A liquid quality management device capable of being added to a liquid supply system, the liquid supply system supplying a liquid within a storage container to a dispensing device through a supply pipe with the liquid pressurized in order to cool the liquid in the dispensing device, and dispensing the cooled liquid to a drinking container from the dispensing device, the liquid quality management device comprising: an actual flow rate preparation unit including a flow rate sensor which is configured to detect the amount of liquid dispensed into the drinking container, and configured to determine an actual measured flow rate of the liquid dispensed into the drinking container from the dispensing device; a dispensing liquid temperature sensor configured to measure a temperature of the liquid dispensed into the drinking container; a determination unit electrically connected to the actual flow rate preparation unit and the dispensing liquid temperature sensor, a warning unit electrically connected to the determination unit and configured to generate warning information in a state it is determined that the cooling performance is insufficient characterised in that the determination unit is configured: to determine a first integral of flow rate obtained by an integration of the liquid dispensed into the drinking container in a period in which the measured liquid temperature is equal to or higher than a set temperature, to compare the first integral of flow rate with a first predetermined determination value, and to determine that a cooling performance of the dispensing device is suitable if the first integral of flow rate is less than the first predetermined determination value and that the cooling performance of the dispensing device is insufficient if the first integral of flow rate is equal to or more than the first predetermined determination value. an actual flow rate preparation unit including a flow rate sensor which is configured to detect the amount of liquid dispensed into the drinking container, and configured to determine an actual measured flow rate of the liquid dispensed into the drinking container from the dispensing device; a dispensing liquid temperature sensor configured to measure a temperature of the liquid dispensed into the drinking container; a determination unit electrically connected to the actual flow rate preparation unit and the dispensing liquid temperature sensor, a warning unit electrically connected to the determination unit and configured to generate warning information in a state it is determined that the cooling performance is insufficient characterised in that the determination unit is configured: to determine a first integral of flow rate obtained by an integration of the liquid dispensed into the drinking container in a period in which the measured liquid temperature is equal to or higher than a set temperature, to compare the first integral of flow rate with a first predetermined determination value, and to determine that a cooling performance of the dispensing device is suitable if the first integral of flow rate is less than the first predetermined determination value and that the cooling performance of the dispensing device is insufficient if the first integral of flow rate is equal to or more than the first predetermined determination value. to determine a first integral of flow rate obtained by an integration of the liquid dispensed into the drinking container in a period in which the measured liquid temperature is equal to or higher than a set temperature, to compare the first integral of flow rate with a first predetermined determination value, and to determine that a cooling performance of the dispensing device is suitable if the first integral of flow rate is less than the first predetermined determination value and that the cooling performance of the dispensing device is insufficient if the first integral of flow rate is equal to or more than the first predetermined determination value.