Fluoride with high concentration in groundwater has been reported from many parts of India. However, a systematic study is required to understand the presence of fluoride in natural water in terms of local hydrogeological setting, climatic conditions, and agricultural practices etc. The present study reveals to assess hydrogeochemistry of groundwater in parts of Amaravathi river basin in Tamil Nadu to understand the fluoride abundance in groundwater and to deduce the chemical parameters responsible for the dissolution activity of fluoride. The study area is geologically occupied by partly sedimentary and partly crystalline formations. A total of 60 dug cum borewell-water samples, representing an area of 8280 Sq.km. The results of the chemical analyses in June 2012 show fluoride abudance with the range of 2.1to4.5mg/l. Presence of fluoride-bearing minerals in the host rock, chemical properties like decomposition, dissociation, and dissolution, and their interaction with water are considered to be the main causes for fluoride in groundwater. Chemical weathering with relatively high alkalinity favours high concentration of fluoride in groundwater. Villagers who consume nonpotable high fluoride water may suffer from yellow, cracked teeth; joint pains; and crippled limbs and also age rapidly.
