How much does one imperial gallon of water weigh?

One imperial gallon of water weighs 8.33 pounds. This weight is derived from the density of water, which is approximately 8.33 pounds per gallon at standard temperature and pressure conditions. This information is important for plumbing and related trades, as understanding the weight of water is crucial for tasks such as calculating system load, designing water storage solutions, and ensuring proper support for plumbing fixtures.

The other choices reflect common misconceptions or rounded figures that may arise from confusion with other units or conversions, such as U.S. gallons, which differs slightly in weight due to its volume being smaller than that of an imperial gallon.