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Federal Drinking Water Rules
The Safe Drinking Water Act (SDWA) directs EPA to establish minimum national drinking water standards. The following pages discuss rules promulgated under the SDWA which apply to New York City's water supply. Additional information on Federal drinking water rules may be obtained by following the suggested links located throughout the pages. Also, EPA's Safe Drinking Water Act Hotline at (800)426-4791 is available to help the public understand the regulations and programs developed in response to the Safe Drinking Water Act.
The Surface Water Treatment Rule
The 1986 amendments to the Safe Drinking Water Act (SDWA) required EPA to promulgate a national drinking water regulation specifying criteria under which filtration would be required for public water systems supplied by surface water sources. In response to this mandate, EPA promulgated the Surface Water Treatment Rule (SWTR) on June 29, 1989.
The SWTR recognizes that surface water is at risk of contamination from protozoa such as Giardia lamblia, viruses and pathogenic bacteria, and that drinking water treatment should be provided to ensure protection from illnesses caused by these contaminants. The rule requires filtration of surface water supplies unless specific filtration avoidance criteria are met. In addition, all systems are required to provide disinfection. For systems where treatment is required, treatment must achieve at least 99.9% inactivation of Giardia cysts and 99.99% inactivation of viruses.
1996 SDWA Amendments required EPA to develop additional rules to further protect drinking water. These rules, announced in December 1998, are meant to balance the risks between microbial pathogens and disinfection byproducts (DBPs), and are part of a group of interrelated regulations developed by EPA collectively referred to as the Microbial Disinfection Byproduct Rules (M/DBP) . Additionally, these rules address the protozoan Cryptosporidium, which is very resistant to disinfection. In 2001 the Interim Enhanced Surface Water Treatment Rule (IESWTR) , and the Stage I Disinfection Byproduct Rule were promulgated, and in 2002 the Long Term 1 Enhanced Surface Water Treatment Rule (LT1IESWTR) promulgated.
Other SDWA rules include the Filter Backwash Recycling Rule (FBRR) , which was promulgated in June 2001 and became effective in August 2001, the Arsenic Rule , which was promulgated in January 2002 and became effective in February 2002, the Ground Water Rule , which was proposed in May 2000, and the Stage 2 DBPR and Long Term 2 Enhanced SWTR , which were finalized in January 2006.
At the same time as the SWTR, EPA also promulgated the Total Coliform Rule (TCR) to provide adequate microbiological protection from contamination in the distribution system. The TCR established a Maximum Contaminant Level Goal (MCLG) for total and fecal coliform bacteria of zero, and a Maximum Contaminant Level (MCL) based on the percentage of positive samples collected during a monthly compliance period. Under the TCR, no more than 5 percent of distribution samples collected in any month can contain coliform bacteria. Coliform bacteria, particularly fecal coliform bacteria, are generally considered indicators of potential recent fecal contamination. The number of samples to be collected in a given month is based on the size of the population served; the location and frequency of sampling is based on a system specific sampling plan to provide representative coverage throughout the distribution system. Combined, the SWTR and the TCR were intended to control for pathogens in both source water and the distribution system. Currently, EPA is reviewing available data and research on distribution system risks and working with stakeholders in an effort to review and possibly revise the TCR as well as possibly add requirements to address finished water quality in the distribution system.
