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 .