Nowadays, precise geoid is importantly and urgently needed in Egypt for many applications. For that reason and for the first time, a lot of terrestrial gravity data are collected as gravity values, gravity anomalies, deflection components, and GPS leveling undulations. These data are collected from governmental agencies, petroleum companies, and research institutes and centers. The collected data covers a large area of the Egyptian territory, but they have been taken with different references, strategies, and methodologies. To get use of those heterogeneous multisource data, they should be verified, investigated, filtered, and modified on scientific bases. In this research, some methods of gravity data verification and investigation are proposed. Data verification through undulation differences, undulation rate of change, and undulation acceleration are introduced. 134 observed GPS leveling stations along the River Nile are verified and the odd values are modified. EGM2008 is used against the observed undulations to help in explaining the proposed ideas in this research.