UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

 WASHINGTON D.C. 20460 

 

OFFICE OF THE ADMINISTRATOR 

SCIENCE ADVISORY BOARD 

March 19, 2010 

EPA-SAB-10-004 

The Honorable Lisa P. Jackson 

Administrator 

U.S. Environmental Protection Agency 

1200 Pennsylvania Avenue, N.W. 

Washington, DC 20460 

Subject: Review of EPA’s Supporting Analysis for Revisions of the Total Coliform Rule 

Dear Administrator Jackson: 

The Total Coliform Rule (TCR) was published in 1989 and became effective in 1990. 

The TCR requires routine sampling by all public water systems (PWSs) to monitor for the 

presence of total coliforms in the distribution system. The monitoring of total coliforms is used 

as an indicator of the adequacy of water treatment and the integrity of the distribution system. 

The TCR is mandated by law to be reviewed every six years as part of the existing drinking 

water regulations requiring revisions to improve/maintain public health protection. In 

preparation for the TCR revisions, EPA assembled a committee of stakeholders that met over 

several months to address the TCR objectives and enhance the approach for protecting public 

health. As a result of these efforts, an Agreement in Principal (AIP) which takes a more 

proactive approach to identifying and fixing problems was developed. The TCR revisions are 

intended to improve the effectiveness of monitoring requirements by balancing public health 

gains from proactive find-and-fix requirements with reduced sampling requirements. Under the 

revised TCR, TC-positive sampling results would prompt an assessment to identify sanitary 

defects instead of having a Maximum Contaminant Level Goal/Maximum Contaminant Level 

(MCLG/MCL) for TC. 

In response to a request from EPA’s Office of Water, the Science Advisory Board (SAB) 

convened the Drinking Water Committee with additional experts from the Board to conduct a 

review of EPA's proposed revision of the Total Coliform Rule (rTCR). The SAB committee 

during their deliberations examined the supporting analysis, AIP and draft chapters of the 

proposed rTCR. Specifically the SAB was asked to comment on: 

(1) the statistical analysis of the monitoring data which were used to estimate the positive result 

rates for total coliform (TC) and E. coli (EC) samples and predict the underlying baseline; 
(2) the list of corrective actions as described by the EPA that PWSs will implement and the 

percentage of systems that will implement certain types of corrective actions; 

(3) the methodology and assumptions used to estimate the net regulatory impacts of the current 

TCR (with and without the effects of other EPA water regulations) as compared to the 

recommendations contained in the Agreement in Principle (AIP) or the Alternative Analysis 

(AA) which has more frequent routine monitoring requirements than the AIP; and 

(4) the use of the reduction in E. coli- and TC-positive sample results and acute violations as an 

indicator of benefits. 

In general, the Committee was impressed by the work the Agency undertook. The 

Agency obviously did a great deal of work and put a significant amount of thought into making 

use of the limited amount of data. The Agency’s engagement with stakeholders and 

development of the AIP which addresses goals for improvement and research needs was laudable. 

The Committee, however, also found that there were several areas that can be enhanced; 

therefore, in their report, they provide a number of recommendations that are aimed at making 

the rTCR more transparent and improve the scientific basis for the proposed revisions. While a 

more detailed description of the technical recommendations is contained in the body of the report, 

the key points and recommendations are highlighted below. 

In response to the first charge question, the Committee found that while the Agency’s 

statistical analysis of the TCR data from monitoring samples used to estimate the underlying 

baseline of TC- and EC- positive result rates was reasonable, it would benefit from some 

refinements and further explanation. The Committee suggests that some of the key issues should 

be further explored through sensitivity analyses. In addition to the Agency’s current analysis, 

these sensitivity analyses would provide a more robust basis for predicting and describing TCand EC- positive result rates. 

In response to the second charge question, the Committee found the types of corrective 

actions that systems would implement was reasonable as described by the Agency. The 

Committee recommends that the Agency explain how this list of corrective actions was compiled. 

The Agency, through its discussion with state representatives, has estimated that only 10% of the 

small systems are able to find the cause of TC- or EC- positive samples and as a result will take 

corrective action. The Committee believes that the rTCR should ideally be revised and designed, 

so that a larger percentage of small systems would take corrective actions that result in long-term 

benefits. Since systems may take corrective actions without knowing the exact cause, such as 

implementation of a flushing program, the Committee recommends that the sensitivity analysis 

use a wider range of implementation of corrective actions up to around 50%, especially after a 

more rigorous examination of the system. Conversely, the Committee questions whether the 

benefits of flushing will result in reduced risks for multiple years as used in the model, since 

PWSs may take actions to correct sanitary defects, yet still continue to have TC-positive results 

for a period of time. 

In response to the third charge question, the Committee believes that a more robust 

database than the current six-year data, that was specifically and voluntarily obtained and used in 

the impact analysis by the Agency, is required to address the long list of assumptions. The 

Committee recommends that the impact analysis and discussion should include identifying and 

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summarizing all the variables with known modeling distributions. It should also be noted that 

until more data are available, the Agency’s model may be used to establish a reference baseline, 

but should not be used as a predictive tool. The Committee also noted that an increased risk of 

waterborne disease outbreaks may occur as a result of the proposed reduced monitoring strategy 

and therefore, the anticipated savings in the annual national costs for the detection assays may 

not be very significant. Furthermore, once a PWS is placed in the reduced monitoring regimen, 

it is highly unlikely, unless the sanitary defect is egregious, that the system will be triggered into 

more frequent sampling. The Committee is concerned that TC- or EC- positive sample results 

will not be detected in a timely fashion by a quarterly or annual sampling plan. Overall, the AA 

with its more frequent monitoring requirements appears to address public health protection 

sooner in time than the AIP proposed implementation. 

In responding to the forth charge question, the Committee felt that because of the 

difficulties in linking TC- and EC- positive results to adverse human health outcomes, it is 

equally difficult to determine whether measurable health-related benefits could be attributable to 

the reductions in monitoring violations (positive results). TC monitoring results are not effective 

sole endpoints for measuring benefits. The Agency’s proposal of using TC as part of an overall 

treatment technique evaluation where sanitary defects are identified and corrected as result of 

TC-positive sampling results instead of having an MCLG/MCL for TC, is seen as a positive step 

forward. The Committee recommends that other indicators should also be considered since TC 

is not an adequate measure of health risk. While E.coli is viewed as a more appropriate measure 

of risk of enteric disease, it does not capture the health risks from other pathogens, such as 

Legionella, for example. Other measures, including structural and hydraulic integrity of 

distribution systems, have been recently considered in a report by the National Research Council 

and may provide valuable supplemental information on health risk associated with distributed 

water. 

 The SAB appreciates the opportunity to provide EPA with advice on this important 

subject. We look forward to receiving the Agency’s response. 

Sincerely, 

/Signed/ /Signed/ 

Dr. Deborah L. Swackhamer, Chair Dr. Joan Rose, Chair 

EPA Science Advisory Board SAB Drinking Water Committee 

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NOTICE 

This report has been written as part of the activities of the EPA Science Advisory Board, a public 

advisory committee providing extramural scientific information and advice to the Administrator and 

other officials of the Environmental Protection Agency. The Board is structured to provide balanced, 

expert assessment of scientific matters related to problems facing the Agency. This report has not 

been reviewed for approval by the Agency and, hence, the contents of this report do not necessarily 

represent the views and policies of the Environmental Protection Agency, nor of other agencies in the 

Executive Branch of the Federal government, nor does mention of trade names or commercial 

products constitute a recommendation for use. Reports of the EPA Science Advisory Board are 

posted on the EPA Web site at: http://www.epa.gov/sab. 

iv
U.S. Environmental Protection Agency 

Science Advisory Board 

Drinking Water Committee 

Augmented for the Review of 

EPA's Supporting Analysis for Revisions of the Total Coliform Rule

CHAIR 

Dr. Joan B. Rose, Professor and Homer Nowlin Chair for Water Research, Department of 

Fisheries and Wildlife, Michigan State University, East Lansing, MI 

MEMBERS 

Dr. Mark Borchardt*, Director, Public Health Microbiology Laboratory, National Farm 

Medicine Center, Marshfield Clinic Research Foundation, Marshfield, WI 

Dr. John (Jack) Colford, Professor, Division of Public Health, Biology & Epidemiology, 

School of Public Health, University of California, Berkeley, CA 

Dr. Penelope Fenner-Crisp, Independent Consultant, North Garden, VA 

Dr. Joseph R. Landolph, Jr., Associate Professor, Molecular Microbiology and Immunology 

and Pathology, Keck School of Medicine and Associate Professor of Molecular Pharmacology 

and Pharmaceutical Science, School of Pharmacy, and Member, USC/Norris Comprehensive 

Cancer Center, University of Southern California, Los Angeles, CA 

Dr. Desmond F. Lawler, Bob R. Dorsey Professor of Engineering, Department of Civil, 

Architectural and Environmental Engineering, University of Texas, Austin, TX 

Dr. Christine Moe, Eugene J. Gangarosa Professor of Safe Water and Sanitation, Hubert 

Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA 

Dr. Christine Owen, Water Quality Assurance Officer, Tampa Bay Water, Clearwater, FL 

Dr. Richard Sakaji, Manager, Planning and Analysis for Water Quality, East Bay Municipal 

Utility District, Oakland, CA 

Dr. Gary Sayler, Beaman Distinguished Professor of Microbiology, and Ecology and 

Evolutionary Biology, Director of the Joint Institute for Biological Sciences and Director of 

the Center for Environmental Biotechnology, Oak Ridge National Laboratory, University of 

Tennessee 

Dr. Gina Solomon, Senior Scientist, Health and Environment Program, Natural Resources 

Defense Council, San Francisco, CA 

v
Ms. Susan Teefy, Principle Engineer, Water Quality and Treatment Solutions, Inc., Canoga Park, 

CA 

Dr. Lauren Zeise, Chief, Reproductive and Cancer Hazard Assessment Branch, Office of 

Environmental Health Hazard Assessment, California Environmental Protection Agency, 

Oakland, CA 

* provided written comments but did not attend the face-to-face meeting 

SCIENCE ADVISORY BOARD STAFF 

Dr. Sue Shallal, Designated Federal Officer, 1200 Pennsylvania Avenue, Washington, DC, 

Phone: 202-343-9977, Fax: 202-233-0643, (shallal.suhair@epa.gov) 

vi
U.S. Environmental Protection Agency 

Science Advisory Board 

CHAIR 

Dr. Deborah L. Swackhamer, Professor and Charles M. Denny, Jr., Chair in Science, 

Technology and Public Policy and Co-Director of the Water Resources Center, Hubert H. 

