UV light provides rapid, effective inactivation of microorganisms through a physical process. When bacteria, viruses and protozoa are exposed to the germicidal wavelengths of UV light, they are rendered incapable of reproducing and infecting. Microorganisms are inactivated by UV light as a result of damage to nucleic acids. The high energy associated with short wavelength UV energy, primarily at 254 nm, is absorbed by cellular RNA and DNA. This absorption of UV energy forms new bonds between adjacent nucleotides, creating double bonds or dimers. Dimerization of adjacent molecules, particularly thymine, is the most common photochemical damage. Formation of numerous thymine dimers in the DNA of bacteria and viruses prevents replication and inability to infect.

  • UV is a chemical-free process
  • UV requires no transportation, storage or handling of toxic or corrosive chemicals: a safety benefit for plant operators and the surrounding community
  • UV treatment creates no carcinogenic disinfection by-products that could adversely affect quality
  • UV is highly effective at inactivating a broad range of microorganisms including chlorine-resistant pathogens like Cryptosporidium and Giardia
  • UV can be used to break down toxic chemical contaminants while simultaneously disinfecting.
  • Annual lamp replacement and electrical consumption comprise the operating costs of UV disinfection
  • UV eliminates or reduces the immediate safety threat of chlorine gas without creating new long term costs associated with chemicals, transportation and delivery
  • Costs for leak response, administration, risk management and emergency planning and operator training are minimized and/or eliminated with UV
Chlorine disinfectionUV disinfection
Disinfection by-products (DBPs)YESNO
Chemical ResidualYESNO
Community Safety RisksYESNO
Cryptosporidium and Giardia effectivenessNOYES