What method is NOT used for making water potable?

The filtration method is indeed commonly used to improve water quality by removing suspended solids, contaminants, and certain pathogens, but it doesn't inherently make water potable on its own. Filtration can reduce turbidity and improve clarity, but it does not eliminate dissolved salts, chemicals, or all microorganisms, which are crucial elements for ensuring water is safe to drink.

In contrast, the other methods listed are recognized for their role in making water potable. The brominator method uses bromine as a disinfectant, effective in killing bacteria and viruses. The chlorine disinfection method is widely used to kill harmful organisms in water supply systems. Reverse osmosis is a process that removes a wide range of contaminants by forcing water through a semi-permeable membrane, providing highly purified water.

Therefore, while filtration contributes to water treatment, it does not encompass the necessary steps required to ensure water is completely safe to drink, making it the method that is not solely effective for making water potable.