This document is one of several technical documents prepared in support of the Ground Water Rule(GWR). The document describes treatment technologies and best management practices (BMPs) that ground water systems can consider as corrective actions or safeguards to reduce or eliminate microbial risks. The document also presents the estimated costs associated with their installation, implementation, and operation. The United States Environmental Protection Agency (EPA) has the responsibility to develop a ground water rule which not only specifies the appropriate use of disinfection but, just as important, also addresses other components of ground water systems to assure protection of public health. Section 1412(b)(1)(A) of the Safe Drinking Water Act (SDWA) requires EPA to establish National Primary Drinking Water Regulations (NPDWRs) for contaminants that 'may have an adverse effect on the health of persons,' are 'known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern,' and for which, 'in the sole judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk reductions for persons served by public water systems.' Section 1412(b)(8) requires the EPA to develop regulations specifying the use of disinfectants for ground water systems as necessary.