March 26, 1996
EPA-SAB-DWC-ADV-96-001
Honorable Carol M. Browner
Administrator
U.S. Environmental Protection Agency
401 M. Street, SW
Washington, DC 20460
Subject: Advisory by the Science Advisory Board's (SAB) Drinking
Water Committee (DWC) concerning EPA's Proposed
Drinking Water Distribution System Research Project
Dear Ms. Browner:
On August 16-18, 1995, the Drinking Water Committee (DWC) of the Science
Advisory Board (SAB) met to review, among other items, EPA's proposed Drinking
Water Distribution System Research Project. At this point in the Agency's planning
process, the Committee was asked to conduct an Advisory. An SAB Advisory is a peer
review of an Agency work-in-progress. Typically, the Agency asks for an Advisory
when it is in the midst of an extensive, complex project that would benefit from an
objective, independent scrutiny of its work to date. The goal of the Advisory is to
provide suggestions for mid-course corrections and/or new thrusts that will refine the
trajectory of the project. The output of the Advisory is similar to that of a Review; i.e., a
written report to the Administrator. Generally, an Advisory would be followed by an
SAB Review of the completed Agency project at some point in the future. The Board
would take steps to insure that the final Review Panel had a significant presence of
new participants so as to insure an independent assessment of the Agency's work.
This letter transmits to you a summary of the Committee's comments and
reactions to the Research Project and to the specific questions raised in the charge to
the Committee. These questions are as follows: a) Has the Office of Research and
Development (ORD) accurately characterized the research issues related to water
quality in distribution systems? b) What areas should be the highest priority for
research? and c) Is the current EPA role appropriate with respect to the research role
of other entities?
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Historically, the Agency's drinking water regulations and research programs
have heavily emphasized water treatment and largely neglected the contribution of the
distribution system on water quality. In recent years there has been increasing
recognition that water quality changes in the distribution system must be given serious
consideration from both a regulatory and a research standpoint. As a result of this
concern, the Agency's Office of Research and Development (ORD) presented the
above tentative charge to the SAB's Drinking Water Committee. The Committee
recommends modification of the charge to recognize that the proposed research project
is not intended to be a comprehensive distribution system research plan, but is focused
primarily on microbiologically related distribution system research issues.
In our view, the tentative charge is too broad. ORD's proposed Drinking Water
Distribution Systems Research Project is not, nor was it intended to be, an exhaustive
listing of distribution system research issues. Rather, the proposed research is
focused primarily on microbiologically related distribution system research issues.
Issues such as corrosion, taste and odor, and the effects on water quality of indirect
additives from distribution system components are not addressed.
a) Has ORD accurately characterized research issues related to Water
Quality in Distribution Systems?
The Committee believes that ORD's characterization of research issues is
accurate and is pleased to note the strong emphasis given to microbiological
issues. However, the Committee recommends the development of a research
plan that allows ORD to better prioritize research issues on the basis of human
health risks. Greater consideration needs to be given to the design and
operational implications of research efforts.
The areas proposed for research on the microbiology of drinking water
distribution systems appear to have potential overlap with the proposal entitled
"Health Significance of HPC Bacteria from GAG Treatment Devices" by Dr.
Stelma of EPA's National Exposure Research Laboratory1. In the Drinking
Water Committee's review of that proposal, it was suggested that the "EPA
drinking water research program should have a plan designed to characterize
microbiota and their microbial ecology in drinking water distribution systems, in
This was a presentation at the August 16-18, 1995 DWC meeting. The DWC conducted an Advisory on this issue which is
reflected in: Advisory by the Science Advisory Board's (SAB) Drinking Water Committee (DWC) concerning the Health Significance of
HPC Bacteria Eluted from POU/POE (Point of Use/Point of Entry) Drinking Water Treatment Devices. EPA-SAB-DWC-ADV-96-002,
March 1996.
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consumer plumbing and at the consumer's tap, and identify their human health
effects". The Committee believes that both of these programs would be
strengthened by interaction between the microbiologists and engineers and
coordination of their research programs related to the microbiology of drinking
water distribution systems.
b) What areas should be the highest priority for research?
The Committee finds it difficult to prioritize areas of research in the
absence of a risk-based research plan; however, even in the absence of a risk-
based prioritization, several areas of proposed research appear to merit a high
priority. High priority areas for research include the development of kinetic
models for chlorine decay in distribution systems, enhancement of the EPANET
distribution system water quality model, and research related to opportunistic
pathogens in distribution system biofilms.
