The risk-targeting strategy in the rules provides for:
Contaminants in question are pathogenic viruses - such as rotavirus, echoviruses, noroviruses - and pathogenic bacteria, including E. coli, salmonella, and shigella. Utilities will be required to look for and correct deficiencies in their operations to prevent contamination from these pathogens.
The EPA says fecal contamination can reach ground water sources, including drinking water wells, from failed septic systems, leaking sewer lines, and by passing through the soil and large cracks in the ground. Fecal contamination from the surface may also get into a drinking-water well along its casing or through cracks if the well is not properly constructed, protected or maintained.
A ground water system is subject to triggered source-water monitoring if its treatment methods don’t already remove 99.99 percent of viruses. Systems must begin to comply with the new requirements by Dec. 1, 2009.
For more information, visit www.epa.gov/safewater/disinfection/gwr.