Humphrey Institute of Public Affairs, University of Minnesota, St. Paul, MN 

SAB MEMBERS 

Dr. David T. Allen, Professor, Department of Chemical Engineering, University of Texas, 

Austin, TX 

Dr. Claudia Benitez-Nelson, Associate Professor, Department of Earth and Ocean Sciences and 

Marine Science Program, University of South Carolina, Columbia, SC 

Dr. Timothy Buckley, Associate Professor and Chair, Division of Environmental Health 

Sciences, College of Public Health, The Ohio State University, Columbus, OH 

Dr. Thomas Burke, Professor, Department of Health Policy and Management, Johns Hopkins 

Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 

Dr. Deborah Cory-Slechta, Professor, Department of Environmental Medicine, School of 

Medicine and Dentistry, University of Rochester, Rochester, NY 

Dr. Terry Daniel, Professor of Psychology and Natural Resources, Department of Psychology, 

School of Natural Resources, University of Arizona, Tucson, AZ 

Dr. George Daston, Victor Mills Society Research Fellow, Product Safety and Regulatory 

Affairs, Procter & Gamble, Cincinnati, OH 

Dr. Costel Denson, Managing Member, Costech Technologies, LLC, Newark, DE 

Dr. Otto C. Doering III, Professor, Department of Agricultural Economics, Purdue University, 

W. Lafayette, IN 

Dr. David A. Dzombak, Walter J. Blenko Sr. Professor , Department of Civil and 

Environmental Engineering, College of Engineering, Carnegie Mellon University, Pittsburgh, 

PA 

Dr. T. Taylor Eighmy, Vice President for Research, Office of the Vice President for Research, 

Texas Tech University, Lubbock, TX 

Dr. Elaine Faustman, Professor, Department of Environmental and Occupational Health 

Sciences, School of Public Health and Community Medicine, University of Washington, Seattle, 

WA 

vii
Dr. John P. Giesy, Professor and Canada Research Chair, Veterinary Biomedical Sciences and 

Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada 

Dr. Jeffrey Griffiths, Associate Professor, Department of Public Health and Community 

Medicine, School of Medicine, Tufts University, Boston, MA 

Dr. James K. Hammitt, Professor, Center for Risk Analysis, Harvard University, Boston, MA 

Dr. Rogene Henderson, Senior Scientist Emeritus, Lovelace Respiratory Research Institute, 

Albuquerque, NM 

Dr. Bernd Kahn, Professor Emeritus and Associate Director, Environmental Radiation Center, 

School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 

Dr. Agnes Kane, Professor and Chair, Department of Pathology and Laboratory Medicine, 

Brown University, Providence, RI 

Dr. Nancy K. Kim, Senior Executive, New York State Department of Health, Troy, NY 

Dr. Catherine Kling, Professor, Department of Economics, Iowa State University, Ames, IA 

Dr. Kai Lee, Program Officer, Conservation and Science Program, David & Lucile Packard 

Foundation, Los Altos, CA 

Dr. Cecil Lue-Hing, President, Cecil Lue-Hing & Assoc. Inc., Burr Ridge, IL 

Dr. Floyd Malveaux, Executive Director, Merck Childhood Asthma Network, Inc., Washington, 

DC 

Dr. Lee D. McMullen, Water Resources Practice Leader, Snyder & Associates, Inc., Ankeny, 

IA 

Dr. Judith L. Meyer, Distinguished Research Professor Emeritus, Odum School of Ecology, 

University of Georgia, Lopez Island, WA 

Dr. Jana Milford, Professor, Department of Mechanical Engineering, University of Colorado, 

Boulder, CO 

Dr. Christine Moe, Eugene J. Gangarosa Professor, Hubert Department of Global Health, 

Rollins School of Public Health, Emory University, Atlanta, GA 

Dr. Eileen Murphy, Manager, Division of Water Supply, New Jersey Department of 

Environmental Protection, Trenton, NJ 

viii
Dr. Duncan Patten, Research Professor , Department of Land Resources and Environmental 

Sciences, Montana State University, Bozeman, MT 

Dr. Stephen Polasky, Fesler-Lampert Professor of Ecological/Environmental Economics, 

Department of Applied Economics, University of Minnesota, St. Paul, MN 

Dr. Stephen M. Roberts, Professor, Department of Physiological Sciences, Director, Center for 

Environmental and Human Toxicology, University of Florida, Gainesville, FL 

Dr. Amanda Rodewald, Associate Professor, School of Environment and Natural Resources, 

The Ohio State University, Columbus, OH 

Dr. Joan B. Rose, Professor and Homer Nowlin Chair for Water Research, Department of 

Fisheries and Wildlife, Michigan State University, East Lansing, MI 

Dr. Jonathan M. Samet, Professor and Flora L. Thornton Chair, Department of Preventive 

Medicine, University of Southern California, Los Angeles, CA 

Dr. James Sanders, Director and Professor, Skidaway Institute of Oceanography, Savannah, 

GA 

Dr. Jerald Schnoor, Allen S. Henry Chair Professor, Department of Civil and Environmental 

Engineering, Co-Director, Center for Global and Regional Environmental Research, University 

of Iowa, Iowa City, IA 

Dr. Kathleen Segerson, Professor, Department of Economics, University of Connecticut, Storrs, 

CT 

Dr. V. Kerry Smith, W.P. Carey Professor of Economics , Department of Economics , W.P 

Carey School of Business , Arizona State University, Tempe, AZ 

Dr. Herman Taylor, Professor, School of Medicine, University of Mississippi Medical Center, 

Jackson, MS 

Dr. Barton H. (Buzz) Thompson, Jr., Robert E. Paradise Professor of Natural Resources Law 

at the Stanford Law School and Perry L. McCarty Director, Woods Institute for the Environment, 

Stanford University, Stanford, CA 

Dr. Paige Tolbert, Associate Professor, Department of Environmental and Occupational Health, 

Rollins School of Public Health, Emory University, Atlanta, GA 

Dr. Thomas S. Wallsten, Professor and Chair, Department of Psychology, University of 

Maryland, College Park, MD 

Dr. Robert Watts, Professor of Mechanical Engineering Emeritus, Tulane University, 

Annapolis, MD 

ix
SCIENCE ADVISORY BOARD STAFF 

Mr. Thomas Miller, Designated Federal Officer, 1200 Pennsylvania Avenue, NW 

1400F, Washington, DC 

x
ACRONYMS 

AA Alternative Analysis 

AIP Agreement in Principle 

CWS Community Water System 

DWC Drinking Water Committee 

EA Economic Assessment 

EC Escherichia coli (E. Coli) 

EPA Environmental Protection Agency 

GW Ground Water 

GWDR Ground Water Disinfection Rule 

HPC Heterotrophic Plate Count 

MCL Maximum Contaminant Level 

MCLG Maximum Contaminant Level Goal 

PCR Polymerase Chain Reaction 

PWS Public Water System 

rTCR revised Total Coliform Rule 

SAB Science Advisory Board 

SDWIS/FED Safe Drinking Water Information System /Federal Version 

SW Surface Water 

SWTR Surface Water Treatment Rule 

TC Total Coliform 

TCR Total Coliform Rule 

TCRDSAC Total Coliform Rule / Distribution System Advisory Committee 

TT Treatment Technique 

TWG Technical Working Group 

UA Uncertainty Analysis 

xi
xii

TABLE OF CONTENTS 

EXECUTIVE SUMMARY ............................................................................................................ 1 

BACKGROUND ON THE REVISIONS TO THE TOTAL COLIFORM RULE (TCR) ............. 4 

CHARGE QUESTIONS TO THE COMMITTEE......................................................................... 5 

RESPONSE TO THE CHARGE.................................................................................................... 6 

DWC’s Overall Critique of Revisions to the Total Coliform Rule (TCR)................................. 6 

Charge Question 1....................................................................................................................... 8 

Assumptions to Justify and Explain........................................................................................ 9 

Explaining and Disentangling Uncertainty and Variability.................................................. 10 

Criterion for Significance and Combining Data Sets ........................................................... 11 

Charge Question 2..................................................................................................................... 11 

Analysis of Percentage of Systems Implementing Corrective Action.................................. 13 

Charge Question 3..................................................................................................................... 15 

Safe Drinking Water Information System /Federal Version and 6-year Review Databases 16 

Corrective Actions ................................................................................................................ 18 

Alternatives and Suggestions................................................................................................ 20 

Charge Question 4..................................................................................................................... 22 

TC as an appropriate endpoint .............................................................................................. 22 

Reductions in acute violations as appropriate endpoints for informing benefits.................. 23 

Added value of the proposed revisions................................................................................. 23 

Other analyses or endpoints that might be considered.......................................................... 24 
EXECUTIVE SUMMARY 

EPA’s Office of Water (OW) requested that the Science Advisory Board (SAB) Drinking 

Water Committee (DWC) review its draft supporting analysis in preparation for revising the 

Total Coliform Rule (TCR). The Total Coliform Rule (TCR) was established in 1989 and is one 

of the primary national regulations governing the microbiological quality of treated drinking 

water in the US. The Total Coliform Rule addresses the monitoring of coliform bacteria and 

E.coli, and is an important element in the protection against waterborne diseases via 

demonstration of appropriate disinfection and groundwater protection. As the Agency embarks 

on revising the TCR, it has expended a great amount of time and effort to include stakeholder 

inputs, setting up meetings with state regulators, water utilities, local governments, 

environmental advocates, public health professionals, consumer advocates, Indian tribes, and 

others through a FACA process. As a result of these discussions, an Agreement in Principle 

(AIP) was developed that is being used as the foundation for the proposed Revised Total 

Coliform Rule (rTCR). This has included a proposed new, more proactive approach for 

identifying sanitary defects and incorrect monitoring practices. 

The DWC of the EPA Science Advisory Board met in June 2009 to deliberate on four 

charge questions raised by OW to address the draft supporting analysis. These questions focused 

on: (1) the underlying statistical analysis of the TCR monitoring data used to inform the 

prediction of the underlying baseline total coliform and E. coli occurrence and violation rates, (2) 

the characterization of the types of corrective actions that systems will implement and the 

percentages of systems that will implement certain corrective actions, (3) the methodology and 

assumptions used to predict the net impacts in total coliform-positive (TC+) samples, E. colipositive (EC+) samples, acute violations, assessments, and corrective actions between the current 

TCR (with and without the effects of the Ground Water Rule), the AIP, and the Alternative 

Analysis, and (4) the use of reduction in E. coli and TC occurrence and acute violations as 

endpoints for informing benefits. 

