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.
Each gallon of sea water contains about 4.5 ounces of salt, which is about 3.5 percent of its total weight. Almost all of the other answers here were correct (with varying degrees of precision) but essentially said that water weighs (for a US gallon) 8.34 pounds so multiply by 5 and your answer is lbs.