Cup sizes are determined based on the time, the Water System remembers how long the button has been held for during the cup size setup. This means the cup size can fluctuate depending on incoming water pressure.

There are lots of possible reasons for water pressure changes. For example equipment such as washing machine or dishwasher can reduce water pressure. The same as opening a tap would do.

For safety reasons there is a limit on the maximum cup size that can be set. Limit is 300ML. Based on the water system running at optimum water pressure and dispensing cold water at 2 Litres per minute and 1.3 Litres per minute on hot water.

Cup sizes are dispensing more than set limit
Cup sizes are dispensing less than set limit