The text of the complete rTCR was not available to the Committee, and the focus was on 

the supporting analyses and drafts of key chapters. The members relied on and examined the 

text of the AIP and several of the rTCR Chapters for their evaluation and to address the charge 

questions. This Executive Summary highlights the outcome of the Committee’s deliberations 

and the recommendations. 

1. The Underlying Statistical Analysis 

The Committee commends the Agency for all the work and analyses undertaken. The 

Agency performed a partial sensitivity analysis which increases confidence in the assessment. 

There was only a limited amount of data from the Safe Drinking Water Information System – 

Federal Version (SDWIS/FED) and in the six-year review databases used in the Economic 

Analysis that was deemed useful for the rTCR analyses and the Agency did a good deal of work 

and put a significant amount of thought and effort into addressing those segments of the database 

that would be useful. The work of the Agency toward engagement with stakeholders and 

1
development of the Agreement in Principle which addresses goals for improvement and research 

needs was laudable. 

The Committee found that the Agency’s statistical analysis of the TCR monitoring data 

used to inform the prediction of the underlying baseline total coliform and E. coli occurrence and 

violation rates is reasonable but would benefit from some refinements and further explanation. 

The Agency is commended for the development and application of a statistical approach to a 

large, complex dataset, thereby enabling the analysis of a difficult and diverse problem. The 

Committee had considered recommending various improvements on the analytical work done, 

but noted that the proposed changes were unlikely to show a substantially different result and 

would involve a significant effort over a protracted period. Instead, the Committee suggested 

that some of the key issues (including seasonality and systems within specific classes and the 

difference in their average characteristics regarding positive TC rates) should be further explored 

through limited sensitivity analyses. The Committee believes that these additional analyses, 

together with the work already performed, will provide a sufficient basis for adequate predictions 

and descriptions of total coliform and E. coli occurrence and violation rates. 

The Committee, after lengthy discussions with Agency representatives, concluded that 

while the analysis was well done, there was, however, insufficient background explanation of the 

assumptions and methods used. The Committee was unable to ascertain whether the analysis 

was reasonable solely by reading the materials provided. For example, the Data Quality Report 

which was referenced through out the document was not available to the Committee. Several 

assumptions were not stated or were not clearly explained. The approach was not completely 

described, thus the analysis and critical assumptions are in need of further justification and this 

needs to be included in the rTCR as it moves forward. 

2. The Characterization of the Types of Corrective Actions 

The Committee agreed that the Agency’s characterization of the types of corrective 

actions that systems would implement was reasonable and complete. Corrective actions are 

closely aligned with the assessments that must follow positive TC/EC test results during routine 

system monitoring. The Committee recommends the Agency explain how it compiled this list of 

corrective actions, and where the information came from (i.e., from expert discussions in the 

Technical Workgroup of the TCRDSAC, and from information provided by utilities). In 

working with states, the Agency found that 10% or less of the utilities were able to find the cause 

of the coliform or E.coli occurrence and as a result take corrective actions. Thus, the Agency 

estimated that only 10% of the small systems will take corrective action which represents only a 

modest benefit from the current rule. This is without the impact of the Ground Water Rule. 

However, there are corrective actions that may be undertaken without knowing the exact cause, 

such as implementation of a flushing program. Therefore, the Committee recommends that the 

sensitivity analysis use a wider range of corrective action implementation including corrective 

actions up to and including 50%, especially after a Level 2 assessment. Disinfection seemed to 

be the main corrective action considered. If this is correct, then, this fact should be stated, and if 

it is not, then the other corrective action options, their costs, and the results of sensitivity 

analyses should be clearly described. The Committee also questioned whether the benefits of 

flushing would result in reduced risks for as long as several years (as used in the model) unless a 

2
routine flushing program is implemented, if so- this should be clarified. Such assumptions 

should also have justification. 

3. The Methodology and Assumptions Used to Predict the Net Impacts as part of the Economic 

Analysis 

The framework and methodology of the Economic Analysis (EA) appear to be consistent 

with the USEPA Guidelines for Economic Analysis (2000). The USEPA guideline should be 

referenced so that readers understand where the framework for this EA originates and better 

understand the reasoning behind the rTCR EA structure. The Committee recommends that an 

analysis and discussion in the EA would better inform policy makers by identifying and 

summarizing all the variables with known distributions. Further, it should also be clearly noted 

that the EA model was developed as a reference baseline and should not be used as a predictive 

tool. Ultimately, the Agency will need a far more robust database than the six-year data review 

database used in the EA to improve the reliability of the model. The number of assumptions can 

be reduced by enhancing the data collection process. 

While a reduction in the annual national costs is likely to result from the reduced 

monitoring strategy, it is unclear from the analysis whether this may be offset by an increased 

risk of waterborne disease outbreaks or endemic waterborne disease. The DWC is skeptical that 

the monitoring frequencies for small systems (< 1,000 people) will provide a change to the TCR 

that improves public health protection. The DWC is not generally supportive of decreased 

monitoring. Overall, the Alternative Analysis (AA) appears to address and protect public health 

sooner in time than the AIP proposed implementation. 

4. The Use of Reduction in E. coli and TC Occurrence and Acute Violations as Appropriate 

Endpoints 

The Committee found it difficult to identify specific measurable health-related benefits 

attributable to the suggested revisions which will be part of the Total Coliform Rule. From a 

public health standpoint, the Committee felt that measuring reductions in total coliforms (TC) 

and E. coli (EC) occurrences are not effective sole endpoints for informing benefits because of 

the difficulties in linking these indicators to adverse human health outcomes. The Committee 

agrees with the Agency’s proposal to use TC as part of an overall treatment technique evaluaton 

and sees this as a positive step forward. Instead of having an MCLG/MCL for TC, TC-positive 

sampling results would trigger an assessment to identify sanitary defects. Implementation of 

appropriate corrective action is expected to decrease waterborne disease and occurrence of acute 

violations. However, several other indicators could be considered, as TC, in itself, is not an 

adequate measure of health risk. While E.coli is viewed as more appropriate measure of risk of 

enteric disease, it does not capture the health risks from other pathogens (e.g., Legionella). 

Other measures may provide valuable supplemental information on health risks from distributed 

water including structural and hydraulic integrity of distribution systems. 

3
BACKGROUND ON THE SUPPLEMENTS TO FUTURE REVISIONS OF 

THE TOTAL COLIFORM RULE (TCR) 

The Total Coliform Rule (TCR), established in 1989, is one of the primary national 

regulations governing the microbiological quality of treated drinking water in the US. As such, 

it is an important element for protecting against waterborne disease. Each standard is mandated 

by law to be reviewed and revised, if appropriate, every six years as part of the existing drinking 

water regulations requiring revisions to improve/maintain public health protection, including the 

TCR. As part of the review and in order to revise the TCR, the Agency and its advisory 

committees conducted a substantial amount of work, which included the evaluation of available 

data and research on aspects of distribution systems that may create risk to public health. The 

Agency also began working with stakeholders to address controls for cross connections and 

requirements for backflow prevention in distribution systems, as these are known to be 

associated with significant risks, but in some cases, may be out of the water system’s direct line 

of control. (C. Rodgers-Jenkins, USEPA, Office of Water, SAB teleconference presentation, 

5/20/09). 

The Agency began the review of the 1989 TCR in 2003. Based on stakeholder comments, 

the Agency prepared a series of white papers on the TCR and distribution system issues1

 (2006). 

In July 2007, the Agency established the Total Coliform Rule/Distribution System Advisory 

Committee (TCRDSAC). The TCRDSAC consisted of fifteen members representing the Agency 

and state regulators, water utilities, local governments, environmental advocates, public health 

professionals, consumer advocates, and Indian tribes. The Agency charged the TCRDSAC with 

two major tasks; 1) provide the Agency with recommendations on how best to revise the TCR, 

and 2) develop information and research needs to improve the understanding of the risks posed 

by distribution system issues. TCRDSAC then formed a technical work group (TWG) to provide 

data analysis and information to contribute to the discussion of the Committee. An Agreement in 

Principle (AIP) was developed as a result of these discussions, and the AIP is being used as the 

foundation for the proposed Revised Total Coliform rule (rTCR). TCRDSAC met thirteen times 

between 2007 and 2008. Each representative on the TCRDSAC agreed to support the proposed 

rTCR components that reflect the elements of the AIP. 

Highlights of TCRDSAC recommendations are: 1) There will no longer be an 

MCLG/MCL for total coliforms (TC); 2) TC- and E. coli (EC) positive sampling results will 

trigger investigation (assessment), leading water managers to find the problem and fix it; 3) 

Monitoring on a quarterly and annual basis may be allowed for some small ground water 

systems; 4) Distribution system research and information collection will need to be a priority; 5) 

There will be an overall shift in focus from monitoring results that lead to public notification to 

monitoring results that trigger an assessment and corrective action. Benefits from these 

recommendations will lead to a more proactive approach to public health protection which can 

be instituted which should reduce confusion associated with the actions needed for TC violations. 

The Agency stated that it was committed to proposing a rule (rTCR) consistent with TCRDSAC 

 

1 See USEPA, Office of Water, Total Colform Rule (TCR) and Distribution System Issue Papers Overview at the 

following URL: http://www.epa.gov//safewater/disinfection/tcr/pdfs/issuepaper_tcr_overview.pdf 

4
recommendations. The initial rule will be proposed in 2011. The final rule will be proposed in 

2012, and compliance with the final rule is expected in 2015. 

The Agency’s recommendations toward the rTCR are to use TC as part of an overall 

treatment technique, where there is no MCLG/MCL for TC, but where TC-positive sampling 

results would trigger an assessment to identify sanitary defects. A sanitary defect finding would 

then trigger corrective action. A treatment technique (TT) violation would be assessed if the 

investigation or corrective action was not completed. The Agency would retain an MCLG = 0 

for E. coli and the current MCL associated with presence of TC/EC. The Agency would not use 

fecal coliforms as a water quality indicator in this Rule, and there would be public notification 

for TT or acute MCL violations. 

In the AIP, for systems serving ≤ 1,000 people, there would be new criteria for both 

increased and reduced monitoring, a transition from the existing monitoring frequency unless the 

primacy agency determines otherwise and a decrease in the number of additional routine 

monitoring and repeat monitoring samples. For systems serving > 1,000 people, there are no 

changes in routine monitoring but a decrease in repeat samples and the elimination of additional 

routine monitoring for systems serving ≤ 4,100 people. 

