CODE OF VIRGINIA DEFINITIONS (ยง 62.1-241.11) As used in this chapter, unless the context requires otherwise: “Combined sewer overflow” or “CSO” means the discharge of untreated sanitary wastes, including industrial wastes and other wastes conveyed through a sanitary sewer system, and stormwater from combined stormwater and sanitary sewers. HISTORY: 1992, c. 363.