Texas Commission on Environmental Quality - Sanitary Sewer Overflows (SSO)

An SSO is a type of unauthorized discharge of untreated or partially treated wastewater from a collection system or its components (e.g., a manhole, lift station, or cleanout) before it reaches a wastewater treatment facility. Collection systems that are properly designed, operated, and maintained will collect and transport all of the sewage and industrial wastewater that flow into them to a facility for appropriate treatment. However, SSOs can occur if there is significant inflow/infiltration, the collection system is poorly operated and maintained, or the system lacks adequate capacity to collect or store flows for treatment, or to treat them.