As a principle of the assessments, the goal is that the rTCR would pro-actively enhance 

public health by identifying sanitary defects and incorrect monitoring practices. In this new 

scenario, the public water system (PWS) is responsible for the investigation which should ensure 

barriers are in place and effective. Two levels of assessment would be created based on the 

severity of the trigger, Level 1 and Level 2. The systems would be required to correct all 

sanitary defects found in the assessments. A TT violation would consist of: 1) failure to perform 

a Level 1 or 2 assessment when triggered, 2) failure to correct all sanitary defects identified in 

the assessment, and 3) failure to correct sanitary defects according to an agreed upon schedule. 

Four types of violations that need public notification are: 1) an E. coli MCL violation (Tier 1); 2) 

a treatment technique violation (Tier 2); 3) a routine monitoring violation (Tier 3); and 4) a 

reporting violation (Tier 4). 

It should be noted that the data analysis to support the revisions to the TCR are based on 

current and historical water quality data and practices in the United States. The SAB DWC 

comments are tailored specifically to those water quality data and practices. 

CHARGE QUESTIONS TO THE COMMITTEE 

The Agency requests that the SAB Drinking Water Committee review the materials provided and 

provide recommendations in the areas specified in the charge questions. As the Committee 

considers the specific charge questions that follow, it is asked to consider whether the overall 

approach that the Agency has taken to assess the impacts of rTCR is appropriate, given the 

availability of the information, and, if it is not, whether there are alternatives that might be 

considered. 

5
1. Is the underlying statistical analysis of the TCR monitoring data used to inform the prediction 

of the underlying baseline total coliform and E. coli occurrence and violation rates 

reasonable? If not, what changes or refinements might be appropriate? 

2. Is the characterization of the types of corrective actions that systems will implement and the 

percentages of systems that will implement certain corrective actions reasonable? If not, 

what else might be considered? 

3. Are the methodology and assumptions used to predict the net impacts in total coliformpositive (TC+) samples, E. coli-positive (EC+) samples, acute violations, assessments, and 

corrective actions between the current TCR (with and without the effects of the Ground 

Water Rule), the AIP, and the Alternative Analysis reasonable? If not, what alternatives 

might be considered? 

4. Are reduction in E. coli and TC occurrence and acute violations appropriate endpoints for 

informing benefits? Do they appropriately capture the added value of the proposed 

revisions? If not, what other analyses or endpoints might be considered? 

The following attachments were included to facilitate the SAB discussions: 

• Draft Supporting Analyses 

• Baseline Conditions (Chapter 4) 

• Occurrence and Predictive Model (Chapter 5) 

• Benefits Analysis (Chapter 6) 

• Cost Analysis (Chapter 7) 

• Draft Technology and Cost Document 

• Agreement in Principle 

• Background on Current TCR and Rule Revisions Development (presentation) 

• Comparison of Current TCR Requirements with the AIP and Alternative Analysis (table) 

RESPONSE TO THE CHARGE 

DWC’s Overall Critique of the Supporting Material, Analyses and Draft Chapters toward the 

Revision of the Total Coliform Rule (TCR) 

The DWC evaluated the five TCRDSAC recommendations and found them to be 

appropriate overall. First, the total coliform (TC) has little relationship to fecal pollution and 

public health risk, and thus it is appropriate that there is no longer an MCLG/MCL for total 

coliforms (TC). The second recommendation, that TC- and E. coli- positive sampling results 

will trigger investigation (assessment), is intended to lead water managers to find the problem 

and fix it. This should place an emphasis on investigating and correcting the deficiencies, rather 

than on just reporting them. The third recommendation, that monitoring on a quarterly and 

annual basis may be allowed for some small ground water systems, is appropriate as long as 

these systems have demonstrated the ability to maintain microbiological water quality and 

groundwater protection, particularly during the rainy seasons. The fourth recommendation, that 

distribution system research and information collection need to be a priority, is also appropriate. 

The fifth recommendation, of an overall shift in focus from monitoring information that only 

result in public notification to monitoring information that trigger an assessment and corrective 

6
action, is a significant advancement if it is properly executed. It places the emphasis where it 

should be, on corrective action. The DWC agrees that benefits from this more proactive 

approach to public health protection should reduce confusion associated with what follow-up 

actions are necessary and taken for TC violations. However the DWC notes that the EPA 

analysis appears to assume a low rate of corrective actions (10% of TC detection events), which 

appears to contradict these stated goals. 

The Agency’s recommendations of using TC as part of an overall treatment technique, 

where TC-positive sampling results would trigger an assessment to identify sanitary defects 

instead of having an MCLG/MCL for TC, is seen as a positive step forward in principle. The 

fact that a sanitary defect finding would trigger corrective action is also very good and 

appropriately places more emphasis on remedial action. The DWC agrees that a treatment 

technique (TT) violation should be assessed if an investigation or corrective action was not 

completed. The DWC also agrees that the Agency should retain an MCLG = 0 for E. coli, as 

well as the current MCL-associated with the absence of TC/EC, and not use fecal coliforms as 

indicators of water quality in this Rule. There should be public notification for any TT or acute 

MCL violations. 

For systems serving ≤ 1,000 people, there are new criteria for increased and reduced 

monitoring, a transition with existing monitoring frequency unless the primacy agency 

determines otherwise and a decrease in number of additional routine monitoring and repeat 

monitoring samples. For systems serving > 1,000 people, there are no changes in routine 

monitoring but a decrease in repeat samples and elimination of additional routine monitoring for 

systems serving ≤ 4,100 people. The DWC is skeptical that the monitoring frequencies for small 

systems (< 1,000 people) will provide a change to the TCR that improves public health 

protection. The DWC is not generally supportive of decreased monitoring. According to the 

Agency’s document, the highest percentage of TCR violations occurs in the smaller systems; 

hence, it appears as though small systems are more vulnerable and are more likely to experience 

a waterborne outbreak. Thus, this vulnerability may be better captured with improved 

comprehensive assessments. The problems in the sanitation of these small water systems, 

which do not have substantial capital and personnel to monitor their systems comprehensively, 

may be best controlled only through a required monitoring scheme. 

The DWC agrees that in the scenario proposed for the rTCR, the PWS should be 

responsible for assessment, and this should strengthen their capacity to ensure barriers are in 

place and effective. DWC also agrees that there should be two levels of assessment, based on 

the severity of the trigger, Level 1 and Level 2, and that the systems should correct all sanitary 

defects found in the assessments. A TT violation would consist of failure to perform a Level 1 

and/or 2 assessment when triggered, failure to correct all sanitary defects identified in the 

assessment, and failure to correct sanitary defects according to an agreed upon schedule. The 

public notification continues to be important and should include not only a description of the 

violation but also the necessary follow-up remedial actions. This would assist in alleviating 

public concerns that the PWS is not attending to the problems. The four types of violations that 

need public notification are: 1) an E. coli MCL violation (Tier 1) which may be of immediate 

public health concern; 2) a treatment technique violation (Tier 2); 3) routine monitoring violation 

7
(Tier 3); and 4) a reporting violation (Tier 4). DWC agrees with these revisions as they would 

apply to the future TCR. 

It appears from the table provided to the DWC, entitled, “Comparison of Current TCR 

Requirements with the AIP and Alternative Analysis,” that the PWS can still do its own 

assessment (left to the discretion of the primacy agency; but the person doing the assessment is 

required to have specific qualifications, unlike a Level 1 Assessment), even if the PWS’s lack of 

action results in frequent Level 1 triggers that then lead to a Level 2 assessment. This could 

result in a public health risk that may be unaddressed in a timely fashion If the issue is raised to a 

Level 2 Assessment. the primacy agency should be deeply involved.). The Drinking Water 

Committee (DWC) generally agrees that the assessment concept will orient the PWS toward 

action and that this will likely improve the microbiological quality of the drinking water 

delivered. 

Charge Question 1. Is the underlying statistical analysis of the TCR monitoring data used 

to inform the prediction of the underlying baseline total coliform and E. coli occurrence 

and violation rates reasonable? If not, what changes or refinements might be appropriate? 

The statistical analysis of the TCR monitoring data is reasonable, and the Agency is 

commended for its systematic and thoughtful analysis of such a large dataset. The 

documentation of the statistical analysis in a draft Chapter 5, however, should be improved, 

which will address transparency and clarity. The Committee recommends that Chapter 5 be 

revised with details which allow the reader to understand better what was done, and all key 

assumptions should be clearly stated and justified. The Committee also suggests that further 

sensitivity analyses be undertaken. 

The Agency did a good job analyzing a difficult and diverse problem. This involved 

developing and applying a statistical approach to a large, complex dataset. Positive samples for 

different classes of water systems were characterized and used for prediction. Water systems 

within a class were allowed to vary in their characteristics. The approach was reasonable and 

appears well executed. A significant amount of thought went into structuring the problem and 

the analysis. 

The Committee had considered recommending various improvements on the analytical 

work done, but noted that the proposed changes were unlikely to show a substantially different 

result and would involve a significant effort over a protracted period with little added benefit. 

Instead, the Committee suggests that some of the key issues be further explored through a limited 

sensitivity analyses. The Committee ultimately finds that these additional analyses, together 

with the work already performed (with a few refinements discussed below), will provide a basis 

for adequate descriptions of total coliform and E. coli occurrence and violation rates. 

In making these findings, the Committee notes, however, that the explanation of the 

analysis is deficient. The Committee was unable to ascertain whether the analysis was 

reasonable solely by reading the materials provided, including the draft Chapter 5, where the 

analysis is laid out. Several assumptions are not stated or are not clearly explained. The 

8
approach is not completely described, and the analysis and critical assumptions need further 

justification. 

The Committee was only able to understand what was done as a result of the discussion 

during the meeting. The Committee members had to ask a number of clarifying questions to 

understand the analyses performed. EPA staff explained what was done and why. After hearing 

these explanations, the Committee was satisfied that the analyses performed were reasonable and, 

with a few minor refinements noted below, adequate and, in fact, commendable. 

The Committee recommends that Chapter 5 be revised to describe the analysis in 

sufficient detail so that the reader can understand the basics of what was done. Assumptions 

should be stated clearly and justified. The key assumptions that affect the entire analysis should 

be stated early in the chapter and better justified. Implicit assumptions should be stated and 

explained. The basic elements of the analysis should be clearly described. As the chapter 

currently stands, the reader is left to use his or her judgment as to whether the assumptions are 

justified and what was done. 

