&EPA
United States
Environmental Protection
Agency
Small Drinking Water Systems:
State of the Industry and
Treatment Technologies to
Meet the Safe Drinking Water Act
Requirements
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EPA/600/R-07/110
September 2007
to the Act
by
Christopher A. Impellitteri, Craig L. Patterson, Roy C. Haught, and James A. Goodrich
Water Supply and Water Resources Division
National Risk Management Research Laboratory
Cincinnati, OH 45268
This report was compiled in cooperation with Shaw Environmental, Inc.
Under EPA Contract EP-C-04-034 WA1-03 and WA 2-03
Work Assignment Manager- Craig L. Patterson
Water Supply and Water Resources Division
National Risk Management Research Laboratory
Cincinnati, OH 45268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
j|ff||, Recycled/Recyclable
Printed with vegetable-based ink on
paper that contains a minimum of
50% post-consumer fiber content
processed chlorine free
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Notice
The EPA has not subjected this report to internal review. Therefore, the research results presented
herein do not, necessarily, reflect Agency policy. Mention of trade names of commercial products does
not constitute endorsement or recommendation for use.
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Abstract
This document summarizes the current national statistics for small drinking water systems (serving less
than ten thousand people). It describes the current status of regulations, treatment technologies, source
water issues, distribution system characteristics, waste residual issues, security/emergency response,
and monitoring as these issues pertain to small systems. This objective of this document is to provide
researchers in the Water Supply and Water Resources Division in the National Risk Management Research
Laboratory with a basis to design and implement future research projects that will focus on the most
pressing needs of small systems. The majority of this report includes data and information acquired
between June 1, 2004 and October 1, 2005, and most of the work was completed on November 1, 2005.
Section 5.6, related to small systems treatment option "affordability" and definition of "unreasonable risk
to health," presents more recent updates (performed in August 2006) based on reviewer comments.
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the ability
of natural systems to support and nurture life. To meet this mandate, ERA'S research program is providing
data and technical support for solving environmental problems today and building a science knowledge
base necessary to manage our ecological resources wisely, understand how pollutants affect our health,
and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center for investiga-
tion of technological and management approaches for preventing and reducing risks from pollution
that threaten human health and the environment. The focus of the Laboratory's research program is
on methods and their cost-effectiveness for prevention and control of pollution to air, land, water, and
subsurface resources; protection of water quality in public water systems; remediation of contaminated
sites, sediments and ground water; prevention and control of indoor air pollution; and restoration of
ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies
that reduce the cost of compliance and to anticipate emerging problems. NRMRL's research provides
solutions to environmental problems by: developing and promoting technologies that protect and
improve the environment; advancing scientific and engineering information to support regulatory and
policy decisions; and providing the technical support and information transfer to ensure implementation
of environmental regulations and strategies at the national, state, and community levels.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is
published and made available by ERA'S Office of Research and Development to assist the user com-
munity and to link researchers with their clients.
Sally Gutierrez, Director
National Risk Management Research Laboratory
IV
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Table of Contents
1.0 Introduction 1-1
1.1 Goals and Objectives of this Document 1-1
1.2 Document Organization 1-1
2.0 Current Status and Issues of Small Drinking Water Systems 2-1
2.1 Introduction 2-1
2.2 Profile of Small Systems in the U.S 2-1
2.3 Status of Drinking Water Plant Violations 2-4
2.4 Source Water Issues 2-5
2.5 Common Current Treatment Technologies 2-5
2.6 Particulate/Turbidity Removal Technologies 2-8
2.6.1 Simple Filtration 2-8
2.6.2 Advanced Filtration 2-9
2.6.3 Reverse Osmosis (RO) 2-9
2.7 Chemical Contaminant Removal 2-9
2.7.1 Ion Exchange (IX) 2-9
2.7.2 Sorption Technologies 2-9
2.7.3 Other Technologies 2-10
2.8 Biological Contaminant Removal 2-10
2.8.1 Chlorination 2-10
2.8.2 Ultraviolet Light (UV) 2-10
2.8.3 Ozone 2-10
2.8.4 Other Disinfection Technologies 2-10
2.9 Distribution System Infrastructure 2-10
2.9.1 Storage Facilities 2-14
2.9.2 Pumping facilities 2-16
2.9.3 Distribution Lines 2-16
2.10 Remote Telemetry - Supervisory Control and Data Acquisition (SCADA) 2-17
2.11 Key Questions 2-20
2.12 References 2-22
3.0 Regulatory Background 3-1
3.1 Safe Drinking Water Act (SDWA) 3-1
3.2 SDWA Provisions 3-1
3.2.1 National Primary Drinking Water Regulations (NPDWR) 3-1
3.2.2 National Secondary Drinking Water Regulations (NSDWR) 3-2
3.2.3 Contaminant Candidate List (CCL) 3-2
3.3 Current Regulatory Issues 3-2
3.3.1 Perchlorate 3-2
3.3.2 Arsenic 3-2
3.3.3 Compliance with Surface Water Treatment Rule 3-3
3.3.4 Stage 1 and 2 Disinfection Byproducts (DBP) Rules 3-4
3.3.5 Proposed Ground Water Rule 3-5
3.3.6 Methyl Tertiary Butyl Ether (MTBE) 3-5
3.3.7 Radionuclides 3-5
3.4 Source Water Assessments 3-6
3.5 Wellhead Protection 3-7
3.6 Vulnerability Assessments (VA), Emergency Planning and Security 3-7
3.7 Variances and Exemptions 3-8
3.7.1 Small System Variances 3-8
3.7.2 Exemptions 3-8
3.8 DWSRF 3-9
3.9 Key Questions 3-9
3.10 References 3-9
4.0 Source Water Issues 4-1
4.1 Background 4-1
4.2 Drinking Water Research Program Multi-Year Plan 4-1
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4.2.1 Long-Term Goals 4-1
4.2.2 Ongoing and Future Research 4-1
4.3 Source Water Assessments 4-2
4.3.1 Delineation 4-2
4.3.2 Contamination Sources 4-2
4.3.3 Susceptibility Determination 4-3
4.3.4 Public Involvement 4-3
4.3.5 Benefits of Source Water Assessment Plans (SWAPs) 4-3
4.3.6 Source Water Protection 4-3
4.4 Other Source Water Assessment and Protection Tools 4-3
4.4.1 Sanitary Survey 4-3
4.4.2 Wellhead Protection Program (WHPP) 4-3
4.5 Sustainability of Community Water Systems (CWSs) 4-4
4.6 EPA Source Water Assessment and Protection Programs 4-4
4.7 Key Questions 4-4
4.8 References 4-4
5.0 Treatment Processes 5-1
5.1 Introduction 5-1
5.2 Packaged Filtration 5-1
5.2.1 Filtration 5-2
5.2.2 Bag Filtration 5-3
5.2.3 Cartridge Filtration 5-4
5.2.4 Membrane Filtration 5-4
5.2.5 Ultra Filtration (UF) 5-4
5.3 Disinfection 5-4
5.3.1 Disinfection by Chlorination 5-5
5.3.2 Disinfection by Ozonation 5-6
5.3.3 Advanced Oxidation Process for Disinfection & Destruction 5-6
5.3.4 Disinfection System Observations 5-7
5.4 Sorption Technologies 5-7
5.4.1 Ion exchange (IX) 5-8
5.4.2 Activated Alumina (AA) and Iron-based Media 5-8
5.4.3 Powdered Activated Carbon/Granular Activated Carbon (PAC/GAC) 5-8
5.5 Lime Softening 5-9
5.6 Affordability of Recommended Treatment Technologies and Protectiveness of Public Health
by Variance Technologies for Small Systems 5-9
5.7 Point-of-Use/Point-of-Entry (POU/POE) Applications 5-10
5.7.1 POU/POE Treatment Cost 5-11
5.7.2 Use of POU/POE Treatment and Bottled Water in Small Systems 5-11
5.8 Key Questions 5-13
5.9 References 5-13
6.0 Distribution Systems 6-1
6.1 Distribution System Overview 6-1
6.2 Distribution System Issues 6-1
6.3 Infrastructure Issues 6-1
6.4 Operational Issues 6-2
6.4.1 Biofilm Growth 6-2
6.4.2 Nitrification 6-3
6.4.3 Finished Water Storage and Aging 6-4
6.5 Contamination Events 6-4
6.5.1 Cross-connection Control 6-4
6.5.2 Permeation and Leaching 6-5
6.5.3 Intrusion and Infiltrations 6-6
6.6 Distribution System Summary 6-6
6.7 Key Questions 6-7
6.8 References 6-7
VI
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7.0 Waste Residuals Generated by Small Systems 7-1
7.1 Introduction 7-1
7.2 Types of Waste Residuals and Disposal 7-1
7.3 Liquid Residuals Handling & Disposal 7-1
7.3.1 Direct Discharge of Liquids 7-2
7.3.2 Indirect Discharge of Liquids 7-3
7.3.3 Land Disposal of Liquids 7-3
7.4 Solid Residuals 7-4
7.4.1 Land Disposal of Solids 7-4
7.4.2 Land Application of Solids 7-4
7.4.3 Incineration of Solids and Liquids 7-4
7.5 Technologically Enhanced Normally Occurring Radioactive Material (TENORM) Residuals 7-4
7.6 Conclusions and Future Research 7-5
7.7 Key Questions 7-5
7.8 References 7-5
8.0 Homeland Security/Emergency Response 8-1
8.1 Background and Directives 8-1
8.1.1 Bioterrorism Act 8-1
8.1.2 Homeland Security Presidential Directive (HSPD)-7 - Critical Infrastructure Identification,
Prioritization, and Protection 8-1
8.1.3 HSPD-8 - National Preparedness 8-1
8.1.4 HSPD-9 - Defense of United States Agriculture and Food 8-1
8.1.5 HSPD-10 - BioDefense for the 21st Century 8-1
8.1.6 EPA's Strategic Plan for Homeland Security 8-2
8.2 EPA's Homeland Security and Emergency Response Initiatives and Resources 8-2
8.3 Threats and Risks to the Water Supply 8-3
8.3.1 Chemical and Radiological Contaminants 8-3
8.3.2 Biological Contaminants 8-3
8.3.3 Risk Assessment and Mitigation 8-3
8.4 Response Protocol Toolbox 8-3
8.5 Recommended Procedures for Securing Small Systems 8-4
8.6 Infrastructure and Bulk Water 8-4
8.7 Telemetry 8-5
8.8 Early Warning Systems for Drinking Water Systems 8-5
8.9 Disinfection in Distribution Systems 8-6
8.10 Preparedness Assessment for Handling Threats 8-6
8.11 Local/State Emergency Planning Committees 8-7
8.12 Alternative Drinking Water Supplies in the Event of an Incident 8-7
8.13 Key Questions 8-8
8.14 References 8-8
9.0 Remote Monitoring and Control 9-1
9.1 Introduction 9-1
9.2 Rationale for Online Monitoring 9-1
9.3 Selection and Implementation of Supervisory Control and Data Acquisition (SCADA) Systems.. 9-1
9.4 Fundamentals of SCADA 9-3
9.4.1 Monitoring Equipment 9-3
9.4.2 Control Equipment 9-4
9.4.3 Data Collection and Processing Unit(s) 9-4
9.4.4 Communication Media and Field Wiring 9-4
9.5 Remote Telemetry Applications for Small Systems 9-4
9.5.1 West Virginia Remote Monitoring Case Study 9-4
9.5.2 Puerto Rico Remote Monitoring Case Study 9-5
9.6 General Security Issues with Remote Monitoring 9-7
9.7 Contamination Warning Systems 9-7
9.8 Key Questions 9-7
9.9 References 9-7
VII
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10.0 Summary 10-1
10.1 Introduction 10-1
10.2 Memorandum of Understanding (MOD) with the National Rural \AfeterAssociation (NRWA) 10-1
10.3 Chapter-Specific Key Questions 10-1
VIM
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List of Tables
Table 2.1 Technologies for inorganic contaminants 2-11
Table 2.2 Technologies for volatile organic contaminants 2-11
Table 2.3 Technologies for synthetic organic contaminants 2-12
Table 2.4 Technologies for radionuclides 2-12
Table 2.5 Technologies for disinfection 2-13
Table 2.6 Technologies for filtration 2-13
Table 2.7 Compliance technology for the Total Coliform Rule 2-14
Table 2.8 Percentage of CWSs (within each system service population category) that have treated-
water storage, before distribution system 2-15
Table 2.9 Percentage of CWSs (within each system service population category) that have treated-
water storage within the distribution system 2-15
Table 2.10 System service connections by system owner 2-20
Table 3.1 Reduced monitoring for radionuclides 3-6
Table 5.1 Surface Water Treatment Rule compliance technologies for disinfection 5-1
Table 5.2 Surface Water Treatment Rule compliance technologies for filtration 5-2
Table 5.3 Summary of disinfectant characteristics relating to biocidal efficiency 5-5
Table 5.4 Key Feature Summary of commonly used POU/POE technologies 5-12
Table 9.1 Amenability of treatment technologies to remote monitoring used for small water 9-2
Table 9.2 Cost estimates of SCADA system components 9-5
Table 9.3 Puerto Rico remote monitoring system component costs 9-6
List of Figures
Figure 2.1 PWSs by system type 2-2
Figure 2.2 Small systems by system type - FY2004 2-2
Figure 2.3 Number of people served by system type - All systems FY2004 2-2
Figure 2.4 Number of PWSs for each service population group 2-3
Figure 2.5 Population served, service connections and number of systems - CWSs only FY2004 .2-3
Figure 2.6 Drinking water system owners - FY 2004-159,796 total systems 2-4
Figure 2.7 Violations reported FY2005 2-4
Figure 2.8 Drinking water system violations for all system sizes - FY2005 2-5
Figure 2.9 Violations reported for systems serving population from 25-10,000- FY2005 2-5
Figure 2.10 MCL violations vs. populations served FY2005 2-6
Figure 2.11 Source water comparison by size category 2-6
Figure 2.12 Percentage of ground water plants using each treatment technique 2-7
Figure 2.13 Percentage of surface water plants using each treatment technique 2-7
Figure 2.14 Percentage of mixed plants using each treatment technique 2-8
Figure 2.15 Percentage of CWSs within each system service population category that have a
clean/veil type finished water storage 2-15
Figure 2.16 Average number of miles of distribution mains (public vs. private systems) 2-16
Figure 2.17 Public vs. private average annual pipe replaced (for CWSs) 5-year average 2-17
Figure 2.18 System service connections 2-18
Figure 2.19 Average number of miles of pipes in distribution systems - privately owned 2-18
Figure 2.20 Average number of miles of pipes in distribution systems - publicly owned 2-19
Figure 2.21 Percentage of pipe in each age category for CWSs 2-19
Figure 2.22 Percentage of Pipe in Each Age Category by Source for CWSs 2-20
Figure 2.23 Percentage of ground water CWS plants (lacking 24/7 operator presence) that have
SCADA systems for process monitoring or control 2-21
Figure 2.24 Percentage of surface water CWS plants (lacking 24/7 operator presence) that have
SCADA systems for process monitoring or control 2-21
Figure 3.1 Structure of the DWSRF program 3-7
IX
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Figure 5.1 Particle size distribution of common contaminants and associated filtration technology....5-3
Figure 5.2 Clogged Prefilter 5-3
Figure 6.1 Distribution System as a "Reactor" 6-3
Figure 6.2 Negative Pressure Transient Associated with a Power Outage 6-6
Figure 7.1 Federal regulations governing the disposal of residuals 7-2
Figure 9.1 Possible layout of remote monitoring system 9-3
Figure 9.2 Schematic layout of the small sytstem in San German, Puerto Rico 9-6
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Acronyms and Abbreviations
AA Activated Alumina
ABRA American Backflow Prevention
Association
ANSI American National Standards
Institute
AOP Advanced Oxidation Processes
APG Annual Performance Goal
APM Annual Performance Measure
ASCE American Society of Civil Engineers
ASDWA Association of State Drinking Water
Administrators
AWQC Ambient Water Quality Criteria
AWWA American Water Works Association
BAT Best Available Technology
BMP Best Management Practices
CCL Contaminant Candidate List
CESQG Conditionally Exempt Small Quantity
Generator
CFR Coliform Rule
CSO Combined Sewer Overflows
CT Contact Time
CWA Clean Water Act
CWS Community Water System
DBP Disinfection By-Product
DBPR Disinfection By-Product Rule
DE Diatomaceous Earth
DHS Department of Homeland Security
DWSRF Drinking Water State Revolving Fund
EBCT Empty Bed Contact Time
ED Electrodialysis
EPA Environmental Protection Agency
EPCRA Emergency Planning and Community
Right-to-Know Act
EPTDS Entry Point to the Distribution
System
ERP Emergency Response Plan
ETV Environmental Technology
Verification
FBRR Filter Backwash Recycle Rule
GAG Granular Activated Carbon
GFH Granular Ferric Hydroxide
GPM Gallons per Minute
GWUDI Ground Water Under Direct Influence
HAAS Haloacetic Acids
HFGP Horizontal Flow Gravel Prefilter
HSPD Homeland Security Presidential
Directive
IT Information Technology
IUP Intended Use Plan
IX Ion Exchange
LEPC Local Emergency Planning
Committee
LGR Local Government Reimbursements
LLRW Low-level Radioactive Waste
LT1ESWTR Long Term 1 Enhanced Surface
Water Treatment Rule
LT2ESWTR Long Term 2 Enhanced Surface
Water Treatment Rule
M/R Monitoring and Reporting
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
MF Microfiltration
MGD Million Gallons per Day
MHI Median Home Income
MOU Memorandum of Understanding
MRDLG Maximum Residual Disinfectant Level
Goal
MTBE Methyl Tertiary Butyl Ether
MWCO Molecular Weight Cut-off
NAS National Academy of Science
NDWAC National Drinking Water Advisory
Council
NDWC National Drinking Water
Clearinghouse
NRMRL National Risk Management
Research Laboratory
NF Nanofiltration
NHSRC National Homeland Security
Research Center
NIPDWR National Interim Primary Drinking
Water Regulations
NOM Natural Organic Matter
NPDES National Pollution Discharge
Elimination System
NPDWR National Primary Drinking Water
Regulations
NRC National Research Council (also
used for Nuclear Regulatory
Commission in Chapter)
NRWA National Rural Water Association
XI
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NSDWR National Secondary Drinking Water
Regulation
NSF National Sanitation Foundation
NTNCWS Non-Transient Non-Cmmunity Water
System
NTU NephelometricTurbidity Units
O3 Ozone
O&M Operation and Maintenance
OCMS Online Contaminant Monitoring
System
OEM Office of Emergency Management
ORD Office of Research and Development
PAC Powdered Activated Carbon
PDCO Pore Diameter Cut-off
PDD Presidential Decision Directive
POE Point-of-Entry
POTW Publicly Owned Treatment Works
POU Point-of-Use
ppb Parts per billion
PTA Packed Tower Aeration
PVC Polyvinyl Chloride
PWS Public Water System
RCRA Resource Conservation and
Recovery Act
RfD Reference Dose
RMCL Recommended Maximum
Contaminant Level
RO Reverse Osmosis
RPTB Response Protocol Toolbox
SAB Science Advisory Board
SBA Strong Base Anion
SCADA Supervisory Control and Data
Acquisition
SDWA Safe Drinking Water Act
SDWIS State Drinking Water Information
System
SEMS Security Emergency Management
Systems
SEMS/ICS Standardized Emergency
Management System/Incident
Command System
SSCT Small System Compliance
Technology
SSF Slow Sand Filter
SWAP Source Water Assessment Plan
SWP Source Water Protection
SWR Solid Waste Residuals
SWTR Surface Water Treatment Rule
TCLP Toxicity Characteristic Leaching
Procedure
TCR Total Coliform Rule
T&E Test and Evaluation
TENORM Technologically Enhanced Naturally
Occurring Radioactive Material
THM Trihalomethane
TMDL Total Maximum Daily Load
TNCWS Transient Community Water System
TOC Total Organic Carbon
TT Treatment Technique
TTHM Total Trihalomethanes
UCMR Unregulated Contaminants
Monitoring Rule
UF Ultrafiltration
USAGE United States Army Corps of
Engineers
UV Ultraviolet light
VA Vulnerability Assessment
VOC Volatile organic compound
WBA Weak Base Anion
WHP Well Head Protection
WHRA Well Head Protection Area
WHPP Well Head Protection Plan
WSD Water Security Division
WSWRD Water Supply and Water Resources
Division
XII
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Acknowledgements
This report was submitted in partial fulfillment of contract number EP-C-04-034 WA1-03 and 2-03 by
Shaw Environmental, Inc. under the sponsorship of the United States Environmental Protection Agency.
The authors extend their thanks to EPA Region 5 reviewers: Ronald Kovach, Miguel Del Toral, Sahba
Rouhani, and William Spaulding. The authors would also like to thank Eric Bissonette, Jenny Bielanski,
and Francine St. Denis in the ERA'S Office of Water for their comments. Lastly, the authors extend their
deepest appreciation to the National Rural Water Association, specifically Jerry Biberstine and Dr. John
Regnier for their comments and suggestions. Collaboration with NRWA is made possible through a
Memorandum of Understanding between the EPA and NRWA.
XIII
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Chapter 1
Introduction
1.1 Goals and Objectives of this
Document
The objective of this document is to summarize the
existing status of drinking water supply in the United
States (U.S.) with particular emphasis on small sys-
tems (i.e., systems serving less that 10,000 people).
This document will then form the backdrop to craft a
research plan that will serve as a roadmap for research-
ers in the U.S. Environmental Protection Agen-
cy's (EPA's), Office of Research and Development
(ORD), Water Supply and Water Resources Division
(WS WRD) by providing focus and direction to the
WSWRD's research efforts. Specifically, the Strategy
for Small Systems Research aims to:
• Provide timely and appropriate research that will
contribute to small system management schemes
for reducing Safe Drinking Water Act (SDWA)
violations and public health risks.
• Chart a research course that will drive new
technologies and improve existing technologies
with emphasis on costs/benefits (reduce costs
and increase simplicity).
This strategy document focuses on the current state of
the following items as they pertain to small systems
and on the direction of future research activities for
these items:
• Source water issues
• Monitoring/Reporting
• Treatment processes
• Distribution systems
• Residuals Management
• Homeland Security
• Overall Utility Management
All research planning in the document should be in
the context of the six-year review of National Primary
Drinking Water Regulations (NPDWR) and the five-
year update of the Contaminant Candidate List (CCL).
Note that the last NPDWR review was in August 2002
and the last CCL update was in February 2005.
1.2 Document Organization
This document is organized into the following sec-
tions:
Chapter 1 - Introduction - This section presents a
brief introduction to this report
Chapter 2 - Current Status and Issues of Small
Drinking Water Systems
Chapter 3 - Regulatory Background - This section
presents a brief background of the
regulations impacting operators of small
drinking water systems
Chapter 4 - Source Water Issues
Chapter 5 - Treatment Processes
Chapter 6 - Distribution Systems
Chapter 7 - Waste Residuals
Chapter 8 - Homeland Security/Emergency Response
Chapter 9 - Remote Telemetry
Chapter 10 - Summary
1-1
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Chapter 2
Current Status and
Issues of Small
Drinking Water
Systems
2.1 Introduction
This Chapter provides an introduction to the current
status of small drinking water systems and the issues
facing small systems in maintaining compliance and
providing safe drinking water to the populace served
by these systems. The chapter begins with a detailed
snapshot profile (Section 2.2) of the distribution of
small systems based on the number of people served
and then provides brief overviews on the compliance
status (Section 2.3) of these small systems and source
water issues (Section 2.4). This chapter also provides
a brief introduction to the following topics:
• Common technologies currently used by small
systems to treat source water to meet drinking
water standards (Sections 2.5, 2.6, 2.7 and 2.8),
• Distribution system infrastructure (including
storage facilities, pumping facilities and
distribution lines) currently employed by small
systems (Section 2.9),
• Status of the use of remote telemetry to monitor
small systems operation (Section 2.10)
• Key questions to be answered through ongoing
research (Section 2.11)
2.2 Profile of Small Systems in the
U.S.
The EPA's Safe Drinking Water Information System
(SDWIS) estimates that there are 159,796 public
water systems (PWSs) in the U.S. (EPA, 2005a). The
SDWIS is a living database and portions of it are pe-
riodically updated. The profile data presented in this
section includes a conglomeration of data extracted
periodically from the SDWIS during the preparation
of this report (between 2004 and 2005). Depend-
ing upon when the data was extracted and when the
underlying SDWIS was updated, the exact numbers
and percentages for individual categories described
in the figures may vary slightly. However, the over-
all trends and statistics are consistent throughout the
period during which the SDWIS was updated. Most
of the SDWIS updates were performed between the
years 2000 and 2005; where information is available,
the specific year of the data presented is clearly identi-
fied. Unless otherwise stated, the graphs and statistics
relating to system types, population served, ownership,
violations, sizes, treatment scheme, piping distance
were all developed using the Pivot tables underlying
SDWIS (EPA, 2005b). Pivot tables are multidimen-
sional spreadsheets/databases that provide analytical
processing capability. The Pivot tables allow for quick
summarization, cross-tabulation, and analysis of large
amounts of data.
A PWS is any water system which provides water to
at least 25 people for at least 60 days annually. These
PWSs provide water from wells, rivers and other
sources to the majority (-85%) of the population in
the U.S. and territories (EPA, 2005b). The PWSs are
classified as follows:
• Community Water Systems (CWS) - A water
system which supplies drinking water to 25 or
more of the same people year-round in their
residences.
• Non-Transient Non-Community Water Systems
(NTNCWS) - A water system which supplies
water to 25 or more of the same people at
least six months per year in places other than
their residences. Some examples are schools,
factories, office buildings, and hospitals that
have their own water systems.
• Transient Non-Community Water Systems
(TNCWS) - A water system which provides
water in a place such as a gas station or
campground where people do not remain for
long periods of time. These systems do not have
to test or treat their water for contaminants that
pose long-term health risks because fewer than
25 people drink the water over a long period (6
months/year). They still must test their water
for microbes and several chemicals.
There are differing standards for PWSs of different
sizes and types. Most (approximately 55%) of the
PWSs in the U.S. belong to the TNCWS variety (EPA,
2005b). Figure 2.1 illustrates the percentage break-
down of the different system types. Most of these
systems represent the very small category (serving 25
- 500 people). Figure 2.2 shows the breakdown of
the number of small systems by system type. For the
purposes of this document, a small system is defined
as a CWS, NTNCWS, or TNCWS serving fewer than
10,000 persons (please note that a PWS serving 3001-
10,000 persons may be referenced as medium in some
graphics).
While most of the PWSs are TNCWSs, the vast majority
2-1
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news
•NTNCWS
DTNCWS
Figure 2.1 PWSs by system type (EPA,
2005b).
of people using PWSs actually obtain their water from
CWSs. As illustrated in Figure 2.3, approximately
90% of all people using public drinking water systems
obtain their water from CWSs. Figure 2.4 shows the
breakdown of system types by population category.
As indicated, approximately 84% of CWSs serve
populations of 3,300 or less. TNCWSs are mostly
represented in the very small category.
There are 159,796 CWSs, which includes both large
and small systems. There exists a great discrepancy
between the number of systems and the distribution of
the population served. Very small CWSs account for
57% of the total number of systems, although these
90
80
w 70
I 60
w 50
1 4°
| 30
i 20
10
000
000
000
000
000
000
000
000
000
0
D Very Small (25-500)
• Small (501-3300)
D Medium (3301-10,000)
CD
8
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CO
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CN
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CD
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Figure
NTNCWS
System Type
2.2 Small systems by system type - FY2004 (EPA, 2005b).
TNCWS
300,000,000
w 250,000,000
E
I 200,000,000
CO
o 150,000,000
L.
s
I 100,000,000
2 50,000,000
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CM
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o
CN
co"
CO
C7)
o
CD
CD
CO
CO"
~7
-s?
CWS NTNCWS TNCWS
Figure 2.3 Number of people served by system type - All systems FY2004 (EPA, 2005b).
2-2
-------
90,000
80,000
70,000
1 60,000
0)
H 50,000
V)
o 40,000
| 30,000
2 20,000
10,000
0^
X
8
o
o"
m
s
in
in
CD
=
^
o
oo
D CWS
• NTNCWS
D TNCWS
CM
CM
CM O h- ^t"
h- h- _|T O . CN
CM" CM" * §> - «?83 C^O^
<=?=& Tlt== ^^^= -?
Very Small Small Medium Large Very Large
(25-500) (501-3,300) (3,301-10,000) (10,001-100,000) (>1 00,000)
System Type
Figure 2.4 Number of PWSs for each service population group (EPA, 2005b).
a, 140,000,000i
o
| 120,000,000
(0
•5 w 100,000,000
(5 o
^+= 80,000,000
Eo
0)
z | 60,000,000
•£ o
°u 40,000,000
re
= 20,000,000
Q. n
u
D Service Connections
• Population
D Systems
—
3 ,1 rTfl
Very Small Small Medium
2,594,626 7,333,945 9,473,250
4,957,131 20,137,604 27,346,264
30,006 14,212 4,707
—
—
—
Large
32,152,151
99,808,668
3,541
n
Very Large
32,984,472
120,246,010
372
r 35,000
30,000 w
25,000 |
>,
20,000 w
M-
15,000 %
£1
10,000 |
5,000
n
u
System Size
Figure 2.5 Population served, service connections and number of systems - CWSs only
FY2004 (EPA, 2005b).
systems serve less than 2 percent of the population
served by CWSs. In contrast, the large and very large
systems account for roughly 7 percent of the total
number of systems but serve over 80% of the popula-
tion. Figure 2.5 shows a breakdown of population
served, number of service connections, and number of
systems for CWSs by system size.
PWSs are owned by various governmental, tribal, pub-
lic, or private entities. There is a relationship between
system size and ownership, with the vast majority of
very small systems (25-500 persons served) being
privately owned and a majority of larger systems being
owned by local government. Figure 2.6 shows the
breakdown of ownership for all systems.
2-3
-------
100,000
i
16,000
14,000
tfl
Figure 2.6 Drinking water system owners - FY 2004-159,796 total systems (EPA, 2005b).
2.3 Status of Drinking Water Plant
Violations
The SDWIS classifies drinking water system violations
into the following four major categories:
• Maximum contaminant level (MCL) violations;
Chapter 3 discusses MCLs in detail.
• Treatment Technique (TT) violations; according
to EPA, a treatment technique is a required
process intended to reduce the level of a
contaminant in drinking water. A few examples
of treatment techniques are disinfection,
filtration, and aeration (further discussed in
Chapter 3).
• Monitoring or Reporting (M/R) Violations.
These violations are primarily record-keeping
issues.
• Violations other than the three types mentioned
above.
Figure 2.7 shows the breakdown of system violations
for all PWSs. This figure shows that most PWS viola-
tions are attributed to M/R.
Figure 2.8 shows system violations by population
served, number of systems, and violation type. Very
small systems have the largest number of violations.
with the vast majority of these being M/R violations.
Figure 2.9 shows the breakdown of system violations
for small systems. Figure 2.9 looks very similar to
Figure 2.8 because the total violation statistics are
overwhelmingly dominated by small systems. Very
4.40%
7.90%
0.0004%
1.67%
• MCL
• Maximum Residual Disinfectant
Level
DTreatment Technique
D Monitoring or Reporting
• Other
86.02%
Figure 2.7 Violations reported FY2005 (EPA, 2005b).
