I'm a worker at Dunkin' Donuts and usually when the coffee tastes watered down its because new coffee was new brewed. New coffee should be ground and brewed every 18 minutes or when the pot is empty. I suggest that you tell the manager your coffee tastes watery and you want it replaced with a better one since you paid for it. Do not leave unless you are satisfied with what you paid for. When customers complain to me that something doesn't taste right I always replace it. Don't be afraid to ask. It's our job to make the customers happy and they are our number one priority. I hope your coffee tastes better next time!