ABSTRACT: Eight formations were recognized in WadiWatir area, SE Sinai; Malha Formation (Early Cretaceous), Galala Formation (Late Cenomanian), Abu Qada Formation (Early Turonian), Buttum Formation (Early Turonian), Wata Formation (Late Turonian), Matulla Formation (Coniacian-Santonian), Brown Limestone Formation (LateCampanian-Early Maastrichtian) and Sudr Chalk Formation (Early-Middle Maastrichtian). The planktonic foraminifera played the great role in age determination for the referred units, in addition to some benthonic foraminifera. Also, three microfacies types were identified; siliciclastic facies, mixed carbonate – siliciclastic facies and carbonate facies reflecting an oscillation of the Cretaceous sea from shoal to shallow marine and marine environments. The diagenetic processes (cementation, neomorphism, dolomitization, silicification, dissolution and compaction) show the impact of textural and mineralogical changes on the studied rock units, groundwater occurrences and possibilities. Furthermore, two main aquifers are dominant in the study area, Lower Cretaceous sandstones and Cenomanian-Turonian Limestones. The geomorphologic and geologic characteristics controlling the groundwater occurrences were discussed.