UV gives fast, successful inactivation of microorganisms through a physical procedure. At the point when microscopic organisms, infections and protozoa are presented to the germicidal frequencies of UV light, they are delivered unequipped for recreating and tainting. UV light has exhibited adequacy against pathogenic living beings, including those liable for cholera, polio, typhoid, hepatitis and other bacterial, viral and parasitic illnesses. What’s more, UV light (either alone or related to hydrogen peroxide) can obliterate synthetic contaminants, for example, pesticides, modern solvents, and pharmaceuticals through a procedure called UV-oxidation. Microorganisms are inactivated by UV light because of harm to nucleic acids. The high vitality related with short frequency UV vitality, principally at 254 nm, is consumed by cell RNA and DNA. This ingestion of UV vitality frames new bonds between adjoining nucleotides, making twofold bonds or dimers. Dimerization of adjoining atoms, especially thymine, is the most well-known photochemical harm. Development of various thymine dimers in the DNA of microorganisms and infections forestalls replication and powerlessness to contaminate.