The United States Environmental Protection Agency (USEPA) developed the Ground Water Rule (GWR) to reduce risk from microbial pathogens entering public water systems that use groundwater sources. The final rule was published in the Federal Register on November 2, 2006. Compliance with this rule is required starting December 1, 2009.
The GWR establishes a risk-based approach to addressing possible fecal contamination of groundwater sources, as an alternative to requiring disinfection for all ground water systems. The GWR prescribes several activities including: routine inspections by Office of Drinking Water (ODW); collection of raw water samples; correction of physical facility deficiencies and operation deficiencies; treatment and public notification for specified situations.
Waterworks with groundwater sources that are currently considering upgrades or improvements to their sources of supply, storage facilities, or treatment systems should pay particular attention to the requirements of the GWR.
Waterworks that Use Chlorine Treatment
Waterworks that use groundwater sources and chlorinate may be affected differently by the monitoring provisions of the GWR. Click Here for more information.
Triggered Source Water Monitoring
The “Triggered Source Water Monitoring” component of the GWR will require waterworks to test their groundwater sources for the presence of E. coli whenever there is a Total Coliform Rule (TCR) positive sample; that is, a sample collected from the distribution system which indicates the presence of coliform bacteria.
New Sampling Tap Requirements
Systems must be able to collect raw water samples from their groundwater source(s) within 24 hours of being notified of a TCR positive sample. For this reason, all groundwater systems will be required to have taps for collecting raw water samples from each individual well.
Sampling taps must be located prior to any treatment system or raw water holding facilities, unless ODW approves an alternate location. The tap should be pointed downward, free of any obstructions, to allow easy access and adequate clearance for sampling containers. Taps should be a threadless type or equivalent.
An indicating and totalizing flow meter to determine raw water production should be installed at the same time as a sampling tap, if one is not currently installed.
More information is also available on EPA’s website