Public water systems are regulated under the Safe Drinking Water Act of 1974 (5), as amended in 1986 (6) and 1996 (7). Microbial contamination is regulated under the Surface Water Treatment Rule of 1989 (8) and the Total Coliform Rule of 1989 (8-10). The SWTR includes regulations for filtration, disinfection, and turbidity, as well as treatment criteria for removing Giardia Lamblia, viruses, Legionella, and heterotrophic plate-count bacteria. All public community and non-community sources that use surface sources or ground sources under the direct influence of surface sources are covered by the SWTR, which requires these systems to disinfect and to maintain a disinfectant residual in their distribution system. Filtration must also be provided unless the sources meet specified criteria for quality and source-water protection.

The Total Coliform Rule was promulgated specifically to identify public systems that are contaminated or vulnerable to contamination. The total Coliform group of organisms (see Glossary), which includes but is not limited to fecal Coliforms and Escherichia Coli (E. coli), is used to indicate the possible presence or absence of pathogens and thus, provides a general indication of whether the source is contaminated. The presence of fecal Coliforms or E.coli provides stronger evidence than does a positive total Coliform test of fecal contamination and the likely presence of pathogens (9).

Additional rules are being developed. The Enhanced Surface Water Treatment Rule, proposed July 29, 1994 (11), and the Ground Water Disinfection Rule, which has yet to be proposed, also will address the prevention of waterborne diseases. This rule will propose changes to the SWTR to provide additional protection against Cryptosporidium parvum and other waterborne pathogens, including Giardia and viruses. The regulation will be implemented in two stages: an interim rule and a final rule. Treatment requirements under the interim ESWTR are scheduled to be announced in late 1998.

The Ground Water Disinfection Rule will apply to both community and noncommunity systems served by groundwater. Maximum contaminant level goals will be set for pathogens. A maximum contaminant level goal of zero will be set for viruses and possibly Legionella. No maximum contaminant level goal is expected for heterotrophic plate-count bacteria. In lieu of monitoring for pathogens, performance criteria for water treatment will be established that are expected to produce the desired reduction in levels of pathogens. Minimum levels of disinfection will be proposed for viruses and Legionella, if included in the new rule.

To fill gaps in existing data on the occurrence of microbial pathogens and other indicators of microbial contamination, the EPA promulgated the Information Collection Rule (12). This rule requires treatment plants that use surface water and supply communities of greater than or equal to 100,000 persons or that use groundwater systems and supply communities of greater than or equal to 50,000 persons to monitor their source water for specific microbes and chemicals beginning in July 1997.

Do you have water filters in your home to protect your family?

 If the concentration of microbes or chemicals exceeds a predetermined threshold, then the utility must also monitor its finished water. Microbial monitoring is intended a) to provide data on the occurrence of pathogens and the effectiveness of treatment for the removal of pathogens and b) to evaluate the adequacy of the Surface Water Treatment Rule and the Total Coliform Rule. The Information Collection Rule requires utilities to monitor for the presence of Cryptosporidium and Giardia, total culturable viruses, and total and fecal coliforms or E. coli at least once a month for 18 months.

Even with these regulations, having water filters in your home guarantees better health for you and your family.

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