Graphycal Abstract: Concentrations of fluoride ions in the Dniester river and Dubasari reservoir, located on the territory of the Republic of Moldova, were analysed for 2011–2024. They ranged 0.05–1.07 mg/L, with higher values during low-water periods. Despite seasonal sampling, no clear dynamics were observed, due to altered hydrological regime. Fluoride levels were lower than the World Health Organization for drinking water.