PUBLIC WATER SUPPLY DISTRIBUTION SYSTEMS: ASSESSING AND REDUCING RISKS
FIRST REPORT
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COMMITTEE ON PUBLIC WATER SUPPLY DISTRIBUTION SYSTEMS: ASSESSING AND REDUCING RISKS
Vernon L. Snoeyink, Chair,
University of Illinois, Urbana-Champaign
Charles N. Haas, Vice-Chair,
Drexel University, Philadelphia, Pennsylvania
Paul F. Boulos,
MWH Soft, Broomfield, Colorado
Gary A. Burlingame,
Philadelphia Water Department, Philadelphia, Pennsylvania
Anne K. Camper,
Montana State University, Bozeman
Robert N. Clark,
Shaw Environmental and Infrastructure, Inc., Cincinnati, Ohio
Marc A. Edwards,
Virginia Polytechnic and State University, Blacksburg
Mark W. LeChevallier,
American Water Corporation, Voorhees, New Jersey
L. D. McMullen,
Des Moines Water Works, Des Moines, Iowa
Christine L. Moe,
Emory University, Atlanta, Georgia
Eva C. Nieminski,
Utah Department of Environmental Quality, Salt Lake City
Charlotte D. Smith,
Charlotte Smith and Associates, Inc., Orinda, California
David P. Spath,
California Department of Health Services, Sacramento
Gary A. Toranzos,
University of Puerto Rico, San Juan
Richard L. Valentine,
University of Iowa, Iowa City
National Research Council Staff
Laura J. Ehlers, Study Director
Ellen A. De Guzman, Research Associate
WATER SCIENCE AND TECHNOLOGY BOARD
R. RHODES TRUSSELL, Chair,
Trussell Technologies, Inc., Pasadena, California
MARY JO BAEDECKER,
U.S. Geological Survey (Retired), Vienna, Virginia
GREGORY B. BAECHER,
University of Maryland, College Park
JOAN G. EHRENFELD,
Rutgers University, New Brunswick, New Jersey
DARA ENTEKHABI,
Massachusetts Institute of Technology, Cambridge, Massachusetts
GERALD E. GALLOWAY,
Titan Corporation, Reston, Virginia
PETER GLEICK,
Pacific Institute for Studies in Development, Environment, and Security, Oakland, California
CHARLES N. HAAS,
Drexel University, Philadelphia, Pennsylvania
KAI N. LEE,
Williams College, Williamstown, Massachusetts
CHRISTINE L. MOE,
Emory University, Atlanta, Georgia
ROBERT PERCIASEPE,
National Audubon Society, New York, New York
JERALD L. SCHNOOR,
University of Iowa, Iowa City
LEONARD SHABMAN,
Resources for the Future, Washington, DC
KARL K. TUREKIAN,
Yale University, New Haven, Connecticut
HAME M. WATT, Independent Consultant,
Washington, DC
CLAIRE WELTY,
University of Maryland, Baltimore County
JAMES L. WESCOAT, JR.,
University of Illinois, Urbana-Champaign
Staff
STEPHEN D. PARKER, Director
LAURA J. EHLERS, Senior Staff Officer
JEFFREY W. JACOBS, Senior Staff Officer
WILLIAM S. LOGAN, Senior Staff Officer
LAUREN E. ALEXANDER, Staff Officer
STEPHANIE E. JOHNSON, Staff Officer
M. JEANNE AQUILINO, Financial and Administrative Associate
ELLEN A. DE GUZMAN, Research Associate
PATRICIA JONES KERSHAW, Study/Research Associate
ANITA A. HALL, Administrative Assistant
DOROTHY K. WEIR, Senior Project Assistant
Preface
The distribution system is a critical component of every drinking water utility. Its primary function is to provide the required water quantity and quality at suitable pressure, and failure to do so is a serious system deficiency. Water quality may degrade during water distribution because of the way water is treated or not treated before it is distributed, chemical and biological reactions that take place in the water during distribution, reactions between the water and distribution system materials, and contamination from external sources that occurs because of main breaks, leaks coupled with hydraulic transients, improperly maintained storage facilities, and other factors. Special problems are posed by the utility’s need to maintain suitable water quality at the consumers tap, and the quality changes that occur in consumers’ plumbing, which is not owned or controlled by the utility. The primary driving force for managing and regulating distribution systems is protecting the health of the consumer, but certainly factors that cause water of poor aesthetic quality to be delivered to the tap or that increase the cost of delivering water are also important. Our nation’s distribution systems are aging and becoming more vulnerable to main breaks and leaks, possibly because they are underground and out of sight, and thus it is easy to delay distribution system investment when budgets are considered. There is an urgent need for new research that will enable cost-effective treatment for distribution and design, construction, and management of the distribution system for protection of public health and minimization of water quality degradation.
This study of the Water Science and Technology Board of the National Research Council (NRC) was undertaken at the request of the U.S. Environmental Protection Agency (EPA). The purpose of this report is to:
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Identify trends relevant to the deterioration of drinking water quality in water supply distribution systems, using available information, and
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Identify and prioritize issues of greatest concern for distribution systems based on review of published material.
This first report was requested by the EPA, as it considers revisions to the Total Coliform Rule in 2005. It will be followed in about 18 months by a more comprehensive final report that evaluates different approaches to characterization of public health risks posed by water-quality deteriorating events, identifies and evaluates the effectiveness of relevant existing codes and regulations, and identifies general actions, strategies, performance measures, and policies that could be considered by water utilities and other stakeholders to reduce the risks posed by water-quality deteriorating events or conditions. Advances in detection, monitoring and modeling, analytical methods, information needs
and technologies, research and development opportunities, and communication strategies that will enable the water supply industry and other stakeholders to further reduce risks associated with public water supply distribution systems will also be addressed.
This report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with the procedures approved by the NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the authors and the NRC in making the published report as sound as possible and to ensure that the report meets institutional standards of objectivity, evidence, and responsiveness to the study charge. The reviews and draft manuscripts remain confidential to protect the integrity of the deliberative process. We thank the following individuals for their participation in the review of this report: Gunther F. Craun, Craun and Associates, Virginia; Jerry Ongerth, East Bay Municipal Utility District, California; Jerald L. Schnoor, The University of Iowa, Iowa; R. Rhodes Trussell, Trussell Technologies, Inc., Califonia; and Jack Wang, Louisville Water Company, Kentucky.
Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Edward Bouwer of the Johns Hopkins University. Appointed by the NRC, he was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee.
Vernon Snoeyink, Chair