Tea is one of the most popular beverages in the world and some varieties are sold by the gallon.
To answer the question, a US gallon (128 ounces) of unsweetened tea weighs approximately 8.34 pounds (3.78 kilograms), although this weight may be slightly higher if a large amount of tea leaves are brewed.
However, adding sweeteners such as sugar or honey can increase the weight of the tea, and many of varieties of tea which are sold in gallon containers are sweetened.