A holder for a hydrostatic level sensor that is placed in a tank below the surface. To keep the sensor with the holder below the surface, it is supplemented with a container into which concrete is placed. Then the container with concrete is glued to the holder. The holder itself consists of two parts. One contains a suction cup against dirt and the other part is the holder itself. The mount is designed for a sensor diameter of 26mm. All parts are glued together, for example, with superglue.