2-4
-------
1 400000 ^
1200000
|2 1000000
0
I 800000
M-
° 600000
0)
1 400000
200000
n
x
/
.^^
D Very Small 25-500
• Small 501 -3,300
D Medium 3,301-10,000
D Large 10,001-100,000
• Very Large >100,000
^ S £P> ^i o
• •^ S U5 CM
co1 *> co o
N. CO CO csj o,
U5CMOOO T-OOCMcolE
307260
m
§
|§
nUj^y||£
MCL Maximum Residual Treatment Monitoring or
Disinfectant Level Technique Reporting
Other
Figure 2.8 Drinking water system violations for all system sizes - FY2005 (EPA, 2005b).
small systems also experience the greatest number of
MCL and TT violations. In addition, PWSs experi-
enced a total of 145,962 MCL violations (2005 data),
with 135,495 (93%) of the violations attributed to
small systems (population served less than 3,300).
Figure 2.10 illustrates the relationship between the
number of MCL violations and population served.
Very small systems (those serving 25 to 500 people)
experience approximately one MCL violation for
every 80 persons served, which is the highest ratio of
all system service population categories. In compari-
son, very large systems (population served greater
than 100,000) experience approximately one MCL
violation for every 196,204 persons served.
2.4 Source Water Issues
PWSs obtain drinking water from either surface or
ground water sources. Over 90% of the PWSs obtain
their water from ground water sources, with a vast
majority (87%) of those using ground water being
represented by small systems (serving a population
less than 3,300). Figure 2.11 shows the distribution of
water sources, by each of the five size categories.
Source waters from streams, rivers, lakes, or aquifers
are used to supply private water systems and PWSs.
The source water moves within a watershed via
overland flow (i.e., surface water), shallow subsurface
storm flow or ground water flow. The surface water
is vulnerable to contamination from both surface
runoff and ground water infiltration. Ground water
can become contaminated through infiltration from
4.47%
7.90%
0.0004%
1.52%
DMCL
D Maximum Residual Disinfectant
Level
D Treatment Technique
D Monitoring or Reporting
• Other
86.11%
Figure 2.9 Violations reported for systems serving
population from 25-10,000 - FY2005 (EPA, 2005b).
the surface, incursion of contaminants from under-
ground storage tanks, septic systems, injection wells.
or by naturally occurring substances in the soil or rock
through which it flows. These issues are discussed in
further detail in Chapter 4.
2.5 Common Current Treatment
Technologies
Most PWSs treat drinking water so that it will be safe
and palatable for the consumer. The application of a
specific TT depends on source water quality, system
size, and operator sophistication. Figures 2.12, 2.13
and 2.14 illustrate the variety and percent predomi-
nance of individual TTs used by the different size
classes of PWSs.
2-5
-------
45,000
40,000
35,000
c
.2 30,000
+J
jD
~ 25,000
M-
° 20,000
0)
E 15,000
3
10,000
5,000
- 40,000,000
^H Violations _ ,,R nnn nnn
+~
— ^— Population ^^"^
^^^ 30,000,000 §
•~
/ —
/ 25,000,000 0
/ c
/ 20,000,000 '~
/ •-
/ 1«
/ 15,000,000 2
/ 3
/ o.
/ °
^ 10,000,000 0.
^^^^
-*** - 5,000,000
Very Small Small Medium Large Very Large
(25-500) (501-3,300) (3,301-10,000) (10,001-100,000) (>1 00,000)
Figure 2. 10 MCL violations vs. populations served FY2005 (EPA, 2005b).
140,000
120,000
100,000
w
E
H 80,000
V)
i|—
O
L.
0)
1 60,000
40,000
20,000
0-
X
/
^=(
t-~
00
CM
D Ground Water
• Surface Water
•=r T-
1 ° Z71 - 8 t m -
1 i^" 1 •<- m "-1 O5 O5
n^ ^ — AL s g >
W W f €- — 0 £- 1^ 0 s s s /
I
Very Small Small Medium Large Very Large
(25-500) (501-3,300) (3,301-10,000) (10,001-100,000) (>100,000)
Figure 2.11 Source water comparison by size category (EPA, 2005b).
2-6
-------
90 -,
80-
70-
0) Rn
O)60-
re
+*
gso-
u
5
"
/
50,001-
100,000
'
ftt
( 7
t
I
^
100,001-
500,000
{
D Disinfection with no
additional treatment
• Other chemical addition
f
t
j£
\j
7
Dion exchange,
activated alumina,
aeration
D Filtration other than
direct or conventional
• Direct filtration
D Conventional filtration
J^l D Membranes
D Softening
t /
Over
500,000
System Service Population
Figure 2.13 Percentage of surface water plants using each treatment technique (EPA, 2002).
2-7
-------
100-
90-
80-
70-
0)60
5
§50-1
40-
30-
20-
10-
100 or
less
10,001-
50,000
50,001-
100,000
100,001-
500,000
Over
500,000
D Disinfection with no
additional treatment
• Other chemical addition
Dion exchange,
activated alumina,
aeration
D Filtration other than
direct or conventional
• Direct filtration
D Conventional filtration
• Membranes
D Softening
System Service Population
Figure 2.14 Percentage of mixed plants using each treatment technique (EPA, 2002).
The individual TTs are designed to be effective in
removing one or more types of contaminants includ-
ing paniculate, chemical and biological contaminants.
Depending upon the type of contamination present in
the source water, one or more TTs may be applied by
the PWS to provide safe drinking water to consum-
ers. A general discussion of available TTs to remove
paniculate (Section 2.6), chemical contaminants (Sec-
tion 2.7) and biological contaminants (Section 2.8)
is presented in this Chapter. A more comprehensive
discussion of TTs is presented in Chapter 5.
2.6 Particulate/Turbidity Removal
Technologies
Paniculate and turbidity removal is an almost univer-
sally used technology for the primary treatment of
drinking water. The primary means of paniculate re-
moval is by means of simple filtration either by using
media filtration (e.g., sand filter) or by the use of bag
and/or cartridge filters. Advanced filtration techniques
include membrane filtration and other technologies.
This section provides a very brief overview of these
technologies.
2.6.1 Simple Filtration
Filtration is a process for removing paniculate matter
from water by passage through porous media. There
are numerous types of filtration processes. Some com-
mon filtration processes are summarized below (these
descriptions are available in many standard text books.
where applicable references have been provided for
specific usage and equipment descriptions):
Slow Sand Filtration - is a process where untreated
water percolates slowly down through a layer
of fine sand, then through a layer of gravel, and
ultimately collects in a system of underdrains.
A biological layer or "schmutzdecke" forms on
the surface of the sand, trapping small particles.
The schmutzdecke also helps to degrade organic
material in the water.
Diatomaceous Earth (DE) - also known as pre-
coat or diatomite filtration, can be used to
directly treat low turbidity raw water supplies
or chemically coagulated, more turbid water
sources. DE filters consist of a pre-coat layer of
DE, approximately 1/8-inch thick, supported by
a septum or filter element (EPA, 1998).
Conventional Filtration - is a method of treating
water to remove particulates. The method
consists of the addition of coagulant chemicals.
flash mixing, coagulation-flocculation.
sedimentation and filtration.
Direct Filtration - also known as "dead-end
filtration" is similar to conventional filtration
with the sedimentation process omitted.
Packaged Filtration - consists of all of the fea-
tures of filtration - chemical addition, flocculation.
sedimentation, filtration - mounted as a unit on a
frame for simple hookup of pipes and services. It
is most widely used to treat surface water supplies
for removal of turbidity, color, and coliform organ-
2-8
-------
isms with filtration processes. Packaged filtration is
often used to treat small community water supplies,
as well as supplies in recreational areas, state parks,
construction sites, ski areas, and military installations
(NDWC, 1996).
2.6.2 Advanced Filtration
Membrane Filtration - Membrane filtration (as
defined under the Long Term 2 Enhanced
Surface Water Treatment Rule-LT2ESWTR) is
a pressure-driven separation process in which
paniculate matter larger than 1-micrometer is
rejected by an engineered barrier, primarily
through a size-exclusion mechanism and which
has a measurable removal efficiency for a
target organism that can be verified through
the application of a direct integrity test (EPA,
2003a). Some common types of membrane
filtration are:
Microfiltration - is a pressure-driven membrane
filtration process that typically employs
hollow-fiber membranes with a pore size
range of approximately 0.1-0.2 micrometers
(nominally 0.1 micrometers) (EPA, 2003a).
Ultrafiltration - is a pressure-driven membrane
filtration process that typically employs
hollow-fiber membranes with a pore size range
of approximately 0.01 - 0.05 micrometer
(nominally 0.01 micrometers) (EPA, 2003a).
Nanofiltration - is a pressure-driven membrane
separation process that employs the principles
of reverse osmosis to remove dissolved
contaminants from water and is typically
applied for membrane softening or the removal
of dissolved organic contaminants (EPA,
2003a).
2.6.3 Reverse Osmosis (RO)
RO resembles membrane filtration processes in that
contamination from water is removed by the use
of a membrane. However, unlike membrane filtra-
tion where water is forced through a media leaving
behind the contaminant, RO uses hydraulic pressure
to oppose the liquid osmotic pressure across a semi-
permeable membrane, forcing the water from the
concentrated solution side to the dilute solution side.
Thus, the RO membrane allows the passage of the
solvent (water) but not the dissolved solids (solutes).
Since the membrane is non-porous, the water does
not travel through pores, but rather dissolves into
the membrane, diffuses across, and then dissolves
into the permeate (EPA, 1998b). RO can effectively
remove nearly all contaminants from water includ-
ing arsenic (III), arsenic (V), barium, cadmium,
chromium (VI), radium, natural organic substances,
pesticides, and microbiological contaminants. The
liquid produced is demineralized water.
2.7 Chemical Contaminant
Removal
Chemical contaminants are commonly removed using
ion exchange and sorption technologies. This section
provides a brief overview of these technologies along
with other TTs that are used to remove chemical con-
taminants in drinking water.
2.7.1 Ion Exchange (IX)
Ion exchange involves the selective removal of charged
inorganic species from water using an ion-specific
resin. The surface of the ion exchange resin contains
charged functional groups that hold ionic species by
electrostatic attraction. As water containing undesired
ions passes through a column of resin beds, charged
ions on the resin surface are exchanged for the unde-
sired species in the water. The resin, when saturated
with the undesired species, is regenerated with a solu-
tion of the exchangeable ion (EPA, 1998b).
Generally, resins can be categorized as anion exchange
or cation exchange resins. Anion exchange resins se-
lectively remove anionic species such as nitrate (NO3~),
sulfate (SO42~), or fluoride (F~) and exchange them
for hydroxyl (OH") or chloride (Cl~) ions. Cation
exchange resins are used to remove undesired cations
such as cadmium (Cd2+) or Barium (Ba2+) from water
and exchange them for protons (H+), sodium ions
(Na+) or potassium ions (K+) (EPA, 1998b). The pH
of the source water is important when employing IX
resins. For example, uranium exists in water at pH
levels of 6.0 and higher as a carbonate complex, which
is an anion, and thus has a strong affinity for anion
resin in the chloride form. The process is effective
on water with a pH of up to 8.2. A higher pH could
result in uranium precipitation; a lower pH changes
the nature of uranium to non-ionic and/or cationic spe-
cies, which would prevent the exchange reaction from
operating efficiently. It is advisable to control the inlet
water pH to above 6.0. Sudden pH changes to below
5.6 can dump any previously removed uranium off the
resin (DeSilva 1996).
2.7.2 Sorption Technologies
Adsorption involves the removal of ions and molecules
from solution and concentrating them on the surface
of adsorbents. Adsorption is driven by the interfacial
forces of the ions and the adsorbent. Adsorption media
employed at drinking water plants include granular
activated carbon, activated alumina, and iron media.
Sorption technologies are used for the removal of
organics, taste and odor, and inorganic contaminants
(such as arsenic).
2-9
-------
2.7.3 Other Technologies
Aeration Technologies - Aeration technologies are
typically used for removal of volatile organic
compounds and for removal of excess carbon
dioxide. In general, aeration is the contacting of
the water with air wherein the target chemical
is transferred from the water to the air stream.
There are a number of methods used for the
mixing of air and water including packed
aeration towers, shallow tray air strippers,
mechanical aeration, and spray aeration.
Softening - Softening is used to remove calcium
and magnesium ions from water. Types of
technologies used include ion exchange,
chemical flocculation, and precipitation.
Electrodialysis (ED) - Another less commonly
used technology for chemical removal is ED,
which is a process in which ions are transferred
through ion-selective membranes by means of
an electromotive force from a less concentrated
solution to a more concentrated solution (EPA,
2003a). ED is very effective in removing
fluoride and nitrate, and can also remove barium,
cadmium, and selenium (NDWC, 1997).
Reverse Osmosis - Can remove many chemical
contaminants effectively. See Section 2.6.3 for
further details.
2.8 Biological Contaminant
Removal
Disinfection is a process for reducing the number of
pathogenic microbes in water and is required by the
Surface Water Treatment Rule (SWTR) for all PWSs
that obtain their water from surface water or ground
water under the influence of surface water. In addition,
PWSs must maintain a residual level of disinfectant
in the distribution system per 40 CFR 141.72. It is
required that, at the point where the water enters the
distribution system, the residual disinfection con-
centration not fall below 0.2 mg/L. In addition, the
residual disinfection concentration must be maintained
throughout the distribution system such that non-de-
tection results are measured in no more than 5% of the
samples collected each month.
2.8.1 Chlorination
Chlorine is the most common method used for disin-
fection. There are a number of methods of delivery
and chemical reactions utilized for chlorination. These
include chlorine gas, chloramines, chlorine dioxide,
and sodium hypochlorite. The goal of all these meth-
ods is to release free chlorine in the form of hypochlo-
rite, or in the case of chloramines, combined available
chlorine (NH2C1 and NHC12).
2.8.2 Ultraviolet Light (UV)
Contaminated water is exposed to UV light, which
penetrates the cell walls of an organism. UV disrupts
the organism's genetic material which inactivates the
organism. A special lamp generates the radiation that
creates UV light by striking an electric arc through
low-pressure mercury vapor (low-pressure UV). This
lamp emits a broad spectrum of radiation with intense
peaks at UV wavelengths of 253.7 nanometers (nm)
and a lesser peak at 184.9 nm. Research has shown
that the optimum UV wavelength range to destroy bac-
teria is between 250 nm and 270 nm. At shorter wave-
lengths (e.g. 185 nm), UV light is powerful enough to
produce ozone, hydroxyl, and other free radicals that
destroy bacteria (NDWC, 2000).
2.8.3 Ozone
Ozone is a colorless, very unstable gas that is effective
as an oxidizing agent in removing bacteria with a rela-
tively short exposure time. Since the gas is unstable
and has a very short life, ozone generators are used to
produce ozone gas on site.
2.8.4 Other Disinfection Technologies
There are a number of other disinfection technologies
used in ultra pure water applications, but are not ap-
plicable nor typically used in water supply situations.
These include ammonium compounds, non-oxidizing
biocides (i.e. formaldehyde), heat, and peracetic acid.
Tables 2.1, 2.2, 2.3, 2.4, 2.5 and 2.6 present candidate
technologies for treatment of inorganic contaminants,
volatile organic contaminants, synthetic organic con-
taminants, radionuclides, disinfection, and filtration
respectively. Table 2.7 identifies compliance technol-
ogy for the Total Coliform Rule.
2.9 Distribution System
Infrastructure
Drinking water is delivered from a water treatment
facility to its customers by means of a distribution
system. This infrastructure generally consists of a
combination of three key elements: treated water stor-
age facilities (e.g., ground storage tanks, elevated stor-
age tanks, standpipes, hydropneumatic tanks), pump-
ing facilities (e.g., booster pumps, piping, control,
pump building), and the distribution lines (e.g., piping,
valves, fire hydrants, meters). Most of the distribution
system infrastructure is located underground, making
it more difficult to detect problems such as leaks and
pipe deterioration. Various standards and procedures
for design, material selection, plumbing code, opera-
tion, and maintenance have been established that help
maintain the integrity of the system (EPA, 1999). The
distribution system issues facing small systems are
2-10
-------
Table 2.1 Technologies for inorganic contaminants (NDWC, undated).
Operator Skill
Unit Technology Limitations* Level Required RawWater Quality Range
1 . Activated Alumina
2. Ion Exchange
3. Lime Softening
4. Coagulation/ Filtration
5. Reverse Osmosis (RO)
6. Alkaline Chlorination
7. Ozone Oxidation
8. Direct Filtration
9. Diatomaceous Earth Filtration
10. Granular Activated Carbon
1 1 . Elecrodialysis Reversal
12. Point of Use (POU)-IX
13. POU-RO
14. Calcium Carbonate Precipitation
15. pH and Alkalinity Adjustment
(chemical feed)
16. pH and Alkalinity Adjustment
(limestone contactor)
17. Inhibitors
18. Aeration
(a)
(b)
(c)
(d)
(e)
(f)
(f)
(g)
(g)
(h)
(i)
Advanced
Intermediate
Advanced
Advanced
Advanced
Basic
Intermediate
Advanced
Intermediate
Basic
Advanced
Basic
Basic
Basic
Basic
Basic
Basic
Basic
Ground waters, competing anion concentrations will
affect run length.
Ground waters with low total dissolved solids, com-
peting ion concentrations will affect run length.
Hard ground and surface waters
Can treat wide range of water quality.
Surface water usually require prefiltration.
All ground waters.
All ground waters.
Needs high raw water quality.
Needs very high raw water quality.
Surface waters may require prefiltration.
Requires prefiltration for surface water.
Same as Technology #2.
Same as Technology #5.
Water with high levels of alkalinity and calcium.
All ranges.
Waters that are low in iron and turbidity. Raw water
should be soft and slightly acidic.
All ranges.
Waters with moderate to high carbon dioxide content.
Limitation Footnotes
a) Chemicals required during regeneration and pH adjustments may be difficult for small systems to handle.
b) Softening chemistry may be too complex for small systems
c) It may not be advisable to install coagulation/filtration solely for inorganics removal.
d) If all of the influent water is treated, post-treatment corrosion control will be necessary.
e) pH must exceed pH 8.5 to ensure complete oxidation without build-up of cyanogen chloride.
f) When POU devices are used for compliance, programs for long-term operation, maintenance, and monitoring must be provided by water utility
to ensure proper performance.
g) Some chemical feeds require high degree of operator attention to avoid plugging.
h) This technology is recommended primarily for the smallest size category.
i) Any of the first five aeration technologies listed for volatile organic contaminants (Table 2.2) can be used.
Table 2.2 Technologies for volatile organic contaminants (NDWC, undated).
Limitations Operator Skill Level Raw Water
Unit Technology (see footnotes) Required Quality Range
1 . Packed Tower Aeration (PTA)
2. Diffused Aeration
3. Multi-Stage Bubble Aerators
4. Tray Aeration
5. Shallow Tray Aeration
6. Spray Aeration
7. Mechanical Aeration
8. Granular Activated Carbon (GAC)
(a)
(a,b)
(a,c)
(a,d)
(a,e)
(a,f)
(a,g)
(h)
Intermediate
Basic
Basic
Basic
Basic
Basic
Basic
Basic
All ground waters.
All ground waters.
All ground waters.
All ground waters.
All ground waters.
All ground waters.
All ground waters.
All ground waters.
Limitation Footnotes
a) Pretreatment for the removal of microorganisms, iron, manganese, and excessive particulate matter may be needed. Post-treatment disinfec-
tion may have to be used.
b) May not be as efficient as other aeration methods because it does not provide for convective movement of the water thus limiting air-water
contact. It is generally used only to adapt existing plant equipment.
c) These units are highly efficient; however, the efficiency depends upon the air-to-water ratio.
d) Costs may increase if a forced draft is used. Slime and algae growth can be a problem but can be controlled with chemcials such as copper
sulfate or chlorine.
e) These units require high air-to-water ratios (100-900 m3/m3).
f) For use only when low removal levels are needed to reach a MCL because these systems may not be as energy efficient as other aeration
methods because of the contacting system.
h)
methods. The units often require large basins, long residence times, and high energy inputs, which may increase costs.
See table 2.3 for limitations regarding these technologies.
2-11
-------
Table 2.3 Technologies for synthetic organic contaminants (NDWC, undated).
Limitations Operator Skill Level Raw Water Quality Range
Unit Technology (see footnotes) Required and Considerations
1 . Granular Activated Carbon (GAC)
2. Point of Use GAC
3. Powdered Activated Carbon
4. Chlorination
5. Ozonation
6. Packed Tower Aeration (PTA)
7. Diffused Aeration
8. Multi-Stage Bubble Aerators
9. Tray Aeration
1 0. Shallow Tray Aeration
(h)
(a, h)
(b,h)
(c)
(c)
(d)
(d,e)
(d,f)
(d,g)
(d,f)
Basic
Basic
Intermediate
Basic
Basic
Intermediate
Basic
Basic
Basic
Basic
Surface water may require prefiltration.
Surface water may require prefiltration.
All waters
Better with high quality waters.
Better with high quality waters.
All ground waters.
All ground waters.
All ground waters.
All ground waters.
All ground waters.
Limitation Footnotes
a) When POU devices are used for compliance, programs for long-term operation, maintenance, and monitoring must be provided by water utility
to ensure proper performance.
b) Most applicable to small systems that already have a process train including basins, mixing, precipitation or sedimentation, and filtration. Site
specific design should be based on studies conducted on the system's particular water.
c) See the Surface Water Treatment Rule compliance technology tables for limitations associated with this technology.
d) Pretreatment for the removal of microorganisms, iron, manganese, and excessive particulate matter may be needed. Post-treatment disinfec-
tion may have to be used.
e) May not be as efficient as other aeration methods because it does not provide for convective movement of the water thus limiting air-water
contact. It is generally used only to adapt existing plant equipment.
f) These units are highly efficient; however, the efficiency depends upon the air-to-water ratio.
g) Forces may increase if a forced draft is used.
h) Pretreatment for removal of suspended solids is an important design consideration. Spent carbon must be regenerated or disposed properly.
Table 2.4 Technologies for radionuclides (NDWC, undated).
Limitations Operator Skill Level Raw Water Quality Range
Unit Technology (see footnotes) Required and Considerations
IX
Point of Use (POU) IX
Reverse Osmosis (RO)
POU RO
Lime Softening
Green Sand Filtration
Co-precipitation with Barium Sulfate
Electrodialysis/Electrodialysis Reversal
Pre-formed Hydrous Manganese
Oxide Filtration
(a)
(b)
(c)
(b)
(d)
(e)
(0
(g)
Intermediate
Basic
Advanced
Basic
Advanced
Basic
Intermediate to
Advanced
Advanced
Intermediate
All ground waters.
All ground waters.
Surface waters, usually require prefiltration.
Surface waters, usually require prefiltration.
All waters.
Ground waters with suitable water quality
All ground waters.
All ground waters.
Limitation Footnotes
a) The regeneration solution contains high concentrations of the contaminant ions. Disposal options should be carefully considered before
choosing the technology.
b) When POU devices are used for compliance, programs for long-term operation, maintenance, and monitoring must be provided by water utility
to ensure proper performance.
c) Reject water disposal options should be carefully considered before choosing this technology. See other RO limitations described in the Sur-
face Water Treatment Rule Compliance Table.
d) The combination of variable source water quality and the complexity of the chemistry involved in lime softening may make this technology too
complex for small surface water systems.
e) Removal efficiencies can vary depending on water quality.
f) This technology may be very limited in application to small systems. Since the process requires static mixing, detention basins, and filtration; it
is most applicable to systems with sufficiently high sulfate levels that already have a suitable filtration treatment train in place.
g) This technology is most applicable to small systems that already have filtration in place.
2-12
-------
Table 2.5 Technologies for disinfection (NDWC, undated).
Limitations Operator Skill Raw Water Quality Range
Unit Technology (see footnotes) Level Required and Considerations
Free Chlorine
Ozone
Chloramines
Chlorine Dioxide
Onsite Oxidant Generation
Ultraviolet (UV) Radiation
(a,b)
(c,d, h)
(e)
(f)
(g)
(h)
Basic
Intermediate
Intermediate
Intermediate
Basic
Basic
Better with high quality. High iron or manganese may require
sequestration or physical removal.
Better with high quality. High iron or manganese may require
sequestration or physical removal.
Better with high quality. Ammonia dose should be tempered
by natural ammonia levels in water.
Better with high quality.
Better with high quality.
Relatively clean source water required. Iron, natural organic
matter and turbidity affect UV dose.
Limitation Footnotes
a) Providing adequate CT may be a problem for some water supplies.
b) Chlorine gas requires special caution in handling and storage, and operator training.
c) Ozone leaks represent hazard: air monitoring required.
d) Ozone used as primary disinfectant (i.e., no residual protection).
e) Long CT. Requires care in monitoring of ratio of added chlorine to ammonia.
f) Chlorine dioxide requires special storage and handling precautions.
g) Oxidants other than chlorine not detected in solution by significant research effort. CT should be based on free chlorine until new research
determines appropriate CT values for electrolyzed salt brine.
h) No disinfectant residual protection for distributed water.
Table 2.6 Technologies for filtration (NDWC, undated).
Limitations Operator Skill Level
Unit Technology (see footnotes) Required RawWater Quality Range and Considerations
Conventional Filtration
(includes dual-stage and
dissolved air flotation
Direct Filtration (includes
in-line filtration
Slow Sand Filtration
Diatomaceous Earth
Filtration
Reverse Osmosis
Nanofiltration
Ultrafi It ration
Microfiltration
Bag Filtration
Cartridge Filtration
Backwashable Depth
Filtration
(a)
(a)
(b)
(c)
(d,e,f)
(e)
(g)
(g)
(g,n,i)
(g,n,i)
(g,n,i)
Advanced
Advanced
Basic
Intermediate
Advanced
Intermediate
Basic
Basic
Basic
Basic
Basic
Wide range of water quality. Dissolved air flotation is more
applicable for removing particulate matter that doesn't
readily settle: algae, high color, low turbidity-up to 30-50
nephelometric turbidity units (NTU) and low-density turbidity.
High quality. Suggested limits: average turbidity 10 NTU;
maximum turbidity 20 NTU; 40 color units; algae on a case-
by-case basis.
Very high quality or pretreatment. Pretreatment required if
raw water is high in turbidity, color, and/or algae.
Very high quality or pretreatment. Pretreatment required if
raw water is high in turbidity, color, and/or algae.
Requires prefiltrations for surface water-may include re-
moval of turbidity, iron, and/or manganese. Hardness and
dissolved solids may also affect performance.
Very high quality of pretreatment. See reverse osmosis
pretreatment.
High quality or pretreatment.
High quality or pretreatment required.
Very high quality or pretreatment required, due to low
particulate loading capacity. Pretreatment if high turbidity
or algae.
Very high quality or pretreatment required, due to low
particulate loading capacity. Pretreatment if high turbidity
or algae.
Very high quality or pretreatment required, due to low
particulate loading capacity. Pretreatment if high turbidity
or algae.
Limitations Footnotes
a. Involves coagulation. Coagulation chemistry requires advanced operator skill and extensive monitoring. A system needs to have direct full-time
access or full-time remote access to a skilled operator to use this technology properly.
b. Water service interruptions can occur during the periodic filter-to-waste cycle, which can last from six hours to two weeks.
c. Filter cake should be discarded if filtration is interrupted. For this reason, intermittent use is not practical. Recycling the filtered water can remove
this potential problem.
d.l
e. Post-disinfection recommended as a safety measure and for residual maintenance.
f. Post-treatment corrosion control will be needed prior to distribution.
g. Disinfection required for viral inactivation.
h. Site-specific pilot testing prior to installation likely to be needed to ensure adequate performance.
i. Technologies may be more applicable to system serving fewer than 3,300 people.
2-13
-------
Table 2.7 Compliance technology for the Total Coliform Rule (NDWC, undated).
40 CFR 141.63(d) - Best technologies or other
means to comply
(Complexity level indicated) Comments/Water Quality Concerns
Protecting wells from contamination, e.g., place-
ment and construction of well(s) (Basic).
Maintenance of a disinfection residual for distribu-
tion system protection (Intermediate).
Proper maintenance of distribution system: pipe
repair/replacement, main flushing programs,
storage/reservoir, and O&M programs (including
cross-connection control/backflow prevention),
and maintenance of positive pressure throughout
(Intermediate).
Filtration and/or disinfection of surface water or
other ground water under direct influence; or disin-
fection of ground water (Basic thru Advanced).
Ground waters: Compliance with State Wellhead
Protection Program (Intermediate).
Ten State Standards and other standards (AWWA, 1995) apply; interfacing
with other programs essential (e.g., source water protection program).
Source water constituents may affect disinfection: iron, manganese, organ-
ics, ammonia, and other factors may affect dosage and water quality. Total
Coliform Rule (TCR) remains unspecific on type/amount of disinfectant, as
each type differs in concentration, time, temperature, pH, interaction with
other constituents, etc.
O&M programs particularly important for smaller systems needing to main-
tain water purity. States may vary on distribution protection measures.
See also EPA's Cross-Connection Control Manual (EPA, 2003b)
Same issues as cited above under maintaining disinfection residual;
pretreatment requirements affect complexity of operation. Refer to Surface
Water Treatment Rule Compliance Technology List; and other regulations
under development.
EPA/State Wellhead Protection Program implementation (per §1428
SDWA): may be used to assess vulnerability to contamination, and in
determination of sampling and sanitary survey frequencies.
further discussed in Chapter 6. The following is a
brief description of each of the key distribution system
infrastructure elements.
2.9.1 Storage Facilities
Storage facilities may be closed tanks or reservoirs and
are designed to store treated water (ground storage)
or to maintain adequate service pressure (elevated,
hydropneumatic, or ground storage that is built at a
location to act as elevated storage).
A clearwell tank is generally the first treated water stor-
age tank and is located at the end of the treatment train
or at the end of a well system. Their primary purpose is
to provide for contact time when chemical treatment ad-
ditives (e.g., chlorine) are used. These storage structures
have limited use as storage reservoirs due to their loca-
tion. The added storage or reserve capability of clear-
wells are an advantage for small system operators that
need time for maintenance of equipment or structures,
or other storage needs such as fire flows, but this is not
their intended use. Utilities should not rely on clearwell
storage as their only means of reserve for the distribution
system. The clearwell tank also serves as a reservoir
for the storage of filtered water of sufficient capacity to
prevent the need to vary the filtration rate with varia-
tions in demand. Clearwell tanks provide both a treated
water reserve for delivery to the distribution system and
additional detention time for more effective disinfec-
tion (EPA, 1999). Figure 2.15 shows the percentage of
CWSs that use clearwell tanks for treated-water storage.
Depending on the complexity and size of the distri-
bution system, the other storage tanks are designed
to provide pressure maintenance for the distribution
system. If the system serves a small number of cus-
tomers, a pressurized tank called a hydropneumatic
tank (controlled by both water and air pressures) is
used to maintain the system pressure, because it is
cheaper to build than an elevated tank. Different
sections of the distribution system are maintained at
different pressures (commonly referred to as pres-
sure zones), depending on the water demand and
pressure head requirements. (EPA, 1999).
Tables 2.8 and 2.9 show the percentage of CWSs that
have treated-water storage either before or within the
distribution system.
Storage tank capacities are designed to be adequate
to meet the water demands of the system, meet
applicable state requirements and industry stand-
ards, and be consistent with accepted engineering
practice. For example, the total capacity of both
ground and elevated storage tanks could be based on
a recommended level of 200 gallons per connection.
