If your tea is cloudy, it could be due to hard water. Calcium and magnesium in hard water react with the theoflavins and theorubigens in black tea forming an insoluble precipitate that is most visible when the tea cools. However, not all clouding is due to hard water. Some teas have a tendency to “cream down” (as it is called) more than others. Assam teas from India are well-known for this trait. To see if your tea is cloudy due to hard water or not, brew a cup with distilled water and compare to your regular water.