Evaluation of fluoride contamination in groundwater sources in hard rock terrain in Garhwa district, Jharkhand, India

The present study involves field and laboratory testing of various sources of potable water in six blocks of Garhwa districts. The 4012 water samples were collected out of which 295 (7.4%) samples were tested in laboratory for estimating the concentration of fluoride. Fluoride concentrations in the water samples vary between 0.018 mg/L to 5.92 mg/L with highest concentration in Kharaundhi and Untari blocks making these blocks prone to dental and skeletal fluorosis. Abnormally high concentration was found in the depth range of 0–100 feet. Potable water available in schools and in public hand pumps recorded the highest fluoride concentration as compared to minimum in the private well indicating need of awareness among masses about ill effects of use of fluoride contaminated water. The safe-unsafe zone with reference to fluoride contamination in the study was delineated using IDW spatial interpolation in GIS platform. The spatial distribution pattern of fluoride concentration varies from place to place and most of the fluoride contaminated water sources are found in the north western parts of the area over the Untari and kharaundhi blocks and only some parts of Majhiaon and Ranka blocks were affected with higher fluoride contamination.