The Committee does recognize that the analysis performed is complex and somewhat 

difficult to explain, and that it may take extra effort than may typically be the case to make the 

chapter clear and understandable. It may help to have a number of technically facile, non-expert 

readers review the revised chapter to see whether they understand the analysis, whether they 

could explain it to someone else based on what was written, and whether they find the analysis 

including assumptions adequately justified. Specific comments, suggestions and 

recommendations are given below. 

Suggestion 1. Assumptions to Justify and Explain 

The Committee found that the assumptions in the statistical analysis were not clearly 

presented and/or justified. Some examples of assumptions and procedures are provided below 

that would benefit from better explanation. These are given only as examples, and we leave it to 

the Agency staff to work through the document to make sure that all major assumptions are 

clearly articulated and adequately explained. Again, the Committee is recommending that the 

key assumptions be presented early, and that other minor ones are explained as they occur in the 

description of the analysis and results. 

• It is not clearly stated that a main goal of the model fitting exercise is to get a 

characteristic distribution of probability of positive hits for each water system class, and 

that the distribution is representing how systems within the class vary from one another in 

that probability. 

• There needs to be an explanation of the basic model structure. Exhibit 5.2 appears to be 

an attempt at showing how different parameters in the beta distribution are related to one 

another for different systems within a water system class. The title is very general, and 

the exhibit has no legend. Subscripts are used to indicate the different water systems 

within the class; however, the subscripts are not used anywhere else in the chapter. What 

9
would be a difficult concept to convey even with full annotation is totally 

incomprehensible. The figure also needs a more explanatory title. If the figure is 

retained, it needs to be explained in a figure legend and in the text. The Committee also 

recommends the addition of another illustration to show data inputs and model outputs, 

with full accompanying annotation and description. 

• The reason for assuming that seasonality does not impact the analysis should be 

discussed and justified, perhaps through a sensitivity analysis. 

• There is a hierarchy to the analysis that is left unexplained. Each water system class has 

its own characteristic beta distribution. Yet, alpha and beta in the figure and text are not 

subscripted. In the text, the probability parameters, number of samples (binomial “N”s), 

positive samples (binomial “K”s), all have no subscript. In the figure, for example, 

subscripts were left out of equations (such as on p 5-7). This made it unclear that they 

were relevant to each individual system. While the use of subscripts can be avoided, the 

underlying assumptions need to be clear, e.g., be clearer about the fact that independent 

analyses (probability distributions) of the routine and repeat samples were performed. 

Suggestion 2. Explaining and Disentangling Uncertainty and Variability 

The Committee noted that the discussion of uncertainty and variability was unclear. At 

times, it appeared that the terms uncertainty and variability were being used interchangeably. 

Both uncertainty and variability are an issue in the analysis as illustrated in the following 

example. Within a given system classification, water systems can vary considerably in terms of 

whether they will test positive and in terms of their violation rates because some of the causes for 

TC positives are not under the control of the PWS. For some classes of systems, there may be a 

large number of systems within the class and the certainty regarding how much they vary from 

one another and the difference in their average characteristics may be high. For other classes, 

there may be far fewer observations which may contribute to less certainty. The Committee 

found that the document needed to be clearer in how these issues were handled and suggests that 

Chapter 5 and the analysis address the issue through further sensitivity analysis and in graphical 

presentations. 

Chapter 5 could, for example, include a figure plotting positive occurrence rates for some 

different prototypical classes of systems. This would provide the reader a visual representation 

for how systems can differ within a class. Chapter 5 could also provide plots of the maximum 

likelihood estimate for mean positive occurrence for a system class and display the uncertainty in 

that estimate. Agency staff has developed some plots like this that could be annotated and 

included with proper explanation in the document. Plots that disentangle uncertainty from 

variability would be helpful. On the basis of the discussion with Agency staff, the Committee 

believes that these plots have been done and that the analysis is fine in this regard, but the 

presentation is somewhat lacking. 

The Committee recognizes that there are data gaps and that assumptions based on best 

professional judgment were made. Therefore, the Committee is not recommending a full Monte 

10
Carlo analysis of uncertainty; rather, we suggest the issue be explored in a limited way in a 

sensitivity analysis. The analysis can be qualitative or semi-quantitative and should explain how 

uncertainty in the beta distribution for classes, where uncertainties are relatively large, may 

affect the ultimate result. The Agency stated that uncertainties are greatest for classes with few 

observations, and that this is due to the fact that the actual number of systems in the class is small. 

However, while this may be a reasonable rationale, it might also be due to one or two outliers 

that skew the distribution. The Committee suggests that some simple calculations should 

adequately illustrate that the overall result is robust and the rationale has been tested rather than 

assumed. 

Suggestion 3. Criterion for Significance and Combining Data Sets 

 The Committee believes that the criterion for testing significance and for deciding to 

combine or not combine different data sets should be more explicitly stated and perhaps more 

rigorously done, including a statistical power test. In a number of places, the chapter asserts that 

systems do not significantly differ in the probability that they will test positive for total coliform. 

That finding is used to justify combining data sets for different types of systems. Figure 5.3 is 

the only attempt to explain this combining, and both the figure itself and the explanation of for 

combining data sets are weak. 

 In the Agency’s analysis, the criterion for deciding whether there is a significant 

difference in probabilities is based solely on whether there is a difference in the mean 

probabilities of a positive test result for the two systems being compared. However, some 

system types can have the same mean, yet the systems may vary within that class. An analysis of 

a class of non-disinfected water systems may, for example, include a large number of systems on 

a pristine water source in a cold climate, and at the same time also include a large number of 

systems with a not so pristine source. The variance for this class can have a wide frequency 

distribution, but the mean may be the same as that for another class that is more homogeneous 

but relatively pristine. Violations may be more common in the first class than the second. Thus, 

in addition to the mean, the variance should also be considered. The beta distributions for these 

two classes will differ. Therefore, an alternative criterion for combining could be based on the 

hypothesis that both systems have the same beta distribution. 

Charge Question 2. Is the characterization of the types of corrective actions that systems 

will implement, and the percentages of systems that will implement certain corrective 

actions, reasonable? If not, what else might be considered? 

To answer charge question 2, the Committee reviewed Chapter 5, Appendix D, and the 

supporting document Technology and Cost Document for the Revised Total Coliform Rule. The 

Committee agrees that the Agency’s characterization of the types of corrective actions that 

systems will implement is reasonable and extensive. The types of corrective actions can be 

ascertained from current practices. Corrective actions are closely aligned with Level 1 and 2 

assessments following positive TC/EC testing during routine system monitoring. Both 

assessments are intended to be part of a proactive approach to identify sanitary defects that may 

11
put public health at risk, due to the potential exposure to and consumption of contaminated 

potable water. Such contamination can arise from source water and ineffective treatment (not a 

sanitary defect, but the lack of a barrier or ineffective barrier), any practice or event that results 

in intrusion into the distribution system, reservoirs such as biofilms, or stagnant and aged waters 

within the system itself (for example as a result of poor operation and maintenance practices). 

The proposed rTCR clearly recognizes these issues and uses an assessment process to 

initiate analysis of system variables that trigger corrective actions. Assessments are intended to 

aid in the following: 

• Identifying inadequacies in sampling sites and protocols, sample processing and 

presumably appropriateness and QA/QC of the TC/EC analytical methodology. 

• Identifying atypical events such as storm flows or construction breaks affecting or 

indicating impaired water quality. 

• Identifying changes in distribution system maintenance and operation that may affect 

water quality. 

• Identifying changes in source water quality and/or treatment resulting in the potential for 

impaired water quality. 

• Identifying inadequacies in the underlying WQ monitoring data itself. 

These assessment elements and corrective actions are clearly identified in supporting 

documentation for the rTCR, specifically in the Technology and Cost Document for the Revised 

Total Coliform Rule. However, they could be more clearly listed in Chapter 5, so the reader does 

not have to delve into supporting reports to find the information. 

Cost estimates principally for salary and wages (including monitoring, reporting, and operations 

and analytical analysis) are also provided. The corrective actions are summarized as follows: 

1) Flushing 

2) Sampler Training 

3) Replacement and Repair 

4) Pressure Maintenance 

5) Hydraulic Residence Time Maintenance 

6) Storage Facility Maintenance 

7) Booster Disinfection 

8) Cross Connection and Backflow Prevention 

9) On-line Monitoring and Control 

10) General Security Measures 

11) Standard Operation Procedure Training and Implementation 

The Committee recommends that the Agency explain how it compiled this list of 

corrective actions and from where the information came (i.e., from expert discussions in the 

Technical Workgroup of the TCRDSAC, and from information provided by utilities). It is 

important for the Agency to acknowledge that this is not a definitive list of all actions that could 

be taken and that it is possible that even if all these actions were implemented in a system, that 

all total coliform positive observations may not be eliminated. Coliform-positive samples may 

be the result of numerous factors in a water system, including cross connections, construction, 

12
sampling, etc. It is also noted that a Level 2 assessment mandates that a “certified” operator 

must respond to violations. Certification is rather ill defined and is a responsibility of the 

individual State. The expertise of the “certified” operator will be very important in determining 

the efficacy of the investigations and the percentage of systems taking corrective action after 

Level 2 assessments. 

The list of corrective actions appears somewhat dismissive of investments in analytical 

methods and monitoring, source water analysis, water quality databases and analysis resulting 

from the Level 1 and 2 assessments. Real time microbial monitoring, ultimately capable of 

targeting specific pathogens of direct public health significance, is on the horizon and real time 

residual chlorine monitoring is only a limited surrogate approach. 

Suggestion 1. Analysis of Percentage of Systems Implementing Corrective Action 

The percentages of systems that will implement corrective actions are un-knowable, so 

there is nothing the Agency or the DWC can do except to take a best guess. An estimate that is 

based on expert judgment is a reasonable approach to this situation. Two things need to be done 

when taking a best guess: (1) a careful justification of what expert information sources were 

relied upon and (2) a sensitivity analysis. The Committee commends the Agency for doing the 

latter, which greatly increases confidence in the assessment. However, the Agency could do a 

much clearer job justifying and explaining how it arrived at these numbers. Specifically, there 

should be some text explaining the tables in Appendix D, and there should be reference to 

Appendix D and the list of corrective actions in Chapter 5. As the tables stand now, it appears 

that large surface water-community water systems (SW CWS) would do nothing in response to a 

TC positive; zero percent implementation is assigned for all Level 1 Corrective Actions for those 

system categories. Presumably, this is because large systems are assumed to already be doing 

assessments and corrective actions. The Agency should clearly document the logic for these 

assigned values. 

