Return flow is water that goes back to a surface-water body or groundwater system after use. In irrigation, it is the portion of applied water that returns instead of being consumed through evaporation and plant use. See the USGS water resources glossary.
Different from a drain backing up
In a property-damage conversation, “water came back” can describe several situations. A plumbing backup, rain runoff entering a doorway and irrigation return flow should not be treated as the same event. The source affects which specialist should investigate.
Useful details for an assessment
Record whether water appeared after rainfall, irrigation or fixture use; identify the first visible entry point; and explain whether it has happened before. Describe what you observed rather than selecting a technical category yourself.
Related information: runoff, groundwater and water damage services.