The importance of fluid intake and the safety of industrial workers are reviewed. Water balance is important to workers whose jobs involve strenuous activities, who work in hot environments, or wear impermeable clothing. The role and importance of body water are discussed. Approximately 57 percent of the adult male body weight is water. Nutrients, hormones, and antibodies are all transported by body water. The normal adult requires about 2.5 liters of water every day. The dangers of dehydration are described. Dehydration results in reduced heat tolerance, performance capabilities, and work time. An increase in heart rate and body temperature also accompanies dehydration. Recommendations for avoiding dehydration are presented. Drinking about two 16 ounce glasses of water before beginning work helps ensure hydration. Eight ounces of water should be ingested for every half pound of weight lost. Fluids ingested during work should contain small amounts of electrolytes and sugar so that they may be absorbed rapidly. Sweating causes an increased electrolyte concentration in the body which increases the need for water. The authors conclude that workers should be properly informed of the importance of fluid balance and on the symptoms and prevention of heat illness.