Based primarily on the results of a limited survey of current TCR requirements, the 

Agency estimates that corrective actions will on average be implemented only 10% of the time 

(section 6.2.7 and associated footnote 1 on page 6-8). It is surprising that such a relatively small 

percentage of systems are projected to take some kind of corrective action – at least by flushing 

their systems - after a Level 1 or Level 2 event. We expect that flushing would (and should) be a 

more common practice. Therefore, we think it would be justifiable for the Agency to use a 

greater than 10% likelihood of taking corrective action. In addition, after a Level 2 event, a 

serious assessment, done by a certified operator, should find some type of corrective action that 

can be taken in most small systems, especially if the menu of corrective actions includes a switch 

to disinfection. 

This entire discussion appears overly weighted on the influence of the ground water rule 

(GWR) and instituting disinfection processes for GW. Does implementation of disinfection in 

ground water (GW) systems bias the presumed 10% of corrective action? The sensitivity 

analysis uses a range of 5-20% for corrective action implementation. We suggest a broader 

range for analysis, including corrective actions up to around 50%, especially after a Level 2 

assessment. In addition, if disinfection is the main corrective action, this should be stated. If it is 

13
not, then the sensitivity analysis results should be clearly discussed for other corrective action 

alternatives and the costs associated with them. 

Assessment and corrective actions are well described. However, the discussion of 

corrective action appears to emphasize flushing in response to a TC/EC positive monitoring 

result. While offering immediate public health protection, flushing alone may not provide 

solutions to the underlying problem causing the positive TC/EC monitoring result. Therefore, 

the Committee questions whether the benefits of flushing will result in decreased risks for 

several years, as the Agency currently estimates in the model. The Committee recognizes that 

from a utility perspective, flushing and disinfection is a cost effective solution, if the origins of 

the TC/EC cannot not be adequately documented, thus avoiding potential costly repair and 

replacement corrective actions that may not ultimately be warranted. It makes sense to switch 

some proportion of GW systems to long-term disinfection in the model, and thus change their 

attributed rates accordingly after a positive finding. 

Overall, the challenge laid down to the Agency by the TCRDSAC was to come up with a 

revised TCR that will foster continuous improvement in the industry by encouraging assessments 

and corrective actions. It is discouraging to see that the Agency’s projections do not fully realize 

that vision. The rule should be designed so that a larger percentage of small systems would take 

corrective actions that result in long-term benefits. The central estimate of 10%, although 

perhaps realistic, represents only a modest benefit from the rule, although it may be better than 

the status quo for small systems. It would be useful for the Agency to run the model with a 

significantly higher percentage of corrective actions (i.e., 50%), to determine whether the 

benefits would increase substantially if the rule can be designed such as to achieve these higher 

rates. 

Suggestion 2. Alternative monitoring and measures 

The AIP recognizes the evolution of analytical capabilities (section 3.2) for TC and EC. 

As part of Assessment and Corrective Action, best available methods are appropriate. As an 

active area of research, future relevant analytical methodologies should be embraced as they 

become available, and the rTCR should not be constrained to current best available technology. 

It is important to note that while various methods may report TC, not all the TC’s mean the same 

thing. There is an ongoing study comparing the methods and the AIP contains a component that 

addresses it. The Committee also suggests that the Agency consider moving to alternative 

measures other than TC which they believe is not a reliable indicator from a public health 

perspective. 

Monitoring needs are also identified. As part of research and information needs (4.2.c), 

Tier 1 should include molecular microbial methods, stable isotope ratio techniques, and mass 

spectroscopic analytical methods for source and contaminant identification which need to be 

developed to assist in focused corrective action, rather than corrective action in immediate 

response to a proposed rTCR monitoring violation. Tier 2 needs emphasis on human and animal 

pathogen detection and real time monitoring. 

14
Charge Question 3. Are the methodology and assumptions used to predict the net impacts 

in total coliform positive (TC+) samples, E. coli-positive (EC+) samples, acute violations, 

assessments, and corrective actions between the current TCR (with and without the effects 

of the Ground Water Rule), the AIP, and the Alternative Analysis reasonable? If not, what 

alternatives might be considered? 

The framework and methodology of the Economic Analysis (EA) appear to be consistent 

with a properly conducted EA based on the USEPA Guidelines for Economic Analysis 

(2000). The USEPA guideline should be referenced so readers understand where the framework 

for this EA originates and better understand the reasoning behind the proposed revision to Total 

Coliform Rule (rTCR) EA structure. Using this framework, the Agency should guide the reader 

through the EA clearly pointing out elements that were completed, where assumptions were 

made, and where steps were omitted (along with justification for omitting them). 

The Council for Regulatory Environmental Modeling notes in their November, 2003, 

guidelines, both an uncertainty analysis and a sensitivity analysis should be conducted on any 

model developed and used as a basis for a regulatory decision. The term “uncertainty analysis” 

itself can lead to confusion, because an overall Uncertainty Analysis (UA) is composed of two 

separate components, sensitivity and uncertainty, one of which uses the same term as the overall 

analysis itself. Both components are necessary to complete the overall uncertainty analysis. The 

sensitivity analysis illustrates the degree of impact that one variable has on the outcome when all 

other values are held constant (possibly using a median or average value), such as the use of the 

lower and upper bound estimates used in the proposed rTCR EA. 

Unlike the sensitivity analysis, the uncertainty analysis examines the inherent variability 

in the data and its subsequent impact on the distribution of the output. Some variability is 

inherent and a portion may be associated with the measurements used to characterize the 

population. The Agency should identify the sources of uncertainty and determine the level of 

confidence that should be placed in the final results. 

In reviewing the EA guideline, it is apparent that one deficiency in the rTCR uncertainty 

analysis originates from the guideline itself and is not a deficiency introduced by the rTCR EA. 

While the EA guideline does admit the approach outlined may be different than what other 

disciplines consider a complete uncertainty analysis, the USEPA EA Guideline appears to 

discuss conducting an Uncertainty Analysis (UA) only. The Agency should identify that the UA 

is comprised of a single part, the sensitivity analysis. Since the Agency’s EA guideline is not a 

regulation or legislated requirement, its structure and content are not so rigid as to preclude 

interpretation and improvement, when and if the application warrants it. In this case, the Agency 

should point out that the UA in the EA is only comprised of a sensitivity analysis, which does 

not include an actual evaluation of uncertainty associated with the output. The analysis and 

discussion in the EA would better inform policy makers by identifying and summarizing all the 

variables with known distributions, and those without, to aid risk managers with the 

interpretation of the results. 

The EA also seems to assume that the variables for which there are no data will not have 

a significant impact on the overall uncertainty. Until the EA can better characterize the error 

15
associated with the output, one should be cautious about inferring too much from the results. 

Statements, such as the one beginning on line 23 pg 5-31 (and others similar to it), should be 

made with consideration for the error or uncertainty surrounding the outcome, as the observed 

difference is probably not significant. The EA discusses some differences as if they are 

significant and other differences as if they are not, without a simultaneous discussion as to how 

the difference is judged to be significant in one case, but not in the other. 

When evaluating the baseline condition, the admission that data are missing from 15 

states, including states with large populations (California, Florida, and Pennsylvania), requires 

additional discussion on what impact this data gap might have on the final result. In addition, the 

number of states submitting TC and EC data in each tier (1 – 4) is not described. Again, there is 

no discussion of how the missing data may have biased the baseline estimate. 

In addition, the Committee recommends that in regard to the effectiveness of the 

corrective actions to reduce future TC- and EC-positive samples, the Agency should repeat the 

analysis with values for the percentage of communities that will actually implement corrective 

actions from 1% for the less effective corrective actions to 50% for the most effective. In 

addition, it is not clear that the reduced monitoring strategy offers significant savings in the 

annual national costs for the assays that are not offset by an increased risk of waterborne disease 

outbreaks. Overall, the Alternative Analysis (AA) appears to provide public health protection in 

a more timely fashion than the AIP . 

The Drinking Water Committee (DWC) of the Science Advisory Board (SAB), while 

providing comments on the methodology and assumptions used to predict the net impacts of the 

proposed rTCR under the current TCR, AIP, and Alternative Analysis (AA), cannot provide an 

adequate assessment which could serve as a substitute for an Uncertainty Analysis. In this EA, 

one can argue the Uncertainty Analysis is not complete, because of the undefined or ill-defined 

distributions associated with many of the input variables. Regardless, it appears that the EA 

represents the best possible analysis given the paucity of available data. 

Suggestion 1. The Safe Drinking Water Information System (SDWIS)/Federal Version 

(FED) and 6-year Review Databases 

The Total Coliform Rule is the drinking water rule that applies to all public water 

systems regardless of size, source or treatment. Utilities across the United States have invested 

billions of dollars in monitoring to meet the requirements of this rule. Unfortunately, 

management for these data has been challenging. There was only a limited amount of data from 

the Safe Drinking Water Information System – Federal Version (SDWIS/FED) and six-year 

review databases used in the EA deemed useful for the rTCR analyses. Given this limited data, 

there was still a good deal of work, along with a significant amount of thought and effort, 

expended on identifying those segments of the database that would be useful. A large amount of 

data has been gathered and screened by the USEPA when the States voluntarily submitted 

electronic monitoring data reflecting records from l998-2005. 

In estimating the baseline in Chapter 4, there is one troubling assumption - basing the 

analysis solely on one year (2005) out of six years of total coliform (TC) and enteric coliforms 

16
(EC) occurrence data. The Agency states, “Using only a single year of data was beneficial in 

that it [sic] simplified the analysis...” (page 4-6, line 36). This assumption completely ignores 

potentially large inter-annual differences in TC and EC occurrence. Such differences could be 

driven, for example, by inter-annual variability in precipitation patterns, which the Agency 

acknowledges with the statement (line 39): “...changing environmental factors may be 

important.” Even groundwater shows large year to year differences in the occurrence and 

quantity of human enteric viruses, as evidenced in studies of municipal wells2. The baseline 

occurrence rate could shift up or down depending on which year of data is analyzed. It may be 

possible to evaluate the importance of TC and EC inter-annual variability using data from the 

states that submitted complete 6 year datasets. It may also be possible to clarify this issue by 

expanding on the statement regarding the consistency of the TC-positive rates in the years 

outside the year selected for this analysis. 

