How much does 100 gallons of water weigh?

Water has a well-known density of about 8.34 pounds per gallon at room temperature. To find the weight of 100 gallons of water, you would multiply the density by the number of gallons:

8.34 lbs/gallon × 100 gallons = 834 lbs.

This calculation shows that the total weight of 100 gallons of water is 834 lbs. Rounding this to a standard figure commonly used in weight estimations provides the closest available choice, which is 830 lbs. This is why the correct answer is identified as 830 lbs; it accurately reflects the weight based on the weight of a gallon of water.