Abstract: Forty five species belonging to nineteen genera of terrestrial fungi were recovered on glucose and cellulose Czapek’s media from one hundred and forty drinking water samples which, were collected from different kids (2 schools), primary (77 schools), mediatory (33 schools) and secondary (28 schools) schools from different regions in Riyadh city, Saudi Arabia. Cellulose Czapek’s (39 species related to 19 genera) was rich than glucose Czapek’s (37 species belonging to 15 genera) with the species diversity. Water samples collected from primary schools were the most contaminant with fungal populations as compared with other tested samples. Both Aspergillus and Penicillium contributed the broadest spectra of the isolated terrestrial fungal species where they were represented by eight and six species, respectively on the media of isolation. The most prevalent isolated species of terrestrial fungi on the two isolation media were; Cladosporium cladosporoides, Trichoderma viride, Curvularia lunata, Aspergillus niger, Emericella nidulans, Mucor circinelloides and Rhizopus rhizopodiformis. The majority of the isolated genera and species were almost similar on both of isolation media although several species were recorded in only one isolation medium.