Further, it should be noted that the EA model was developed to produce a reference 

baseline and not to be used as a predictive tool. The EA uses the SDWIS/FED database of 

violations as the reference for their model. The data for the model came from the six-year data 

review data set, which contained all sample results (with the stated limitations). The model 

output was compared to the SDWIS/FED data as the means of validating it. The violations in the 

SDWIS/FED database should reflect the sampling results in the six-year data review for those 

same periods of time, since the sampling results determine PWS compliance. However, this 

should not be considered a “validation” of the model as a predictive tool. A model should only 

be considered validated as a predictive tool if it can be shown that it accurately forecasts events 

that have not yet taken place. Until additional data are available to confirm the model output, the 

EA model should be considered for establishing a reference baseline only. The Agency will 

need a database that is far more robust than the 1 year of data from the six-year data review 

database used in the EA to validate the model and decrease the long list of assumptions used in 

the current EA (see comments in next section). 

Given the scheduling of the revised total coliform rule (rTCR), the assumptions used to 

fill the data gaps identified in the six-year review database should be considered adequate for this 

EA. However, they indicate a deficiency in the data collection system that should be rectified 

prior to implementation of the proposed rTCR. On page 4-7 one justification includes the line 

“...single year data allows for a single database.” This statement implies that the databases were 

of such different format and structure that the information in the database from the years prior to 

2005 could not be combined into a single database. This points to a need to improve data 

management and collection practices. To address at least one of the items in Section 3.17 of the 

AIP, the Agency will need a database that is far more robust than the six-year data review 

database used in the EA. 

To assess the long-term effectiveness of the proposed rTCR (Section 3.17 of the AIP), the 

metrics will need to be established and the data collection systems put into place, before the rule 

is promulgated. This will allow data collected, under the current TCR, to be used as a reference 

 

2 MA Borchardt, PD Bertz, SK Spencer, and DA. Battigelli, (2003) Incidence of Enteric Viruses in Groundwater from 

Household Wells in Wisconsin. Applied and Environmental Microbiology, p. 1172-1180, Vol. 69, No. 2. 

17
baseline against which future regulatory actions and their impacts can be compared. Failure to 

do so will result in the need to employ similarly weak assumptions in future regulatory 

documents and evaluations. 

Suggestion 2. Corrective Actions 

Filling data gaps by making assumptions is sometimes necessary, especially when the 

data needed are not available or have not been collected. Such is the case for the corrective 

actions in Exhibit 7.16. These data have never been collected, so the table was populated using 

the professional judgment of the TCRDSAC Technical Workgroup (TWG). However, the 

Agency should recognize that current data systems are not set up to collect this information as 

the rTCR moves forward. Until the data systems are set up to collect this information, future 

EAs and regulation assessments will be limited in their usefulness as quantitative assessments 

upon which risk managers can and should base their policy decisions. 

 

The biggest red flag (assumption) is the effectiveness of the corrective actions in 

reducing future TC- and EC-positive samples. The Agency should repeat the analysis with more 

extreme values for the percentage of communities that will actually implement corrective actions, 

e.g., 1% for the less effective corrective actions and 50% for the most effective. It is not clear 

how the current values in the analysis -10%, 5%, and 20% - were selected. The extreme values 

are justified, in our opinion, given the absence of any previous knowledge on how well these 

assessments will be performed or the true long-term effectiveness of the corrective actions. 

The assumption that systems following a corrective action will be TC -free for a period of 

time should be reconsidered. As the EA implies, there are a number of causes for a TC-positive 

result. Each of the causes may or may not be linked to a corrective action. In addition, the 

causes should be viewed as independent events. Just because a corrective action has been taken 

and a sanitary defect corrected, does not mean the public water systems (PWS) will be free of 

TC-positive results for a period of time. Granted, some actions may result in long-term solutions, 

such as rebuilding a problematic sampling station or modifying sampling habits. However, 

given the reports on the aging infrastructure of our water distribution systems in the U. S. and the 

fact that distribution systems are continually being exposed to disruptive external conditions 

(plumbing activities, excavation, pipe replacement), assuming a system will be coliform-free for 

a period of time following a corrective action is a not a justifiable assumption. Assuming that a 

corrective action will result in TC and EC compliance for three to five years assumes that once a 

sanitary defect is found and corrected, a similar incursion won’t happen again for another three 

to five years. As there are a variety of events, separated by time and space, that could produce a 

TC or EC violation, there is no guarantee that one of these events would not produce a TC or EC 

violation immediately following remedial action in an entirely different part of the system. 

Each column or corrective action in Exhibit 7.16 represents an action triggered by an 

independent event. These actions are not dependent on each other. Thus, the corrective actions 

should not be pooled or linked. The causes listed in Exhibit 7.16 appear to be all inclusive as 

each line (for a given size system) seems to add to 100%. By summing to 100% for a given size 

18
category, it appears as though the corrective actions listed are the only ones that could mitigate a 

sanitary defect identified in a Level 1 or 2 triggered assessment. 

The list of corrective actions focuses on actions associated with the distribution system to 

correct a TC or EC trigger. The list does not include remedial actions taken on other components 

of the multiple barriers (source and treatment) that may contribute to a TC or EC trigger. The 

discussion of corrective actions should acknowledge changes or modifications made in the 

maintenance or operation of the treatment process train, as the assessments may trigger changes 

in or the addition of treatment. While it is assumed that the actions taken on the treatment 

barriers would be an appropriate response under the Groundwater Disinfection Rule (GWDR) or 

Surface Water Treatment Rule (SWTR), these actions may be triggered by monitoring in the 

distribution system under the rTCR and identified by the assessment. The linkage between the 

rules and the subsequent impact on the EA needs to be fully and clearly explained so the reader 

knows which impacts are being included and which have been attributed to previous rules. 

The rTCR allows for reduced monitoring, which opens up a policy and technical issue 

regarding the adequacy of sampling. 1) The public water systems given more options to qualify 

for reduced monitoring are the small systems. Unfortunately, these are the very same systems 

most likely to have water sanitary quality problems. This is evident in Exhibit 4.10 where the 

public water systems (Community Water Systems + Non-transient, non-community water 

systems + Transient Non-Community Water Systems) serving a population size less than 1,000 

are responsible for 90% (7,822/8,734) of the TCR violations! The DWC believes that these 

small water systems simply do not have the capital investment to provide the necessary 

monitoring and corrective actions to reduce this high level of violations. A possible solution is 

to encourage smaller water systems to combine with larger systems which may reduce the 

number of TCR violations. 2) The TC and EC assays are the only routine, widely-available 

distribution system monitoring tool for assessing and ensuring the microbiological quality of 

drinking water delivered to the public. The TC and EC monitoring has its limitations, but why 

does that translate to requiring less rather than more monitoring? 3) The TC and EC assays are 

inexpensive. It is difficult to believe that a reduced monitoring strategy offers significant savings 

in the annual national costs for the assays that are not offset by an increased risk (and costs) of 

waterborne disease outbreaks. 

4) Experience with viral pathogens in groundwater and distribution systems shows that 

occurrence is amazingly variable in space and time (Borchardt et al). Thus it may be there is no 

such thing as steady-state fecal contamination. Granted, TC and EC are not 100% correlated 

with virus occurrence, but the bacterial indicators do provide some information, particularly if 

there is a positive test result. The only way to counter the variability and not miss an event is to 

perform more frequent sampling, not less. A quarterly or annual sampling plan is highly 

unlikely to detect a TC or EC event lasting only one week. Therefore, once a public water 

system is placed in this reduced monitoring regimen, it is highly unlikely, unless the sanitary 

defect is egregious, to be triggered into more frequent sampling. 

Delaying rule implementation to improve the data sets on which this EA is based would 

not be protective of public health. From the discussion, it is clear that the Agency needs to 

improve the databases containing monitoring and compliance information. Without 

improvements, future EAs will be hampered by the issues discussed herein. As the TCRDS FAC 

19
recognized, it is important to characterize the impacts of promulgated rules by identifying, 

establishing, and collecting the necessary metrics to do so. The long list of assumptions needed 

to cover data gaps in the EA reinforces the need for better data collection. 

It is understood the analytical and labor costs listed represent national averages for 

routine sampling. However, a coliform-positive test will trigger additional sampling, 

assessments, or other actions that may not be accommodated within normal work schedules. As 

noted in the previous paragraph, other responsibilities may force TCR activities, especially nonroutine activities, into overtime. Hence, some cost factor to account for these activities outside 

of the normal labor rates should be considered. After all, one would hope that repeat sampling 

and assessment activities are not routine, but that they are conducted by personnel trained and 

knowledgeable in these areas. (If assessments are conduced using outside contracts, the labor 

costs may actually be higher than the utility’s pay scale, considering the level of expertise that 

might be required.). In addition, the projected labor costs include fringe benefits, but do not 

include overhead (an additional multiplier to cover administrative activities, utilities, office space, 

etc.). 

Not including the state costs in the ratepayer cost table could skew the underlying cost 

distribution. Those states (CA and AL) that operate their regulatory programs on a cost recovery 

basis will have their fees passed along directly to the ratepayer (in 2005, the labor cost for an 

hour of a state engineer’s time was $105). This raises a concern, because when the state costs 

and the utility costs (both of which are higher in CA than the national average) are combined, the 

cost to the CA ratepayer will be greater. If one considers the distribution of ratepayers, this will 

skew the ratepayer costs among the states, pushing the states with higher costs even further out 

(widening one end of the distribution). 

The Drinking Water Committee believes the model output with respect to the relative 

impacts of the AIP and AA is satisfactory, given the limitations of the corrective actions input 

data. Since the frequency distributions for TC and EC monitoring results for the AIP and AA are 

the same, the only principle difference between the AIP and AA appears to be the initial 

monitoring requirements (AIP allows for a transitional period, while AA does not). Since the 

AA requires more initial monitoring, not allowing for a transition period, the impacts of the 

rTCR under the AA will be observed sooner. However, the overall frequency of TC- or ECpositives remains essentially the same in both cases. From the standpoint of public health 

protection, the AA would be preferred because the endpoint improvements are achieved 

relatively sooner than the timeline in the AIP. In addition, getting such a program running at the 

small utility and state level would pose initial logistical and administrative challenges. The net 

cost for the AA is slightly higher than the AIP, but given the absence of underlying distributions, 

the significance of the net difference is not known. In fact, given all the assumptions made, the 

difference in the net cost between the AA and AIP is likely not significant, which an uncertainty 

analysis would probably verify. 

Suggestion 3. Alternatives and Modifications 

The following is a summary of some of the changes that could be considered. 

• Consider revisions to the Federal data collection system to ensure the data collected are 

adequate to establish a baseline from which to measure the future rTCR impact. 

20
• Rerun the EA using more extreme values for the proportion of water systems that 

implement corrective actions, e. g., 1% and 50%. 