For elevated storage tanks alone, a recommended
capacity of 100 gallons per connection is often used.
For systems using hydropneumatic tanks instead
of elevated tanks, recommended capacities are 20
gallons per connection with ground storage and 50
gallons per connection without ground storage (EPA,
1999).
2-14
-------
Table 2.8 Percentage ofCWSs (within each system service population category) that have
treated-water storage, before distribution system.
System Service Population Category
Primary Source 25- 501- 3,301- 10,001- Over
ofWater Configuration 500 3,300 10,000 100,000 100,000
Ground Water
Systems
Surface Water
Systems
3urchased Water
Systems
With Dedicated Entry and Exit Points
With a Common Inlet and Outlet
With Dedicated Entry and Exit Points
With a Common Inlet and Outlet
With Dedicated Entry and Exit Points
With a Common Inlet and Outlet
31.6
16.8
41.3
6.5
10.6
10.5
17.0
15.6
16.6
18.3
5.3
7.6
23.1
8.8
27.7
16.7
13.5
15.3
26.2
16.5
32.3
7.4
11.9
1.5
32.4
25.3
33.1
25.9
33.6
0.0
Table 2.9 Percentage ofCWSs (within each system service population category) that have
treated-water storage within the distribution system.
System Service Population Category
Primary Source 25- 501- 3,301- 10,001- Over
ofWater Configuration 500 3,300 10,000 100,000 100,000
Ground Water
Systems
Surface Water
Systems
Purchased Water
Systems
With Dedicated Entry and Exit Points
With a Common Inlet and Outlet
With Dedicated Entry and Exit Points
With a Common Inlet and Outlet
With Dedicated Entry and Exit Points
With a Common Inlet and Outlet
2.9
11.9
6.0
20.5
3.5
14.4
10.0
68.6
4.1
73.6
8.8
55.4
16.5
54.0
29.2
73.0
22.6
61.6
31.9
70.7
39.8
72.8
35.5
63.9
51.8
82.8
58.6
72.0
56.8
64.6
I Primarily Ground Water Systems • Primarily Surface Water Systems D Primarily Purchased Water Systems
1 VJVJ
90
80
70
w
E
Si 60
ercentage of Sy
CO Ji. en
O O O
°- 20
10
-
|
100 or
less
^
_
^
1
101-
500
\\
*=o-
^
=\
—
I
501- 3,301-
3,300 10,000
L
^
^
=
I
10,001-
50,000
p
^
=
L
-
^
t
i
50,001- 100,001-
^
\\
Over
100,000 500,000 500,000
System Service Population
Figure 2.15 Percentage of CWSs within each system service population category that have
a clearwell type finished water storage (EPA, 2002).
2-15
-------
2.9.2 Pumping facilities
Pumps are used for moving fluid (e.g., water, chemi-
cal) through the distribution system, sludge removal.
air compression and sampling. The three types of
pumps generally used to pump water at a treatment
plant are: positive displacement, centrifugal, and
ejector. A positive displacement pump delivers water
at a constant rate regardless of the pressure it must
overcome. A centrifugal pump is used when an even
flow rate is needed to meet the demands placed on it.
Ejector pumps are typically used to deliver treatment
chemical to the water being treated. Pump capacity is
typically dependent on the application or purpose.
Most pumping applications rely on a pumping station
that includes a pump(s), a structure to house or support
the pump, piping - suction and discharge, lighting.
ventilation, an electrical center and control panel for
the pump(s) and lighting, and appurtenances.
2.9.3 Distribution Lines
Underground pipes are the largest component of the
distribution system and as such, design standards are
established that specify the minimum requirements for
all water lines. Typically, the design standards also
specify many of the following items (EPA, 1999):
• Minimum pipe size (typically there should be no
lines less than 2-inch);
• Minimum line size criteria (either maximum
water velocity or number of connections served
for a given line size);
Minimum line size where fire hydrants are to be
provided (6-inch is the minimum);
Minimum line size for specific requirement of
the distribution system (e.g., transmission line
should be at least 12-inches);
Design flow for each type of connection (e.g..
residential, commercial, industrial);
Design fire flow for specific areas of
development (e.g., residential, commercial.
industrial);
Location of line relative to other utilities
(sanitary sewer, in particular) and right-of-way
limits;
Location or spacing of valves;
Direction of valves (right or left opening);
Type of valves to be used (vacuum/air release.
butterfly, or gate valve);
Location or spacing of fire hydrants;
Type of fire hydrants to be used (dry or wet barrel);
Pipe material, including requirements for
internal as well as external corrosion;
Appurtenances required for flushing of dead-end
lines;
4,000
3,500
J8 3,000
i
o 2,500
L.
0)
E 2,000
3
z
o) 1,500
2
0)
< 1,000
500
0
I Public Systems
D Private Systems
100 or less 101-500 501-3,300
10,001-
50,000
O)
CO
CO
^
o
E8
T
1
T
1
50,001- 100,001-
100,000 500,000
Over
500,000
3,301-
10,000
System Service Population
Figure 2.16 Average number of miles of distribution mains (public vs. private systems). Error
bars represent the 95% confidence interval (EPA, 2002).
2-16
-------
• Minimum cover or depth-to-bury requirements;
• Pressure testing to determine that there are no
leaks in the line;
• Construction or installation requirements; and
• Location and construction of appurtenances in
the floodplain.
The vast majority of piping used for distribution lines
in CWSs is used by very large systems serving popula-
tions over 500,000 persons. Also, for small systems.
private systems tend to have more miles of pipe in
place than public systems (when comparing the same
system service population size) (Figure 2.16).
Most of the piping replaced each year is performed in
the private rather than the public sector (Figure 2.17)
and as would be expected, very large systems replace
more piping per year than smaller systems.
There are 293,087,350 customer connections, over
55% of which are part of CWSs (Figure 2.18). Very
small systems account for almost 73% of customer
connections, with the majority of those systems being
privately owned (Table 2.10).
CWS distribution pipes are of various diameters. In
all but the very largest of systems (those serving over
500,000 persons), there is a tendency to use more dis-
tribution pipes that average less than 6-inches than it
is to use distribution pipes of 6-to 10-inches or greater
than 10-inches. Very large systems (especially those
that are privately owned) on average use more distribu-
tion pipes of the 6-to 10-inch variety than either of the
other two sizes (Figures 2.19 and 2.20). Typically, as
would be expected, the distribution mains (or trunk
lines) are of the larger diameter in size.
The vast majority of CWS piping (approximately
78%) is less than 40 years old. Approximately 18% is
between 40 and 80 years old and the remaining 4% is
over 80 years old (Figure 2.21). Publicly owned sys-
tems tend to have slightly older piping on average than
do privately owned systems, with approximately 24%
of public systems piping averaging 40 to 80 years old
as compared to approximately 8% of private systems
in the same age range (Figure 2.22).
2.10 Remote Telemetry-
Supervisory Control and Data
Acquisition (SCADA)
Remote telemetry or SCADA is used to control all
aspects of a device from a centralized location. In
the past, small systems did not always use SCADA
to their fullest potential due to complex operating
systems and controls that usually required specially
300
•2 250
E
0)
o
Q.
0)
as
c
c
<
0)
01
2
0)
200
150
100
50
I Public Systems
D Private Systems
o
CM
00
C.J-
° OJ
100 or less 101-500 501-3,300 3,301- 10,001- 50,001- 100,001- Over
10,000 50,000 100,000 500,000 500,000
System Service Population
Figure 2.17 Public vs. private average annual pipe replaced (for CWSs) 5-year average.
Error bars represent the 95% confidence interval (EPA, 2002).
2-17
-------
c
o
Connect
Number of
180,000,000-
160,000,000-
140,000,000-
120,000,000-
100,000,000-
80,000,000-
60,000,000-
40,000,000-
20,000,000 -
0-
D CWS
• NTNCWS
D TNCWS
1
"
^
L rL
Very Small
(25-500)
83,572,950
72,247,798
58,042,062
£ >
^ fl f S\
H3U, flk_ 1L
Small Medium Large Very Large rrand Totai
(501-3,300) (3,301-10,000) (10,001-100,000) (>100,000)
7,279,586 9,140,490 30,871,660 31,703,961 162,568,647
111,881 24,432 1,931 98 72,386,140
84,909 3,253 141 2,198 58,132,563
System Service Population
Figure 2.18 System service connections (EPA, 2002).
c
'(5
M-
o
L.
0)
£1
E
z
0)
01
re
L.
0)
(J
2
2
1
1
1
1
1
400
200
r> i->i->
000
800
600
400
200
000
800
600
400
200
D Distribution Mains Less Than 6 Inches
• Distribution Mains 6 to 1 0 Inches
c
s
•^
)
!
D Distribution Mains Greater Than 10 Inches
CO
8
0 CO ^ "• L" IT
^T P P code) n ° K"^
^- o o j —
100 or less 101-500 501-3,300 3,301-
t
Jl
a
s
&
5 CO
: ^~
3 ^ SS "^
- g y § T,
T 5 CD m^ g
•^ rhi2 n*i
Iptfel
-
T
1
11^"
1
10,001- 50,001- 100,001- Over
10,000 50,000 100,000 500,000 500,000
Figure
System
2. 19 Average number of miles of pipes in
Service
Population
distribution systems - privately owned (EP/-
2002).
2-18
-------
1,100
1,000
900
w
c
're 800
"5 700
J2 600
E
J 500
CD
0) 400
2
0)
> 300
200
100
03
£ <°
ST
D Distribution Mains Less Than 6 Inches
• Distribution Mains 6 to 10 Inches
D Distribution Mains Greater Than 1 0 Inches
Q
&
T 5
co q IK q
8 S3 [If £
>" r ^ iT-~ ° j_^ T
^ & ° a> rn1" ^ r^r^i!^ TI
^ ^ S % z 5 ^S § ri^J^ | Ri]
T
m
hs
--TTls
1
y
--
100 or less 101-500 501-3,300 3,301- 10,001- 50,001- 100,001- Over
10,000 50,000 100,000 500,000 500,000
System Service Population
Figure 2.20 Average number of miles of pipes in distribution systems - publicly owned (EPA,
2002).
More than
80 Years
Between 40
and 80
Years
ess than
40 Years
Figure 2.21 Percentage of pipe in each age
category for CWSs (EPA, 2002).
2-19
-------
120.0-1
100.0-
80.0-
0)
oi
I
a
Q.
60.0-
40.0-
20.0-
0.0
Less than 40 years old
Between 40 and 80 years old
More than 80 years old
cp
oj
00
GW
SW
Water Source
Purchased
Figure 2.22 Percentage of Pipe in Each Age Category by Source for CWSs (EPA, 2005b).
trained computer programmers or technicians and
costly service agreements. In the last few years.
SCADA vendors have changed the way they design
and fabricate their systems, thus making them more
accessible to small drinking water treatment operators
(EPA, 2003c).
Figures 2.23 and 2.24 illustrate how large CWSs (lack-
ing continuous operator presence) use more SCADA
systems than small CWSs, for both process control
and process monitoring. Chapter 9 presents further
details on the use of SCADA for small systems.
2.11 Key Questions
• How will demographic changes in the US
change the way small systems obtain, treat, and
distribute drinking water?
• How can the EPA help minimize monitoring
and reporting violations? (e.g., develop simple.
standardized forms with sampling timetables,
etc., with input from primacy agencies).
• Should resources be concentrated in any one
area between NTNCWS, TNCWS, and CWS?
Table 2.10 System service connections by system owner (EPA, 2002).
System Service Population
Large
Very Small Small Medium 10,001- Very Large
Owner 25-500 501-3,300 3,301-10,000 100,000 >100,000 Grand Total
Federal Government
Local Government
Native American
Private
Public/Private
State Government
Unknown
Grand Total
5,539,450
38,323,943
24,287
169,809,399
95,004
38,750
31 ,977
213,862,810
42,023
5,306,605
44,279
1 ,685,804
298,709
55,126
43,830
7,476,376
99,527
7,455,702
15,852
1 ,267,290
190,848
91,817
47,139
9,168,175
210,244
25,591,319
66
4,408,959
422,711
180,955
59,478
30,873,732
3
27,338,61 1
NA
3,995,009
372,491
143
NA
31 ,706,257
5,891,247
104,016,180
84,484
181,166,461
1,379,763
366,791
182,424
293,087,350
2-20
-------
90
80
70
"5T
« 60
+*
0)
i2 50
S
<2 40
> 30
V)
20
10
Process Monitoring
Process Control
100 or 101-500 501-3,300 3,301- 10,001- 50,001- 100,001- Over
less 10,000 50,000 100,000 500,000 500,000
System Service Population
Figure 2.23 Percentage of ground water CWS plants (lacking 24/7 operator presence) that
have SCADA systems for process monitoring or control (EPA, 2002).
100-
90-
80-
"5T
0) 70-
5
£ 60-
u
I 50-
1 40-
0)
to on
^« ou ~~
V)
20-
10-
0-
J Process Monitoring
in
I I Process Control j*
.^^B
CO
CD
_r — p
CD
CM
^
m
co
100 or 101-500
less
h
"
1
CD
ci
in
n
^^
4
501-3,300 3,301-
10,000
h
m-,
—
i
CD
O)
^
CD
7\_G>
i
>
§
^
1
in
CD
t
s—
in
10,001- 50,001- 100,001- Over
50,000 100,000 500,000 500,000
System Service Population
Figure 2.24 Percentage of surface water CWS plants (lacking 24/7 operator presence) that
have SCADA systems for process monitoring or control (EPA, 2005b).
2-21
-------
(These systems have different demands. For
example, CWSs typically have demands
throughout the year, while the non-community
systems may have more sporadic demands.)
2.12 References
All references to Code of Federal Regulations (CFR)
Documents in this chapter may be found at http://
www.access.gpo.gov/nara/cfr and Federal Register
Documents may be found at http://www.gpoaccess.
gov/fr/index.html
American Water Works Association (AWWA).
AWWA Standard for Water Wells - ANSI/AWWA
A100-90,
AWWA, Denver, CO, 1995.
DeSilva, F. J. At the Heart of POU - Ion Exchange
Resins, available at: http://www.watertechonline.com/
article.asp?IndexID=5190203, 1996.
EPA. Small System Compliance Technology List for
the Surface Water Treatment Rule and Total Coliform
Rule, EPA 815-R-98-001, 1998.
EPA. Small System Compliance Technology List for
the Non-Microbial Contaminants Regulated Before
1996, EPA 815-R-98-002, 1998b.
EPA. Guidance Manual for Conducting Sanitary
Surveys of Public Water Systems; Surface Water and
Ground Water Under the Direct Influence (GWUDI),
EPA815-R-99-016, 1999.
EPA. Community Water System Survey 2000. EPA
815-R-02-005B, 2002.
EPA. Membrane Filtration Guidance Manual, EPA
815-D-03-008, 2003a.
EPA. Cross-Connection Control Manual, EPA 816-R-
03-002, 2003b.
EPA. Small Drinking Water Systems Handbook: A
Guide to Packaged Filtration and Disinfection Tech-
nologies with Remote Monitoring and Control Tools,
EPA 600-R-03-041, 2003c.
EPA. Safe Drinking Water Information System (SD-
WIS), available at: http://www.epa.gov/enviro/html/sd-
wis/, 2005a.
EPA. Data & Databases PivotTables, available at:
http://www.epa.gov/safewater/data/pivottables.html,
2005b.
National Drinking Water Clearinghouse (NDWC).
NDWC Fact Sheet - Technical Brief on Filtration,
available at: http://www.nesc.wvu.edu/ndwc/pdf/OT/
TB/TB2_filtration.pdf, 1996.
NDWC. NDWC Fact Sheet - Technical Brief on Ion
Exchange and Demineralization, available at: http://
www.nesc.wvu.edu/ndwc/pdf/OT/TB/TB4_IonEx-
change.pdf, 1997.
NDWC. NDWC Fact Sheet - Technical Brief on Ultra-
violet Disinfection, available at: http://www.nesc.wvu.
edu/ndwc/pdf/OT/TB/OT_TB_fOO.pdf, 2000.
NDWC. NDWC Fact Sheet - Technical Brief Poster
on Treatment Technologies for Small Drinking Water
Systems, available at: http://www.nesc.wvu.edu/ndwc/
pdf/OT/TB/TB 1 l_TTposter.pdf, undated.
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Chapter 3
Regulatory
Background
3.1 Safe Drinking Water Act
(SDWA)
In response to the public health community's and
general public's increased concern and awareness of
drinking water contamination, Congress passed the
Safe Drinking Water Act (SDWA) in 1974. The Act
was intended to protect public health by regulating the
Nation's public drinking water supply. The SDWA
establishes national enforceable standards for drinking
water quality and makes certain that water suppliers
monitor their water to ensure that it meets national
standards.
From 1974 to 1986 when the SDWA was amended,
state regulations varied in many respects, including
differing requirements for ground water disinfection,
mandated filtration, monitoring of organic chemi-
cals, and operator certification requirements. Interim
standards known as maximum contaminant levels
(MCLs) were developed in 1975. The 1986 Amend-
ments declared these interim standards to be final,
required the EPA to regulate 83 contaminants within
three years after enactment, and required disinfection
of all public water supplies and filtration for surface
water systems. States that have primary enforcement
responsibility, known as primacy, were required to
adopt regulations and begin enforcing them within 18
months of EPA's promulgation. The 1986 Amend-
ments also required the EPA to regulate an additional
25 contaminants every three years and to designate
the best available treatment technology for each
contaminant regulated. The amendment initiated the
ground water protection program, established fund-
ing for sole source aquifer special needs identification
and protection, and created a new category of water
system (non-transient, non-community water system)
which greatly increased the number of systems that
states were required to regulate.
The SDWA was amended again in 1996 (Public Law
[PL.] 104-183), addressing concerns about an overly
burdensome regulatory structure and funding needs
for PWS infrastructure and state program manage-
ment. The Amendments allowed EPA to establish a
process for selecting contaminants to regulate based
on scientific merit rather than having to regulate an
additional 25 contaminants every three years and
established the Drinking Water State Revolving
Fund (DWSRF) to help public water systems finance
the costs of drinking water infrastructure needs.
The Amendments also changed the emphasis from
drinking water treatment to contaminant preven-
tion (through source water protection and enhanced
water system management). The 1996 Amendments
allowed for flexibility of regulations and monitoring
for small systems, and required the EPA to conduct
cost-benefit analyses of new regulations and analyze
the likely effect of the regulation on the viability of
public water systems (EPA-Drinking Water Academy,
2003). Over the years, EPA has released many docu-
ments related to SDWA. The most recent document
that provides a detailed understanding of the SDWA
was released on the 30th Anniversary of its promulga-
tion in June 2004 (EPA, 2004).
3.2 SDWA Provisions
The SDWA has many regulatory provisions; a detailed
review of all these provisions is beyond the scope of
this document. A brief overview of SDWA regulatory
provisions related to PWS operations is presented in
the following subsections.
3.2.1 National Primary Drinking Water
Regulations (NPDWR)
The 40 CFR 141 establishes the NPDWR and 40 CFR
142 establishes the implementation of NPDWR pursu-
ant to section 1412 of the SDWA of 1974, as amended
(PL. 93-523). The NPDWR established both Recom-
mended Maximum Contaminant Levels (RMCLs)
and MCLs. As part of the 1986 amendments to the
SDWA, RMCLs were renamed MCLGs or Maximum
Contaminant Level Goals and the National Interim
Drinking Water Regulations were renamed as the
NPDWR. The NPDWR is designed to protect drink-
ing water quality by limiting the levels of specific
contaminants that can adversely affect public health
and are known or anticipated to occur in water. The
NPDWR specifies two types of numeric standards.
The first is the primary standard which is enforceable
and establishes the MCL. The other (non-enforce-
able) secondary standard is referred to as a MCLG.
The 40 CFR 141.2 defines MCL as the maximum
permissible level of a contaminant in water which is
delivered to any user of a PWS. This is water "de-
livered to the free flowing outlet of the ultimate user
of a PWS, except in the case of turbidity where the
maximum permissible level is measured at the point
of entry to the distribution system." Contaminants
added to the water under circumstances controlled
by the user are excluded from this definition, except
those contaminants resulting from the corrosion of
piping and plumbing caused by water quality.
MCLGs are set at a level at which no known or an-
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ticipated adverse human health effects occur. Where
it is not economically or technologically feasible to
determine the level of a contaminant, a treatment tech-
nique (TT) is prescribed by EPA in lieu of establishing
an MCL. For example, Giardia lamblia is a microbial
contaminant that is difficult to measure. To ensure
proper removal, experimental work has established
optimum treatment conditions for the water at a speci-
fied pH, temperature, and chlorine concentration for
a specified length of time to achieve a fixed level of
inactivation.
3.2.2 National Secondary Drinking Water
Regulations (NSDWR)
The 40 CFR 143 establishes NSDWR pursuant to sec-
tion 1412 of the SDWA, as amended (42 U.S.C. 300g-
1). These standards are non-enforceable guidelines
for controlling contaminants in drinking water for
aesthetic considerations, such as taste, color, and odor.
Although the EPA recommends secondary standards,
it does not enforce compliance. States may, however,
choose to adopt them as enforceable standards.
3.2.3 Contaminant Candidate List (CCL)
The 1996 SDWA Amendments require the EPA to
publish a list of contaminants that are not regulated by
any NPDWR provisions (at the time the list is pub-
lished), are anticipated or known to occur in PWSs,
and may later require regulation under the SDWA.
This list, CCL, was required to be published initially
within 18 months of enactment of the Amendments
and every 5 years thereafter. Contaminants for priority
drinking water research, occurrence monitoring, and
guidance development, including health advisories, are
drawn from the CCL. The first CCL was published in
1998. The second was issued in February of 2005.
3.3 Current Regulatory Issues
Besides the SDWA, there are several other rules and
contaminants of interest which may impact small
systems. A brief summary of these rules and con-
taminants of interest are presented in the following
subsections.
3.3.1 Perchlorate
The EPA's National Center for Environmental As-
sessment first released an external review draft report
concerning perchlorate in 1998 and later released a
revised document entitled Perchlorate Environmen-
tal Contamination: Toxicological Review and Risk
Characterization in 2002. According to this docu-
ment, "perchlorate (C1O4~) is an anion that originates
as a contaminant in ground water and surface waters
when the salts of ammonium, potassium, magnesium,
or sodium dissolve in water. One major source of
contamination is the manufacture or improper disposal
of ammonium perchlorate that is used as the primary
component in solid propellant for rockets, missiles,
and fireworks." The document also states that an "ap-
preciation of widespread contamination in the United
States emerged in the Spring of 1997 when develop-
ment of an analytical method with a quantitation level
at 4 ppb became available."
The EPA draft assessment concludes that the potential
human health risks of perchlorate exposures include
effects on the developing nervous system and thyroid
tumors and presents a reference dose (RfD) that is
intended to be protective for both types of effects.
The draft RfD is 0.00003 milligrams per kilogram per
day (mg/kg/day), which is a preliminary estimate of a
protective health level. The RfD is undergoing science
review and deliberations by the external scientific
community and within EPA. The National Research
Council (NRC) released a report that suggested a safe
level of perchlorate at 24.5 micrograms/liter (based on
2 liter/day consumption by a 70 kg individual) (NRC,
2005).
EPA may at some point issue a Health Advisory that
will provide information on protective levels for drink-
ing water. The draft document goes on to state that
"this is one step in the process of developing a broader
response to perchlorate including, for example, tech-
nical guidance, possible regulations and additional
health information. A federal drinking water regulation
for perchlorate, if ultimately developed, could take
several years."
Perchlorate was placed on EPA's CCL, for considera-
tion for possible regulation, in 1998. The next year
EPA required drinking water monitoring for perchlo-
rate under the Unregulated Contaminant Monitoring
Rule (UCMR). Under this rule, monitoring was re-
quired of all large public water systems and a repre-
sentative sample of small public water systems over
a two year period (from 2001 to 2003) to determine
whether the public was being exposed to perchlorate
in drinking water nationwide. As of March 2004, the
sampling period had expired; however, the EPA had
not received all the data from the PWSs. The EPA will
not disseminate a final revision of its draft risk assess-
ment until it has fully evaluated the recommendations
made by a National Academy of Science (NAS) panel.
3.3.2 Arsenic
The first arsenic drinking water standard was estab-
lished by the U.S. Public Health Service in 1942 for
interstate water carriers. The standard was set at 0.05
mg/L, and under the SDWA of 1974 the EPA issued
this limit as a National Interim Primary Drinking Wa-
ter Regulation (NIPDWR). The 1986 SDWA renamed
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the NIPDWRs to NPDWRs, directed the EPA to revise
NPDWRs by 1989, and specified that MCLGs be
promulgated simultaneously with MCLs (EPA, 2002a)
The 1996 SDWA Amendments set deadlines for
regulating arsenic. The EPA was required to propose
a revised Arsenic Rule by January 1, 2000, and issue a
Final Rule by January 1, 2001. On June 22, 2000, the
EPA proposed to revise the existing NPDWR MCL for
arsenic to 0.005 mg/L. The Final Rule was published
on January 22, 2001 and established an MCL for
arsenic at 0.010 mg/L, which became enforceable on
January 23, 2006 (40 CFR 141) (EPA, 2002a).
According to EPA's Report to Congress: Small Sys-
tems Arsenic Implementation Issues (EPA, 2002b),
"small systems are being asked - in some cases for the
first time - to grapple with a whole new set of public
health challenges. This situation poses enormous
implementation, timing, resource, technical, and ca-
pacity challenges for public water systems across the
country." The document also states that small system
infrastructure may be outdated and in poor condi-
tion. Source water available to small systems may be
of poor quality and limited quantity. Technical water
system planning and operations expertise necessary to
evaluate and install new treatment technologies may
also be lacking. In addition, small systems face con-
siderable financial challenges in that they have a small
customer base and, thus, often lack the opportunity to
benefit from economies of scale.
The above referenced Report to Congress estimates
that 3,341 small systems out of a total of an estimated
75,000 potentially affected systems nationally will
have to make improvements or take other measures
(e.g., locate a different source of water) to meet the
new arsenic standard. This represents a substantial
number of small systems, particularly ground water
systems, that will need to make treatment changes.
Because of the importance of the Arsenic Rule and
the national debate surrounding it related to science
and costs, EPA's Administrator publicly announced on
March 20, 2001, that the Agency would take additional
steps to reassess the scientific and cost issues associat-
ed with this Rule. After taking public comment on the
Agency's plan to review the basis for the Arsenic Rule,
EPA extended the effective date to February 22, 2002,
while maintaining the compliance dates of January
23, 2006, for the arsenic MCL and January 22, 2004,
for the clarifications to compliance and new source
contaminants monitoring (66 FR 28350). The EPA
implementation guidance (EPA, 2002a) specifies a
request by the EPA for a review of the Arsenic Rule by
the National Academy of Science (interpretation and
application of arsenic research), the National Drinking
Water Advisory Council (assumptions and methodolo-
gies), and the EPA's Science Advisory Board (ben-
efits). Information on the findings is available in the
EPA implementation guidance (EPA, 2002a).
The EPA announced on October 31, 2001 that the 10
ppb standard for arsenic would remain. The "EPA will
continue to evaluate the expert panel reports, the volu-
minous public comments received, and other relevant
information and comments as they become available
as part of the next round of review of the existing
NPDWR under SDWA § 1412(b)(9). As part of this
review due August 2008, EPA expects to make a deci-
sion on whether to further revise the arsenic standard"
(EPA, 2002a).
EPA expects that new, more cost effective approaches
to comply with drinking water requirements will be
developed, and that small systems will be better able to
meet the challenges posed by the new arsenic drinking
water standard as well as other, future drinking water
standards (EPA, 2002b).
3.3.3 Compliance with Surface Water
Treatment Rule
The Surface Water Treatment Rule (SWTR) was first
published in June 1989. A final Long Term 1 En-
hanced SWTR (LT1ESWTR) was later published (for
systems serving fewer than 10,000 persons - EPA,
2002c). Thereafter, the Long Term 2 Enhanced
Surface Water Treatment Rule (LT2ESWTR) was
published for all PWSs using surface water or ground
water under direct influence-GWUDI (EPA, 2003a).
These regulations appear in 40 CFR 141, Subpart H
and establish criteria under which filtration is required
as a treatment technique for public water systems sup-
plied by surface water or GWUDI. These regulations
also establish TT requirements (in lieu of MCLs) for:
Giardia lamblia, viruses, heterotrophic plate count
bacteria, Legionella, and turbidity.
The regulations state that a system is in compliance
with 40 CFR 141.70(a) if it meets the requirements for
avoiding filtration (40 CFR 141.71) and the disinfec-
tion requirements (40 CFR 141.72(a)) or it meets the
requirements for avoiding filtration (40 CFR 141.73)
and the disinfection requirements (40 CFR 141.72(b)).
In other words, "systems must either provide filtration
and disinfection or comply with the requirements to
avoid filtration" (EPA, 2003b)
The criteria for avoiding filtration may be summarized
as follows:
• Limitations on source water quality conditions
concerning fecal conform concentrations and
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turbidity levels;
• Site-specific conditions concerning disinfection;
• Maintaining a watershed control program which
minimizes the potential for Giardia lamblia cyst
and virus contamination in the source water;
• An annual on-site inspection to assess the
watershed control program and disinfection
treatment process;
• Conditions for being an identified source of a
waterborne disease outbreak;
• Conditions for complying with the MCL for
total coliforms; and
• Conditions for complying with specified
requirements for total trihalomethanes,
haloacetic acids, bromate, chlorite, chlorine,
chloramines, and chlorine dioxide.
The regulations for disinfection are presented in 40
CFR 141.72 and are subdivided into disinfection re-
quirements for PWSs that do not provide filtration and
those that do provide filtration. The filtration regula-
tions are provided in 40 CFR 141.733. In general,
"systems may avoid filtration if they have low conform
and turbidity in their source water and meet other
site-specific criteria. Systems that do not meet these
criteria must install one of the following filtration
treatments: conventional filtration treatment or direct
filtration; slow sand filtration; diatomaceous earth fil-
tration; or another filtration if the state determines that,
in combination with disinfection, the proper amount
of Giardia and virus removal and/or inactivation is
achieved" (EPA, 2003b).
As stated above, the LT1ESWTR affects those PWSs
that use surface water or GWUDI (Subpart H system)
serving fewer than 10,000 persons. The regulations
governing this rule are meant to improve control
of microbial contaminants and prevent increases in
microbial risk while systems control for disinfection
by products (DBFs) and are presented in 40 CFR 141,
Subpart T. The regulations establish requirements for
filtration and disinfection that are in addition to Sub-
part H criteria. The regulations in Subpart T establish
or extend treatment technique requirements in lieu
of MCLs for: Giardia lamblia, viruses, heterotrophic
plate count bacteria, Legionella, Cryptosporidium and
turbidity. Management at Subpart T systems must
establish a Disinfection Profile and Benchmark. Also,
if a Subpart T system plans on making significant
changes to its disinfection practices, it must first get
approval from the state.
The LT2ESWTR is applicable to all Subpart H sys-
tems and is intended to require higher levels of treat-
ment for source waters of lower quality. Depending on
the initial monitoring results, systems that filter would
be put into groups or "bins." Under the proposed rule,
each bin (except the bin for the lowest levels) requires
a system to install a treatment technology and sets a
monitoring schedule, both based on contamination
levels in the source water. Under the proposed rule,
some new treatment options could possibly involve
watershed control, reducing influent Cryptosporidium
concentrations, improving system performance, and
including additional treatment barriers such as pre-
treatment" (EPA, 2003b).
