The aim of this study is to present environmental variables which were effective on habitat preferences of Hydrophilidae and Helophoridae species found in western region of Turkey. The surveys were conducted in Izmir, Manisa and Aydin provinces and specimens were collected regularly during the years 2013 and 2014. Totally, 30 species classified in 8 genera of the two families were recorded. Physicochemical parameters including temperature, dissolved oxygen, pH, electrical conductivity and salinity were measured from 99 different aquatic sites. The relationships between the species and the effect (s) of the mentioned parameters on the presence or absence of the beetles were evaluated by various statistical tests. According to the results; electrical conductivity, salinity and temperature are the main water parameters associated with aquatic beetle distribution. Pearson's correlation analysis coefficient between the salinity and electrical conductivity parameters was calculated as 0.965 which is statistically significant (p<0.01). The relationships between environmental variables and the determined species were also evaluated with canonical correspondence analysis (CCA), and the distributions of species according to these variables were presented by using a CCA plot.