By Kelly A. Reynolds, MSPH, PhD

On February 13, the newly revised Total Cloriform, Rule was published. According to the Federal Register publication on the final rule, “The Revised Total Coliform Rule (RTCR) offers a meaningful opportunity for greater public health protection beyond the 1989 Total Coliform Rule…”

Nearly 25 years after the original Total Coliform Rule (TCR) was published, US EPA has revised the rule, requiring increased contaminant and distribution system monitoring. Although the new TCR revisions promise to reduce risks related to the most common sources of waterborne outbreaks in public water systems, the greatest risk reduction can only be realized with properly maintained POU water devices designed to remove priority contaminants.

TCR history
Total coliform are a group of bacteria used to monitor water quality since the 1920s. Although total coliform bacteria do not cause disease in humans, they have been used internationally to monitor the quality of treated water supplies. Increased coliform counts in water often indicate a treatment failure or contamination event that may be associated with disease outbreaks.

In June 1989, US EPA published the Total Coliform Rule, requiring all public water systems to monitor for the presence of coliforms in their distribution systems.1 The maximum contaminant level mandates that no more than five percent of samples can be coliformpositive in a month. Every sample that is positive must be analyzed for fecal coliformsbacteria present in the feces of warmblooded animals and a clearer indication of potentially harmful contaminants. No fecal coliforms are permitted in any sample. The original TCR mandates that total coliform samples must be collected at regular time intervals throughout the month and at various locations throughout the distribution system expected to best represent water quality throughout the system. Utilities serving larger populations are required to sample more frequently. Specifically, utilities serving less than 1,000 persons may sample once a month or less, those serving 50,000 persons are required to collect a minimum of 60 samples per month, while those serving 2.5 million persons are required to sample 420 times per month.

It is common for utilities to monitor more than the required number as a precautionary measure. If a system tests positive for total coliforms, additional samples must be collected to determine the presence of fecal coliforms or E. coli. If any routine sample is total coliform-positive, repeat samples must be taken from the same tap and within five service connections upstream and downstream of the original sample within 24 hours. A violation of the TCR means that either unacceptably high levels of coliforms or a fecal coliform or E. coli were found in the water. A fecal coliform or E. coli violation requires state and public notification, often resulting in a boil water notice.

After 25 years of monitoring for total coliform bacteria, stakeholders in the drinking water industry have concluded that they are not appropriate as an indicator of water quality in the distribution system and that the current criteria for monitoring frequency may be inadequate to identify certain problems.

Distribution system contamination
A series of 19 papers have been published identifying drinking water distribution system contamination pathways and concerns. These papers were summarized in a separate white paper and used to justify the need to revise the TCR. Events such as intrusion from pressure transients, backflow contamination through cross-connections, leaching of metals or other pipe materials, introduction of microbes or chemicals following repairs, finished and stored water contamination and microbial growth and biofilms may all impact water quality in the distribution system.2 From 1981 to 1998, 57 waterborne disease outbreaks due to cross-connection contamination events were documented by the Centers for Disease Control and Prevention. These outbreaks resulted in 9, 734 illnesses. Overall, distribution contamination is documented to have caused 24 percent (37/153) of all waterborne outbreaks from 1991 to 2000. As reviewed by Reynolds et al., 2008, during 2001 through 2002, 5/25 (20 percent) of the documented waterborne outbreaks were associated with drinking water distribution system deficiencies, and of the seven outbreaks reported involving community water systems, four (57.1 percent) were linked to distribution system problems.3 Although the overall number of reported outbreaks associated with community water systems has decreased in the last decade, the proportion of outbreaks associated with distribution systems has increased. The reduction in total waterborne outbreaks is largely attributed to the promulgation of numerous regulations by US EPA, including the surface water treatment rule, primarily aimed at reducing the risks of waterborne protozoa and improving water treatment. However, the current regulatory requirements do not appear to reduce the proportion of outbreaks associated with distribution systems.

