Compositions and methods for inhibiting corrosion of metallic surfaces in contact with an aqueous medium such as copper, copper alloy, and steel surfaces of an open recirculating cooling water system. In certain embodiments, an aromatic triazole having an anionic substituent bonded to a nitrogen atom of the triazole (ANST) is used as the corrosion inhibitor. In other embodiments, the corrosion inhibitor is a reaction product of an aromatic triazole and an aldehyde (ATA).