The prevention of corrosion on the surfaces of metallic pipes, heat exchangers, and the like which are in contact with industrial cooling waters, and particularly industrial cooling waters containing low levels of hardness is controlled utilizing a corrosion inhibiting amount of a composition including an alkali metal silicate, a hydroxycarboxylic acid or its water soluble salts, an organophosphonate, and a water soluble polymer which acts as a dispersant. Superior corrosion inhibition is achieved using the compositions of this invention as corrosion inhibitors, particularly in cooling water systems employing mild steel metallurgy.