A flood occurs when rising levels of surface water are not contained or conveyed within the water’s normal drainage path. A sewer backup occurs when water leaving a structure’s plumbing is restricted from entering the main sewer pipe located in the street. In extended wet conditions, the water is pushed back and enters the structure through “any way possible”, including drains and fixtures.
A flood and a sewer backup can occur at the same time. This is most prevalent in areas where open drainage courses are adjacent to developments where footing drains are connected to the sanitary sewer.