Viruses in Water

Viruses in our water are infectious organisms which range in size from 10 to 25 nanometers, basically invisible to the human eye. Viruses are particles composed of an acidic nucleus surrounded by a protein shell. They depend totally on living cells and lack an independent metabolism. There are over 100 types of enteric viruses. Enteric viruses are the viruses which infect humans. Enteric viruses which are problematic in our drinking water are hepatitis A, Norwalk-type viruses, rotaviruses, adenoviruses, enteroviruses, and reoviruses. The test for coliform bacterial in a water supply is widely accepted as a barometer whether or not the water is safe to drink; therefore tests for the above specific viruses are not usually conducted. The US EPA has established an MCL which states that 99.99% reduction or inactivation for viruses in water supplies. Major enteric viruses found in water and their diseases are shown below.

Enteroviruses: Polio, Aseptic meningitis, and Encephalitis
Reoviruses: Upper respiratory and gastrointestinal illness
Rotaviruses: Gastroenteritis
Adenoviruses: Upper respiratory and gastrointestinal illness
Hepatitis A: Infectious hepatitis
Norwalk-type: Gastroenteritis

Virus Water Removal and Treatment - Chemical oxidation / disinfection is the preferred treatment to remove viruses from drinking water. Chlorine feed with 30 minute contact time for retention, followed by activated carbon filtration is the most widely used treatment. Ozone or iodine may also be utilized as oxidizing agents. UV water purification or water distillation may also be used for the treatment of viruses.