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Statement of Need: Public water systems (PWSs) that use groundwater as their sole source of water, as opposed to surface water PWSs, are not federally regulated as to treatment for microorganisms. There is data that indicates that a number of groundwater PWSs are contaminated with microorganisms of fecal origin that can and have caused illness.

Summary of the Legal Basis: Section 1412(b)(8) of the Safe Drinking Water Act requires that EPA develop regulations specifying the use of disinfectants for groundwater systems as necessary and "...(as part of the regulations) promulgate criteria...to determine whether disinfection shall be required as a treatment technique for any public water system served by groundwater."

Alternatives: EPA considered four regulatory alternatives in the development of the GWR proposal: the proposed regulatory alternative (multibarrier option); the sanitary survey option; the sanitary survey and triggered monitoring option; and the across-the-board disinfection option. All options include the sanitary survey provision. The sanitary survey option would require the primary agency to perform surveys every three to five years, depending on the type of system. If any significant deficiency is identified, a system is required to correct it. The sanitary survey and triggered monitoring option adds a source water fecal indicator monitoring requirement triggered by a total coliform positive sample in the distribution system. The multibarrier option, which was proposed by EPA, adds a hydrogeologic sensitivity assessment to these elements which, if a system is found to be sensitive, results in a routine source water fecal indicator monitoring requirement. The multibarrier option and the sanitary survey and triggered monitoring options are both a targeted regulatory approach designed to identify wells that are fecally contaminated or are at a high risk for contamination. The across-the-board disinfection option would require all systems to install treatment instead of trying to identify only the high risk systems; therefore, it has no requirement for sensitivity assessment or microbial monitoring.

Anticipated Costs and Benefits: EPA estimates the cost of the proposed GWR will be $183 million dollars per year (using a 3 percent discount rate). More than half of the estimated costs are for corrective actions which systems will be required to take to fix or prevent fecal contamination. The remainder of the costs are due to increased scope and frequency of sanitary surveys, hydrogeologic sensitivity assessments and source water monitoring. System costs are expected to be $162 million per year for implementation of the GWR. States are expected to incur costs of $21 million per year. Cost estimates do not include land acquisition, public notification or the potential cost of illness due to exposure to disinfection byproducts. The total estimated value of these benefits is $205 million per year, $139 million from avoided illness and $66 million from avoided deaths. These benefits are monetized based on a cost of illness and a value of statistical life. These estimates do not include pain and suffering associated with viral and bacterial illness, avoided outbreak response costs (such as the costs of providing public health warnings and boiling drinking water), and possibly the avoided costs of averting behavior and reduced uncertainty about drinking water quality.

Risks: EPA estimates that currently over 200,000 illnesses and 18 deaths occur each year due to viral and bacterial contamination of public ground water systems. Children, the elderly and the immunocompromised are particularly sensitive to the waterborne pathogens and account for between 20 and 30 percent of the illnesses and deaths. The proposed GWR is expected to reduce the total number of illness by 115,000 and the total number of deaths by 11 each year. The GWR in conjunction with the Surface Water Treatment Rule (SWTR), Total Coliform Rule (TCR) the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Filter Backwash Rule (FBR) and the Long Term Enhanced Surface Water Treatment Rules (LT1ESWTR & LT2ESWTR) will provide protections to the consumers of public water supply systems from waterborne pathogens.