I drink it a pint at a time, so it takes me 8 'servings' to get through the gallon. One each with breakfast, lunch and dinner. One with a morning snack, one with an afternoon snack. Two with protein shakes (morning & afternoon) and one after dinner.
Of course, I drink fluid constantly so getting through the gallon has never been a problem for me. Believe it or not, I usually still drink additional water/tea/etc during the day.
Brian