Contaminant Level Goal (MCLG)
Norovirus is the name of a group of viruses in the Caliciviridae family, named for the original strain, the Norwalk virus, discovered during an outbreak of the disease at an elementary school in Norwalk, OH, in 1968.
Norovirus is spread through poor toilet hygiene, drinking infected water or eating infected food, and through contact with infected people or surfaces.
It is often associated with septic, sewer or fecal contamination of private wells, small water systems, community water systems, recreational waters and pools. Cross-connection of sewage and drinking water systems is a cause.
Washing food with contaminated water is a cause, as is eating shellfish (raw or steamed) from polluted waters.
Norovirus causes a form of gastroenteritis sometimes called “winter vomiting disease” or “stomach flu.” A common disease, but usually not fatal, with no long-term effects. Vulnerable people (children, elderly, immuno-compromised) may require medical attention.
Reverse osmosis, nanofiltration and some ultrafiltration systems are the preferred treatment methods, but a variety of disinfection methods may be effective, including chemical oxidation, ultraviolet, distillation, etc. Note that noroviruses have survived in water with up to 10 parts per million (ppm) chlorine, well above public drinking water levels.
Source: Water Technology Magazine, Volume 32, Issue 2 - February 2009, Image: CDC/ Charles D. Humphrey
(whole house & well units)