A basic unit for a mobile water analyzing system includes a photometer, a test element receptacle, a photometric measuring track, and a pump actuator. The photometer comprises a light source configured to generate a measurement beam and a light detector configured to receive the measurement beam. The test element receptacle is configured so as to allow a separate test element comprising a measuring section and a pump port to be inserted into the test element receptacle. The photometric measuring track is defined by the measuring section when the separate test element is inserted into the test element receptacle. The measurement beam and the photometric measuring track are aligned during a photometric measurement so that a photometric measurement occurs along a longitudinal length of each of the photometric measuring track and the measuring section. The pump actuator is cooperatively connected with the pump port.