The Committee highly commends ORD for its work on APPEND. This
software provides a highly effective, low-cost model which accurately depicts
distribution system performance. Water quality modeling software is often
developed at great expense but has little practical value. APPEND is a sparkling
exception. The Committee highly recommends that the model be further
enhanced, as proposed.
Design and operational implications of distribution system research - The
Committee strongly recommends that ORD be sensitive to the practical
implications of its research on the design and operation of drinking water
distribution systems. Research needs to be taken to the point where the Agency
can develop practical guidelines for design and operation of water distribution
systems. Practical issues such as minimization of disinfectant residual decay,
minimization of HPC and other opportunistic pathogens, and minimization of
biofilms in the distribution system need to be considered. Design and operation
of drinking water storage reservoirs can be greatly improved by conducting
appropriate research. Baffling of reservoirs, design of inlet-outlet structures and
using air and/or water pumping to mix reservoirs could lead to significant water
quality improvements. These, and many other distribution system
enhancements, can be effectively evaluated if research projects are conducted
keeping such design and operational considerations in mind.
In reality, water utilities often operate distribution systems to minimize
pumping and other operational costs with little thought being given to the water
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quality impacts of such decisions. The development of Agency guidelines for
thedesign and operation of distribution systems would be a valuable aid to water
utilities in balancing operating costs and water quality considerations.
c) Is the current EPA role appropriate with respect to the research role of
other entities?
The research role of EPA is largely established by law. The Agency's
role with respect to other entities such as the American Water Works
Association Research Foundation (AWWARF) and other research
organizations, including private sector research groups, appears appropriate.
The Agency should continue to leverage research efforts by partnering with
AWWARF and other research groups, including the private sector.
The Committee believes that the Agency's proposed Drinking Water Distribution
System Research Project is appropriately focused on microbiologically related research
issues; however, a comprehensive research plan is needed which is based on human
health risk prioritization. High priority should be given to future research related to
kinetic models for chlorine decay in distribution systems, enhancement of the APPEND
model, and research related to opportunistic pathogens in biofilms. Drinking water
distribution system research needs to be conducted with the goal of developing
practical guidelines for the design and operation of distribution system pumps, piping
and storage facilities.
Thank you for the opportunity to provide our input at an early stage in the
development of this Research Project. We look forward to providing further advice and
assistance as the Research Project is developed.
Sincerely,
Dr. Genevieve M. Matanoski, Chair Dr. Verne Ray, Chair
Executive Committee Drinking Water Committee
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NOTICE
This report has been written as part of the activities of the Science Advisory
Board, a public advisory group 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.
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ENVIRONMENTAL PROTECTION AGENCY
SCIENCE ADVISORY BOARD
DRINKING WATER COMMITTEE
CHAIRMAN
Dr. Verne Ray, Medical Research Laboratory, Pfizer Inc., Groton, CT
VICE CHAIRMAN
Dr. Vernon Snoeyink, Department of Civil Engineering, University of Illinois, Urbana, IL
MEMBERS
Dr. Judy A. Bean, Professor and Director of Biostatistics, University of Miami, Miami, FL
Dr. Keith E. Cams, EPRI, Community Environmental Center, Washington University,
Campus, St Louis, MO
Dr. Lenore S. Clesceri, Rensselaer Polytechnic Institute, Materials Research Center,
Troy, NY
Dr. Anna Fan, OEHHA/PETS, State of California, Berkeley, CA
Dr. Charles Gerba, Program in Microbiology, University of Arizona, Tucson, AZ
Dr. Curtis Klaassen, Department of Pharmacology, University of Kansas Medical Center,
Kansas City, KS
Dr. Ellen O'Flaherty, Assoc. Professor of Environmental Health, College of Medicine,
University of Cincinnati, Cincinnati, OH
Dr. Edo D. Pellizzari, Research Triangle Institute, Research Triangle Park, NC
Dr. Rhodes Trussell, Montgomery Watson, Pasadena, CA
Dr. Marylynn V. Yates, Department of Soil and Environmental Sciences, University of
California, Riverside, CA
SCIENCE ADVISORY BOARD STAFF
Mr. Robert Flaak, Designated Federal Officer, Science Advisory Board (1400F), U.S.
EPA, 401 M Street, SW, Washington, DC 20460 (202) 260-5133 FAX (202) 260-7118
Mrs. Mary L. Winston, Staff Secretary, Science Advisory Board (1400-F), U.S. EPA, 401
M Street, SW, Washington, DC 20460 (202) 260-6552 - FAX (202) 260-7118
DISTRIBUTION LIST
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