In this paper, a novel sensor system for the detection of bacterial contamination in drinking water supply equipment and in technical water recirculation systems is presented, which allows a permanent monitoring of the drinking water piping. The implemented measuring system is based on the two-sensors principle with the main sensor containing a porous polyamide substrate trap serving as a trap for microorganisms, which can grow and build a biofilm, and a reference sensor. The three-dimensional structure of the substrate trap was designed and implemented by means of additive manufacturing. As a result, it was possible to find an optimal compromise between fluidically optimized 3D structure and technological feasibility using 3D printing. The sensor was connected to a process measuring and control unit using a data interface. This enabled the comparison of the impedimetric signals of the measuring and reference channels as well as a difference signal output. The antibacterial treatment of the water recirculation components should be performed if the difference signal of the sensor exceeds a given threshold value. This early maintenance prevents a health threat due to water contamination. The sensor system is designed as an interchangeable unit. Its components fulfil the hygienic requirements of the Drinking Water Guidelines for the use in drinking water piping.