3.3.4 Stage 1 and 2 Disinfection Byproducts
(DBF) Rules
As discussed in Chapter 2, a disinfectant is any
oxidant, including but not limited to chlorine, chlo-
rine dioxide, chloramines, and ozone, that is added
to water in any part of the treatment or distribution
process and is intended to kill or inactivate pathogenic
microorganisms. A DBF is a compound formed by
the reaction of a disinfectant such as chlorine with
naturally occurring organic material in the water
supply. Many of the DBFs are suspected of causing
cancer, reproductive and developmental problems in
humans (EPA 2003b). The Stage 1 Disinfectants/
Disinfection Byproducts Rule (Stage 1 DBPR) was
published in December 1998 to reduce the levels of
disinfectants and DBFs in drinking water supplies,
including byproducts that were not previously covered
by drinking water rules. The rule sets MCLs for
haloacetic acids (HAAS), chlorite (a major chlorine
dioxide byproduct), bromate (a major ozone byprod-
uct), and total trihalomethanes (TTHM). It also set
Maximum Residual Disinfectant Levels and Maxi-
mum Residual Disinfectant Level Goals for chlorine,
chloramines, and chlorine dioxide.
The Stage 1 DBPR affects CWSs and NTNCWSs
that add a chemical disinfectant to the water in any
part of the drinking water treatment process. Certain
requirements apply to TNCWSs that use chlorine
dioxide (EPA, 2003b) Systems that use conventional
filtration must remove specified percentages of total
organic carbon (TOC) using either enhanced coagula-
tion or enhanced softening. The removal requirement
depends on the TOC concentration and alkalinity of
the source water.
The Stage 2 DBPR builds on the public health protec-
tion provided by the Stage 1 DBPR. Along with the
proposed LT2ESWTR, it aims to reduce the risks
associated with DBFs without increasing the risk of
microbial contamination. The rule affects CWSs and
NTNCWSs that add a disinfectant other than ultra-
3-4
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violet light or deliver water that has been disinfected
(EPA, 2003b).
supplies undrinkable due to its offensive taste and odor
(Squillaceetal.,2000).
3.3.5 Proposed Ground Water Rule
In addition to regulations guiding surface water treat-
ment, the EPA published the proposed Ground Water
Rule in May of 2000. A final rule is expected in
late 2006. This rule has the potential to affect small
systems that use ground water as a source. The rule
proposes periodic sanitary surveys; once every three
years for community water systems (CWS) and once
every five years for non-community water systems
(NCWS). Any deficiencies uncovered during the
survey would need to be corrected in 90 days. Sanitary
survey methodology would be based on the eight com-
ponents found in the "Guidance Manual for Conduct-
ing Sanitary Surveys of Public Water Systems; Surface
Water and Ground Water Under the Direct Influence of
Surface Water" (EPA 815-R-99-016). The proposed
rule also seeks comment on the use of grandfathered
data from surveys used for the Total Conform Rule
(TCR). The proposed Ground Water Rule would also
require a hydrogeologic sensitivity analysis for all non-
disinfecting ground water systems in order to identify
systems that may be prone to fecal contamination (e.g.
Karst topography). Source water monitoring would be
required for systems that do not treat for 4-log removal
of viruses. A system would be required to collect
a source water sample within 24 hours of receiving
notification of a positive total-coliform sample taken
in compliance with the TCR and test the sample for E.
coli, enterococci or coliphage. Any system deemed
hydrogeologically sensitive would be required to
conduct monthly monitoring for E. coli, enterococci
or coliphage. If the deficiency can not be corrected at
the source, systems would be required to implement
treatment for 4-log removal/inactivation of viruses
before or at the first customer. Examples of treatment
technologies capable of 4-log virus removal include:
chlorination, chloramination, and ultraviolet radiation.
Systems serving 3,300 or less people would be required
to monitor disinfectant levels via daily grab samples.
3.3.6 Methyl Tertiary Butyl Ether (MTBE)
MTBE is a chemical compound that is manufactured
by the chemical reaction of methanol and isobuty-
lene. It is a gasoline additive (used to help prevent
engine "knocking") that can leak into the environment
wherever gasoline is stored, transported, or transferred.
MTBE has been used at higher concentrations in some
gasoline to fulfill the oxygenate requirements set by
Congress in the 1990 Clean Air Act Amendments. A
growing number of studies have detected MTBE in
ground water throughout the country; in some instanc-
es, these contaminated waters are sources of drinking
water. Low levels of MTBE can make drinking water
Most human health-related studies have so far focused
on the effects of inhaling MTBE. Researchers have
limited data regarding the health effects MTBE may
have on a person who ingests it. EPA's Office of Water
has concluded that available data are not adequate
to estimate potential health risks of MTBE at low
exposure levels in drinking water but that the data sup-
port the conclusion that MTBE is a potential human
carcinogen at high doses. Recent work by EPA and
other researchers is expected to help determine more
precisely the potential for health effects from MTBE
in drinking water (EPA, 2003 c).
MTBE is also on the EPA's CCL and the EPA is
continuing to study both the potential health effects
and the occurrence of MTBE. Beginning in 2001, the
EPA required (under the Unregulated Contaminants
Monitoring Rule-UCMR) all large drinking water
systems and a representative sample of small systems
to monitor for MTBE and report their findings.
3.3.7 Radionuclides
The EPA began regulating radionuclides in 1976, as
interim regulations under the authority of the SDWA
of 1974. On December 7, 2000, the EPA issued the
Radionuclides Rule, which refined the legally binding
requirements for radionuclides set forth in the 1986
SDWA Amendments. The Radionuclide Rule took
effect on December 8, 2003, setting MCLs as well as
monitoring, reporting, and public notification require-
ments for radionuclides. Under this rule, all systems
must complete initial monitoring for radionuclides
by December 31, 2007. States will determine initial
monitoring requirements during this 4-year initial
monitoring period.
Radionuclides generally enter drinking water through
the erosion or chemical weathering of naturally occur-
ring mineral deposits, although human activity (such
as mining, industrial activities, or military activities
that use or produce man-made radioactive materials)
can also contribute to their presence in water (EPA,
2002d).
There are three basic kinds of high-energy radiation:
alpha, beta, and gamma. The EPA has set limits (i.e.
MCLs) for four groupings of radionuclides: alpha
particles, beta particles and photon emitters, Radium-
226 and Radium-228 (combined), and uranium (EPA,
2002d).
The Radionuclides Rule changed monitoring require-
ments for small drinking water systems by requiring
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monitoring at each entry point to the distribution
system (EPTDS), rather that just monitoring at a "rep-
resentative" point in the distribution system. It may
be possible to reduce the frequency of monitoring at
each EPTDS based on the initial sample results. The
following table (Table 3.1) shows the reduced monitor-
ing frequencies.
Table 3.1 Reduced monitoring for
radionuclides (EPA, 2002d).
If the initial monitoring results Monitoring frequency
are: is reduced to:
< Defined detection limit
> Defined detection limit,
but less than or equal to % the MCL
> % the MCL,
but less than or equal to the MCL
>MCL
1 sample every 9 years
1 sample every 6 years
1 sample every 3 years
Quarterly samples
Systems with EPTDS on a reduced monitoring sched-
ule (i.e., collecting 1 sample every 3, 6, or 9 years) can
remain on that reduced schedule so long as the most
recent sample results support that monitoring sched-
ule. An increase in a radionuclide level at an EPTDS
may increase the frequency of monitoring for that
radionuclide at that sampling point. If an entry point
result is above the MCL while on reduced monitor-
ing, the system operator must begin to take quarterly
samples in the next quarter. Quarterly sampling must
continue until four consecutive quarterly samples are
below the MCL" (EPA, 2002d)
Unless told otherwise by the state, a system which
uses an intermittent source of supply (i.e., a source that
is used seasonally) or that uses more than one source
and that blends water from more than one source
before distribution, must sample at an EPTDS during
periods of normal operating conditions. Normal oper-
ating conditions include when water is representative
of all the sources being used. (EPA, 2002d)
There are several ways that small systems with high
levels of radionuclides can protect their customers,
including: source water changes, water blending, con-
solidation, and treatment (EPA, 2002d). Treatment to
lower the levels of radionuclides in drinking water will
be necessary if the source water contains high levels of
radionuclides and an alternative source is not available
or switching sources is cost prohibitive. A listing of
the best available technologies (BATs) and small sys-
tem compliance technologies (SSCTs) for removing
radionuclides from water is provided by EPA (EPA,
2002d). Additionally, information on complying with
the Radionuclide Rule is also provided by EPA (EPA,
2002e).
3.4 Source Water Assessments
Source water is water in its natural state, prior to any
treatment for drinking. The water may come from
rivers, lakes, or underground aquifers used to supply
private wells and PWSs. Source water is vulnerable to
contamination by (EPA, 2003d):
• Surface water - runoff (from surface areas in a
watershed, either near a drinking water supply
intake or in upstream tributaries) and ground
water infiltration (recharge streams or lakes)
• Ground water - infiltration from the surface,
injection of contaminants through injection
wells (including septic systems), or by naturally
occurring substances in the soil or rock.
Source water may contain many different contami-
nants prior to treatment, such as:
• microbial contaminants (viruses and bacteria,
primarily from human and animal wastes),
• inorganic contaminants (salts and metals),
• pesticides and herbicides,
• organic contaminants (including synthetic and
volatile organic chemicals), and
• radioactive contaminants.
Contaminated source water can be very costly to a
community and state, both economically and public
health-wise, as the burden falls to the community to
solve the problem. "Reducing the threat of water-
borne illnesses helps save hundreds of millions of
dollars annually by eliminating costly health care
expenses, lost wages, work absences, decreased job
productivity, and additional treatment costs incurred
by PWSs required to meet federal drinking water
quality standards" (EPA, 20021). In the long term, it
is much more economical to protect source water from
contamination than it is to treat contaminated water or
find a new source. Source water protection is also the
first line of defense in preventing waterborne illnesses.
"The government regulates land-use and the construc-
tion-location^) of water treatment facilities to control
potential source(s) of pollution from contaminating
source water" (EPA, 2003e).
The 1996 Amendments to the SDWA (Section 1453)
placed a new focus on source water protection, requir-
ing each state to develop and implement a Source
Water Assessment Program (SWAP). Indian tribes are
not explicitly required by the amendments to imple-
ment SWAPs; however, the EPA recommends such
implementation. Source water assessment is unique to
each water system which provides basic information
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about the water used to provide drinking
water. These assessments identify the
area of land that most directly contributes
the raw water used for drinking water.
and identifies the major potential sources
of contamination to drinking water sup-
plies. The information gathered can then
be used to determine how susceptible
the water system is to contamination.
The State Source Water Assessment and
Protection Programs Guidance, Final
Guidance (EPA, 1997) provides imple-
mentation guidance for State SWAPs
and Source Water Protection (SWP)
Programs. This document also defines
the goals for SWAPs as follows: "to
provide for the protection and benefit of
public water systems and for the support
of monitoring flexibility." SWAPs are
further discussed in Section 4.3.
Federal
EPA Grant
H
State
Set-asides (up to 31%)
Administration of DWSRF
Small system tech assistance
Source water assessments
Source water protection
Drinking water program
Capacity development
Operator certification
Revolving Loan Fund
(includes repayments,
bond proceeds,
interest, etc.)
*Repayments return to Fund for future assistance
Assistance to Public
Water Systems
• Treatment
• Sources
• Storage
• Transmission &
> distribution ,
Figure 3.1 Structure of the DWSRF program (EPA 2003f).
3.5 Wellhead Protection
The 1986 Amendments to the SDWA, specifically
Section 1428, strengthened the regulations govern-
ing ground water protection by requiring each state
to develop and implement a Wellhead Protection Plan
(WHPP). The SDWA requires that every state well-
head protection plan address the following areas of
concern (Thompson et al., 1997):
• The roles and duties of state and local
governments and public water suppliers with
respect to the development and implementation
of a wellhead protection plan for a public water
supply.
• Acceptable criteria and methodologies for
delineation of Wellhead Protection Areas
(WHPAs) for each wellhead based on
reasonably available hydrogeologic data and
other information.
• Identification and risk assessment of
contaminant sources within each WHPA.
including all potential sources that may have an
adverse health impact.
• Management approaches that may include
technical assistance, financial assistance.
implementation of control measures, education.
training, and demonstration projects.
• Development of contingency plans for PWSs
indicating the location of alternate drinking
water supplies in the event of well or well-field
contamination.
• Recommendations for proper siting of new wells
to minimize potential contamination.
• Development of processes to ensure public
participation.
State WHP Programs vary greatly. For example, some
require CWSs to develop management plans, while
others rely on education and technical assistance to
encourage voluntary action. WHPPs are the founda-
tion for many of the state SWAPs required under the
1996 SDWA amendments.
Despite the obvious need for source water protection.
just 28 percent of the smallest systems and only 50
percent of systems serving 10,000 or more persons
participate in some form of source water or wellhead
protection program. Some small systems might
be less likely to adopt wellhead protection or SWP
programs than larger systems because they lack the
technical and financial resources to implement and
manage such programs (EPA, 1999).
3.6 Vulnerability Assessments
(VA), Emergency Planning and
Security
The Public Health Security and Bioterrorism
Preparedness and Response Act of 2002 (Bioter-
rorism Act) amended the SDWA by adding Section
1433 (Public Law 107-188). The Bioterrorism
Act required every community water system that
serves a population of greater than 3,300 persons to
conduct a vulnerability assessment and to develop
an Emergency Response Plan (ERP). Chapter 8
presents further information on VAs, ERPs and
other security related information.
3-7
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3.7 Variances and Exemptions
PWSs can request variances or exemptions from the
primacy agency. Variances and exemptions allow
PWSs to not meet a specific drinking water standard
while continuing to protect public health to the maxi-
mum extent possible. They are identified and defined
in the SDWA. The following subsections present a
brief overview of these allowances. A more detailed
summary of variances and exemptions specific to
small systems may be found in Variances and Exemp-
tions for Small Drinking Water Systems (EPA, 1998).
3.7.1 Small System Variances
Section 1415(e) of the SDWA authorizes the Admin-
istrator i.e., EPA (for states that do not have primary
enforcement responsibility) or a state (for states that
do have primary enforcement responsibility) to issue
variances from the requirement to comply with MCLs
or treatment techniques to systems serving fewer than
10,000 persons.
States exercising primary enforcement responsibility
may grant a small system variance to PWSs serving
3,300 or fewer persons without EPA approval, but
must receive EPA approval to grant a small system
variance to PWSs serving more than 3,300 persons but
fewer than 10,000 persons. 40 CFR 142.312 specifies
what EPA action is necessary when a state proposes
to grant a small system variance to a PWS serving a
population of more than 3,300 and fewer than 10,000
persons. A small system variance is not available for
microbial contaminants or for contaminants regulated
prior to 1986 (if the EPA revises a pre-1986 MCL
making it more stringent, then a small system variance
could be granted but only up to the pre-1986 MCL).
In order to obtain a small system variance, it must be
determined that the PWS cannot afford to comply with
the NPDWR (in accordance with state criteria or, for
states that do not have primary enforcement responsi-
bility, with the EPA established criteria). According to
40 CFR 142.306, this includes:
• Treatment;
• Alternative sources of water supply;
• Restructuring or consolidation changes,
including ownership change and/or physical
consolidation with another public water system;
or
• Obtaining financial assistance pursuant to
Section 1452 of the SDWA or any other federal
or state program.
Another requirement for obtaining a small system
variance is that the PWS must meet the source water
quality requirements for installing the small system
variance technology developed pursuant to guidance
published under Section 1412(b)(15) of the SDWA.
The PWS must also be financially and technically
capable of installing, operating and maintaining the
applicable small system variance technology. The
terms and conditions of the small system variance
must ensure adequate protection of human health,
taking into consideration the quality of the source
water and the removal efficiencies and expected useful
life of the small system variance technology. 40 CFR
142.307 specifies the terms and conditions that must
be included in a small system variance.
Notice of a proposed small system variance must be
provided to all persons served by the PWS at least 15
days prior to the date of proposal and at least thirty
days prior to a public meeting to discuss the variance.
The state or EPA will decide who does the notifying
(i.e. state, EPA, or PWS). Also, a state or the EPA
must hold at least one public meeting on the variance
no later than 15 days after the variance is proposed.
Any person served by the PWS may obtain an EPA
review of a state proposed small system variance by
petitioning the EPA to object to the granting of a small
system variance. The petition must be submitted
within 30 days after a state proposes to grant a small
system variance for a PWS. The Administrator has 60
days (from petition receipt) to respond.
40 CFR 142.311 specifies what procedures allow
the EPA to object to a proposed small system vari-
ance or overturn a granted small system variance for
a PWS serving 3,300 or fewer persons. Periodically
EPA must review each state program to determine if
state-granted small system variances comply with the
requirements of the SDWA, 40 CFR 142.313, and the
affordability criteria developed by the state.
3.7.2 Exemptions
For granting an exemption, the state or EPA must de-
termine whether management or restructuring changes
(or both) would improve water quality or achieve
compliance. Additionally, a schedule for compli-
ance must be developed when granting an exemption.
Schedules for compliance must include "increments
of progress" (retained from old law) or "measures to
develop an alternative source of water supply" (new
law). A system is not eligible for an exemption if the
system receives a small system variance. The period
of an exemption is lengthened from 1 year (old law)
to 3 years. Eligibility for renewable exemptions is
expanded from systems serving fewer than 500 service
connections (approximately 1500 persons) under the
old law, to systems serving fewer than 3,300 persons.
3-8
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Renewals are limited to a total of 6 years (SDWA 1416
Sec. 117).
In granting exemptions, a state may consider whether
a community may be defined as "disadvantaged" for
the purpose of receiving Drinking Water State Revolv-
ing Funds (DWSRF), or whether DWSRF funds are
reasonably likely to be received. If qualified, the com-
munity (PWS operator) may receive funding that can
be used improve the infrastructure to meet the drinking
water standards. The DWSRF is further discussed in
Section 3.8.
3.8 DWSRF
The 1996 SDWA Amendments addressed the problem
many PWSs were facing; a lack of funding for infra-
structure improvements that would enable systems
to comply with NPDWS and protect public health.
The SDWA Amendments created the DWSRF which
makes funding available to PWSs to finance infrastruc-
ture improvements. EPA provides these funds to states
in the form of capitalization grants; states, in turn,
provide low-interest loans to drinking water systems
(EPA, 2002g). The DWSRF program encourages
states to develop long-term sources of drinking water
infrastructure funding. States that do not meet certain
requirements are subject to withholding of a portion of
their DWSRF allotment. EPA provides capitalization
grants to states based on the DWSRF allotment. States
must annually prepare "intended use plans" (IUP)
as part of their DWSRF capitalization grant applica-
tion. lUPs identify eligible projects and their priorities
based primarily on three criteria:
• Projects that address the most serious human
health risks;
• Projects that ensure or maintain compliance; and
• Projects that assist systems with greatest
economic needs.
Public involvement in developing the IUP is mandated.
Figure 3.1 shows the overall structure of the DWSRF
program.
As Figure 3.1 shows, a state may set-aside up to 31
percent of its capitalization grant for other eligible
drinking water program related activities. Of this set-
aside, the state may use (EPA, 2003f):
• Up to 4 percent for administering the DWSRF
and/or providing technical assistance
• Up to 10 percent for source water protection,
capacity development, and operator certification
programs, as well as for the state's drinking
water program.
• Up to 15 percent (but no more than 10 percent
for any one purpose) for projects in water
systems, including source water protection
loans, technical and financial aid for capacity
development, source water assessments, and
wellhead protection.
• Up to 2 percent for technical assistance for water
systems serving fewer than 10,000 people.
Referring to set-asides, the EPA report to congress
(EPA, 2003f) states "Nationally, states have reserved
approximately 16 percent of federal grants for these
purposes, although on an individual state basis the
amount reserved has ranged from 7 to 31 percent.
Through state FY 2001, states had expended 43 per-
cent of the $576 million in funds they reserved to con-
duct set-aside activities." In this report, EPA also ex-
pressed concerns about slow progress in expenditures
of set-asides, but expenditures have increased from 9
to 42 percent from state FY 1998 through 2001.
States must make funds available to small systems and
can establish provisions for disadvantaged community
assistance as part of their DWSRF programs. Through
its disadvantaged assistance program, a state may
provide additional subsidies such as principal forgive-
ness, or extend loan repayment periods for up to 30
years. The DWSRF program also encourages the use
of funds for programs that use pollution prevention to
ensure safe drinking water (EPA, 2002g).
3.9 Key Questions
• What are the most crucial areas of research
for small systems with regard to regulations
that have already been promulgated? (e.g.
radionuclides, arsenic, residual disposal?)
• What contaminants on the CCL should
WSWRD researchers focus on with respect to
treatment, distribution system issues, and source
water protection?
• How can research help small systems to
comply with the LT2ESWTR (e.g. source water
monitoring costs)?
3.10 References
All references to Code of Federal Regulations (CFR)
Documents in this chapter may be found at http://
www.access.gpo.gov/nara/cfr and Federal Register
Documents may be found at http://www.gpoaccess.
gov/fr/index.html
EPA. State Source Water Assessment and Protection
Programs Guidance, Final Guidance, EPA-816-R-97-
009, 1997.
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EPA. Variances and Exemptions for Small Drinking
Water Systems, EPA-816-F-98-008, 1998.
EPA. National Characteristics of Drinking Water
Systems Serving Populations Under 10,000, EPA-816-
R-99-010, 1999.
EPA. Implementation Guidance for the Arsenic Rule,
EPA-816-K-02-018, 2002a.
EPA. Small Systems Arsenic Implementation Issues,
EPA-815-R-02-003, 2002b.
EPA. Final Long Term 1 Enhanced Surface Water
Treatment Rule, EPA-815-F-02-001, 2002c.
EPA. Radionuclides in Drinking Water: A Small En-
tity Compliance Guide, EPA-815-02-001, 2002d.
EPA. Implementation Guidance for Radionuclides,
EPA-816-F-00-002, 2002e.
EPA. Consider the Source: A Pocket Guide to Pro-
tecting Your Drinking Water, Drinking Water Pocket
Guide #3, available at: http://www.epa.gov/safewater/
protect/pdfs/swppocketpdf, 2002f.
EPA. Sources of Technical and Financial Assistance
for Small Drinking Water Systems, EPA-816-K-02-
005, 2002g.
EPA-Drinking Water Academy. An Overview of the
Safe Drinking Water Act, available at:
http ://www. epa. gov/safewater/dwa/electronic/presenta-
tions/sdwa/sdwa.pdf, 2003.
EPA. Proposed Long Term 2 Enhanced Surface Water
Treatment Rule, EPA-815-F-03-005, 2003a.
EPA. Small Systems Guide to Safe Drinking Water
Act Regulations, EPA 816-R-03-017, 2003b.
EPA. Methyl Tertiary Butyl Ether (MTBE) - FAQ,
available at: http://www.epa.gov/mtbe/faq.htm, 2003c.
EPA. Introduction to EPA's Drinking Water Source
Protection Programs, available at:
http ://www. epa. gov/safewater/dwa/electronic/presenta-
tions/swp/swp.pdf, 2003d.
EPA. Small Drinking Water Systems Handbook: A
Guide to Packaged Filtration and Disinfection Tech-
nologies with Remote Monitoring and Control Tools,
EPA600-R-03-041, 2003e.
EPA. The Drinking Water State Revolving Fund Pro-
gram Financing America's Drinking Water from the
Source to the Tap, EPA-918-R-03-009, 2003f
EPA. Safe Drinking Water Act 30th Anniversary Un-
derstanding the Safe Drinking Water Act,
EPA816-F-04-030, 2004.
National Research Council (NRC). Health Implica-
tions of Perchlorate Ingestion. The National Acad-
emies Press. Washington, D.C. 2005.
Squillace, P.J., J.S. Zogorski, W.G. Wilber, and C.V
Price. A Preliminary Assessment of the Occurrence
and Possible Sources of MTBE in Ground Water of the
United States, 1993-94. U.S. Geological Survey Open-
File Report 95-456, available at: http://sd.water.usgs.
gov/nawqa/pubs/ofr/ofr95.456/ofr.html. March 2000.
Thompson, C.A., E.N. Nealson, and M.K. Anderson.
Iowa Wellhead Protection Plan, available at: http://
www.iowadnr.com/water/iwp/files/iwpp_full.pdf,
September, 1999.
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Chapter 4
Source Water Issues
4.1 Background
PWSs derive their source water from both ground and/
or surface water. Most (over 90%) systems use ground
water as their source of drinking water; however, the
majority of people (65%) are served by PWSs that
use surface water as their source (EPA, 2005). Source
water is untreated water from streams, rivers, lakes,
or aquifers which is used to supply private wells and
public drinking water systems. Most public and some
private well drinking water is treated prior to delivery
to our homes. While some treatment is usually neces-
sary, the treatment costs and public health risks can
be reduced by ensuring that source water is protected
from contamination.
Contaminated source water can cause both acute and
chronic health effects if consumed without proper
treatment. Acute health effects are immediate effects
that may result from exposure to certain contaminants
such as pathogens (e.g. viruses, bacteria, parasites,
protozoa or cysts), organic chemicals (e.g. pesticides),
and/or inorganic chemicals (e.g. arsenic) that may be
in source water. Sources of contaminants that cause
acute health effects include industry, animal feeding
operations, agriculture, septic systems, and cesspools.
Chronic health effects are the possible result of expo-
sure over many years to a drinking water contaminant
at levels above its maximum level established by EPA.
Sources of contaminants that cause chronic health
effects include industrial and commercial activities,
agriculture, landfills, surface impoundments, and
urban activities.
Long-term exposure to contaminants such as volatile
organic chemicals, inorganic chemicals, or synthetic
organic chemicals can result in chronic health effects
including birth defects, cancer, and other long-term
health effects.
Considerable information about source water protec-
tion is already available, much of it from EPA. This
chapter presents a strategy for small systems source
water research based on the EPA ORD's Multi-Year
Plan, descriptions of source water assessment and pro-
tection tools, and problems and solutions for building
sustainable community water systems.
4.2 Drinking Water Research
Program Multi-Year Plan
The scientific questions associated with source water
protection encompass a broad range of issues. Source
water protection is a component of other ORD re-
search programs, although the protection of drinking
water quality may not be their primary goal. The wa-
ter industry has an active research program in source
water protection. ORD's drinking water research pro-
gram is therefore focused on areas that are not being
fully addressed by other means and that match ORD's
technical capabilities.
The Drinking Water Research Program Multi-Year
Plan (EPA, 2003) presents ORD's proposed research in
source water issues over the next 5 to 8 years. Many
of these issues are broad in scope and are intended to
apply to all PWSs. The source water program goals
focus on the protection of the source water supply,
including both surface and ground water. Because
most of small CWSs use ground water as their source,
programs that address ground water have the potential
to have the greatest benefit to small community water
systems. The plan establishes long-term goals and
research projects that are discussed in the following
sub-sections.
4.2.1 Long-Term Goals
Annual Performance Goals (APGs) for source water
protection from FY 2006 to 2009 are designed to
assist decision makers at the national, state and local
level by providing tools and information that contrib-
ute to more effective management practices. Annual
Performance Measures (APMs) include reports that
describe how to better assess the vulnerability of wa-
tersheds, how to detect specific contaminants and other
changes in water quality using improved diagnostic
tools, and how to more effectively manage different
types of contamination problems. Potential areas of
additional research include:
• Source water assessment and protection, with
a focus on such areas as reducing impacts of
septic systems and other non-point sources, wet
weather flow and the development of real-time
monitoring systems.
• Expansion of the new program on molecular
technologies for screening, prioritizing and
monitoring contaminants of concern. This
would have applications for risk assessment
(e.g., to support hazard evaluations), risk
management (e.g., to monitor water sources),
and research planning in general.
4.2.2 Ongoing and Future Research
Research projects have been developed specific to
source water assessments. These are applicable to
drinking water systems of all sizes and source wa-
ter, but several will benefit small community water
4-1
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systems that do not have the resources to complete this
type of work. Specific projects include the following:
• Report on siting of wells and operations to
control arsenic.
• Report on the use of geochemical data to
manage risks to public water supply wells from
arsenic contamination.
• Report on early warning upstream monitoring
network to protect source waters.
• Report on the role of municipal sewage
effluents in contributing to the occurrence
of enterohemorrhagic Escherichia coli in
watersheds.
• Assessment of Best Management Practices
(BMPs) for atrazine in rural watersheds.
• Optimization of BMPs design/location for
atrazine.
• Final report on the characterization of
Cryptosporidium and Giardia in combined
sewer overflows (CSOs).
• Biosensor evaluation and demonstration as a
tool to protect source waters.
• State-of-the-science report for on-site sewage
management and septic systems technology.
• Placement of BMPs in urban watersheds to meet
water quality goals.
• Watershed boundary condition identification.
• Report on modeling and placement of structural
BMPs as a source water protection approach.
• Report on molecular microarrays for detection
of non-pathogenic bacteria and bacterial
pathogens in drinking water source waters.
• State-of-the-science report on real time early
warning systems for source water protection.
• Determine the fate and transport of
Nitrosodimethyl Amine and other disinfection
byproducts in aquifer and large multiple-use
source waters.
• Evaluate the effectiveness of selected structural
BMPs to help macronutrient balances and
sediments in source water turbidity, algae, taste
and odor.
By 2009, EPA plans to provide data, tools, and
technologies to support management decisions by the
Office of Water, state, and local authorities to protect
source waters.
4.3 Source Water Assessments
Under the SDWA, states are required to develop
comprehensive Source Water Assessment Programs
(SWAPs) that will:
• identify the areas that supply public drinking
water;
• inventory contaminants and assess water system
susceptibility to contamination;
• inform the public of the results.
States are required by the SDWA Amendments of
1996, Sections 1453 and 1428(b), to complete a source
water assessment for each public water system PWS.
These assessments can be done for each system or on
an "area-wide" basis involving more than one PWS.
A source water assessment provides important infor-
mation for carrying out protection programs. This
"know your resource and system susceptibility" part
of protection involves identifying the land that drains
to the drinking water source and the most prominent
potential contaminant risks associated with it. To be
considered complete, a SWAP must include vari-
ous elements described in the following sub-sections
(EPA, 1997).
4.3.1 Delineation
The source water protection area should be deline-
ated in accordance with wellhead protection methods.
Sometimes, it may be necessary to delineate source
water protection areas either inside of or in addition to
typical wellhead protection areas. A wellhead protec-
tion area is the surface and subsurface area surround-
ing a well or well field though which contaminants can
reach a water supply.
4.3.2 Contamination Sources
Community groups can become especially involved in
the second step of an assessment: identifying potential
sources of pollutants that could contaminate the water
supply. This inventory usually results in a list and a
map of facilities and activities within the delineated
area that may release contaminants into the ground
water supply (for wells) or the watershed of the river
or lake (for surface water sources).
Some examples of the many different types of poten-
tial pollutant sources include landfills, underground or
above-ground fuel storage tanks, residential or com-
mercial septic systems, storm water runoff from streets
and lawns, farms that apply pesticides and fertilizers,
and sludge disposal sites.
