Normal adults need 2500-3500ml of water per day, which means that in addition to drinking water, there is also water taken from food soup, and also includes other functional drinks to supplement water, all constitute the daily water needs of adults. However, for the elderly, because of the low basal metabolic rate, it is necessary to subtract 500ml from the adult water intake, which is the water needed by the elderly every day. In addition, patients with liver and kidney insufficiency or reduced heart function, the amount of water needed at this time should be reduced by 500-800ml of drinking water on the basis of adult drinking water. However, in summer, when sweating increases or heat stroke occurs, it is necessary to add more than 1500ml of drinking water on top of the daily water consumption of adults.