Water and Wastewater Terms Beginning R

A B C D E F G H I J K L M N O P Q R S T U V W Y Z

retention

  1. That part of the precipitation falling on a drainage area that does not escape as surface stream flow during a given period. It is the difference between total precipitation and total runoff during the period, and represents evaporation, transpiration, subsurface leakage, infiltration, and, when short periods are considered, temporary surface or underground storage on the area.
  2. The delay or holding of the flow of water and water-carried wastes in a pipe system. This can be caused by a restriction in the pipe, a stoppage, or a dip. Retention also means the time water is held or stored in a basin or wet well. Also called detention.