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4.3.3 Susceptibility Determination
A susceptibility determination refers to a determi-
nation of the susceptibility of the water supply to
contamination, based on the contamination source
inventory and other relevant factors. The suscepti-
bility determination is useful for decisions regarding
management of the source water protection area and
source water protection activities. The susceptibil-
ity determination may be based on:
• Hydrologic and hydrogeologic factors such as
ground water or surface water movement;
• Characteristics of the contaminants (e.g.,
toxicity, environmental fate and transport);
• Characteristics of the potential source of the
contaminant (location, likelihood of release,
effectiveness of mitigation measures); and
• Other factors such as well intake and well
integrity.
The susceptibility determination may be an absolute
measure of the potential for contamination of the
public water supply, a relative comparison between
sources within the source water protection area, or
a relative comparison to findings by other assess-
ments.
4.3.4 Public Involvement
After a state completes the assessment of a particu-
lar water system, it will summarize the information
for the public. Such summaries help communities
understand the potential threats to their water supplies
and identify priority needs for protecting the water
from contamination. States will make the assessment
summaries available to the public in a variety of ways
including: public workshops, making copies available
in public libraries and from local government offices
or water suppliers, and posting assessment summaries
on the Internet. The results of the assessments will
also be included in the annual water quality reports
that community water systems are required to prepare
for their customers.
4.3.5 Benefits of Source Water Assessment
Plans (SWAPs)
The 1996 Safe Drinking Water Act Amendments has
given states access to funding for implementation of
SWAPs. With this funding, states are now able to as-
sess areas serving as public sources of drinking water
in order to identify potential threats and initiate protec-
tion efforts.
Once completed, the source water assessments can
be used to focus prevention resources on drinking
water protection. EPA strongly encourages linking the
source water assessments to implementation of source
water protection programs.
4.3.6 Source Water Protection
Protection of drinking water at the source can be
successful in providing public health protection and
reducing the treatment challenge for public water
suppliers. Source water quality can be threatened by
many everyday activities and land uses, ranging from
industrial wastes to the chemicals applied to suburban
lawns. Water systems are heavily regulated through
the Public Water System Supervision Program, and
must respond to this threat to public health with regu-
lar water quality monitoring and actions ranging from
well closure to expensive treatment. In some cases,
source water protection can eliminate or forestall the
need to change or modify treatment processes, saving
consumers significant money.
4.4 Other Source Water
Assessment and Protection
Tools
Two valuable tools for source water assessment and
protection activities include the Sanitary Survey and
the Wellhead Protection Program.
4.4.1 Sanitary Survey
A sanitary survey is an inspection of all components
of a water system from source to tap. The inspection
should identify potential sources of contamination
and can provide the opportunity for states to conduct
source water delineations and assessments, update
SWAPs, and follow up on the development of source
water protection (SWP) activities. In addition, states
could use information collected in source water as-
sessments, whether done separately or concurrently,
to enhance sanitary survey information and to identify
systems of concern that should receive priority for
surveys.
4.4.2 Wellhead Protection Program (WHPP)
Wellhead protection (WHP) efforts are significant
because many small community water systems use
ground water as their primary source of drinking
water. Establishing and implementing a local WHP
program includes: forming a WHP planning team,
delineating a WHP area, identifying potential sources
of contamination, choosing management tools, and
planning for contingencies.
The public information requirements for the SWP
program do not apply to the WHP program. How-
ever, throughout its development and implementation,
education and outreach are essential to the success of a
local WHP effort.
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4.5 Sustainability of Community
Water Systems (CWSs)
A water system must have technical, managerial, and
financial "capacity," according to the SDWA. Techni-
cal capacity may be defined in terms of three issues:
source water adequacy, infrastructure adequacy, and
technical knowledge. Source water adequacy is
related to the availability of reliable water sources,
awareness of source water issues, and should be
included a SWAP plan. Source water assessments can
provide information directly relevant to determining
source water adequacy, and, in turn, building of the
infrastructure capacity and an infrastructure capac-
ity development strategy. The technical knowledge of
a fully-trained operator, as the on-site professional,
requires understanding the benefits of multiple barriers
to prevent contamination of drinking water supplies.
The technical knowledge of the operator should also
include insights into the risks to water supplies from
different, potential sources of contamination. The
managerial and financial capacities are serf explana-
tory. The three major problems that can potentially
impede the sustainability of a CWS include:
• A major source of contamination of drinking
water source water from wastewater intrusion
from septic systems and/or contaminant spills
from industrial activities. It is costly to provide
supplemental treatment processes to improve the
water quality of contaminated drinking water
source waters.
• Seasonal weather changes can result in floods
and droughts. Remedies include design options
to bypass treatment during rain and storm events
and identification of alternative water supplies
(including water reuse sources) to increase
capacity during droughts.
• Deteriorating collection and distribution systems
compromise source water quality and increase
the cost of water treatment. Remedies include
replacement of collection and distribution
systems and the use of point of use systems in
homes and businesses.
4.6 EPA Source Water Assessment
and Protection Programs
The EPA's Office of Ground Water and Drinking Water
has extensive information available about source water
protection on the Internet at: http://www.epa.gov/safe-
water/protect. html.
4.7 Key Questions
The key scientific questions for source water protec-
tion fall into the following categories: (a) water quality
criteria; (b) source water assessments; (c) preventative
measures to address sources of contamination; and (d)
contingency planning. A range of scientific issues ex-
ists within each of these categories. Some of the most
important questions include (EPA, 2003):
• How adequately do the Ambient Water Quality
Criteria (AWQC) that address the major
drinking water contaminants protect public
health?
• What improved techniques are needed to better
define source water characteristics and sources
of contamination?
• What are the fate and transport characteristics of
certain types of contaminants in surface water
and ground water?
• How effective are candidate protection measures
(i.e., Best Management Practices) on improving
the quality of the source water?
• What are the impacts of sudden increases in
source water contaminant concentrations on
drinking water treatment performance?
• What early warning and monitoring systems
should be developed to alert utility operators
of contaminant incursions at the source so that
corrective actions might be employed?
• Should source water research focus on ground
water for small systems?
4.8 References
EPA. State Source Water Assessment and Protection
Programs Guidance, Final Guidance, EPA-816-R-97-
009, 1997.
EPA. Drinking Water Research Program Multi-Year
Plan, available at: http://www.epa.gov/osp/myp/
dw.pdf, 2003
EPA. Data & Databases PivotTables, available at:
http://www.epa.gov/safewater/data/pivottables.html,
2005
4-4
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Chapter 5
Treatment Processes
5.1 Introduction
When the SDWA was reauthorized in 1996, it ad-
dressed Small System drinking water concerns and
required EPA to assess treatment technologies relevant
to small systems serving fewer than 10,000 people.
The 1996 SDWA Amendments also identified two
classes of treatment technologies for small systems:
• Compliance technologies which may refer to:
1. a technology or other means that is affordable
and that achieves compliance with the MCL, and
2. a technology or other means that satisfies a
treatment technique requirement.
• Variance technologies which are only specified
for those system size/source water quality
combinations for which there are no listed
compliance technologies (EPA, 1998a).
While variance technologies may not achieve compli-
ance with the MCL or treatment technique require-
ment, they must achieve the maximum reduction or
inactivation efficiency that is affordable considering
the size of the system and the quality of the source
water. Variance technologies must also achieve a level
of contaminant reduction that is protective of public
health. Possible compliance technologies include
packaged or modular systems and point-of-use (POU)
or point-of-entry (POE) treatment units.
The 1996 SDWA Amendments do not specify the
format for the compliance technology lists and state
that the variance technology lists can be issued either
through guidance or regulations. Rather than provide
the compliance technology list through rule-mak-
ing, EPA provided the listing in the form of guidance
without any changes to existing rules or the passing of
new ones. A sample of this guidance for disinfection
technologies is summarized in Table 5.1, which may
also be found in:
• Small System Compliance Technology List for
the Surface Water Treatment Rule and Total
ColiformRule (EPA, 1998b)
• Small System Compliance Technology List for
the Non-Microbial Contaminants Regulated
Before 1996 (EPA,1998a)
• Variance Technology Findings for Contaminants
Regulated Before 1996 (EPA, 1998c)
5.2 Packaged Filtration
Table 5.2 presents a summary of filtration compliance
technology for surface water (EPA, 2003), a major-
ity of the EPA WS WRD small systems research has
focused on the evaluation of "packaged" filtration
and disinfection technologies that are most useful
to small system operators. Filtration efforts have
focused on evaluating various bag, cartridge and
membrane filters. Disinfection techniques evaluated
include a variety of onsite chlorine generators and
packaged UV/ozonation plants. Details regarding
these treatment methods and research are presented
in Table 5.2.
Table 5.1 Surface Water Treatment Rule compliance technologies for disinfection (EPA,
2003).
Removals:
Log Giardia & Log Virus w/CT's
Unit Technologies indicated in () Comment
Free Chlorine
Ozone
Chloramines
Ultraviolet Radiation
On-Site Oxidant
Generation
Chlorine
Dioxide
3 log (1 04) & 4 log (6)
3 log (1 . 43) & 4 log (1.0)
3 log (1 850) & 4 log (1491)
1 log Giardia (80-1 20) & 4 log vi-
ruses (90-1 40) mWsec/cm2 doses in
parentheses 2
Research pending on CT values
3 log (23) & 4 log (25)
Basic operator skills. Better for larger drinking water systems
with good quality source water, low in organics and iron/man-
ganese. Concerns with disinfection byproducts. Storage and
handling precautions required.
Intermediate operator skills. Ozone leaks can be hazardous.
Does not provide residual disinfection protection for distributed
water.
Intermediate operator skills. The ratio of chlorine to ammonia
must be carefully monitored. Requires long CT.
Basic operator skills. Relatively clean water source necessary.
Does not provide residual disinfection protection for distributed
water.
Basic operator skills. May be inexpensive to procure and oper-
ate. Chlorine production rates may vary.
Intermediate operator skills. Better for larger drinking water
systems. Storage and handling precautions required.
5-1
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Table 5.2 Surface Water Treatment Rule compliance technologies for filtration (EPA, 2003).
Removals:
Unit Technologies Log Giardia & Log Virus Comment
Conventional Filtration
and Specific Variations
on Conventional
Direct Filtration
Slow Sand Filtration
Diatomaceous Earth
Filtration
Reverse Osmosis
Nanofiltration
Ultrafiltration
Microfiltration
Cartridge/
Bag/Backwashable
Depth
Filtration
2-3 log Giardia & 1 log viruses
0.5 log Giardia & 1-2 log
viruses (and 1 .5-2 log Giardia
with w/coagulation)
4 log Giardia & 1 -6 log viruses
Very effective for Giardia (2
to 3-log) and Cryptosporidium
(up to 6-log); low bacteria and
virus removal
Very effective, absolute barrier
(cysts and viruses)
Very effective, absolute barrier
(cysts and viruses)
Very effective Giardia, >5-6
log 7 ; Partial removal viruses
disinfect for virus credit)
Very effective Giardia, >5-6
log; Partial removal viruses
(disinfect for virus credit)
Variable Giardia removal &
Disinfection required for virus
Removal
Advanced operator skills required. High monitoring requirements.
May require coagulation, flocculation, sedimentation or flotation as
prefiltration. Will not remove all microorganisms.
Advanced operator skills required. High monitoring requirements.
May require coagulation, flocculation, sedimentation or flotation as
prefiltration. Will not remove all microorganisms.
Basic operator skills required. Most effective on high quality water
source. Will not remove all microorganisms.
Intermediate operator skills required. Good for source water with low
turbidity and color. Will not remove all microorganisms.
Intermediate to advanced operator skills required, depending on the
amount of pretreatment necessary. Post disinfection required under
regulation. Briny waste can be toxic for disposal.
Intermediate to advanced operator skills required, depending on the
amount of pretreatment necessary. Post disinfection required under
regulation.
Intermediate to advanced operator skills required, depending on the
amount of pretreatment necessary. Post disinfection required under
regulation.
Intermediate to advanced operator skills required, depending on the
amount of pretreatment necessary. Disinfection required for viral
inactivation.
Basic operator skills required. Requires low turbidity water. Disinfec-
tion required for viral inactivation. Care must be taken towards end of
bag/cartridge life to prevent breakthrough.
5.2.1 Filtration
Source water may contain turbidity, particles, and/or
organic material. Filtration is the removal of particu-
lates, and thus some contaminants, by water flowing
through a porous media. Filtration is considered to be
the most likely and practical treatment process or tech-
nology to be used for removal of suspended particles
and turbidity from a drinking water supply. Federal
and state laws require all surface water systems and
systems under the influence of surface water to filter
their water. Filtration methods include slow and rapid
sand filtration, diatomaceous earth filtration, direct
filtration, membrane filtration, bag filtration, and car-
tridge filtration. The other filtration methods typically
use natural filtration media (e.g., granulated media
particles such as carbon, garnet, or sand, alone or in
combination). Bag and cartridge filtration media are
commonly made from synthetic fibers designed with a
specific pore size. The type of filter media most suited
for an application depends mainly on the impurities
present in the source (raw) water. Specifically, the
particle size of the impurity present in the raw water
typically dictates the type of filter media. The particle
sizes of common water contaminants and the filtration
devices required for their treatment (or removal) are
shown in Figure 5.1.
If the source water contains particle (large size)
impurities, prefiltration is generally applied in front
of bag or cartridge type filters. Prefiltration removes
the larger paniculate material from the water stream
by using coarse, often back-washable granular media.
The prefilters protect the more expensive bag and/or
cartridge type units from frequent "fouling." Figure
5.2 shows a picture of a clogged prefilter.
Bag and cartridge filters can be used to remove con-
taminants down to around the 1-micron particle size
(l/10th the size of a human hair). However, a prefilter
(such as another bag or cartridge filter of greater pore
size) is typically recommended prior to using a submi-
cron filter. Microfiltration is used to remove particles
in the 0.5 to 10 micron size range with the membrane
acting as a simple sieving device. In ultrafiltration, na-
nofiltration, and reverse osmosis processes, one stream
of untreated water enters the unit but two streams
of water leave the unit: one is treated water and the
other is reject water containing the concentrated
contaminants removed from the water. Microfiltration
systems will remove some microbes such as protozoa
and bacteria but not viruses. Unlike nanofiltration
and reverse osmosis, microfiltration cannot remove
calcium and magnesium from water. Ultrafiltration is
5-2
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Microns
(Log Scale)
Approx. Molecular Wt.
200 1000 10,000 !0,000
Relative
Size of
Common
Materials
Dissolved
Metal
Compound
Salt
Virus
Tobacco Smoke
Bacteria
Coal Dust
Crypt- Giarda
Beach Sand
Pollen
Human Hair
Filtration
Technology
Reverse Osmosis
Ultrafiltration
Cartridge/Bag/Granular Filtration
Nanofiltration
Microfiltration
Figure 5.1 Particle size distribution of common contaminants and associated filtration technology (EPA,
2003).
used to remove some dissolved material (such as large
organic molecules) from water (0.001 to 0.02 micron
size range). Most microbial contaminants are removed
by ultrafiltration including bacteria, protozoa, and the
larger virus sizes. Nanofiltration is used to remove
particles in the 0.001 to 0.002 micron size range,
polyvalent ions, and smaller organic molecules (down
to a molecular weight of about 200-500 daltons).
Reverse osmosis (RO) can remove most contaminants
dissolved in water including arsenic, asbestos, pro-
tozoa, pyrogens, sediment, and viruses (Craun et al.,
1997).
5.2.2 Bag Filtration
Bag filtration systems are based on physical screening
processes. If the pore size of the bag filter is smaller
than the microbe, some removal will occur. Depend-
ing on the quality of the raw water, EPA suggests a
series of filters, such as sand or multimedia filters
followed by bag or cartridge filtration, to increase
paniculate removal efficiencies and to extend the life
of the secondary filter. Bag filters can be used as pre-
filtration for other filters as well.
Bag filters are disposable, non-ridged replaceable
fabric units contained either singly in series or parallel
or grouped together in multiples within one vessel.
The vessels are usually fabricated of stainless steel for
corrosion resistance, strength, cleaning, and disinfec-
tion. Supply (non-treated or treated) water can be in-
troduced into the vessel from the top, side, or bottom,
and flows from the inside of the bag to the outside.
Research conducted by EPA has not shown any spe-
cific method of water introduction into the vessel to be
superior to others (EPA, 2003).
Bag filtration is generally not recommended for
use as a single barrier to remove parasites such as
Cryptosporidium. However, it can be used as a
pretreatment step before cartridge filtration to remove
large particles and high levels of turbidity to improve
parasite removal. The water can then be polished or
treated to remove any remaining microbial or bacte-
rial contaminant (EPA, 2003). For smaller systems
that have a very high quality of source water, such as
ground waters under the influence of surface waters,
bag filters may serve as an effective single barrier
against parasites such as Cryptosporidium. In an
EPA sponsored Environmental Technology Verifica-
tion (ETV) study conducted by NSF, a log removal
range between 1.9 and 3.7 was observed for similar
sized micro-sphere particles. Micro-spheres of 3.7
um and 6.0 um size were selected for testing due to
their similarity in size to Cryptosporidium oocysts
and Giardia cysts, respectively. The source water
characteristics for this testing were: turbidity average
0.75 NTU, pH 7.1, and temperature 12.1°C (NSF,
2001).
Figure 5.2 Clogged Prefilter (EPA, 2003).
5-3
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5.2.3 Cartridge Filtration
Cartridge filtration is a technology suitable for remov-
ing microbes and reducing turbidity. These filters are
easy to operate and maintain, making them suitable for
treating low-turbidity water. They can become fouled
relatively quickly and must be replaced with new
units. Although these filter systems are operationally
simple, they are not automated and can require rela-
tively large operating budgets. A disinfectant may be
recommended to prevent surface-fouling via microbial
growth on the cartridge filters and to reduce microbial
pass-through.
Cartridge filters are rigid cores (usually poly vinyl
chloride-PVC) with surrounding deep-pleated filter
media. Cartridge filters housings are generally made
of stainless steel or fiberglass-reinforced plastic for
chemical resistance. The filters are available in vari-
ous pore sizes and materials depending on the inten-
tion of filtration and the source water quality. The
filter media are typically constructed of polypropylene
or polyester but may be of other fibers for specific
applications. The pore sizes available may vary by
vendor and material, but are typically 100, 50, 25, 10,
5, and 1 micron. Cartridge filters may be disposable or
washable, depending on the material and vendor. De-
pending on the inlet water quality, flow rate, and filter
pore size, a filter may last from one hour to longer than
a month. If inlet water quality is poor, a pre-filtration
step may be best to reduce filter changes and minimize
cost. This can be achieved by using one cartridge filter
system with a 50 or 25 micron filter for pre-filtration,
followed by another cartridge filter system with a 5 or
1 micron filter for finer filtration (EPA, 2003).
Like a bag filter, one of the most cost-effective benefits
of the cartridge filter is that it is commonly used
without costly chemical additions such as those used
in coagulation and flocculation. Like bag filtration
technology, cartridge filters are designed for proto-
zoan, parasite, or oocyst capture. These filters have
"absolute" pore sizes designed and engineered into
them that are reported to be uniform to contain and
capture oocysts, protozoans, or parasites. At the same
time, these filters permit bacteria, viruses, and fine
colloids to pass through, depending on the pore size
(EPA, 2003).
5.2.4 Membrane Filtration
Membranes act as selective barriers, allowing some
contaminants to pass through the membrane while
blocking the passage of others. Membranes may be
made from a wide variety of polymers consisting of
several different materials for the substrate, the thin
film, and other functional layers of the membranes.
The thin film is typically made from materials like
cellulose acetate that have tiny pores that allow the
passage of water while blocking bigger molecules
(EPA, 2003).
The movement of material across a membrane typi-
cally requires water pressure as the driving force.
There are four categories of pressure-driven membrane
processes: microfiltration (MF), ultrafiltration (UF),
nanofiltration (NF), and RO. Membrane filters (such
as MF and UF) act as sieves, much like the bag and
cartridge filters, just with smaller pore sizes (0.003
to 0.5 microns). Other membrane systems, NF and
RO, actually block contaminants dissolved in water
down to the molecular level. RO and NF processes
are typically applied for the removal of dissolved
contaminants, including both inorganic and organic
compounds (EPA, 2003).
5.2.5 Ultra Filtration (UF)
UF systems have shown to be effective for the re-
moval of pathogens, while being affordable for small
systems. UF is one of many processes used to remove
particles and microorganisms from water. The UF
technology falls between NF and MF on the filtration
spectrum. Systems may be designed to operate in a
single pass or in a recirculation mode.
UF systems are operated by pumping water through a
recirculation loop containing the membrane housing,
and through several membranes, which are usually
positioned in series. The UF membranes are usually
large cartridges that can range in pore size from 0.003
to 0.1 microns. They are usually constructed of plastic
material. These can be hollow-fiber or spiral-wound
membranes. The membranes are also classified by
pore diameter cut off (PDCO) which is the diameter of
the smallest particles that are retained by it, typically
in the range of 0.1 to 10 microns. UF is used for the
separation of large macromolecules such as proteins
and starches in other industry sectors. Sometimes, UF
membranes are classified by the molecular weight cut
off (MWCO) number. MWCO is defined as the mo-
lecular weight of the smallest molecule, 90% of which
is filtered by the membrane. The range of UF systems
typically spans between 10,000 to 500,000 MWCO
(EPA, 2003).
5.3 Disinfection
Disinfection is the process used to reduce the number
of pathogenic microbes in water. The Surface Wa-
ter Treatment Rules require PWSs to disinfect water
obtained from surface water supplies or ground water
sources under the influence of surface water (EPA,
1989). The Ground Water Rule requires PWSs to
disinfect their well water supplies. As shown by
the MCL and M/R violations of the SDWA and its
5-4
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amendments over the years, small systems are either
(1) unable to simply disinfect their water or (2) record
and submit their data to the appropriate state agency.
Typically, some form of chlorine is used as a disinfect-
ant; more recently, ultraviolet (UV) radiation, ozona-
tion (O3) or a combination of UV/O3 technologies are
being used for disinfection.
On-site ozone generating equipment is costly com-
pared to other disinfection technologies. The effec-
tiveness of the forms of chlorine and ozone in killing
micro-organisms (i.e., biocidal efficiency) varies with
the type of micro-organism and the water quality
conditions (such as pH). The relative effectiveness of
chlorine and ozone in killing microbes and the stability
of each disinfectant are summarized in Table 5.3.
The use of UV light as a mean for water disinfection
has been a proven process for many years. The benefit
of the UV disinfection process is that it does not use
any chemicals and is effective for Cryptosporidium in-
activation. However, residual disinfection via UV (to
account for contamination via the distribution system)
is not possible.
The optimum amount of disinfecting agent needs to be
used to achieve appropriate disinfection and minimize
DBF formation. Currently, the regulated DBFs in
the United States are total triaholmethanes (TTHMs)
with a MCL of 80 parts per billion (ppb). However,
the practice of chlorination for pre-oxidation or for
disinfection purposes can result in the formation of
chlorinated organic by-products. The Stage 1 DBF
Rule will result in the regulation of several other
by-products of chlorination such as haloacetic acids
(HAAS) to 0.060 mg/L, along with a potential reduc-
tion in the current trihalomethane (THM) standard of
80 ppb. In some cases, this might result in a change
to an alternative pre-oxidant, or disinfectant, use of
membranes, or elimination of the use of free chlorine
(Pollack et al., 1999). To minimize the formation of
DBFs under the SWTR (EPA, 1989) and the Enhanced
Surface Water Treatment Rule (EPA, 2002), most
utilities are required to filter their water unless the fol-
lowing conditions are met in the surface water prior to
disinfection:
• fecal coliform bacteria <20/100 mL in 90% of
samples,
• total coliform bacteria <100/100 mL in 90% of
samples,
• turbidity <5 Nephelometric Turbidity Units
(NTU), and
• other MCLs met.
Treatment plants exempted from filtration must
disinfect to achieve 99.99% inactivation of viruses,
and 99.9% inactivation of Giardia lamblia cysts. For
systems that use chlorine for disinfection, compliance
with these requirements must be demonstrated with
the CT approach (the product of the average disinfect-
ant concentration and contact time). CT values esti-
mated for actual disinfection systems must be equal to
or greater than those published in the SWTR Guidance
Manual for viruses and G. Lamblia cysts (Pollack et
al., 1999).
Also, EPA studies have demonstrated that the pli-
ability of Cryptosporidium oocysts may permit the
pass-through of oocysts through a filtration system
thus making disinfection that much more important
as a barrier (Li, 1994). Just like large systems, small
systems have to be concerned with the safety, ease of
handling, shipping, storage, capital costs, and opera-
tion and maintenance (O&M) costs associated with the
use of appropriate disinfectant technology.
EPA has evaluated several disinfection technologies
that are affordable and easy to use from a small sys-
tems perspective. A summary of these technologies is
presented in the following subsections.
5.3.1 Disinfection by Chlorination
The use of chlorine as a disinfectant is commonly
accepted worldwide. Chlorination is a popular choice
because of its residual disinfection characteristics. Its
effectiveness is very simple to test; one needs only to
measure the residual chlorine at the point of consump-
tion to ensure proper disinfection.
People are becoming more concerned about the DBFs
Table 5.3 Summary of disinfectant characteristics relating to biocidal efficiency (Lykins et al.,
1990).
Ranka
pH FffprtQ on Fffiripnry
Disinfectant Biocidal Efficiency Stability (pH ranges 6-9)
Ozone
Chlorine dioxideb
Free Chlorine13
1
2
3
4
2
3
Little effect
pH increase is beneficial
pH increase is detrimental
aRanking: 1 = best, 4 = worst.
*>Ranking influenced by pH.
5-5
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of chlorine, and alternatives to chlorine are being
investigated. Chlorine reduces bacteria levels, but it
also reacts with other organic impurities present in
water producing various DPBs which are listed as
probable or possible human carcinogens (cancer-caus-
ing agents). Other disadvantages of chlorination are
undesirable tastes and odors, requirement of additional
equipment (such as tanks) to guarantee proper contact
time, and extra time to monitor and ensure proper
residual concentration level. It also performs poorly
in reducing viruses (such as enterovirus and hepatitis
A) and protozoa (such as Cryptosporidia and Giardia)
(EPA, 2003).
Chlorine is generally obtained for disinfection in the
form of gaseous chlorine, onsite chorine dioxide gen-
erators, solid calcium hypochlorite tablets, or liquid
sodium hypochlorite (bleach). Gaseous chlorine and
onsite chlorine dioxide generators are typically found
at larger drinking water systems. Small drinking water
systems sometimes use solid calcium hypochlorite,
which is typically sold as a dry solid or in the form of
tablets for use in proprietary dispensers. This method
of disinfection however, is expensive, suitable mainly
for low flow applications, and the use of calcium
can lead to scale formation. For the most part, small
system operators continue to disinfect water using
common household liquid bleach or swimming pool
chlorine (EPA, 2003).
There are, however, other chlorination processes that
small system operators should consider. One such al-
ternative that has been evaluated extensively by EPA's
WSWRD is the on-site salt brine electrolysis chlorine
generator system. The salt brine solution, together
with the electrolytic cell, generates a solution (liquor)
of primarily sodium hypochlorous (chlorine) acid.
Operators should be aware that some vendors claim
that their electrolytic generator enhances pathogen
(Cryptosporidium sp. and Giardia sp.) inactivation by
using the combined actions of various mixed oxidant
reactions that are generated from the electrolytic
cell. The claim is that this mix of oxidants minimizes
the formation of DBFs. However, EPA has not been
able to demonstrate the presence of any other oxidant
(other than sodium hypochlorous acid) generated from
these units (EPA, 2003).
5.3.2 Disinfection by Ozonation
Ozonation is another disinfection method. Ozone is ef-
fective as an oxidizing agent in removing bacteria with
a relatively short exposure time. Ozone generators
are used to produce ozone gas on site, since the gas
is unstable and has a very short life. These generators
must be installed and monitored cautiously, because
high concentration levels of ozone will oxidize and
deteriorate all downstream piping and components.
With home ozone systems, leftover ozone must be
removed with an off-gas tank to ensure homeowners
are not exposed to ozone gas, which is a strong irritant.
Ozone reacts with bromide resulting in the forma-
tion of highly carcinogenic DBFs including bromate,
bromoform, and dibromeacetic acid. In PWSs, UV
equipment or biological filters are typically installed to
remove ozone residuals prior to filtration (EPA, 2003).
5.3.3 Advanced Oxidation Process for
Disinfection & Destruction
EPA evaluated a packaged UV/O3 (also referred to
as Advanced Oxidation Process or AOP) system for
removal of microorganisms. The unit evaluated was
capable of processing up to 10 gpm of water and
engineered to ensure adequate UV intensity and ozone
residuals for AOPs.
The combined UV/O3 system achieved the highest
removal rates for bacterial contamination. The UV/O3
disinfection technology is also useful in removing
chemical organic contaminants such as MTBE, per-
chloroethylene, and trichloroethylene (EPA, 2003).
Advanced oxidation processes use oxidants to destroy
organic and microbial contaminants in drinking water.
Several different oxidants, such as ozone, hydrogen
peroxide, and hydroxyl radicals, may be used. EPA
evaluated the use of an AOP system comprised of
UV/O3 for disinfection potential and MTBE destruc-
tion. This effort was intended to investigate if an AOP
system could be used to disinfect the water and, at the
same time, destroy organic compounds.
Ultraviolet irradiation and Ozonation are known to ef-
fectively destroy organic compounds in drinking water
and other matrices. Thus, in addition to treatment for
Cryptosporidium, UV/O3 systems have also shown
the ability to treat MTBE in drinking water. The
combined UV/O3 process showed the best potential
for MTBE removal. Complete MTBE removal was
observed within a 20 minute reaction time. Several
byproducts are generated as a result of MTBE treat-
ment. These by-products include t-butyl alcohol,
t-butyl formate, formaldehyde, isopropyl alcohol,
acetone, and acetic acid methyl ester (Vel Leitner et
al., 1994, Liang, 1999).
In anticipation of the states' needs for innovative and
cost-effective small system treatment technology,
EPA's WSWPJD has focused on the smallest of these
systems in the 25-500 population range and on those
technologies that are easy to operate and maintain.
Alternative treatment systems/technologies (package
plants) are perceived as "high tech" and are some-
5-6
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times more expensive to purchase than state-accepted
conventional technologies. However, in many cases,
alternative treatment systems/technologies are easier to
operate, monitor, service, and less expensive to main-
tain and service in the long-term (EPA, 2003).
Operators should find a mechanism to filter particles,
turbidity or organic material from the source water
and should realize that each particle removed by a
filter could be a microscopic parasite such as Crypt-
osporidium sp. . Removing particles also allows the
disinfectant to be more effective. However, the best
option would be to find a good quality source water,
i.e., a source water that has very low particle counts,
turbidity, or organic material (EPA, 2003).
In anticipation of small system needs in meeting the
Stage 1 DBPR, the proposed Ground Water Rule, and
the LT1ESWTR, the EPA's WSWRD has investigated
alternative technologies focusing on their ability to in-
activate Cryptosporidium while at the same time being
affordable and easy to operate and maintain.
Several guidance manuals are available to assist PWS
operators in complying with the Stage 1 DBF Rule.
Examples of such guidance manuals include:
• Disinfection Profiling and Benchmarking
Guidance Manual (EPA, 1999a).
• Alternative Disinfectants and Oxidants
Guidance Manual (EPA, 1999b).
