The possible reasons for drinking a lot of water but not much urine: First, the loss of body fluids through other means, such as increased heat loss from the skin or increased sweating, diarrhea, vomiting, etc., resulting in excessive loss of body fluids from the digestive tract, when the amount of water drunk is not enough to reach the amount of body fluids lost, and the phenomenon of not much urine, the need to continue to replenish water to restore the amount of urine. Secondly, if there are respiratory diseases or fever, it will lead to excessive fluid loss. Respiratory diseases can lead to an increase in the evaporation of body fluids from the respiratory tract, which can also lead to a small amount of urine, but a lot of water to drink. Third, the water drunk in after absorption, filtered by the kidneys will produce concentration, dilution, according to the degree of saturation of the body’s blood to regulate. If the body has a state of hypotension or insufficient blood perfusion, then the kidneys will play its concentration function and the volume of urine is relatively small.