Groundwater development has rapidly expanded in the six decades since independence meeting the drinking and irrigation requirements, especially of the rural population. However, the hydro-geological conditions which favor the development of groundwater are complex and understanding the intricacies involved can assist in scientific and sustainable development of groundwater. Supporting the scientific development of groundwater, a study titled ‘Geohydrological Investigation in Nyoil river basin, Tamil Nadu’ was commissioned by the Government of Tamil Nadu in 1971. We were invited to contribute to this study in 3550 sq km of the Nyoil river basin. A collaboration, support and guidance from the Central and State Groundwater Boards were also received under the project. Key components of the study included mapping of local geological and hydro geological conditions, electrical resistivity surveys, geophysical well logging, and short duration pumping tests, water level fluctuations and water sample analysis. Findings from the systematic and scientific survey of the basin have served as inputs and support to local drilling programmes.