ABSTRACT: In Slovakia, more than 80% inhabitants and other consumers are supplied with potable water gained from groundwater resources. Water is gained mostly in wells which may differ in diameter, depth and equipment. Due to pumping of groundwater from the wells, certain physical, chemical and biological changes occur, which affect the lifetime of the wells. These phenomena are called ageing of well s and their overall effect is reduction of the well capacity. Therefore, maintenance of well s have to be carried out with special care. Effective maintenance programs beg in with well construction records showing, geologic conditions, water quality and pumping performance. So many variables are involved, however, that a single maintenance program cannot be devised that will work for every hydrogeologic condition and every type of well.