Given the fact that water is a basic need of every living being, it is important to ensure its health, whether it is water for human consumption or that intended for recreation and rehabilitation. In this paper, the presence of the microbiological indicator P. aeruginosa in drinking water (N=4171) as well as in pool water (N=5059) in the Primorje-Gorski Kotar County during the five-year period (2016.-2020.) was examined. Also, the legislation is presented and the national legislation is compared with neighboring countries and beyond, related to the use of P. aeruginosa as a microbiological indicator in drinking water and pool water. According to the obtained results, the proportion of P. aeruginosa-positive samples was similar in drinking water (3,9%) and pool water (4,6%), with the highest number of positive samples in the low load category (<10 CFU / 100 mL ). The prevalence of this bacterium was most pronounced in the warmer period of the year (July-October). P. aeruginosa is statistically significantly associated with most of the examined microbiological and physicochemical parameters. P. aeruginosa-positive samples of drinking water were mostly collected during technical inspections of buildings, and in the case of swimming pools, the largest share of positive samples were in entertainment and jacuzzi / hydromassage pools. They had a higher proportion of positive samples than outdoor pools, as sweet compared to seawater-filled pools. According to the purpose of the pool, the highest degree of P. aeruginosa load was recorded in rehabilitation pools. The Republic of Croatia, Serbia and Montenegro are countries that have included P. aeruginosa in their national regulations as an indicator of the health safety of drinking water and packaged water, while Slovenia and Bosnia and Herzegovina have limited the testing of this bacterium to packaged water only. In the Republic of Croatia, the opinion of experts is that P. aeruginosa should be examined in places of public health interest (hospitals, homes for the elderly and infirm). When assessing the health safety of pool water, this parameter is tested in all countries covered by this study.