Usually the daily intake of water is 2500-3500ml, but it should be increased or decreased according to the specific situation. If the elderly have water and sodium retention, insufficient water transport and metabolism, the daily water intake needs to be reduced as appropriate, usually by 500-1000ml under the standard water intake, otherwise it will increase the burden of the body and metabolism. In patients with hypometabolic diseases, such as thyroid insufficiency or adrenocortical insufficiency, the daily intake of water should be reduced by 500-1000 ml, usually by 500 ml. For patients with endocrine disorders, such as hyperthyroidism or heat stroke in summer, they need a lot of rehydration, and the daily intake of water should be increased by 1000-1500ml in addition to the original basic amount.