<p>The Groundwater quality index and vulnerability mapping for vellore district Tamil Nadu&nbsp;</p><p>Groundwater data (1981–2020) from IWSTaramani, was analyzed for Vellore district. Physiochemical parameters showed moderate influence on water quality. Using QGIS, thematic maps were prepared for five taluks (Vellore, Katpadi, Pernambut, Gudiyattam, Anaicut). A total of 25 samples were tested, and Water Quality Index (WQI) along with multivariate statistical analysis was carried out. Interpolation maps revealed that Pernambut has the poorest groundwater quality compared to other taluks.</p>