• Microbial and Disinfection Byproduct Rules
Simultaneous Compliance Guidance Manual
(EPA, 1999c).
On-site salt-brine electrolysis chlorine generator sys-
tems can be very attractive to small system operators,
because they are generally safer to handle and oper-
ate than chlorine gas or liquid (sodium hypochlorite
or calcium hypochlorite) systems. EPA conducted
studies to evaluate three different on-site salt brine
based chlorine generators and compared them to each
other and to liquid bleach. EPA noted a wide variation
in prices when purchasing these units. The costs for
the three salt-brine generators, designed specifically
for small systems, range from $18,000 to $35,000
(depending on the manufacturer). Since most small
treatment system operators and facilities have a limited
budget, EPA evaluated other avenues and options for
the small system operator. As a fourth system, EPA
purchased a salt-brine generator from a swimming
pool supply company for $750 and added other acces-
sories such as plumbing, a pump, a pressure gauge,
flow control and a brine tank for $525 for a total
equipment cost of $1,275 (EPA, 2003).
5.3.4 Disinfection System Observations
Research on on-site chlorine generators and UV/O3
treatment technologies has resulted in the following
observations:
The disinfection capabilities of disinfection systems
are a function of dosage and contact time. For the on-
site chlorine generators, the chlorine dosage and free
residual chlorine are critical performance parameters.
For UV/O3 treatment technologies, the UV intensity
and ozone dosage are critical performance parameters.
For both technologies, a reaction chamber or a contact
tank provides a mixing "area" for the disinfecting
agent(s) and microorganisms in the water.
On-site chlorine generators are designed to convert
salt to chlorine via an electrolytic cell. As a result, the
hazards associated with the handling of liquid chlorine
are not a concern. Salt is added to the chlorine genera-
tor or contact tank in bulk and requires lifting by the
operator. Brine concentration levels are critical for
proper operation of on-site chlorine generators. The
accumulation of salt residue requires maintenance of
system tanks and piping.
UV/O3 systems oxidize organics instantaneously.
Ozone reacts quickly without leaving a residual disin-
fectant. UV disinfection is dependent on the intensity
of the light contacting the water. As a result, waters
with low turbidity and color are preferred for UV treat-
ment. Providing stable ozone dosage and UV intensity
is critical for providing consistent disinfection.
Several things can be done to improve UV/O3 system
performance. The air dryer dessicant can be replaced
on a regular basis to improve ozone generation. Ozone
dosage can be improved by increasing the air flow into
the ozone generator and optimizing the vacuum at the
venturi injector. For optimal performance, the UV/O3
system should be operated as specified by the manu-
facturer. Alternatively, an oxygen generator can be
used to feed the ozone generator; this, however, can be
an expensive option.
5.4 Sorption Technologies
Sorption is the common term used for both absorption
and adsorption. When a substance is incorporated into
another substance, the process is called absorption.
Adsorption is a surface phenomenon in which the ions
and molecules of one substance physically adheres or
bonds onto the surface of another molecule. In many
cases, it is not always clear which process (or both) is
responsible for the removal of a contaminant. Sorp-
tion is the preferred term for these processes.
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Sorption mechanisms are generally categorized as
either physical adsorption, chemisorption, or electro-
static adsorption. Weak molecular forces, such as Van
der Waals forces, provide the driving force for physical
adsorption, while a chemical reaction forms a chemi-
cal bond between the compound and the surface of
the solid in chemisorption. Electrostatic adsorption
involves the adsorption of ions through Coulombic
forces, and is normally referred to as ion exchange,
which is addressed separately in the ion exchange
modules. Common sorption technologies include ion
exchange, activated alumina, iron-based media, and
Granular Activated Carbon (GAC) (EPA, 2000).
5.4.1 Ion exchange (IX)
IX is a physical/chemical process in which ions held
electrostatically on the surface of a solid phase are
exchanged for ions of similar charge in a solution (i.e.,
drinking water). The solid is typically a synthetic ion
exchange resin which is used to preferentially remove
particular contaminants of concern. Ion exchange is
commonly used in drinking water treatment for soften-
ing (i.e., removal of calcium, magnesium, and other
cations in exchange of sodium), as well as removing
nitrate, arsenate, chromate, and selenate from munici-
pal water. Due to its higher treatment cost compared
to conventional treatment technologies, IX application
is limited primarily to small/medium-scale and point-
of-entry (POE) systems.
Anion exchange resins come in two classes, strong-
base anion (SBA) and weak-base anion (WBA). The
functional groups on the SBA resins are strongly basic
and ionized to act as ion exchangers over the pH range
of 0 to 13. The WBA resins are useful only in the
acidic pH region where the functional groups are pro-
tonated to form positively charged exchange sites for
anions. Both SBA and WBA resins may be present in
the hydroxide or chloride form. Typically, SBA resins
are used for arsenic removal because they tend to be
more effective over a larger pH range than WBA resins
(EPA, 2000).
5.4.2 Activated Alumina (AA) and Iron-based
Media
AA adsorption is a physical/chemical process by
which ions in solution are removed by the available
adsorption sites on an oxide surface. AA is porous
and highly adsorptive. AA filters a variety of contami-
nants, including fluoride, arsenic, and selenium. The
alumina can be regenerated. AA is usually prepared
through dehydration of A1(OH)3 at high temperatures
and consists of amorphous and gamma alumina oxide.
AA is used primarily in packed beds to remove con-
taminants such as fluoride, arsenic, selenium, silica,
and natural organic matter (NOM). To remove con-
taminants, feed water is passed continuously through
one or more AA beds. When all available adsorption
sites are occupied, the AA media may be regener-
ated with a strong base, NaOH, or simply disposed
of. Many studies have shown that AA is an effective
treatment technique for arsenic removal. Factors such
as arsenic oxidation state (As [III] vs. As[V]), pH,
competing ions, and empty bed contact time (EBCT)
significantly affect arsenic removal. Other factors
affecting the use of the AA process include regenera-
tion practice, spent regenerant disposal, and alumina
disposal (EPA, 2000).
The competition for adsorption sites by other ions such
as phosphate, silicate, sulfate and fluoride somewhat
limits the use of A A. More recently, iron based media
such as granular ferric hydroxide (GFH) and zero-
valent iron are being used for arsenic removal. Both of
these methods involve chemical adsorption of As(III)
and As(V) species to iron oxides. In most cases
neither media is intended to be regenerated. The spent
iron media generally passes the EPA leaching tests.
Recent adsorption tests conducted by EPA (EPA,
2001), demonstrate the potential of iron-based media
and resins to remove arsenic. In the adsorption testing,
the iron-based GFH media have outperformed the AA-
based media and IX resin for removal of arsenic over a
wide pH range. Although the GFH appears to be more
specific than AA for arsenic binding, it also suffers
from competitive adsorption of phosphate and silicate.
Competitive displacement of arsenic by sulfate is mi-
nor. The optimal system design will depend upon the
specific treatment scenario and source water quality.
5.4.3 Powdered Activated Carbon/Granular
Activated Carbon (PAC/GAC)
Activated carbon is carbon that has been exposed to
very high temperatures, creating a vast network of
internal pores. Two types of activated carbon, granu-
lar and powdered, are used widely in drinking water
treatment. Powdered activated carbon (PAC), which
is frequently used for taste and odor control, is added
directly to raw water and removed by settling in sedi-
mentation basins (NDWC, 1997).
PAC and GAC remove many organic contaminants
as well as taste and odor from water supplies. GAC
removes contaminants through adsorption, primarily
a physical process in which dissolved contaminants
adhere to the porous surface of the carbon particles.
In some cases, the adsorption process can be reversed
relatively easily. The ease of reversing adsorption is
another key factor in activated carbon's usefulness be-
cause it facilitates the recycling or reuse of the carbon
(NDWC, 1997).
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GAC can be used as a replacement for existing media
(such as sand) in a conventional filter, or it can be used
in a separate contactor (a vertical steel pressure vessel
used to hold the activated carbon bed) (NDWC, 1997).
5.5 Lime Softening
Although lime softening has been used successfully by
ground water systems serving fewer than 3,000 people,
it is unlikely to be suitable for treating ground water
in systems serving 500 or fewer people unless those
systems have some form of contract or satellite opera-
tion that would enable a trained operator to monitor
the treatment process. Prefabricated lime softening
equipment is available for small systems. Also, there
is an American Water Works Association Standard for
quicklime and hydrated lime (ANSI/AWWA B202-93)
that provides purchasers, manufacturers, and suppliers
with the minimum requirements, including physical,
chemical, packaging, shipping, and testing require-
ments (NDWC 1998).
Either hydrated lime [Ca(OH)2] or quicklime (CaO)
may be used in the softening process. The choice
depends upon economic factors, such as the relative
cost per ton of the two materials as well as the size
and equipment of the softening plant. Hydrated lime
is generally used more in smaller plants because it
stores better and does not require slaking (producing a
chemical change in lime by combining it with water)
equipment. On the other hand, quicklime costs less
per ton of available calcium oxide and is thus more
economical for use in large plants (NDWC, 1998).
Softened water has high causticity and scale-formation
potential; hence, recarbonation is employed to reduce
pH and mitigate scaling of downstream processes and
pipelines. Onsite combustion generation of carbon di-
oxide (CO2) or liquid CO2 is the most common source
of carbon dioxide for recarbonation (NDWC, 1998).
5.6 Affordability of Recommended
Treatment Technologies and
Protectiveness of Public Health
by Variance Technologies for
Small Systems
Many small system operators have argued that some
of the treatment technologies mentioned in this report
are simply not affordable to them. The SDWA requires
EPA to identify affordable compliance treatment tech-
nologies for small systems for each new drinking wa-
ter standard. EPA must evaluate treatment technologies
and their costs for three categories of small systems:
systems serving 25 to 500 people, systems serving 501
to 3,300 people and systems serving 3,301 to 10,000
people. If EPA cannot identify affordable compliance
technologies for some or all of the systems in these
categories, EPA must identify variance treatment tech-
nologies that achieve the maximum reduction afford-
able, and determine if the variance technologies are
protective of public health.
EPA currently determines if compliance with a drink-
ing water standard is affordable by comparing the
current cost of water plus the estimated additional
treatment cost of the new standard to an affordability
threshold of about $1,000 (this threshold is calcu-
lated by taking 2.5% of the annual median household
income (MHI) of -$40,000 among small systems).
Since the small system variance provisions became a
part of the SDWA in 1996, EPA has found compliance
with all new drinking water regulations to be "afford-
able" using the 2.5% of MHI criteria for all small
systems. As a result, states have not had the ability to
grant small system variances. However, evidence sug-
gests that there may in fact be significant numbers of
systems that have struggled with compliance costs for
some recent regulations.
As part of the 2002 appropriations process, Congress
directed EPA to review the methodology by which it
evaluates the affordability of drinking water standards
for small systems. In response, EPA sought the advice
of Science Advisory Board (SAB) and National Drink-
ing Water Advisory Council (NDWAC). The SAB
and NDWAC both recommended that EPA consider
modifications to its current methodology. Additionally,
small system operators have argued that the current
criteria are too stringent and fail to recognize situa-
tions in which small systems may find a regulation
unaffordable. After seven years of experience with
the current criteria, EPA agreed that it was time to
consider refinements to address the situations of com-
munities with below average incomes and/or above
average drinking water and treatment costs.
The SAB and NDWAC made a number of recommen-
dations regarding the method by which EPA evaluates
the affordability of compliance with drinking water
standards. Some key recommendations made by both
the SAB and the NDWAC include: (1) EPA should
consider the household cost of each new regulation
on an incremental basis rather than a total cost of all
water treatment regulations, and (2) EPA should con-
sider reducing the current affordability threshold. The
options being considered by EPA are based on a range
of income percentages significantly below the current
threshold (2.5% of MHI) and are much more likely to
make variances available to small drinking water sys-
tems. Both SAB and NDWAC reports (listed below)
are available online on the EPA website.
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• SAB report - Affordability Criteria for Small
Drinking Water Systems: An EPA Science
Advisory Board Report
• NDWAC report - Recommendations of the
National Drinking Water Advisory Council
to U.S. EPA on Its National Small Systems
Affordability Criteria - July 2003
Even after these variance technologies become avail-
able to small systems, the SDWA limits these vari-
ance technologies to those that are determined to be
"protective of public health." The SDWA does not
specify how one makes this determination; however,
it is clear from the provisions, that Congress intended
that a technology could be considered "protective" for
the purpose of SDWA even if the concentration of a
contaminant in the treated water was greater than the
concentration allowed by the drinking water stand-
ard (i.e. a MCL). Subsequently, on March 2, 2006,
EPA issued a proposed regulation for small drinking
water systems variances that proposed revisions to
the existing national-level affordability methodology
and the methodology to identify variance technologies
that are protective of public health. In this regulation,
EPA proposed that a variance technology for future
regulated contaminants is considered to sufficiently
protective of public health for purposes of the SDWA
provision 1412(b)(15) if the concentration of the target
contaminant after treatment by the variance technol-
ogy is no more than three times the MCL. EPA views
this 3x level as a general guideline which might be
modified for a specific contaminant if unusual factors
are associated with the contaminant or if risk assess-
ment suggests that an alternate level, whether higher
or lower, was appropriate. In addition, EPA requested
comments on a number of questions related to the
methodology EPA uses to evaluate the affordability of
national primary drinking water regulations. Three of
the key issues are:
1. The size of the system EPA should consider
as representative of each of the system size
categories specified under the SDWA. This
question is critical to determining the cost
each household must pay for the treatment
to comply with a new regulation. Smaller
systems have fewer households over which
the fixed costs of treatment can be distributed
and, therefore, experience higher household
costs. EPA specifically asked if the median (or
middle sized) or tenth percentile (a system that
serves fewer people than 90 percent of the other
systems in the category) should be selected as
the representative system for the category.
2. The affordability threshold (the maximum
cost that is affordable to customers served by
small systems). EPA proposed to calculate the
affordability threshold by taking a percentage
of the MHI among small systems (which as
of September 2005 was between $40,000 and
$44,000). EPA requested comments on the
following three different alternative thresholds:
• 0.25% MHI ($100 to $110 under Sept. 2005
income estimates)
• 0.50% MHI ($200 to $220 under Sept. 2005
income estimates)
• 0.75% MHI ($310 to $330 under Sept. 2005
income estimates)
3. Whether or not EPA should evaluate
affordability strictly on a national level, or use
a two step process that includes both a national
level evaluation of affordability, and a second
analysis conducted at the County level. EPA
would perform this second step only when the
first step found a standard to be affordable at the
national level. EPA would evaluate economic
data to identify economically disadvantaged
areas in the U.S. that cannot afford to comply
regardless of the outcome of the national
determination.
These methodologies, once finalized, will be applied
by EPA in evaluating small system affordability for
future drinking water standards with the exception
of regulations that address microbial contaminants
(including bacteria, viruses, or other organisms) or in-
dicators for microbial contaminants. The law does not
allow small system variances for microbial contami-
nants (SDWA section 1415(e)(b)(B)).
5.7 Point-of-Use/Point-of-Entry
(POU/POE) Applications
In many cases, small drinking water treatment systems
such as POU/POE units may be the best solution for
providing safe drinking water to individual homes,
businesses, apartment buildings, and even small towns.
Such consumers may not have the financial resources,
technical ability, or physical space to own and oper-
ate custom-built treatment plants. These small system
alternatives can be used for not only treating some raw
water problems, but are excellent for treating finished
water that may have degraded in distribution or stor-
age or to ensure that susceptible consumers such as
the very young, very old, or immuno-compromised
receive safe drinking water.
The 1996 SDWA Amendments provided that POU/
POE units could now be considered a "Final Solu-
tion". The 1996 regulations required the POU/POE
units to be "owned, controlled, and maintained by
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the PWS or by a person under contract with the PWS
operator to ensure proper operation and maintenance
and compliance with the MCLs or treatment technique
and equipped with mechanical warnings to ensure that
customers are automatically notified of operational
problems" (EPA, 1998a). Under this rule, POE de-
vices are considered an acceptable means of compli-
ance because POE can provide water that meets MCLs
at all points in the home. It is also possible that POE
devices may be cost effective for small systems or NT-
NCWS. In many cases, these devices are essentially
the same as central treatment. In 1998, POU devices
were listed as "compliance technologies" for inorgan-
ics, synthetic organic chemicals, and radionuclides, but
not for volatile organic chemicals.
Basically, the same technology used in treatment
plants for community water systems can be used in
POU/POE treatment. POU/POE treatment is applied
to reduce levels of organic contaminants, turbidity,
fluoride, iron, chlorine, arsenic, nitrate, ammonia,
microorganisms including cysts, and many other con-
taminants. Aesthetic parameters such as taste, odor,
or color can also be improved with POU/POE treat-
ment (Lykins et al., 1992). Table 5.4 summarizes key
features of commonly used POU/POE technologies
(EPA, 2003).
5.7.1 POU/POE Treatment Cost
The cost and application of POU/POE units as a final
solution for a small system or portion of a larger sys-
tem is highly dependent on the situation. A major fac-
tor is whether there is an in-place distribution system
versus whether additional treatment must be installed
in the existing central system. Approximately 80%
of the total cost of any water utility is the installation
and maintenance of the distribution system. In cases
where a distribution system would have to be installed
to treat a contaminated drinking water source, it may
be more cost-effective to install POU/POE units (EPA,
2003). An example of this would be a community
where each home has a well and it was discovered that
the ground water was contaminated with a pesticide,
fertilizer, or chemical. Rather than install miles of
pipe, pumps, and storage facilities, a small system
could get state approval to install and maintain units
in each home. This might be economical for upward
of 100 homes depending on the cost of the home units
versus the amount and difficulty of installing a distri-
bution system and central treatment facility. For those
small systems that already have a distribution system
in-place, the break-even point could be for fewer home
units (< 50). However, in situations where the existing
treatment plant could not be economically or physical-
ly upgraded or if the water quality is severely degraded
while in the distribution system, POU/POE treatment
may once again be a practical alternative (Goodrich et
al., 1992).
A recent report from EPA (EPA, 2005) on POU/POE
systems for As removal in a small rural town (pop.
400) concluded that centralized treatment modifi-
cations would result in monthly cost increases of
$24.71 per connection. POU/POE unit costs ranged
from $11.46 to $18.00 per connection depending on
frequency of monitoring and POU/POE cartridge
replacement.
5.7.2 Use of POU/POE Treatment and Bottled
Water in Small Systems
The financial instability of many small PWSs to com-
ply with the SDWA often forces state and local gov-
ernments to seek alternatives to centralized treatment
as sources of safe drinking water. For example, EPA's
new arsenic standard of 10 ug/L is expected to affect
5% of CWSs, but 77% of these affected CWSs serve
1,500 or fewer customers. POU treatment, approved
by EPA for permanently complying with this drink-
ing water standard, may be an economical alternative
for arsenic removal when compared to a central-
ized treatment for these smaller CWSs. Gurian and
Small (2002) studied three (base-case, high-cost, and
low-cost) POU scenarios to meet the 10 ug/L arsenic
standard by calculating the per-household cost for
implementing each POU option. The per-household
costs were compared with those of the least-expensive
centralized treatment methods for removing arsenic
(presented in published studies). The authors found
that POU treatment costs varied significantly with the
monitoring and maintenance schedule adopted by the
CWS; annual arsenic monitoring of each POU device
coupled with frequent maintenance and filter replace-
ment increased the POU costs to the point where
centralized treatment was more cost-effective. The
published costs of centralized treatment, however, also
varied significantly, and these discrepancies somewhat
masked the economic advantage of POU treatment.
Also, the results of this study point out some of the
difficulties in designing and running a POU treatment
program. For a POU program to be successful, CWS
operators must get cooperation from their customers.
This POU treatment scenario complexity may discour-
age CWSs from implementing POU treatment, even
when centralized treatment is not cost feasible. In
these cases, the authors suggest providing bottled wa-
ter to customers as a temporary compliance measure.
Bottled water can be considered as a principal alterna-
tive source for use in emergencies and/or on an interim
(or permanent) basis for small PWSs. Bottled water
can serve as a permanent supply of potable water for
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Table 5.4 Key Feature Summary of commonly used POU/POE technologies (EPA, 2003).
Technology Comments
Filtration Filtration and disinfection of water supplies are highly effective public health practices. MF, UF, and RO
filtration systems have been shown to be effective technologies for the removal of pathogens while being
affordable for small systems. Generally, pore-size of the filtration media determines its effectiveness in
teh removal of a specific pathogen. Filtration media such as bags, cartridges and membranes require
periodic maintenance and/or replacement.
Activated Carbon
Activated Carbon is the most widely used POU/POE systems for home treatment of water. Easy to install
and maintain with low operating costs, usually limited to filter replacement. Can remove most organic and
some inorganic contaminants.
Membranes
Most POU membrane systems are reverse osmosis filters installed under the kitchen sink, typically with
either an activated carbon prefilter or an additional UV light disinfection step such as to combat bacteria
since the water is often stored under the sink until used.
Ion Exchange
Commonly called water softeners when used for removal of calcium and magnesium from water. Other
types of units remove anions such as arsenic (arsenate), hexavalent chromium, selenium (selenate), and
sulfate.
Distillation
Distillation is most effective in removing inorganic compounds such as metal (iron and lead) and nitrates,
hardness, and particulates from contaminated water. Distillation also removes most pathogens. The
effectiveness of distillation in removing organic compounds varies, depending on the chemical charac-
teristics of the compounds such as water solubility and boiling point. Distilling units have relatively high
electrical demands and require about 3 kilowatt-hours per gallon of water treated.
Air Stripping or
Aeration
Aeration is a proven technology for removing volatile organic chemicals (for example, dry cleaning fluid)
from drinking water supplies for POE applications. Aeration systems include: packed tower systems,
diffused bubble aerators, multiple tray aerators, spray aerators, and mechanical aerators. Storage, re-
pumping, and possibly disinfection facilities are needed after air stripping to distribute treated water. Air
stripping is typically used for POE applications where high concentrations of volatile organics have to be
removed from drinking water where carbon can be used only for short periods of operation. Radon gas
can also be removed by aeration.
Modular Slow Sand
Filtration
Slow sand filters housed in round fiberglass tanks (approx. 6 ft tall x 2.5 ft in diameter) can treat 400-500
gallons daily. The systems are simple to operate and have low capital (approx. $2,000) and operating
costs. The unique feature of this system is a very thin 1/8" thick filter blanket followed by a 1" thick poly-
propylene filter blanket (similar to a furnace filter) to replace the biological mat that typically grows on top
of the sand (schmutzdecke). The blankets can simply be replaced when flow is restricted without losing
much sand or significant down-time.
Disinfection and
Destruction
Disinfection is an important consideration for POU/POE systems. Disinfectants that are usually used in
POU/POE systems are ultraviolet light, ozone, chlorine, silver impregnated carbon, and iodine.
Chlorine - The most widely used water disinfectant. Can be used in the form of liquid bleach, solid tab-
lets, or generated onsite in portable generators.
Ultraviolet Light (UV) - Ultraviolet light is a popular home disinfection method in combination with other
treatment techniques. Does not add chemicals that can cause secondary tast and odor problems. Units
require little maintenance and overdose is not a danger.
Ozone - Ozone has been for disinfection and destruction of iron, manganese, and some chemical con-
taminants. Ozone has to be generated and used on-site as needed.
Iodine - Iodine has been used as an alternate disinfectant to chlorine because it is easier to maintain a
residual.
Silver impregnated carbon - These units contain a small amount of silver to keep bacteria growth under
control. They are not designed to remove or kill bacteria. However, the effectiveness of the silver in the
carbon filter is questionable. The only advantage noted in studies of silver-impregnated carbon was that
in the first month of use, the bacterial counts were lower than carbon without silver (Seelig, B., Bergsrud,
F, and Derickson, R, 1992).
an entire small community or non-community system,
or for residential areas served by private wells in an
aquifer that has become contaminated. This option is
attractive when centralized treatment is costly. Bottled
water can serve as a temporary solution during the in-
termediate period while permanent solutions are being
devised. Bottled water may be used by water systems
facing water quality problems due to an emergency
situation. The use of bottled water has been expressly
recognized by the U. S. Army Corps of Engineers
(USAGE), the Federal Emergency Water Administra-
tion and the EPA under the National Contingency Plan
for responding to contamination of drinking water sup-
plies. Bottled water can serve as a permanent alterna-
tive source for special segments of the population such
as small children and pregnant women who require
low nitrate levels in the water supply. The SDWA al-
lows EPA to authorize the use of bottled water, where
appropriate, to achieve the goals of the SDWA. Other
government policies authorizing the use of bottled wa-
ter to meet drinking water needs are: EPA's National
Contingency Plan under the Superfund Act, the De-
partment of Interior's Emergency Water Supply Plan,
and the USACE's' Emergency Water Plan (Marker,
1985). In some scenarios, a central treatment station
with bottled water delivered to each customer may be
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advantageous. This option provides high quality water
for consumption and at the same time obviates the
need for expensive treatment of water that is used for
activities such as toilets, yard watering, and laundry.
5.8 Key Questions
• How can WSWRD research begin to address
treatment of multiple contaminants in Small
Systems?
• Should research focus on treatment of ground
water since most Small Systems source waters
are underground?
• What are the most pressing future needs for
water treatment technology in small systems?
• Should research focus on inexpensive treatment
technologies rather than "cutting-edge"
technologies which tend to be more expensive?
5.9 References
ANSI/AWWA. AWWA Standard for Quicklime and
Hydrated Lime. Revision of ANSI/AWWA B202-93,
AWWA, Denver, CO. 1993.
Craun, G., Goodrich, J. A, Lykins, B. W, Schwartz,
E., How to Select a Personal and Household Drink-
ing Water Treatment System: A Guide to Peace Corps
Personnel, 1997.
EPA. 40 CPR Parts 141 and 142; Drinking Water; Na-
tional Primary Drinking Water Regulations; Filtration,
Disinfection
EPA. Turbidity, Giardia lamblia, Viruses, Legionella,
and Heterotrophic Bacteria; Final Rule, Federal Regis-
ter, 54(124), 27486-27541, 1989.
EPA. Small System Compliance Technology List for
the Non-Microbial Contaminants Regulated Before
1996,EPA-815-R-98-002, 1998a.
EPA. Small System Compliance Technology List for
the Surface Water Treatment Rule and Total Conform
Rule,EPA-815-R-98-001, 1998b.
EPA. Variance Technology Findings for Contaminants
Regulated Before 1996, EPA-815-R-98-003, 1998c.
EPA. Disinfection Profiling and Benchmarking Guid-
ance Manual, EPA-815-R-99-013, 1999a.
EPA. Alternative Disinfectants and Oxidants Guid-
ance Manual, EPA-815-R-99-014, 1999b.
EPA. Microbial and Disinfection Byproduct Rules
Simultaneous Compliance Guidance Manual, EPA-
815-R-99-015, 1999c.
EPA. Arsenic Removal from Drinking Water by Ion
Exchange and Activated Alumina Plants, EPA-600-R-
00-088, 2000.
EPA. Treatment of Arsenic Residuals from Drinking
Water Removal Processes, EPA 600/R-01/033, 2001
EPA. Final Long Term 1 Enhanced Surface Water
Treatment Rule, EPA-815-F-02-001, 2002.
EPA. Small Drinking Water Systems Handbook: A
Guide to Packaged Filtration and Disinfection Tech-
nologies with Remote Monitoring and Control Tools,
EPA-600-R-03-041, 2003.
EPA. Feasibility of an Economically Sustainable
Point-of-Use/Point-of-Entry Decentralized Public
Water System, Final Report. EPA Grant: X82952301,
2005.
Goodrich, J.A., J.O. Adams, B.W Lykins, and R.M.
Clark. Safe Drinking Water from Small Systems and
Treatment Options. Journal American Water Works
Association, 84(5): 49-55 1992.
Gurian, PL. and Small, M.J. Point-of-Use Treatment
and the Revised Arsenic MCL, Journal American Wa-
ter Works Association, 94(3): 101-108, 2002.
Harker,T.L. Regulatory Flexibility and Consumer Op-
tions Under the Safe Drinking Water Act, Safe Drink-
ing Water: The Impact of Chemicals on a Limited
Resource. Lewis Publishers, Chelsea Michigan. 1985.
Li, S. Y. Cryptosporidium potential surrogate and
compressibility investigations for evaluating filtration-
based water treatment technologies. Master's thesis,
Miami University, Oxford, Ohio, November 1994.
Liang, S. Oxidantion of MTBE by Ozone and Per-
oxone Processes" Journal American Water Works
Association, 91(6): 104-114(1999).
Lykins, B.W, J.A. Goodrich, and J.C. Hoff, Concerns
with using Chlorine-dioxide Disinfection in the USA.
Journal of Water Supply Research Technology 39(6):
376-386 (1990).
Lykins, B. W, R.M. Clark, and J.A. Goodrich. Point-
of-Use/Point-of-Entry for Drinking Water Treatment,
Lewis Publishers, Ann Arbor, MI. 1992.
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National Drinking Water Clearinghouse (NDWC).
NDWC Fact Sheet - Technical Brief on Organic
Removal, available at: http://www.nesc.wvu.edu/ndwc/
pdf/OT/TB/TB5_organic.pdf, 1997.
NDWC. NDWC Fact Sheet - Technical Brief on Lime
Softening, available at:
http://www.nesc.wvu.edu/ndwc/pdf/OT/TB/TB8_
lime_softening.pdf, 1998.
NSF. ETV Report - Physical Removal of Giardia- and
Cryptosporidium-sized Particles in Drinking Water,
Lapoint Industries Aqua-Rite Potable Water Filtra-
tion System Used in Drinking Water Treatment, NSF
01/24/EPADW395, available at: http://nsf.org/busi-
ness/drinking_water_systems_center/pdf/lapoint_fi-
nal_report.pdf, 2001
Pollack, A. I, A.S.C. Chen, R.C. Haught, J.A.
Goodrich. Options for Remote Monitoring and Con-
trol of Small Drinking Water Facilities, Battelle Press,
Columbus, Ohio. 1999.
Seelig, B., Bergsrud, K, and Derickson, R. Treatment
Systems for Household Water Supplies Activated
Carbon Filtration. AE-1029, available at: http://www.
ext.nodak.edu/extpubs/h2oqual/watsys/ael029w.htm,
1992
Vel Leitner, N.K., A.L. Papailhou, J.P Croue, J. Pey-
rot, and M. Dore. Oxidation of Methyl t-Butyl Ether
(MTBE) and Ethyl-Butyl Ether (ETBE) by Ozone and
Combined Ozone/Hydrogen Peroxide. Ozone Science
and Engineering 16: 41-44 (1994).
5-14
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Chapter 6
Distribution Systems
6.1 Distribution System Overview
Drinking water distribution system infrastructure
is generally the most valuable asset of a water util-
ity, even though most of the components are either
buried or located inconspicuously. These systems
are designed to deliver water from a source (usu-
ally a treatment facility) to individual consumers in
a utility's service area in the required quantity at a
satisfactory pressure. In general, to continuously and
reliably move water between a source and a customer,
a distribution system requires storage reservoirs/tanks,
pipes, pumps, valves and other appurtenances. This
infrastructure is collectively referred to as the distribu-
tion system (Walski et al. 2003).
Almost universally, the manner in which industrial
and residential customers use water drives the overall
design and operation of a water distribution system.
