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Regarding the quality of natural recreational water for bathing purposes, the limit values of E. coli and coliforms, faecal coliforms and totalcoliforms, respectively, laid down by the Council of the European Community, differ considerably from those prescribed by some Land Governments of the Federal Republic of Germany and by the DIN Standard Regulation No. 19643 entitled 'Processing and Disinfection of Water in Swimming Pools and Basins in Public Baths'. It must be concluded by virtue of hygienically plausible considerations, as well as for juridical reasons, that only the limit values of the EC-Code of Practice are authoritative, whereas standards of the DIN 19643, especially in respect of E. coli and coliforms, differing from the limit values of the EC-Code of Practice are not legally binding. Moreover, coliforms are not relevant for controlling swimming pools and basins in public baths. Staphylococcus aureus should therefore be investigated instead whereas other parameters such as E. coli, Pseudomonas aeruginosa, and total colony counts are good markers. However, the standards of these organisms as established by the DIN 19643 are more in line with technical practibility and biased aesthetics instead of the hygienically important prinicple of commensurability.

Four lakes situated in the recultivated area of the Rhenish brown-coal district were examined bacteriologically during a period of one year. Total colony count and the number of Escherichia coli and coliforms were determined and compared with the influence of meteorological factors and human and animal impacts.

The EC guideline of 1976 applies to the examination and assessment of water bodies used for bathing in the Federal Republic of Germany. The main aspect of hygienic assessment is to find out whether the water bodies in question involve the risk of infection from sewage water etc. (microbiological examination for the presence of faecal germs). Chemical parameters are of secondary importance. To obtain comparable results of investigation it will be necessary to elaborate examination methods that go beyond the formulations of the EC guideline and are well defined. Relevant suggestions have been made by an ad hoc working group of the Federal German coastland administrations. A special working team of the Federal Bathing Water committee is also engaged in finding a solution. Besides the examination methods themselves it is also important to pay attention to marginal conditions such as water depth, water renewal or standstill time etc. Of particular relevance are examinations of the site concerned (location, environment conditions etc.) Attention is drawn to the basic differences between assessing surface water from a hygienic and from an ecological point of view.