In functional terms, a water tower is just about the most uninspiring piece of construction imaginable. Ubiquitous and enormous, they are used to create the pressure that pumps water into local taps, showerheads and swimming pools. But these hulking storage units have become a surprise success story of municipal architecture. Perhaps because of the way they define horizons, water towers invite the fanciful imagination of architects and planners. American water towers have often taken on novelty shapes (corncobs, ketchup bottles, pineapples) while modern architects have built new towers with bold lines—a phenomenon faithfully documented by mid-century photographers Hilla and Bernd Becher, who published a whole photo book, Anonymous Sculptures, dedicated to water towers and other in...