Generally, water use varies both spatially and tempo-
rally. Besides customer consumption, a major function
of most distribution systems is to provide adequate
standby fire-flow (Fair and Geyer 1956). For this
purpose, fire hydrants are installed in areas that are eas-
ily accessible by fire fighters and are not obstacles to
pedestrians and vehicles. In order to satisfy this need
for adequate standby capacity and pressure, most distri-
bution systems use standpipes, elevated tanks, and large
storage reservoirs. Additionally, for service areas with
significant differences in ground elevation, the distribu-
tion systems are "zoned" to maintain relatively constant
pressures. Sometimes, zoning may also result from the
way in which the system has expanded over time.
6.2 Distribution System Issues
Proper operation and maintenance of distribution
systems plays a key role in ensuring that safe drinking
water is provided to the consumers. The PWS opera-
tors need to adequately understand and address the fol-
lowing three categorical issues facing the distribution
system infrastructure components:
• Infrastructure issues (repair and rehabilitation).
• Operational issues (e.g., biofilm growth/
disinfectant by product [DBF] formation,
nitrification, and finished water aging).
• Contamination events (e.g., cross-connections,
permeation/leaching, and intrusion/infiltration).
A brief discussion of these three categorical issues is
presented in this chapter.
6.3 Infrastructure Issues
A majority of distribution piping installed in the U.
S., beginning in the late 1800s and up until the late
1960s, was manufactured from cast iron. Specifically,
the three older vintages of cast iron pipe (pit cast, spun
cast, and spun cast with leadite joints) that were prima-
rily installed prior to the 1960s are of biggest concern
to PWSs. The thicknesses of the pipes between the
1800s and 1960s were gradually lowered as new tech-
nology improved the performance of the pipe during
this period. However, because of the design changes
during this period, the failure rates also increased
over time. The result is that the three aforementioned
vintage types of cast iron pipes, installed in different
time periods, may be reaching the end of their respec-
tive service lives at approximately the same time. This
will increase the financial burden on the PWSs, as the
cost of replacement will be borne over a shorter time
span than that of the original installation period (EPA,
2002a).
The American Society of Civil Engineers (ASCE)
rates the Nation's drinking water infrastructure at a
D- (A through F scale). The report card states that the
Nation's 54,000 drinking water systems face an annual
shortfall of $11 billion needed to replace facilities that
are nearing the end of their useful life and to comply
with federal water regulations (ASCE, 2005). How-
ever, most (77.6% - 80.5%) small PWS pipes are less
than 40 years old (EPA, 2002b). Small PWS piping
age ranges are as follows (according to EPA's 2000
Community Water System Survey, EPA, 2002b): less
than 40 years old (77.6% - 80.5%), between 40 and 80
years old (17.5% -19.4%), and more than 80 years old
(0.1% - 4.0%). Furthermore, the small system piping
age ranges for private systems are as follows: less
than 40 years old (92.6% - 98.7%), between 40 and 80
years old (1.3% - 7.4%), and more than 80 years old
(0.0% - 0.6%).
For small PWSs that have to repair, replace, and/or
install new pipes, an understanding of the risks to
distribution systems is necessary. The American Water
Works Association (AWWA) white paper, "New or Re-
paired Water Mains" (AWWA, undated) indicates that
the installation and/or repair of water mains provides a
potential route for direct contamination of the distribu-
tion system. According to the white paper, contamina-
tion can occur before, during, or after construction/re-
pair activities. For example, before the construction
activities have commenced, the piping materials may
be exposed to contaminant sources at the manufac-
turer, including:
• Accumulation of soils, sediments, and trash
6-1
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which can carry and/or harbor microbial
contaminants.
• Exposure to storm water runoff and other
waters that can carry microbial and chemical
contaminants.
• Exposure to harmful chemicals.
• Exposure to chemically contaminated soils and
sediments.
• Exposure to animals and humans and their
wastes.
Water main construction or repairs are most commonly
done in open trenches or excavations. Therefore, dur-
ing construction activities, the interiors of pipes and
fittings can come into contact with soil and water in
the trench. In addition, the chance of soil and water
contacting pipe materials during construction or repair
activities is potentially much greater than it is dur-
ing storage and handling prior to construction/repair.
The damp soil of a main repair trench is a potential
source of bacterial contamination during repairs (EPA,
2002c).
Finally, after construction or repair activity has been
completed, contamination can occur from external
sources such as:
• Leaking pipe joints with stagnant, unsanitary
water infiltrating into the distribution system,
• Cross-connections, back-flow, and
• Transitory pressures.
To address these potential infrastructure issues, the
small PWS operators must carefully inspect and disin-
fect the pipe material before commencing the repairs.
The AWWA Standard C-651-99 (AWWA, 1999) has
been developed to address potential microbial con-
tamination during main construction or repair. Small
PWS operators should closely follow the guidance
provided in this Standard C-651-99. The external
contamination events are discussed in Section 6.5 of
this report.
6.4 Operational Issues
PWS operators must operate their distribution system
in a manner to minimize the deterioration of water
quality delivered to the consumer after it leaves the
treatment plant. The water quality can potentially
degrade in a distribution system due to a variety of
reasons. The main reasons include: excessive growth
of biofilm, DBF formation, nitrification, and improper
storage of finished water. These issues are briefly
discussed in the following subsections.
6.4.1 Biofilm Growth
Virtually anywhere a surface comes into contact
with the water in a distribution system, one can find
biofilms. Biofilms are formed in distribution system
pipelines when microbial cells attach to pipe surfaces
and multiply to form a film or slime layer on the pipe
(EPA, 2001). Biofilms are complex and dynamic
microenvironments, that include processes such as me-
tabolism, growth, and product formation, and finally
detachment, erosion, or "sloughing" of the biofilm
from the surface. The rate of biofilm formation and
its release into a distribution system can be affected by
many factors including surface characteristics, avail-
ability of nutrients, and flow velocities. Biofilms grow
until the surface layers begin to slough off into the
water (Geldreich and Rice 1987). The pieces of bio-
film released into the water may continue to provide
protection for the organisms until they can colonize
a new section of the distribution system. In addition,
biofilms may increase pipe corrosion (microbially in-
duced corrosion), adversely affect pipe hydraulics and
reduce the utility of total coliforms as indicator organ-
isms. Thus, microbial growth in biofilms may result in
deterioration of water quality, generation of bad tastes,
colors, and odors, and proliferation of macroinverte-
brates (EPA, 2002d).
Few organisms living in distribution system biofilms
pose a threat to the average consumer. Bacteria,
viruses, fungi, protozoa, and other invertebrates have
been isolated from drinking water biofilms (EPA
1992). The fact that such organisms are present within
distribution system biofilms shows that, although
water treatment is intended to remove all pathogenic
(disease-causing) bacteria, treatment does not pro-
duce sterile water. In fact, some otherwise harmless
organisms (opportunistic pathogens) may survive the
treatment process and cause disease in individuals
with low immunity or compromised immune sys-
tems (EPA, 2001). Therefore, a disinfectant residual
in the distribution system is necessary to inactivate
pathogens, maintain water quality, and protect the
distribution system against regrowth (Snead et al.,
1980). The SWTR provides minimum requirements
on the amount of disinfection residual that must exist
in treated water. Specifically, the SWTR requires that
filtration and disinfection must be provided to ensure
that the total treatment of the system achieves at least
a 3-log (99.9 percent) removal/inactivation of Giardia
cysts and a 4-log (99.99 percent) removal/inactivation
of viruses (EPA, 1989). In addition, the PWS must
demonstrate, by monitoring and recording, that the
disinfectant residual concentration in water entering
the distribution system is never less than 0.2 mg/L and
that a detectable residual is maintained in the distribu-
tion system.
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Although a disinfectant residual is generally neces-
sary to maintain water quality, it is recognized that an
excessive amount of disinfectant residual may also
pose a threat to health by contributing to the increased
formation of harmful DBFs. Natural organic matter
(NOM) contained in water (in the form of humic and
non-humic [or fulvic] substances) serves as a precur-
sor in DBF formation. NOM belongs to a family of
compounds having similar structural and chemical
properties and are formed during the decomposition
of carbon-based life forms. The NOM reacts with the
residual disinfectant (e.g., chlorine, chloramine) in the
distribution system to form DBFs such as chloroform,
bromodichloromethane, and haloacetic acids (HAAS).
Many of these DBFs are suspected of causing cancer,
reproductive and developmental problems in humans.
To minimize the formation of DBFs, EPA has prom-
ulgated regulations that specify maximum residual
disinfectant level goals (MRDLGs) for chlorine (4
mg/L), chloramines (4 mg/L), and chlorine diox-
ide (0.8 mg/L). In addition, MCLs for TTHMs and
HAAS have been established at 0.080 mg/L and 0.060
mg/L, respectively. The TTHMs include: chloroform,
bromodichloromethane, dibromochloromethane and
bromoform. The HAAS include: monochloroacetic
acid, dichloroacetic acid, trichloroacetic acid, mono-
bromoacetic acid and dibromoacetic acid. In order to
meet these requirements, PWSs may need to remove
the DBF precursor material from the water prior to
disinfection by applying appropriate treatment tech-
niques.
In a cooperative effort with the Montana State Univer-
sity's Biofilm Research Center, EPA is studying the
interactions among factors that influence biofilms, bac-
terial regrowth, and corrosion in distribution systems.
The goal of this work is to generate information which
can lead to a better understanding of the interactions
among those factors which influence microbial growth
in water distribution systems and the mitigating effects
of chlorination and commonly used corrosion control
techniques. This research is also designed to address
specific fundamental questions about the availability
of sorbed humic substances for biofilm growth. Figure
6.1 shows the various distribution system interactions
that can potentially affect water quality.
In summary, the distribution system can act as a giant
reactor; with excess residence times, the water qual-
ity can deteriorate substantially. Small PWSs must
be aware of these issues and optimally operate their
system to control both biofilms and DBFs.
6.4.2 Nitrification
Nitrification is a microbial process by which reduced
nitrogen compounds (primarily ammonia) are sequen-
tially oxidized to nitrite (NO2 ) and nitrate (NO3 ).
Ammonia is present in drinking water through either
naturally-occurring processes or through ammo-
nia addition during secondary disinfection to form
chloramines (EPA, 2002e). The use of chloramine is
expected to increase in the near future as a result of
more stringent DBF MCLs associated with the Stage
I and Stage II DBF rule. Nitrification can adversely
impact the distribution system by increasing nitrite and
nitrate levels, reducing alkalinity, pH, dissolved oxy-
gen, and chloramine residuals, and promoting bacterial
regrowth (EPA, 2002e).
The formation of nitrite and nitrate within the distri-
bution system poses a potential direct public health
threat. Human babies are extremely susceptible to
acute nitrate poisoning because of certain bacteria
that may live in their digestive system during the first
few months of life. These bacteria change nitrate into
toxic nitrite (NO2~). The nitrite reacts with hemo-
globin (which carries oxygen to all parts of the body)
to form methemoglobin, which does not carry oxygen.
The level of oxygen being carried throughout the body
decreases in proportion to the amount of hemoglobin
converted to methemoglobin. As the oxygen level de-
creases, the baby is suffocated. This condition is called
methemoglobinemia. The most obvious symptom of
nitrate poisoning is a bluish color of the skin, particu-
larly around the eyes and mouth. These symptoms are
referred to as cyanosis (Runyan, C. 2002).
Under the Safe Drinking Water Act (SDWA), primary
MCLs have been established for nitrite (measured as
Nitrogen [N]), nitrate (as N), and the sum of nitrite
plus nitrate. The MCLs are 1 mg/L for nitrite, 10
mg/L for nitrate, and 10 mg/L for nitrite + nitrate (as
N). These standards are measured at the point of entry
to the distribution system; any subsequent elevated
nitrite/nitrate levels resulting from nitrification within
The Distribution System as Reactor
PIPE SURFACE
Biofilm/regrowth
Figure 6.1 Distribution System as a "Reactor"
(Figure used with permission from the Montana
State University Center for Biofilm Research).
6-3
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the distribution system are typically not identified
by compliance monitoring. Therefore, small PWS
operators must be aware of nitrification and optimally
operate their system to minimize it.
6.4.3 Finished Water Storage and Aging
Finished water facilities (including ground storage and
elevated storage, but not clearwells which are part of
treatment) are designed to meet temporary surges in
water demands, reduce pressure fluctuations in the dis-
tribution system, and provide reserves for fire-fighting,
power outages, and other emergencies. Many finished
storage facilities are operated to provide adequate
pressure and are kept full to be better prepared for
emergency demands. This emphasis on hydraulic con-
siderations in past designs has resulted in many stor-
age facilities operating today with larger water storage
capacity than is needed for normal (non-emergency)
usage (EPA, 2002c). This built-in excess capacity,
if not properly utilized, can result in water quality
deterioration. In addition to underutilization, short
circuiting within a storage reservoir can also cause
long detention times, resulting in excessive water age.
Furthermore, poor mixing (including stratification)
can exacerbate the water quality problems by creat-
ing zones within the storage facility where water age
significantly exceeds the average water age through-
out the facility. For larger distribution systems that
contain storage facilities where water cascades from
one facility to another (such as pumping up through
a series of pressure zones), poor mixing can result in
exceedingly long water age in the most distant tanks
and reservoirs (EPA, 2002c).
Long detention times can allow the disinfectant resid-
ual to be completely depleted, thereby not protecting
the finished water from additional microbial contami-
nants that may be present in the distribution system
downstream of the storage facility. Although the loss
of disinfectant residual within a storage facility does
not necessarily pose a direct public health threat (many
systems throughout the world are operated without
use of a disinfectant residual), disinfectant decay
can contribute to biofilm growth and related prob-
lems described in Section 6.4.1. The rate of residual
disinfectant decay can be further affected by external
contamination, temperature, nitrification, exposure
to ultraviolet light (sun), and the amount and type of
chlorine demanding compounds present such as organ-
ics and inorganics. Chlorine decay in storage facilities
can normally be attributed to bulk water decay rather
than wall effects due to the large volume-to-surface
area ratio (EPA, 2002c).
Sediment accumulation may also occur within storage
facilities due to quiescent conditions which promote
particle settling. Potential water quality problems as-
sociated with sediment accumulation include increased
disinfectant demand, microbial growth, DBF forma-
tion, and intermittent increased turbidity within the
bulk water (EPA, 2002c).
Finally, uncovered finished water storage reservoirs
provide the greatest opportunity for contaminant entry
into the distribution system. These reservoirs are
potentially subject to contamination from bird and
other animal excrement that can transmit disease-caus-
ing organisms to the finished water. Microorganisms
can also be introduced into open reservoirs from
windblown dust, debris and algae. Algae proliferate
in open reservoirs with adequate sunlight and nutrients
and impart color, taste and odor to the water on a sea-
sonal basis. Organic matter, such as leaves and pollen,
is also a concern in open reservoirs. Water fowl are
known carriers for many different waterborne patho-
gens and have the ability to disseminate these patho-
gens over a wide area. Even reservoirs with floating
covers are susceptible to bacterial contamination and
regrowth from untreated water that collects on the cov-
er surface. Also, if the cover rips or is otherwise dam-
aged, any untreated water on the cover would mix with
the stored water, potentially causing health problems.
Floating covers on storage reservoirs are susceptible
to rips and tears due to ice damage, vandalism, and/or
variable operating water levels (EPA, 2002c).
6.5 Contamination Events
Distribution systems are vulnerable to a variety of
external contamination events such as cross-connec-
tions, permeation/leaching, and intrusions/infiltrations.
These issues are briefly discussed in the following
subsections.
6.5.1 Cross-connection Control
Distribution systems contain locations where non-
potable water can be accidentally cross-connected to
potable sources. These cross-connections can provide
a pathway for backflow of non-potable water into
potable sources. Backflow can occur either because
of reduced pressure in the distribution system (termed
backsiphonage) or the presence of increased pres-
sure from a non-potable source (termed backpres-
sure). Backsiphonage may be caused by a variety of
circumstances, such as main breaks, flushing, pump
failure, hilly terrain, limited pumping capacity, high
demand by consumers, or emergency firefighting water
drawdown. Backpressure may occur when heating/
cooling, waste disposal, or industrial manufacturing
systems are connected to potable supplies and the
pressure in the external system exceeds the pressure in
the distribution system. Both situations act to change
the direction of water, which normally flows from the
6-4
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distribution system to the customer, so that non-pota-
ble and potentially contaminated water from industrial,
commercial, or residential sites flows back into the
distribution system through a cross-connection (EPA,
2002f).
The risk posed by cross-connection backflow can be
mitigated through preventive and corrective meas-
ures. For example, preventative measures include the
installation of backflow prevention devices and as-
semblies and formal programs to seek out and correct
cross-connections within the distribution system and,
in some cases, within individual service connections.
Corrective measures include activities such as flushing
and cleaning the distribution system after a detected
incident. This may help mitigate any further adverse
health effects from any contaminants that may remain
in the distribution system (EPA, 2002f).
There are no national reporting requirements for back-
flow incidents, and no central repository for backflow
incident information. Nonetheless, data on backflow
incidents have been actively collected by several
organizations. EPA compiled data on 459 reported
backflow incidents that occurred in the U. S. between
1970 and 2001. During these reported incidents of
backflow, chemical and/or biological contaminants
have caused illness and deaths, with contamination af-
fecting a number of service connections. This number
of reported incidents is believed to be a small percent-
age of the total number of backflow incidents in the
U. S. (EPA, 2002f). Because backflow incidents are
underreported, this data cannot support conclusions
about the full magnitude of risks associated with back-
flow (EPA, 2002f).
The American Backflow Prevention Association
(ABPA) created and distributed a survey to collect
data on cross-connection control programs throughout
the country. Two separate surveys were created. One
survey of water system programs was mailed to ap-
proximately 400 systems in 44 states asking details of
their cross-connection control program. Only 135 sur-
veys were returned, representing 30 states. Of the 135
returned surveys, 25 were from small systems (those
serving less than 10,000 people). One hundred and
three responses represented systems serving popula-
tions larger than 10,000. Seven systems did not report
their population size, making it unable to determine if
they were small or large (ABPA, 1999). Based on the
survey responses, ABPA estimates that average annual
cost for cross-connection control programs is $3.40
per water service connection for a small system and
$1.28 per water service connection for a large system.
The EPA's SDWIS database (forFY2002) shows a
total of 230,507,361 service connections for small
systems and a total of 62,579,989 service connections
for large systems.
There is a lack of public general awareness about
the threat posed by cross-connections and backflow
through illegal and unprotected taps into the distribu-
tion system. PWS operators must be aware that there
is a potential for intentional contamination of a distri-
bution system through such cross-connections. See
Chapter 8 - Homeland Security/Emergency Response
for additional information for responding to such
events.
6.5.2 Permeation and Leaching
As presented in Section 6.4.1, distribution system
infrastructure and appurtenances including piping, lin-
ings, fixtures, and solders can react with the water sup-
ply as well as the external environment. Permeation
and leaching are two mechanisms that can result in the
degradation of the distributed water (EPA, 2002g).
Permeation of piping materials and non-metallic joints
can be defined as the passage of contaminants external
to the pipe, through porous, non-metallic materials,
into the drinking water. The problem of permeation
is generally limited to plastic, non-metallic materi-
als. Volatile organic compounds (VOCs) present in
the ground water or vadose zone can permeate plastic
piping and gaskets. Permeation is typically most
severe for small diameter, low-flow pipes. The smaller
water lines contain the highest ratio of mass transfer
surface area to pipe volume, and are often associated
with stagnant or low-flow conditions. Also, there
are instances where VOC MCL violations have oc-
curred at the point-of-consumption. However, current
provisions of the SDWA do not require monitoring
for VOCs beyond the point-of-entry to the distribu-
tion system. Additionally, in most instances, the risk
threshold of chemical contaminants such as VOCs is
substantially lower than either the taste or odor thresh-
olds, suggesting that utilities cannot rely confidently
on customers' perception of taste and odor for identi-
fying contamination events (EPA, 2002g).
Leaching can be defined as the dissolution of metals,
solids, and chemicals into drinking water. Leaching
from cement linings can occur in soft, aggressive,
poorly buffered waters. Under static conditions, met-
als such as aluminum, arsenic, barium, chromium,
and cadmium can leach from cement linings, even
when NSF-approved materials are used and linings
are applied according to AWWA standards. Current
provisions of the SDWA do not require monitoring for
heavy metals beyond the point-of-entry to the distribu-
tion system, and additional research would be required
to assess the degree of metals accumulation within the
6-5
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distribution system. Vinyl chloride can leach from
pre-1977 PVC pipe. No instances of MCL violations
were cited in association with post-1977 PVC pipe
(EPA, 2002g).
Unidirectional flushing can be used to rid the distri-
bution system of stagnant, contaminated water, but
additional research is needed to determine the fraction
of heavy metals and organics that can be removed
through flushing. Permeated plastic piping must be
replaced since the piping retains its swollen porous
state after permeation (EPA, 2002g). NSF Standard 61
and numerous AWWA Standards have been devel-
oped to prevent the degradation of drinking water due
to contact with pipe materials. Materials selection,
design, and installation considerations based on water
quality and environmental conditions are addressed in
these Standards.
Small PWS operators using non-metallic pipes must
be aware of permeation and leaching problems and
address them appropriately.
6.5.3 Intrusion and Infiltrations
A pressure transient in a drinking water pipeline
caused by an abrupt change in the velocity or direction
of water can cause a surge or "water hammer." When
a rapidly closed valve suddenly stops water flowing
in a pipeline, pressure energy is transferred to the
valve and pipe wall. Shock waves are set up within
the system and pressure waves travel backward until
encountering the next solid obstacle, resulting in a
series of forward and backward movements. The pres-
sure wave's velocity is equal to the speed of sound;
therefore it "bangs" as it travels back and forth, until
dissipated by friction losses.
A less severe form of water
hammer is called surge where
a slow motion mass oscillation
of water is caused by internal
pressure fluctuations in the
system (EPA, 2002h). If these
pressure transients are not
controlled, they can damage
pipes, fittings, and valves,
causing leaks and shorten
the life of the system. Both
the pipe and the water are
incompressible and therefore
do not absorb the shock. The
production of transient low-
and negative-pressures creates
the opportunity for contami-
nated water to enter the pipe
from outside.
In a series of research projects (LeChevallier et al.,
2003; Gullick et al., 2004), the frequency and location
of low-and negative-pressures in representative distri-
bution systems were measured under normal operat-
ing conditions and during specific operational events.
Figure 6.2 illustrates a transient event that results in a
negative pressure transient for 20-seconds caused by a
power outage associated with a lightning strike.
These investigators also confirmed that fecal indica-
tors and culturable human viruses were present in
the soil and water exterior to the distribution system
pipes. Therefore, they concluded that it was possible
for these micro-organisms to infiltrate/intrude into the
distribution system. Their research also shows that a
well-calibrated hydraulic surge model can be used to
simulate the occurrence of pressure transients under a
variety of operational scenarios, and a model can also
be used to determine optimal mitigation measures.
Although there are insufficient data to indicate
whether pressure transients pose a substantial risk to
water quality in the distribution system, mitigation
techniques can be implemented. These techniques
include the maintenance of an effective disinfect-
ant residual throughout the distribution system, leak
control, redesign of air relief venting, installation of
hydro-pneumatic tanks, and more rigorous application
of existing engineering standards.
6.6 Distribution System Summary
EPA research indicates that there is a different level
of risk associated with the various distribution sys-
tem infrastructure components. The relative risk of
pathogens entering a distribution system (through the
X / ^
1M2.03
J
Figure 6.2 Negative Pressure Transient Associated with a Power
Outage. (Figure used with permission from Kala K. Fleming,
Ph.D. at American Water.)
6-6
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various mechanisms discussed in the previous sections
of this chapter) can be summarized as follows (EPA,
2002d):
• High risk - treatment breakthrough, intrusion,
cross-connections, main repair/break
• Medium risk - uncovered water storage facilities
• Low risk - New main installation, covered water
storage facilities, growth and re-suspension,
purposeful contamination.
6.7 Key Questions
• Do flow models need to be improved/developed
specifically for small distribution systems?
• What are typical water residence times in small
distribution systems? (This will play a key role
in contaminant sorption/desorption and biofilm
development).
• What are the interrelations between biofilms and
contaminants?
• How do changes in water chemistry affect
sorption/desorption of contaminants?
6.8 References
ABPA. 1999 Survey of State & Public Water System
Cross Connection Control Programs. Available at:
http ://www. abpa. org/originalsite/ABPA_Survey_Re-
port.pdf. 1999.
ASCE. Report Card for America's Infrastructure.
Available at: http://www.asce.org/reportcard/2005/in-
dex.cfm. 2005.
AWWA. New or Repaired Water Mains, available at:
http://www.epa.gov/safewater/tcr/pdf/maincontam.pdf.
Undated
AWWA. Disinfecting Water Mains, AWWA C651-99,
AWWA, Denver, CO. 1999.
EPA. Deteriorating buried infrastructure management
challenges and strategies. American Water Works
Service Company, Voorhees, NJ http://www.epa.gov/
safewater/tcr/pdf/infrastructure.pdf, 2002a.
EPA. Community Water System Survey 2000, EPA-
815-R-02-005B, 2002b
EPA. Finished water storage facilities. American Water
Works Association and Economic Engineering Serv-
ices, Inc., Voorhees, NJ http://www.epa.gov/safewater/
tcr/pdf/storage.pdf. 2002c.
EPA. Health risks from microbial growth and bio-
films in drinking water distribution systems. Office of
Ground Water and Drinking Water, Washington, DC
http://www.epa.gov/safewater/tcr/pdf/biofilms.pdf.
2002d.
EPA. Nitrification. American Water Works Association
and Economic Engineering Services, Inc., Voorhees,
NJ http ://www. epa. gov/safewater/tcr/pdf/nitrification.
pdf. 2002e.
EPA. Potential contamination due to cross connections
and backflow and the associated health risks. Office of
Ground Water and Drinking Water, Washington, DC
http://www.epa.gov/safewater/tcr/pdf/ccrwhite.pdf.
2002f.
EPA. Permeation and leaching. American Water Works
Association and Economic Engineering Services, Inc.,
Voorhees, NJ. http://www.epa.gov/safewater/tcr/pdf/
permleach.pdf. 2002g.
EPA. The potential for health risks from intrusion
of contaminants into the distribution system from
pressure transients. American Water Works Service
Company, Voorhees, NJ. http://www.epa.gov/safewa-
ter/tcr/pdf/intrusion.pdf. 2002h.
EPA. Controlling Disinfection By-Products and
Microbial Contaminants in Drinking Water, EPA-600-
R-01-110, 2001.
EPA. National Characteristics of Drinking Water
Systems Serving Populations Under 10,000, EPA-816-
R-99-010, 1999.
EPA. Research Plan for Microbial Pathogens and Dis-
infection By-Products in Drinking Water, EPA-600-R-
97-122, 1997.
EPA. Seminar publication: Control of biofilm growth
in drinking water distribution systems, EPA-625-R-92-
001, 1992.
EPA. National Primary Drinking Water Regulations;
Giardia lamblia, viruses, and legionella, maximum
contaminant levels, and turbidity and heterotrophic
bacteria ("Surface Water Treatment Rule"), Final Rule.
43 FR 27486. 1989.
Fair, G.M., and J.C. Geyer. Water Supply and Waste-
Water Disposal, John Wiley and Sons, Inc., NY. pp
339-441. 1956.
6-7
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Geldreich, E.E. and E. W. Rice. Occurrence, signifi-
cance, and detection of Klebsiella in water systems.
Journal of the American Water Works Association,
79(5), 74. (1987).
Gullick, R.W., M.W. LeChevallier, R.C. Svindland,
and M. Friedman. Occurrence of Transient Low and
Negative Pressures in Distribution Systems. Journal of
the American Water Works Association 96(11): 52-66
(2004).
Kirmeyer, G., M. LeChevallier, M. Friedman, J. Funk,
K. Mattel, M. Karim, and J. Harbour. Pathogen Intru-
sion Into the Distribution System, AWWARF and
AWWA, Denver, CO. 2000.
LeChevallier, M.W., R.W. Gullick, M.R. Karim, M.
Friedman and J.E. Funk. The Potential for Health
Risks from Intrusion of Contaminants into the Distri-
bution System from Pressure Transients. Journal of
Water and Health, IWA Publishing, pp. 3-14. 2003.
Montana State University (MSU) Center for Biofilm
Engineering. Image provided by Pat Dirckx. 2005
Runyan, C. Nitrate in Drinking Water Guide M-l 14,
New Mexico State University, Cooperative Extension
Service College of Agriculture and Home Economics.
Available at: http://www.cahe.nmsu.edu/pubs/_m/m-
114.pdf, 2002.
Snead, M.C., V.P Olivieri, and C.W Krause. Benefits
of Maintaining a Chlorine Residual in Water Supply
Systems, EPA-600-2-80-010. 1980.
Walski, T M, D.V. Chase, D.A. Savic, W.M. Grayman,
S. Beckwith, and E. Koelle. Advanced Water Distri-
bution Modeling and Management, Haestad Press,
Waterbury, CT pp 1-4. 2003.
6-8
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Chapter 7
Waste Residuals
Generated by Small
Systems
7.1 Introduction
Issues concerning the generation and treatment of
waste residuals from small-scale drinking water treat-
ment plants have received little attention in past and
current research. Yet in a national survey of consulting
engineers, residual disposal was voted the second most
pressing need (behind disinfection by-products) in
the area of "treatment processes and facilities needing
additional studies" (AWWARF, 1997). Many small
systems simply dispose of waste residuals on-site and/
or by utilizing local waste treatment venues (landfills,
sewer lines, etc.). There are currently no regulations
or standards from the EPA that specifically cover water
treatment plant residuals (National Drinking Water
Clearinghouse, 1998). Depending on the residuals'
composition and method of disposal, general regula-
tions governing the disposal of solid and liquid wastes
will determine the fate of these materials. These gen-
eral regulations can be found under the Clean Water
Act (CWA), the Resource Conservation and Recovery
Act (RCRA), Safe Drinking Water Act (SDWA), and
in some instances, the Clean Air Act.
On December 7, 2000, EPA promulgated the NPDWR
for radionuclides. With this rule, EPA updated its
standards for radionuclides in drinking water. In addi-
tion, EPA set a new standard for uranium, as required
by the 1986 amendments to the SDWA. The revised
standards are: combined radium 226/228 (5 pCi/L);
beta emitters (4 mrems); gross alpha standard (15 pCi/
L); and uranium (30 ug/L). Treating water to remove
naturally occurring radioactive material (NORM)
results in residual streams that are classified as "tech-
nologically enhanced naturally occurring radioactive
materials," or TENORM. TENORM is defined as
naturally occurring materials, such as rocks, minerals,
soils, and water whose radionuclide concentrations or
potential for exposure to humans or the environment
is enhanced as a result of human activities (e.g., water
treatment). Numerous regulations govern the disposal
of waste streams containing radionuclides (although
there are no federal waste disposal regulations specifi-
cally for TENORM wastes), and their interaction is
complex. States and disposal facilities can place ad-
ditional restrictions on TENORM disposal.
Little has been published on the quantities and types of
residuals generated by PWSs, but waste residuals are
certainly going to be as varied as are the methods used
for water treatment in small system scenarios. This
chapter will discuss the types of waste residuals that
small systems can potentially generate, disposal pos-
sibilities, and future waste residual issues that small
systems could face in the near future.
