more water to stay fresh.
Being sick with a fever, vomiting, or diarrhea can make you lose water, so drink more to make up for it.
Women who are pregnant or who are nursing should drink more water to meet their higher fluid needs.
Since alcohol makes you lose water, drinking water with or after drinking alcohol can help lessen its effects.