The chapter discusses the impact of armed conflicts on the territory of Ukraine on the hydrochemical composition of aquatic ecosystems. The authors consider such a factor of water quality degradation as the destruction of water infrastructure. In particular, the cases of enemy attacks on filtration plants, sewage treatment plants, electrical equipment of water management systems, dams and reservoirs and their consequences were analysed. The threats of explosive devices and destroyed military equipment entering rivers and lakes, as well as enemy shelling of oil depots and warehouses with fuels and lubricants are investigated. The main problems that have arisen as a result of the full-scale invasion in terms of water quality monitoring in Ukraine are outlined. The hydrochemical composition of the surface waters of the river basins of the Southern Bug, Dnipro, and Don is described. The section analyses hydrochemical water quality studies taken from nine control points in regions with different intensity of hostilities in the summer of 2023. Priority practical measures necessary for post-war recovery in the field of water resources are proposed.