Focusing on the important role of water in living cellular chemistry, this case emphasizes the general solubility rule, "like dissolves like," which explains how water can serve as a medium for transporting the cell's soluble nutrients and wastes. The case covers how the different interactions between water and glycerophospholipids' polar heads and non-polar tails direct the formation of the cell's membrane bilayer, and teaches students that water is instrumental in positioning amino acids according to their polarities during protein folding. Also reviewed are the chemical reactions of water during photosynthesis, respiration, dehydration, and hydrolysis. The case has been used with nursing students in the second semester of a General, Biological, and Organic Chemistry course. It can also be used as a review of basic biology and chemistry for upper level students in biochemistry.