surprised nobody has mentioned water cooler, like an igloo brand for drinking water. this wouldn't work for long distance cruising, but we use one primarily in the summer. Fill with ice and tap water, last several days and is easily strapped somewhere in the cockpit. Using one of these reduces the bottles = less trash, is easily cleaned, and reduces going in and out of the refrigerator / cold box.
In the summer we can go through one of those large igloo water coolers in a few days easily with four people. That's probably equal to two cases of deer park bottles
We have used the same idea for a favorite beverage such as iced tea.