Water is essential for the body's chemical reactions and transport of nutrients and waste. It enters the body through drinking and food, and is lost through breathing, sweating, urine, diarrhea and vomiting. Dehydration can be dangerous and lead to health issues. It is important to drink enough water daily, especially with exercise or illness, to replenish what is lost and avoid dehydration. Staying hydrated provides many benefits such as flushing out toxins, moisturizing skin and organs, regulating appetite, and boosting the immune system.