Where should the water be filled to in a Venti Cool Lime Refresher?

The water should be filled to the middle line in a Venti Cool Lime Refresher. This measurement ensures that the drink maintains its intended balance of flavors and strength, providing the right concentration of the flavoring ingredients. The middle line indicates the appropriate amount of water needed to dilute the concentrate adequately without overpowering the drink. By adhering to this filling guideline, the customer can enjoy a refreshing beverage that is characteristic of the Cool Lime Refresher, highlighting the bright lime flavor and the added components while still achieving a well-mixed drink. The other options would either lead to an overly diluted or too strong drink, detracting from the overall experience.