Five gallons would weigh around 42lbs or 19kg because the weight of a gallon of water is 8.3496 lbs. or 3.78 kg, so five gallons would weigh around 42lbs or 19kg. This is just an approximation.
How Much Does 5 Gallons Of Water Weigh
To summarize how much does 5 gallons of water weigh is about 42 pounds in US customary unit and about 35 pounds in UK customary unit.