ABSTRACT: Basic principles of compilation of digital natural water quality map are discussed in the paper. A fundamental structure of information database is proposed following the requests of Directive of Slovak Environment Ministry 2/2000 on the processing and delivering of the results in geographical information system. The all achieved results from the investigation must be available for the next analyticai and synthetic execution as the geo information system. The complex map of natural water quality serve the information on chemical content and qualitative properties of groundwater, surface water and precipitation. The main information layers in the map regarding the procedure Rapant, Bodiš (2003) concern qualitative properties of natural waters, environmental characteristic s of waters, features of rock environment and database of water chemistry. Other additional thematic layers are also included into the information system according to methodicai principles of map preparing.