Patients suffering from kidney disorders ought to receive hemodialysis therapy several times a week. Considering that during hemodialysis treatment session large amounts of water are circulating through patients bloodstream, water used for preparation of hemodialysis solution must undergo a purification process to be of appropriate quality and health safety. In addition to risk of chemical contamination, microbiological contamination of hemodialysis water presents a significant risk for the health of patients. Therefore, it is necessary to regularly practice microbiological analyzes of water to confirm the safety of water used in hemodialysis. This paper will describe bacteria isolated in hemodialysis centers in Primorje-Gorski Kotar County during a period of six years (2016-2021). There are 23 species of Gram-positive and Gram-negative bacteria species found in samples from four hemodialysis centers, and outbreaks of certain species in Europe and in the world is described by review of professional papers using the key words: „bacterial species, hemodialysis, total number of bacteria“. The paper also deals with statistical processing of data on total number of bacteria that are incubated in two different temperature conditions (37°C/48h and 22°C/72h) on the same nutrient agar, and the data is compared between different hemodialysis centers, between years and between seasons. It was found that hemodialysis center A has the highest number of isolated bacteria species in its water samples, while samples from hemodialysis center D have no isolated types of bacteria. Also, comparing values of total number of bacteria between four hemodialysis centers, between six years and between four seasons using statistical tests, statistically significant differences were determined.