In response to the request of January 26, the American Society for Microbiology's (ASM) Committee on Environmental Microbiology has formulated the following comments for the revision of the Total Coliform Rule (TCR). The comments are limited to sections 141.63 and 141.21 of the Rule.
Section 141.63 - Maximum Contaminant Levels
The current TCR Maximum Contaminant Level (MCL) is based on both the frequency of detection of total coliform bacteria (no more than 5% for systems collecting at least 40 samples per month) or the combination of a positive Escherichia coli sample (or fecal coliform) with a positive total coliform sample.
On August 10-11, 1998, the Environmental Protection Agency (EPA) conducted a workshop on "Improved Microbial Indicator Methods" that concluded that E. coli was a better indicator of fecal contamination of drinking water than total coliforms. The workshop also recommended that indicators for viral and protozoan be developed. ASM recommends that the EPA accept these findings by adopting E. coli as the primary public health indicator of drinking water, and explore the possibility of using bacteriophage and Clostridium spores as indicators of viral and protozoan contamination. Furthermore, designating total coliforms as a secondary standard of optimum treatment performance (not related to fecal contamination) recognizes the value of the total coliform group to indicate treatment performance separate from the acute public health consequences of fecal contamination.
Section 141.21 - Coliform Sampling
The current TCR requires a monitoring plan commensurate with the population served. This monitoring plan has resulted in an unwieldy maze of primary, upstream and downstream, sampling locations. TCR's mandate to monitor from many locations requires that samples be manually collected and processed by simple, low-cost methods. This results in a disincentive to develop alternative techniques that could automate sampling and employ new analytical techniques.
ASM recommends that the EPA consider the Hazard Analysis and Critical Control Point (HACCP) methodology for determining the critical monitoring points within a distribution system. The HACCP approach would evaluate the critical risk points within the distribution network and focus monitoring efforts in those areas. This approach would eventually lead to around-the-clock testing and risk-based monitoring.
The Food and Drug Administration (FDA) and the food processing industry have successfully employed HACCP concepts for food safety and will soon be joined by the World Health Organization (WHO).
To summarize, the ASM recommends the following:
- Use E. coli as the primary indicator of fecal contamination
- Employ other indicators of viral and protozoan contamination
- Use the total coliform group as a secondary standard of treatment optimization
- Adopt the HACCP approach for risk-based distribution system monitoring
- Encourage the development of automated and advanced analytical techniques
- Streamline and simplify the TCR to reduce monitoring and reporting problems
The ASM is pleased to have the opportunity to provide comments in response to the revision of the Total Coliform Rule and hopes that these comments and recommendations are of assistance to the EPA. The ASM recognizes that the revision process may take several years and welcomes the opportunity to further assist the EPA in this effort.