Abstract: A method and apparatus for detecting leakage in a liquid transporting line using a line leak detector connected to the liquid line within a manway containing a pumphead of a submersible pump. The line leak detector contains a piston moving within a cylinder to detect changes in the liquid volume to determine a leak. The movement of the piston is converted to an electrical signal by a core, affixed to the piston, moving within a coil. Retrofit installation of the line leak detector in a fuel service station is facilitated by the use of the existing electrical power wiring between the pumphead and remote pump controller.