A water detection assembly having an electronic fluid-sensing probe located in-line within a primary drain line associated with a fluid-producing unit via probe connection to an access port used for clearing and removing clog-causing debris from the primary drain line. The probe has no moving parts and quick-disconnect connection to a signal-generating unit. The access port is configured for vertical or horizontal installation and introduction of chemicals to clean the drain without retrograde backflow into the fluid-producing unit. The probe is inserted into the access port through a longitudinal opening when vertically installed, and alternatively through a lateral opening in a horizontal installation. When the probe detects fluid, the connected signal-generating unit sends an electronic signal that shuts off fluid production, activates an alarm or pump, and/or provides remote notification. One of the two power potentials in the electronic fluid-sensing probe needed for signal generation may have a circular configuration.