Abstract: The invention relates to a probe (1) to detect the level of a liquid. particularly water, within a boiler (10), particularly in a small electric household appliance, comprising a probe plug (2), provided at the bottom with a joint (5) for coupling with the boiler body (10), a metallic disc element (7) for the electric contact, a metallic spring (6), provided on said probe plug (2), and in contact with said metallic disc (7), and the upper part of which contacts said spring, and means (11) for supplying said probe and/or transmitting the signal to an electric board, coupled with said metallic disc (7).