A method of sanitizing a surface is described that includes: (a) providing a pH control composition that includes at least one pH control agent (such as sodium bisulfate); (b) contacting a first feed aqueous stream with the pH control composition, thereby forming a first treated aqueous stream; (c) combining at least a portion of the first treated aqueous stream with a feed sanitizing aqueous stream that includes free available halogen, thereby forming a treated sanitizing aqueous stream that includes free available halogen (such as free available chlorine). The surface sanitizing method further includes, (d) elevating the temperature of the treated sanitizing aqueous stream, thereby forming a heated treated sanitizing aqueous stream having an elevated temperature that includes free available halogen. The heated treated sanitizing aqueous stream is applied to a surface to be sanitized (such as a poultry carcass surface).