Water is a prime natural resource, a basic human need and a precious national asset. Natural water always contains dissolved and suspended substances of organic and mineral origin. Water is polluted with metabolites of aquatic plants and animals and the products of their decay. All these cause so many water borne diseases. The excessive amount of fluoride in water and environment is harmful. The quality and availability of water depend on the way, We use and misuse this precious resource, which is the most important life supporting substance. The present study has been undertaken for the determination of fluoride in drinking water collected at rondom from Koshi region. The fluoride concentration values vary from 0.6 mg/L to 1.6 mg/L. In the affected areas, it was found that citizens are suffering with different types of fluorosis. Authors have suggested the people to use generally alum and lime to avoid all types of fluorosis.