Typical capacities of the water dispensers installed in a refrigerator range between 14 and 33 ounces. However, the internal capacity of a refrigerator's water dispenser mainly affects how quickly the refrigerator can produce chilled water, as the tank is usually connected to a water supply.
Some refrigerators with water dispensers opt for a coil system rather than an internal tank for cooling water. While these systems often have less capacity than a tank, they are more efficient for cooling water as it comes into the refrigerator from the supply line. Coil systems can often begin dispensing cooled water more quickly than tank systems after the initial water supply in the dispenser is depleted.