In this review an attempt is made to find correlations between the occurence of (groups of) waterbeetles and their ecological demands, based on data from literature. To do so, several similarity-indices were calculated by means of a computer. The assumption was made, that species with comparable demands will often be found together in sampling-sites. By means of a clustering-program dendrograms are made, in which groups and sampling-sites with a high mutual similarity are grouped. Ideally, these groups shall contain species with similar ecolocical demands or ecologically comparable sites. In this study, the qualitative similarity-index of Jaccard resulted in better interpretable dendrograms than the Euclidian distance, a quantitative index, did. In the dendrogram based on the Jaccard-index, eight, groups of species came forward, linked with definite parametres of the sampling-sites (see “bijlage II”). The first group consists of six species, all limited to waters which desiccate every year. Several references give comparable habitats for species in this group. The second group contains species that occur in far more sampling-sites; however, brackish waters are almost devoid of these species. The third group consists of three species, that only occur in semi-permanent, waters like those of the first group. However, these species also occur in waters that dry out at irregular intervals, not yearly. Apparently these species have a wider ecological amplitude than the species of the first group. The fourth group is the counterpart of the first and third. The species of this group are limited to permanent waters, which is confirmed in literature. The species of this group hardly occur in brackish waters. On the contrary, the species in group five mainly occur in brackish waters; they fail completely in the freshwater sites of the “Veluwe”. The sixth group contains very common species, that are limited to the permanent water-bodies. The seventh group is also found in permanent waters only. The group can be subdivided into four smaller groups. The first, consists of species characteristic for wide, slowly moving canals. Group VIIb contains many Haliplus -species, probably also showing a connection with wider water-bodies. The species in group VIIc are mainly limited to brackish waters; subgroup VIId is very heterogenous and hardly interpretable. Finally the last group of species has its main distribution in brackish water; some species occur in highly organically or chemically polluted waters. Based on these results a system is proposed, to list characteristic species for particular types of water bodies, analogous to synecological groups of plants.