In order to determine current water quality but also to evaluate quality development in the course of time the IAWR through its affiliate associations operates a monitoring system along the Rhine. At more than 20 monitoring stations water samples will be checked for a variety of parameters on a monthly basis. A total of 9 of these monitoring stations are so-called main monitoring stations having an extended monitoring programme. Analyses will be carried out mainly in the laboratories owned by member waterworks or at the Technologiezentrum Wasser (TZW) Karlsruhe; professional coordination is the responsibility of the analyst group.