How did the refinement of activated carbon improve upon earlier charcoal usage in water treatment?

Scientists processed the carbon to create an extremely high internal surface area, vastly improving its ability to adsorb organic contaminants, odors, and bad tastes.

Although basic forms of charcoal had been used anciently, the 20th-century advancement involved sophisticated material processing of carbon to maximize its functional efficiency. Scientists learned to engineer the carbon structure to possess an enormous internal surface area relative to its size. This high surface area maximizes the potential for adsorption—the process where molecules adhere to the surface. This made refined activated carbon exceptionally effective at chemically binding and removing a wide spectrum of organic contaminants, chemical impurities, odors, and tastes that mechanical or simple physical straining methods could not address.