A water line mapping assembly includes a remote unit that is held by a user. The remote unit has a remote transceiver that is in electrical communication with a global positioning system (gps). A capsule is provided that has an outside diameter sufficiently small to fit into a buried pipe. The capsule is comprised of a buoyant material to float in the buried pipe, and the capsule is comprised of a fluid impermeable material. A tracking unit is positioned inside the capsule and the tracking unit is in wireless electrical communication with the gps. Thus, the gps can establish a depth and a position of the tracking unit when the capsule is positioned in the buried pipe. The tracking unit is in electrical communication with the remote unit thereby facilitating the remote unit to display the depth and position of the tracking unit. In this way the remote unit can map the buried pipe.