One US gallon of water at room temperature weighs approximately 8.34 pounds (3.78 kilograms).
It’s important to note that the weight of a gallon of water can vary slightly depending on the temperature and pressure conditions. For example, water expands as it warms up and contracts as it cools down, so a gallon of hot water will weigh slightly less than a gallon of cold water. However, the difference in weight is usually negligible for everyday purposes.