How much does one gallon of water weigh?

One gallon of water weighs 8.33 pounds. This weight is based on the density of water, which is approximately 8.34 pounds per gallon at its maximum density (around 39 degrees Fahrenheit). For practical purposes, the figure is often rounded to 8.33 pounds. This understanding is crucial in various applications, including swimming pool maintenance, as accurately calculating the weight of water can impact design, construction, and maintenance procedures. Knowing the weight of water helps pool contractors and service professionals ensure that equipment, such as pumps and filters, are adequately sized to handle the water volume and weight within pools, thereby ensuring safety and efficiency in pool operations.