Approximately 26 percent of the distribution pipes in the US are in poor condition and the annual number of documented main breaks has significantly increased from about 250 in 1970 to 2,200 in 1989. It is estimated that even well-run water distribution systems experience about 25 to 30 breaks per 100 miles of piping per year; however, variation between utilities is considerable.3

Revisions of the TCR
Under the 1996 amendments to the Safe Drinking Water Act, US EPA is required to review each National Primary Drinking Water Regulation at least every six years. Driven, in part, by the documented contribution of distribution system contamination in waterborne disease outbreaks, the impact of treated water contamination in storage tanks, and the progressively aging distribution system, US EPA focused their attention on improving the total coliform monitoring tool. In 2003, the agency determined that the Total Coliform Rule needed revision to assure public health protection and in July 2007, a Total Coliform Rule Distribution System Advisory Committee (TCRDSAC) was formed. The TCRDSAC included 15 key stakeholder organizations who began meeting to discuss the efficacy and applicability of the TCR with a specific focus on distribution contamination concerns and TCR revision needs.

Over time, the advisory committee stated that:4

“….finished water storage and distribution systems may have an impact on water quality and may pose risks to public health.”

“…cross-connections and backflow in distribution systems represent a significant public health risk.”

“….water quality problems can be related to infrastructure problems and that aging of distribution systems may increase risk of infrastructure problems.”

“…distribution systems are highly complex and that there is a significant need for additional information and analysis on the nature and magnitude of risk associated with them.”

On February 13, the newly revised TCR was published. According to the Federal Register publication of the final rule, “The Revised Total Coliform Rule (RTCR) offers a meaningful opportunity for greater public health protection beyond the 1989 TCR. Under the RTCR there is no longer a monthly maximum contaminant level (MCL) violation for multiple total coliform detections. Instead, the revisions require systems that have an indication of coliform contamination in the distribution system to assess the problem and take corrective action that may reduce cases of illnesses and deaths due to potential fecal contamination and waterborne pathogen exposure.”

Therefore, water utilities must track the source and pathway of monitored contaminants. Such source identification is expected to then lead to efforts to repair identified contaminant sources. Water utilities with a history of noncompliance with previous standards are required to sample more often. Further, the RTCR requires that water systems now inform the public if E. coli rather than coliform monitoring exceeds maximum contaminant level standards. The rule also establishes criteria for utilities to reduce coliform monitoring if they can show effective system operation. Compliance with the Revised Total Coliform Rule must be in place by April 1, 2016.5

Public health implications
RTCR affects approximately 154,000 public water systems serving over 300 million customers. The estimated cost of the RTCR is $14 million (USD) per year, assumed mostly (90 percent) by the public water systems. Given the increased ratio of documented waterborne outbreak associations with the distribution system, the rule is expected to have a positive impact on the human disease burden. The uncertainty of the source and frequency of distribution system contamination, however, still leave the public vulnerable. Properly maintained POU devices aimed at the removal of priority contaminants, therefore, continue to offer the best potential for public health protection.


  1. US EPA, “Guidelines Establishing Test Procedures for the Analysis of Pollutants; Analytical Methods for Biological Pollutants in Ambient Water. Vol. 68, No. 139,” Federal Register, Vol. 68, No. 139. Washington, DC. July 21, 2003.
  2. Total Coliform Rule (TCR) and Distribution System Issue Papers Overview, December 2006. [Online]. Available: tcr/pdfs/issuepaper_tcr_overview.pdf. [Accessed February 2013].
  3. Reynolds, K.A.; Mena, K.D. and Gerba, C.P. “Risk of Waterborne Illness Via Drinking Water in the United States,” Reviews in Environmental Contamination and Toxicology, Vol. 192, pp. 117-158, 2008.
  4. Barr, P. Drivers for Revision of the Total coliform Rule and Consideration of Distribution System Requirements, 30 January 2007. [Online]. Available: [Accessed 12 February 2013].
  5. US EPA, Federal Register: National Primary Drinking Water RegulationsRevisions to the Total Coliform Rule, 13 February 2013. [Online]. Available: [Accessed 15 February 2012].

About the author  
Dr. Kelly A. Reynolds is an Associate Professor at the University of Arizona College of Public Health. She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at [email protected]


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