The widespread use of artificial sweeteners as additives in food, beverages, medicines and oral care products has led to the accumulation of these substances in aquatic ecosystems around the world. Since most of them are metabolically inert and are incompletely eliminated in wastewater treatment plants, municipal wastewater is the main source of these compounds in the environment. Due to the limited knowledge of their environmental fate and ecotoxicity, artificial sweeteeners are recognized as high-priority emerging contaminants. Some of them, such as acesulfame and sucralose, are very persistent in the aquatic environment, so they can be used as chemical markers of municipal wastewater pollution. In this paper, the presence of the most commonly used sweeteners in the Republic of Serbia (acesulfame, saccharin, cyclamate, sucralose and aspartame) was investigated in groundwater from two Belgrade Ranney wells, as well as in the Sava River, in order to assess the impact of untreated municipal wastewater on water sources, using liquid chromatography–tandem mass spectrometry.ers as additives in food, beverages, medicines and oral care products has led to the accumulation of these substances in aquatic ecosystems around the world. Since most of them are metabolically inert and are incompletely eliminated in wastewater treatment plants, municipal wastewater is the main source of these compounds in the environment. Due to the limited knowledge of their environmental fate and ecotoxicity, artificial sweeteeners are recognized as high-priority emerging contaminants. Some of them, such as acesulfame and sucralose, are very persistent in the aquatic environment, so they can be used as chemical markers of municipal wastewater pollution. In this paper, the presence of the most commonly used sweeteners in the Republic of Serbia (acesulfame, saccharin, cyclamate, sucralose and aspartame) was investigated in groundwater from two Belgrade Ranney wells, as well as in the Sava River, in order to assess the impact of untreated municipal wastewater on water sources, using liquid chromatography–tandem mass spectrometry.