Answer and Explanation: 100 gallons of water weights about 834 pounds or 378 kilograms. We can calculate this answer easily, but we first need to know that a standard gallonClick to see full answer. Besides, how much does 120 gallons of water weigh?A quick Google shows that a gallon of water weighs approximately 8.34 pounds, so you just multiply that by 120 to get the total weight.Additionally, how much does 200 gallons of water weigh? Answer: A US gallon of water weighs 8.34 lbs or 3.78 kg at 62 °F (17 °C). An imperial gallon (UK) weighs 10.022 lbs or 4.546 kg, at its most dense temperature, which is 2.20456 lbs / L at 4 °C or 39 °F. Hereof, how much does 1000 gallons of water weigh? Weight of Water for Different Volumes Volume Weight (oz) Weight (g) 1 gallon 8.345 lb 3,785.4 g 1 milliliter 0.002205 lb 1 g 1 liter 2.205 lb 1,000 g 1 cubic inch 0.0361 lb 16.387 g How much does 125 gallons of water weigh? Large Aquariums Tank Size L x W x H Filled Weight 90-gallon 48″ x 18″ x 24″ 1050 lbs. 125-gallon 72″ x 18″ x 21″ 1400 lbs. 150-gallon 72″ x 18″ x 28″ 1800 lbs.