The correct answer for How Much Does a Gallon of Water Weigh?
A gallon of water weighs roughly 8lb, but the precise weight varies according to its level of density, which in turn depends on its storage temperature. 1 gallon of water is equal to 133.53 oz or 8.345 lb or 3,785.4 g or 3.785 kg.
In the US, a gallon is 128 fluid ounces, or 3.785 liters. In the UK, however, a gallon is 160 fluid ounces, or 4.546 litres.