• Revise the assumption that corrective actions will lead to extended periods of TC- and 

EC-negative results. 

• Revise cost estimates to compensate for the overtime needed for repeat sampling and 

analyses in response to TC- or EC positives samples or the additional costs for 

contracting out an assessment. 

• List, identify, and separate those actions and costs associated with TC- or EC- positives 

that would be mitigated by other rules, such as the surface water treatment rule or 

groundwater disinfection rule. This will more clearly identify those actions and impacts 

associated with the different rules and show how the rules are linked. 

The Agency should continue its long-term research efforts to develop tests to identify 

specific disease-causing organisms, particularly pathogenic strains of E. coli and other 

pathogenic bacteria, to enable public water systems to eliminate these disease-causing organisms 

from their water systems. This would require a long-term research project(s) which should 

commence now with high priority. It is important to take advantage of the latest techniques in 

molecular biology, such as Polymerase Chain Reaction (PCR), which have exquisite sensitivity 

and specificity, to advance the problem of identification of pathogenic bacteria in the water 

systems. One could visualize first moving to pathogenic strains of E. coli by culture methods 

and biochemical methods, and later by PCR methodology, which is very rapid and very specific. 

The PCR detection of pathogens fits within the rubric of other recommendations made by the 

DWC to the EPA concerning the monitoring for, and the rapid detection of, pathogens. This is 

yet one more example of how moving along to this form of monitoring would be helpful and 

protective of public health. The DWC recognizes that this form of monitoring acts to address 

multiple threats to public health, and has the potential to provide timely and specific information. 

This should be done carefully and with extensive validation of molecular biology methodology 

against classical culture and microbiology methodology to determine whether adoption of these 

methodologies would actually advance water sanitation. In addition, the Agency still has to 

balance maintaining a broad bacterial screen vs. moving to screens for specific pathogenic 

organisms. 

Those small and large water systems that fail to comply with corrective action 

requirements should perhaps be tasked with more frequent monitoring and reporting 

requirements to encourage them to rapidly become compliant with the proposed rTCR for long 

periods of time, at which point the requirements could be relaxed. 

Overall, the Drinking Water Committee (DWC) advises USEPA to move forward 

deliberately to ensure any changes made in generating the rTCR actually result in a significant 

reduction in the frequency and severity of Total Coliform observations in our drinking water 

systems. DWC recommends substantial caution in developing the rTCR. To date, most U. S. 

water systems are maintained well, hence, DWC recommends being very careful in adopting 

new changes to the TCR, unless there is a very high probability they will improve water 

distribution system sanitation, i.e., The DWC recommends caution in making changes to the 

TCR, and incorporating only those changes that have a high probability of making water systems 

more sanitary as this is likely a means to lower frequencies of water-borne illnesses. 

21
The rTCR should be written to make it clear and easy to comply with for the convenience 

of the PWS. In addition, the DWC strongly recommends placing all information related to 

aspects of the rTCR on one website with links to supporting materials. The DWC believes that 

development of a similar book embodying all the rules contained within the rTCR would be very 

valuable to the water quality community. 

Charge Question 4. Are reductions in E. coli and TC occurrence and acute violations 

appropriate endpoints for informing benefits? Do they appropriately capture the added 

value of the proposed revisions? If not, what other analyses or endpoints might be 

considered? 

The Committee struggled with its response to Charge Question 4 in trying to determine 

whether there are measurable health-related benefits that could be attributable to the revised 

Total Coliform Rule (rTCR). If the goal of the Rule is to protect public health, the Committee 

feels that measuring reductions in total coliforms (TC) and E. coli (EC) occurrences are not

effective sole endpoints for informing benefits because of the difficulties (discussed below) in 

linking these indicators to human health outcomes. It is expected that there will be a decrease in 

the number of acute violations with the assumption that assessment, followed by corrective 

action will decrease the occurrence. The Committee believes there is value in the TT-model. 

However, there are a number of other indicators that need to be considered, as TC is not an 

adequate measure of health risk. Even though E. coli is viewed as a more appropriate measure of 

risk of enteric illness, they do not capture the health risks from Legionella, for example Other 

measures, including structural and hydraulic integrity, have been recently considered in a report 

by the National Research Council and may provide valuable supplemental information on health 

risks of distributed water. 

Suggestion 1. TC as an appropriate endpoint 

With respect to the use of TC, the Committee notes the following: 

• TC can be considered an indicator of treatment efficacy at the point of treatment. To that 

end, it may be judicious to encourage utilities to sample for TC at plant effluent. 

However, there is no evidence (of which we are aware) to suggest that the detection of 

TC in the distribution system indicates risk to human health. The Committee recognizes 

that there are many reasons why TC could be detected in the distribution system, e.g.

release from biofilms, intrusion, regrowth, improper sampling, nitrification, and crossconnections. Therefore, the significance of TC detection is difficult to interpret and 

depends in part on context (such as temperature, season and climate). 

• For many systems, the number of samples that will be collected under the revised TCR is 

inadequate to measure statistically significant reductions in TC and EC occurrence. 

• There exist acknowledged problems with false negative and false positive results that 

further complicate the interpretation of results. 

• These indicators are not used by most other industrialized countries around the world as a 

measure of drinking water quality. We believe that they are used only by the US and 

Canada (and only under some circumstances). 

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Despite these limitations, the Committee recognizes that: 

• The use of TC represents a tool that is already in place, relatively inexpensive, and 

familiar to users. Specifically, there is already existing expertise and infrastructure with 

which to conduct these analyses in most water systems. 

• The presence of TC is indicative of gross contamination, a breach in treatment or 

distribution system failure. 

• The fact that there exist differences in occurrence between disinfected and nondisinfected water systems suggests that, at some level, there is a correlation with water 

quality improvement. 

With respect to E. coli, the Committee felt that it represents a more credible indicator of 

public health risk. The utility of E. coli testing, however, is limited by the rarity of its detection. 

It is useful as a confirmatory, follow-up test, and the Committee felt it appropriate to retain it as 

an MCL. The Committee notes that the Agency’s modeling does not predict much effect on E. 

coli occurrence, potentially limiting its usefulness as an indicator of improvement. 

Suggestion 2. Reductions in acute violations as appropriate endpoints for informing 

benefits 

It is expected that there will be a decrease in the number of acute violations and 

associated Public Notifications following implementation of the rTCR. This expectation is 

fueled by the assumption that many Level 1 and Level 2 assessments will be done, that 

corrective actions will be taken, and that EC-positive occurrences will decrease. Because 

information on the relationship between EC-positive occurrence rates and illness rates is not 

available, we have to assume that a reduction in acute violations will lead to reduction in 

waterborne illness, which is reasonable. This seems like a reasonable assumption but it is 

currently not supported by data. Further, in the years since the implementation of the original 

TCR, there has been a persistent level of acute violations among small water systems that has not 

changed substantially. Generally, these small water systems lack sufficient resources to bring 

their systems into compliance. It is assumed that the number of systems in this acute violation 

category will be reduced by the new emphasis in the revised rule on assessments and repairing 

defects. This is an appropriate and measurable endpoint. 

 

 Suggestion 3. Added value of the proposed revisions 

The DWC agrees that there is value in moving from an MCL-model to a TT-model to 

better address the nature of the issue. It is more logical to treat these microorganisms as 

indicators of the possible presence of pathogens and to require corrective action than to employ a 

fixed number (e.g. 5% of all samples) as a “bright line” indicator of a public health problem. 

There is value in having a regulation that is more rational and closely aligned with the nature of 

the contamination problems. This is discussed briefly at the end of Chapter 6. Increasing the 

awareness and familiarity of the operators of small water systems with their specific issues and 

23
focusing efforts on correcting deficiencies rather than meeting strict numerical targets is more 

likely to decrease overall risk to the communities served. 

Suggestion 4. Other analyses or endpoints that might be considered 

Given the limitations of TC and EC as endpoints (as measures of health benefit), the 

Committee questioned whether there may be value in adding additional endpoints, even though 

these additional endpoints may also have limitations. The question raised was whether several 

endpoints, in combination, may be more effective than the use of single indicators. It was not 

our intention to suggest these additional endpoints as replacements for TC and EC. Several 

possible additional indicators were discussed. 

First, the Committee considered measures of improvement in public health, such as 

surveillance for waterborne disease outbreaks and/or measures of endemic gastrointestinal 

illnesses in communities. The Committee recognized that there are issues of sensitivity, 

timeliness and cost associated with any surveillance system. However, there may be 

circumstances when enhanced surveillance systems (such as monitoring nurse hotline calls, 

monitoring sales of anti-diarrheal medication, monitoring hospital emergency department visits 

for gastrointestinal illness) could be useful in areas where there is concern about water quality 

and/or vulnerable populations. For example, New York City used enhanced surveillance systems 

for gastrointestinal disease as part of their strategy to protect public health while avoiding water 

filtration (see Watershed Management for Potable Water Supply: Assessing the New York City 

Strategy, National Research Council, 2000). 

In addition to considering health endpoints, the Committee also considered indicators of 

health risk and asked the following questions and looked to the NAS study for guidance. a) What 

factors are “known” to be associated with health risk? b) What factors can be measured by small 

systems?; by large systems? A recent study by the National Research Council entitled Drinking 

Water Distribution Systems: Assessing and Reducing Risks (2006) suggested the following 

measures as useful indicators of risk associated with drinking water distribution systems: 

1. Measures of hydraulic integrity following the use of the indicators:

• Decreased frequency of pressure drops 

• Areas of the distribution system with extreme water age 

2. Measures of structural integrity and distribution system management 

• Chlorine residual 

• Heterotrophic Plate Count (HPC) bacteria 

• Assessment of biofilms using snaking cameras 

• Number of utilities with routine prophylactic flushing program 

• Number of utilities with active leak detection program 

• Number of utilities with active cross-connection detection program 

• Number of utilities with active backflow prevention program (e.g. Increased number of 

utilities that adopt better management practices) 

24
25

Some combination of these measures may serve as helpful endpoints when trying to assess the 

impact of the revised TCR. 

Finally, the Committee also discussed concerns about health risks that are not adequately 

captured by these endpoints, in particular, risks due to Legionella that is associated with a 

significant number of waterborne disease outbreaks each year (Surveillance for Waterborne 

Disease and Outbreaks Associated with Drinking Water and Water not Intended for Drinking -

United States, 2005–2006, MMWR, September 12, 2008 / Vol. 57 / No.SS-9). Thus, some of these 

pathogen-specific measures may need to be monitored if they are not captured by the fecal 

endpoints.