Bioengineering and biomedical engineering merge the disciplines of engineering, biology, and medicine to create techniques and devices that are based on an understanding of living systems and serve the objective of improving the quality of human and animal life.
Weight of 1 US Gallon of water = approx. 8.35 lb (about 3.785 kg). Weight of 1 Imperial gallon (i.e. UK measure) of water weighs 10 pounds (4.536 kg) by definition, at a specified temperature and pressure.
Google says water weighs 8.344 pounds per gallon at freezing and 7.996 pounds per gallon at boiling with 8 1/3 pounds per gallon as a reasonable estimate for normal temperatures. So a 5 gallons of water will weigh about 42 pounds plus the weight of the container, depending on the temperature.