This paper presents a geological characteristic in Karak for water transfer tunnel. A dense population that exists year by year in the urban area created a problem which is high demand water consumption. In order to avoid running out of water in the future, the government has planned to make a water transfer tunnel that connects from catchment area from Karak to Langat. The objectives of this study are to study the joint pattern and overburden at NATM-2 and to investigate the relationship between joint pattern, overburden, and water inrush. Fieldwork has been carried out to collect the data from the site. The data collected is tunnel face mapping. From the data, we can accomplish the objective needed. Analysis for this study involved the analysis of the structural map, geological map, tunnel face mapping along 1927 m of total length at NATM-2. The geological structures especially in the strength and water inrush that presents within meta-sedimentary rock have affected the excavation process and decreased the tunnel performance. Three types of joints orientations observed are parallel with the main lineament orientation, perpendicular to the tunnel, and crossing random voids. Most water inrush occurrences are seen as in line with the joint sets orientation which are parallel orientations, perpendicular to the tunnel drive direction and 1 most least is cross voids that crossing with random pocket water zones.
