The issue of fluoride exceeding permissible limits in drinking water (DW) and its associated problems has been extensively documented, both within and outside India. The excessive presence of fluoride in DW causes detrimental effects on human health. Challenges related to elevated fluoride levels in DW are particularly prevalent in countries such as India. Fluorosis, an illness caused by the assimilation of fluoride, is a serious health problem. This chapter discusses various health issues that arise due to the increased fluoride concentration in water such as impaired joint mobility, neuropathic effects, decreased thyroid function, lower intelligence levels in children, hindered mental growth, elevated risk of kidney stone risk, and potential carcinogenicity. The leaching of fluoride from minerals in the earth's crust is the primary source of fluoride in groundwater. Many rivers in various regions of India have recorded different concentrations of fluoride, ranging from 0.1 to 12.0 ppm. Several countries, including India, China, Ethiopia, Pakistan, Senegal, Sri Lanka, Algeria, Ghana, Kenya, Ivory Coast, Uganda, Tanzania, Mexico, and Argentina, are among the nations severely affected by fluoride contamination. Various solutions have been proposed in the literature to address these issues. Techniques such as ion exchange/adsorption, and coagulation/precipitation are effective in fluoride removal from water or wastewater. The ion exchange/adsorption processes are effective for both concentrated and diluted solutions, ensuring complete removal when applied under appropriate conditions. The selection of the most suitable method for a particular situation should be done carefully, considering various factors. This chapter provides a wide-ranging summary of fluoride, mainly its presence in the atmosphere, sources of origin, impact on human health, and methods for defluoridation.