7.2 Types of Waste Residuals and
Disposal
Liquid residuals from water treatment operations
include brines, caustics, filter backwash, sedimenta-
tion basin wash water, and solutions used for recharg-
ing solid media. Solid residuals can include sludge,
schmutzdecke (biological surface layer in slow sand
filtration units), and spent treatment media. The residu-
als (both solid and/or liquid), classified as TENORM,
may contain non-exempt levels of radioactive material.
Section 7.5 presents an overview of the options for
disposing TENORM residual with non-exempt levels
of radioactive material. Figure 7.1 summarizes federal
regulations involved with the disposal of solid and
liquid residuals that contain exempt levels of radioac-
tive material. The majority of liquid waste residuals
generated by PWSs are most likely disposed on-site
(land application) or by sanitary sewer. Solid residuals
are disposed on-site (land application) or discarded for
transport and disposal in municipal landfills.
7.3 Liquid Residuals Handling &
Disposal
A significant source of liquid residuals is filter back-
wash. In 2001, EPA published the final version of the
Filter Backwash Recycling Rule (FBRR). The pri-
mary goal of the FBRR is to minimize consumer expo-
sure to microbial contaminants (e.g. Cryptosporidium)
during cleaning/backwashing operations. The rule was
developed following the findings that filter backwash
waters contributed to the outbreak of waterborne dis-
ease. The rule applies to all public water systems that:
1. Use surface water or ground water under direct
influence of surface water
2. Utilize direct or conventional filtration
processes, and
3. Recycle filter backwash water, sludge thickener
supernatant, or liquids from dewatering
processes.
The FBRR essentially requires that backwash water,
thickener supernatant, or dewatering liquids be proc-
essed through the system's existing conventional or
direct filtration units or through an alternate recycle
location as approved by the state and/or local agencies.
7-1
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Liquid Residuals
(e.g., brine, filter
backwash
Solid/Sludge Residuals
(e.g., sludge, schmudzdecke,
spent treatment media)
Interim Treatment
(e.g., chemical precipitation,
evaporation, coagulation/
flocculation)
Direct Discharge
(e.g., surface
water, wetland,
ocean)
'
Underground
Injection (e.g.,
„.
Discharge (e.g.
sanitary sewer)
deePwe") Land Disposal (e.g.,
municipal landfill,
hazardous landfill)
Reuse (e.g., land
application)
Incineration
Clean Water Act:
NPDES Program
40CFR Parts
122-133
Safe Drinking Water Act:
Underground Injection
Control Program
40CFR Parts 141-149
Clean Water Act:
Pretreatment
Program
40CFR Part 403
Water/
.and/Oce
Disposal
RCRA
Subtitle C & D
Programs
40CFR Parts 257-266
Resource Conservation
Recovery Act (RCRA):
Subtitle C & D Programs
40CFR Parts 257-270
•/
ean
al
Clean Air Act/
RCRA:
40CFR Parts 50,
60-63, 26
Clean Water Act:
Dredge and Fill
Program
40CFR Parts 230-233
Figure 7.1 Federal regulations governing the disposal of residuals (EPA, 2000).
Conventional filtration treatment is defined as a series of
processes including coagulation, flocculation, sedi-
mentation, and filtration resulting in substantial particle
removal. Direct filtration is defined as a series of proc-
esses including coagulation and filtration but excluding
sedimentation that results in substantial particle removal
(CWA - 40 CFR Section 141.2). The FBRR was imple-
mented on June 8, 2004.
Small systems that recycle filter backwash (and other
liquid residuals listed in the FBRR) will need to ensure
that the recycle is sent to the appropriate re-entry point
in the system. The FBRR also requires that PWSs
notify the primacy agency that the PWS will recycle
backwash and provide the primacy agency with:
1. A plant schematic showing recycle origin,
transport, and location of recycle back into the
plant,
2. Typical recycle flow (gpm),
3. Highest observed plant flow experienced in the
previous year (gpm),
4. Design flow for the treatment plant (gpm), and
5. If applicable, the state-approved operating
capacity for the plant.
Public water systems must also collect and maintain
information for review by the primacy agency includ-
ing copies of all materials submitted to the primacy
agency, list of recycle flows and recycling frequency,
average and maximum flows and durations of recy-
cling events, filter run length, type of treatment for
recycle flows, and information on the physical and
chemical parameters involved in the recycle treatment
process (see [EPA, 2001] for details).
As shown in Figure 7.1, liquid waste residuals may be
disposed by direct/indirect discharge, underground in-
jection, and land disposal. The following subsections
briefly describe direct and indirect discharge options.
For PWSs, underground injection is not a viable option
because of cost (except in extreme situations).
7.3.1 Direct Discharge of Liquids
Direct discharge to surface waters can be performed
by PWSs under the guidance of the CWA's National
Pollutant Discharge Elimination System (NPDES
- 40 CFR Section 122). The Federal Water Pollu-
7-2
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tion Control Act (which, after the 1977 amendments,
became known as the CWA) defines "pollutant" as
dredged spoil, solid waste, incinerator residue, sewage,
garbage, sewage sludge, munitions, chemical wastes,
biological materials, radioactive materials, heat,
wrecked or discarded equipment, rock, sand, cellar dirt
and industrial, municipal, and agricultural waste. The
NPDES requires that direct dischargers hold a permit
and may discharge only those pollutants in accordance
with the terms in the permit (see http://cfpub.epa.gov/
npdes/index.cfm for more information). The NPDES
permits generally include technology-based effluent
limits for a particular industry. Currently, EPA does
not have technology-based effluent limits for water
treatment plants. In this situation, discharge permits
are usually based on best professional judgment and
water quality-based effluent limits. Individual states
conduct discharge permitting. Alaska, Idaho, Arizona,
Massachusetts, and New Hampshire are not currently
authorized to implement the NPDES program (EPA,
2003).
Public water systems opting to discharge liquid residu-
als such as filter backwash and sedimentation basin
wash water to the waters of the Nation must obtain a
NPDES permit for such discharge. To obtain a permit,
the PWS operator must first submit a completed No-
tice of Intent to the appropriate state agency delegated
to implement the NPDES program. The Notice of In-
tent requires the submittal of information such as loca-
tion of the facility, name of the owner/operator, contact
details, location of the receiving waters, description of
the plant operations including a listing of any additives
used in the treatment process, design capacity of the
plant, the number and volume of sedimentation basins,
the source of raw water, the number of filters that are
backwashed, the frequency and volume of backwashes
and sedimentation basin washouts, a water balance
for backwashes and sedimentation basin washouts, a
description of how sludge is disposed, type of treat-
ment provided for backwash and sedimentation basin
wash waters and the design capacity of the system. In
addition, a facility location map with boundaries that
extend a few miles beyond the site property (annotated
with the specific locations of the discharges) is gener-
ally required. Also, the PWSs must comply with the
Total Maximum Daily Load (TMDL) requirements
developed and approved for the receiving water body.
If a TMDL is not developed, the PWS must certify that
the treatment and control methods employed at this
location are most appropriate for the reduction of pol-
lutants generated at this site. The PWSs must certify
that they will neither degrade the environment (com-
monly referred to as the "anti-degradation" certifica-
tion) nor threaten any endangered species as a result of
this discharge.
It should be noted that as long as a facility producing
an industrial waste stream has a NPDES permit, liquid
residuals that could otherwise be classified as hazard-
ous waste under RCRA can be legally discharged
assuming that the discharge is in compliance with the
RCRA terms cited in 40 CFR Section 261.4. Direct
discharges to marine environments are subject to addi-
tional restrictions under the CWA (see 40 CFR Section
125.123 for details).
7.3.2 Indirect Discharge of Liquids
Public water systems could also discharge liquid
residuals to sanitary sewers (i.e. "down the drain").
Indirect discharge does not require a NPDES per-
mit, but a pretreatment (prior to indirect discharge)
program may have to be implemented by the opera-
tor. EPA has developed pretreatment guidance and
regulations for industrial discharges to water treat-
ment plants (see Effluent Guidelines cited in 40 CFR
Section 403). The small quantities of waste generated
by PWSs typically do not meet the criteria that EPA
uses for requiring pretreatment of industrial waste.
Additionally, the pretreatment program places most
of the responsibility on organizations at the munici-
pal level. Publicly owned treatment works (POTWs)
that process 5 MOD (or more) or smaller plants that
have "significant industrial users" are required to
have a pretreatment program in place (EPA, 1999).
Included in the definition of significant industrial
users are those operations that could adversely affect
the POTW operations and/or violate any pretreatment
standards. Thus, it may be necessary for some small
systems that are utilizing sanitary sewers for liquid
residual disposal to coordinate with local POTWs
to ensure that they are meeting the requirements set
by the POTW and/or state authorities. Furthermore,
several states (e.g., Ohio) require that significant in-
dustrial users discharging to a POTW obtain a permit
for discharge.
7.3.3 Land Disposal of Liquids
Liquid residuals are generally not disposed in landfills
due to the prohibitive costs involved with transport
and disposal, the regulations surrounding such dispos-
al, and the availability of alternative methods. Liquid
residuals generated by PWSs that are reused through
land application and not classified as hazardous waste
are subject to little federal regulation, but may be
regulated by the state. States generally implement
and enforce the provisions defining sanitary landfills
(as opposed to open dumping, see RCRA Section
4005). These provisions include (but are not limited
to) requirements that address location requirements,
protection of endangered species, source water protec-
tion, non-point discharge violations, minimization of
disease vectors, protection of air quality, and mini-
7-3
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mization of explosive gases. Thus, on-site disposal
of non-hazardous liquid residuals by PWSs may be
regulated by the state. Liquid residuals classified as
hazardous waste are subject to comprehensive genera-
tor, transport, storage, treatment, and land disposal
restrictions defined in RCRA (see solids disposal
section).
It is possible that some PWSs may discharge liquid
residuals to lagoons or evaporation ponds. In these
cases, the SDWA and RCRA impose requirements for
non-hazardous wastes that aim to protect wellhead/
source waters, surface water, and ground water. States
may have further requirements concerning non-haz-
ardous liquid residual lagoons. Lagoons containing
hazardous waste are subject to RCRA regulations
covering design and operation standards (40 CFR Part
264, Subpart K).
7.4 Solid Residuals
Examples of solid waste residuals (SWR) generated
by PWSs include sludge, spent treatment media, and
schmutzdecke. Solid waste residuals are subject to
RCRA regulations and therefore classified as hazard-
ous or non-hazardous (as defined in RCRA). A waste
is characterized as hazardous or non-hazardous based
on its ignitability, corrosivity, reactivity, and/or toxicity
(see RCRA 40 CFR Sections 261.21 to 261.24). In
most cases, state and local regulations may also govern
the treatment/disposal of SWR as many of the regula-
tions set forth in RCRA are administered by state and
local governments. Some PWSs may qualify as con-
ditionally exempt small quantity generators (CESQG)
of hazardous waste (RCRA 40 CFR Section 261.5).
To be classified as a CESQG, the operation must not
generate more than 100 kg (220 Ibs.) of hazardous
waste per month. The CESQG may not store more
than 1000 kg (2200 Ibs.) of hazardous waste on-site
at any time. The regulations governing CESQGs are
generally less stringent than those governing small
quantity generators or large quantity generators. At
a minimum, a PWS that qualifies as a CESQG must
characterize each waste as hazardous or non-hazard-
ous, maintain monthly waste generation inventories
for amounts of hazardous waste stored on-site, and
manage hazardous wastes in compliance with federal,
state, and local regulations.
Sludge generated by PWSs is not subject to regula-
tion under the Biosolids Rule (Sewage Sludge Rules
defined in 40 CFR Section 503.6(i)(e)). The Biosolids
Rule (included in the CWA Amendments of 1987) was
promulgated to protect public health and the environ-
ment from any anticipated effects from the beneficial
recycling of sewage sludge biosolids (EPA, 1994).
7.4.1 Land Disposal of Solids
Waste residuals generated by PWSs will predomi-
nantly be characterized as hazardous or non-hazardous
based on toxicity. The toxicity of SWRs is assessed
by the Toxicity Characteristic Leaching Procedure
(TCLP). If contaminant concentrations in the TCLP
leachate are in excess of those listed in the Land Dis-
posal Restrictions (RCRA 40 CFR 268.40), the SWR
would be classified as hazardous and must be disposed
in a RCRA Subtitle C class landfill. Transport and
disposal costs for SWRs classified as hazardous will
be considerably higher than costs for non-hazardous
SWRs, which can be sent to municipal solid waste
landfills.
7.4.2 Land Application of Solids
Because sludge generated by PWSs is not subject to
the Biosolids Rule, on-site recycling of SWR by land
application may be an option for PWSs to pursue with
certain kinds of SWRs (e.g. schmutzdecke from slow-
sand filtration processes).
7.4.3 Incineration of Solids and Liquids
Incineration processes are most likely cost-prohibitive
for small systems and would not be an option except
in extreme cases (e.g. disposal of acutely toxic waste).
Regulations governing incineration are covered in the
Clean Air Act.
7.5 Technologically Enhanced
Normally Occurring
Radioactive Material
(TENORM) Residuals
Low-Level Radioactive Waste (LLRW) landfills may
be an option for some systems generating wastes with
radionuclide concentrations deemed to be unaccept-
able for disposal at a solid or hazardous waste landfill.
LLRW landfills are licensed by the Nuclear Regula-
tory Commission (NRC) or by a state under agreement
with NRC, and guidelines for disposing of radioac-
tive sludges and solids are more stringent than in a
standard landfill. These facilities are licensed, based
on projected performance and have packaging and
burial requirements that are progressively stricter as
the radionuclide concentrations increase. Currently,
there are three LLRW disposal facilities in operation
that are located at Barnwell, SC, Richland, WA and
Envirocare, UT EPA has developed a guidance docu-
ment titled, "A Regulators' Guide to Management of
Radioactive Residuals from Drinking Water Treatment
Technologies (EPA, 2005)." Small system operators
are encouraged to review this document for guidance
and then contact the state regulators for state-specific
requirements and disposal options.
7-4
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7.6 Conclusions and Future
Research
Residuals transport, treatment, and disposal can be
a significant cost to small communities. For small
community wastewater treatment operations, handling
of residuals may account for 50 percent of the total
operating budget (EPA, 1992). While it is expected
that waste residual generation at PWSs would be less
than that of a wastewater treatment plant, costs and
regulatory issues surrounding waste residuals may still
be of concern. It will be important in the short term
(1 to 2 years) to ascertain both the types and quanti-
ties of waste residuals generated by small systems.
Another area that will require more research will be
on arsenic, radium, and uranium chemistry and its
behavior in waste residuals (an active research area for
large-scale systems also). Once more accurate data are
obtained on the quantities and types of waste residuals,
more focused efforts may be made in developing new
techniques for the disposal of waste residuals, includ-
ing on-site land application which would minimize
transport and disposal costs.
7.7 Key Questions
• What types of waste residuals are generated by
small systems?
• What quantities of waste residuals are generated
by small systems?
• Are small systems' waste residual transport/
disposal issues significant?
• What are future issues regarding small systems'
waste residuals?
7.8 References
All references to Code of Federal Regulations Docu-
ments in this chapter may be found at http://www.ac-
cess.gpo.gov/nara/cfr and Federal Register Documents
may be found at http://www.gpoaccess.gov/fr/index.
html
National Drinking Water Clearinghouse. Tech Brief:
Water treatment plant residuals management. West Vir-
ginia University Research Corporation, Morgantown,
WV, 1998.
EPA. Manual: Wastewater treatment/disposal for small
communities. EPA/625/R-92/005, EPA, Washington,
DC, 1992.
EPA. A plain english guide to the EPA Part 503 Bio-
solids Rule. EPA/832/R-93/003, EPA, Washington,
DC, 1994.
EPA. Introduction to the National Pretreatment
Program. EPA/833/B-98/002, EPA, Washington, DC,
1999.
EPA. Regulations on the Disposal of Arsenic Residuals
from Drinking Water Treatment Plants. EPA/600/R-
00/025, Office of Research and Development, Wash-
ington, DC, 2000.
EPA. 40 CFR Parts 9, 141, and 142 National Primary
Drinking Water, Filter Backwash Recycling Rule,
Final Rule. Washington, DC. EPA, Washington, DC,
2001.
EPA. National Pollutant Discharge Elimination
System, State Program Status. EPA, Washington, DC,
2003.
EPA. A Regulators' Guide to Management of Ra-
dioactive Residuals from Drinking Water Treatment
Technologies. EPA/816/R-05/004, EPA, Washington,
DC, 2005.
Small Systems Research Committee. Research needs
for small water systems: A survey. Journal of the
American Water Works Association 89: 101-113
(1997).
7-5
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Chapter 8
Homeland Security/
Emergency Response
8.1 Background and Directives
Under Presidential Decision Directive (FDD) 63 -
Protecting America's Critical Infrastructures, issued in
May 1998, EPA was designated as the lead agency for
the water supply sector. In November 1998, a prelimi-
nary plan (National Infrastructure Assurance: Water
Supply Sector) was drafted. While the preliminary
plan showed a scheduled completion date of the end
of 2003 for these activities, the schedule was acceler-
ated in response to the terrorist acts of September 11,
2001. In October 2001, a Water Protection Task Force
was established to ensure that activities to protect and
secure water supply infrastructure were comprehensive
and were carried out expeditiously. Also, in October
2001, EPA disseminated information to the water utili-
ties about steps they could take to protect their sources
of supply and infrastructure, which include pumping
stations, treatment facilities, and computer systems.
EPA worked with the Sandia National Laboratory to
develop training materials for water utilities to help
them conduct thorough assessments of their vulner-
abilities.
The Public Health Security and Bioterrorism Prepared-
ness and Response Act (Bioterrorism Act), passed in
June 2002 (P. L. 107-188), provided EPA the mandate
to work in water security. This law, coupled with the
Homeland Security Presidential Directives (HSPDs)
7, 8, 9, 10 and EPA's own strategic plan for homeland
security, guides the Agency's research and technical
support activities to protect the Nation's water and
wastewater infrastructure. The Bioterrorism Act of
2002, HSPDs 7, 8, 9, 10 and EPA's overall strategic
plan are briefly discussed below.
8.1.1 Bioterrorism Act
The Bioterrorism Act amended the Safe Drinking Wa-
ter Act and required all public water suppliers serving
populations greater than 3,300 to complete Vulner-
ability Assessments (VAs) and to develop or modify
Emergency Response Plans (ERPs). Smaller systems
were encouraged, but not required, to follow the same
planning and management activities. VAs were intend-
ed to identify potential threats, assess the critical assets
of the system, evaluate the likelihood and consequenc-
es of an attack, and develop a prioritized set of system
upgrades to increase security. Once completed, VAs
were required to be submitted to the EPA according to
a pre-set schedule based on the size of the utility. The
deadline for medium and small size systems (serving
populations between 3,300 and 50,000) was June 30,
2004. Additionally for these systems, ERPs providing
details on response, recovery and remediation actions
in the event of a contamination or flow disruption
event were to be submitted within 6-months of the
submittal of VA and no later than December 31, 2004.
8.1.2 Homeland Security Presidential Directive
(HSPD)-7 - Critical Infrastructure
Identification, Prioritization, and
Protection
Under this HSPD, EPA is identified as the "Sector-
Specific Agency" for drinking water and water treat-
ment systems. The term "Sector-Specific Agency"
means a federal department or agency responsible
for infrastructure protection activities in a designated
critical infrastructure sector or key resources category.
The Sector-Specific Agencies are required to conduct
their activities under the various HSPD directives in
accordance with guidance provided by the Department
of Homeland Security (DHS) Secretary. Under this
directive, EPA must:
• Collaborate with all relevant federal departments
and agencies, state and local governments, and
the private sector;
• Conduct or facilitate vulnerability assessments
of the sector; and
• Encourage risk management strategies to protect
against and mitigate the effects of attacks against
critical infrastructure and key resources.
8.1.3 HSPD-8 - National Preparedness
HSPD-8 directs the federal government agencies and
departments to be prepared to respond to nationally
significant terrorist incidents. EPA is identified as an
agency that provides assistance for first responder pre-
paredness, and has responsibilities under this HSPD.
8.1.4 HSPD-9 - Defense of United States
Agriculture and Food
Under this HSPD, the EPA Administrator is required
to build upon/expand current drinking water monitor-
ing and surveillance programs. This work requires
both detection methods as well as laboratory networks
needed to accomplish this task.
8.1.5 HSPD-10 - BioDefense for the 21st
Century
Under this HSPD, EPA is required to survey Chemical,
Biological, Radiation and Nuclear laboratory capacity
and capability. EPA and other agencies are required to
develop standards, protocols, and capabilities to ad-
dress the risks of contamination following a biological
weapons attack. EPA and other agencies are also re-
8-1
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quired to develop strategies, guidelines, and plans for
decontamination of persons, equipment, and facilities.
8.1.6 EPA's Strategic Plan for Homeland
Security
In September 2002, EPA published a Draft Strategic
Plan for Homeland Security which describes the ex-
pansion of EPA activities under existing programs and
new initiatives in direct response to potential threats
and vulnerabilities. The strategic plan (EPA, 2002) is
organized into four mission-critical areas:
1. Critical Infrastructure Protection
2. Preparedness, Response, and Recovery
3. Communication and Information
4. Protection of EPA Personnel and Infrastructure.
To meet the responsibilities specified under the
aforementioned directives, EPA's Office of Water
established the Water Protection Task Force which
was formally organized as the Water Security Division
(WSD) in August 2003. Additionally, EPA's ORD
officially established the National Homeland Security
Research Center (NHSRC) in February 2003.
These organizations work synergistically to provide
research and technical support to the drinking water
and wastewater sectors. NHSRC's Water Security
Team contributes by conducting applied research and
then reporting on ways to better secure the Nation's
water systems from threats and attacks. The Team is
producing various products, such as analytical tools
and procedures, technology evaluations, models and
methodologies, decontamination techniques, techni-
cal resource guides and protocols, and risk assessment
methods. All of these products are for use by EPA's
key water infrastructure customers — water utility
operators, public health officials, and emergency and
follow-up responders. Other research programs in NH-
SRC deal with the protection of buildings and rapid
risk assessment. WSD provides support to drinking
water and wastewater systems by preparing vulner-
ability assessment and emergency response systems
and tools, providing technical and financial assistance,
and developing information exchange mechanisms.
WSD is also charged with supporting best security
practices, providing security enhancement guidance,
and incorporating security into the day-to-day opera-
tions of the drinking water and wastewater industries.
In addition, WSD works closely with NHSRC in
delivering research results in a timely and appropriate
fashion. EPA's WSWRD provides technical support to
NHSRC in conducting bench-and pilot-scale research
at the EPA's Test and Evaluation (T&E) Facility in
Cincinnati, Ohio. Assistance is also provided for
field implementation of technologies to complement
NHSRC's research.
8.2 EPA's Homeland Security
and Emergency Response
Initiatives and Resources
Many of EPA's ongoing homeland security and emer-
gency response initiatives and resources are summa-
rized on the EPA website link on water security (EPA,
2005c). Additionally, the water security resources
for small systems are summarized at the EPA website
(EPA, 2005c). The resources available for small water
systems at this web site include links to:
• VA Tools
• Serf-Assessment Guide for Drinking Water
Systems.
• Guide for Wastewater Systems.
• Security Emergency Managements Systems
(SEMS) software program developed by the
National Rural Water Association (NRWA).
• Automated Security Survey and Evaluation
Tool developed by New England Water Works
Association.
• Emergency/Incident Planning
• ERP Guidance - This document provides
guidance to small and medium-sized community
drinking water systems on developing or
revising their ERPs.
• Response Protocol Toolbox (RPTB) - This
document is composed of six interrelated
modules that provide guidance on planning
for and responding to both threats and actual
incidents of intentional contamination of public
drinking water supplies.
• Emergency Response Workshops - EPA is
conducting a series of ongoing nationwide
workshops for all sizes of water utilities that
provides instruction on the RPTB and the
Incident Command System. This workshop also
includes an enhanced tabletop exercise that will
test and develop emergency response skills.
• ERP Enhancement to Vulnerability Self-
Assessment Tools Software.
• Tools & Technical Assistance
• Security Product Guides - EPA has developed
these guides to provide information on products
available to enhance physical and cyber security
and to present information on monitoring
protocols.
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• Top Ten List to protect small ground water
suppliers from contamination events.
• Water Security Guide - This guide, currently
under development, will provide security
guidance to drinking water managers and
operators of systems serving 3,300 people or
fewer. The guide is expected to be available in
Calendar Year 2005.
As indicated earlier in this chapter, the VAs and ERPs
have already been completed by most small systems.
Therefore, the tools and resources related to these top-
ics are not discussed further in this document.
8.3 Threats and Risks to the Water
Supply
Smaller PWSs, where source areas are known to occur
at some significant distance from an actual supply, are
more likely to be severely threatened (Field, 2002).
The risk of contamination using chemical, biological
and/or radiological substances with subsequent conse-
quences must be understood by small system manag-
ers to provide appropriate security, employ suitable
detection systems and develop strategies to deal with
contamination events.
8.3.1 Chemical and Radiological
Contaminants
Chemical contaminants include inorganic, organic, ra-
diological and other chemical warfare compounds that
have a wide range of impacts on water quality and the
consumer. For example, the impacts can range from
a harmless change in color to introduction of highly
toxic neurotoxins (e.g., Sarin, VX) that would cause
significant fatalities in the exposed population.
8.3.2 Biological Contaminants
According to Providing Safe Drinking Water in Small
Systems (NSF International World Health Organiza-
tion, 1999), there is an average of 10 to 15 outbreaks
of disease from tap water in the U.S. per year, with
"over 100 types of bacteria, viruses and protozoa that
can be found in contaminated water." The book states
that "in both developed and developing countries water
quality has continued to deteriorate (Bank, 1992)."
The book also summarizes that "the potential rise in
waterborne disease outbreaks may be due to increasing
susceptible populations, political upheaval and high
numbers of refugees in developing countries. Natural
disasters such as flooding and droughts due to climatic
changes may also be affecting global water quality."
8.3.3 Risk Assessment and Mitigation
Risk assessment was a required element of the feder-
ally mandated VAs. Furthermore, small systems were
encouraged to implement actions that specifically
addressed the potential threats and vulnerabilities
identified during the federally mandated vulnerability
assessments. Some key measures that were recom-
mended include:
• Routine or around-the-clock monitoring of
treatment and key supply infrastructure (using
video surveillance, intrusion detection, alarm
systems).
• General increase in security procedures such
as identification for employees and visitors
with continuing emphasis on security at staff
meetings.
• Routine inspection of key facilities and
suspension of public access to these facilities.
• Routine testing of water quality to ensure that it
continues to meet or exceed the required federal
and state standards.
Along with providing research and technical support,
WSWRD, NHSRC and WSD encourage information
sharing and risk communication strategies among key
water infrastructure customers. This includes making
use of the Water Information Sharing and Analysis
Center. Small system operators are encouraged to
contact (through available state and local channels
or directly) both WSD and NHSRC periodically for
resources and technology related inputs that might be
available to address their needs.
8.4 Response Protocol Toolbox
EPA released the "Interim Final Response Protocol
Toolbox: Planning for and Responding to Contamina-
tion Threats to Drinking Water Systems," in December
of 2003 (EPA, 2003). The RPTB is composed of six
interrelated modules, in addition to an overview, which
focus on different aspects of planning a response to
contamination threats and incidents. The module titles
are listed below:
Overview (EPA-817-D-03-007)
Module 1 - Water Utility Planning Guide (EPA-817-
D-03-001)
Module 2 - Contamination Threat Management
Guide (EPA-817-D-03-002)
Module 3 - Site Characterization and Sampling
Guide (EPA-817-D-03-003)
Module 4 -Analytical Guide (EPA-817-D-03-004)
Module 5 - Public Health Response Guide (EPA-
817-D-03-005)
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Module 6 - Remediation and Recovery Guide
(EPA-817-D-03-006)
These modules provide emergency response planning
tools that may be adopted voluntarily. The RPTB is
designed to help the water sector to effectively and
appropriately respond to intentional contamination
threats and incidents. EPA produced the RPTB, build-
ing on the experience and expertise of several drinking
water utilities, particularly the Metropolitan Water Dis-
trict of Southern California. The users are encouraged
to review the overview before using other Modules.
Since the release of RPTB, EPA received feedback
and suggestions from several sources concerning im-
provements in the RPTB. Subsequently, EPA devel-
oped RPTB: Response Guidelines (EPA, 2004)- An
action oriented document (easy to use document for
field and crisis conditions) to assist drinking water
utilities, laboratories, emergency responders, state
drinking water programs, technical assistance provid-
ers, and public health and law enforcement officials
during the management of an ongoing contamination
threat or incident. The RPTB Response Guidelines
are not intended to replace the RPTB and do not
contain the detailed information contained within the
six complete modules. The RPTB Response Guide-
lines are to be viewed as the application of the same
principles contained in the RPTB during an actual
incident.
8.5 Recommended Procedures for
Securing Small Systems
The Association of State Drinking Water Administra-
tors (ASDWA)TNRWA document, titled Security Vul-
nerability Self-Assessment Guide for Small Drinking
Water Systems (ASDWA/NRWA, 2002), suggests the
following:
• restrict or limit access to the critical components
of the water system (i.e., a part of the physical
infrastructure of the system that is essential for
water flow and/or water quality) to authorized
personnel only;
• secure the facility perimeter with a fence;
• lock all building doors and windows, hatches
and vents, gates, and other points of entry to
prevent access by unauthorized personnel, and
check the locks regularly;
• assure adequate lighting around the critical
water system components, which is a good
deterrent to unauthorized access (motion
detectors that activate switches that turn lights
on or trigger alarms also enhance security;
• post warning signs (tampering, unauthorized
access, etc.) on all critical components;
• patrol and inspect critical components;
• clear the area around critical components of
any objects that may be used for breaking and
entering;
• assure that entry points to the water system
are easily seen (clear fence lines of vegetation,
including overhanging or nearby trees);
• consider installing an alarm system that notifies
the authorities or designated contact when there
has been a breach of security;
• record locks and associated keys and to whom
the keys have been assigned;
• limit entry codes and/or keys to water system
personnel only;
• form a neighborhood watch system;
• properly seal wellheads;
• properly install vents and caps to help prevent
the introduction of a contaminant into the water
supply;
• properly secure observation/test and abandoned
wells;
• secure surface water sources, where possible,
with fences or gates;
• control the use of hydrants and valves;
• monitor distribution system for positive
pressure;
• implement a backflow prevention program.
8.6 Infrastructure and Bulk Water
The DHS developed a document entitled National
Strategy for the Physical Protection of Critical Infra-
structures and Key Assets (DHS, 2003). This Strategy
document identifies a clear set of national goals, objec-
tives and outlines, and guiding principles that underpin
the Nation's efforts to secure the infrastructures and
assets vital to national security, governance, public
health and safety, economy, and public confidence.
This Strategy also provides a unifying organization
and identifies specific initiatives to drive the near-term
national protection priorities and inform the resource
allocation process. Most importantly, it establishes
a foundation for building and fostering the coopera-
tive environment in which government, industry, and
private citizens can carry out their respective protec-
tion responsibilities effectively and efficiently. The
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Strategy states the following concerning water:
"On the supply side, the primary focus of critical infra-
structure protection efforts is the Nation's 170,000
public water systems. These utilities depend on reser-
voirs, dams, wells, and aquifers, as well as treatment
facilities, pumping stations, aqueducts, and transmis-
sion pipelines." The Strategy also states that "in order
to set priorities among the wide range of protective
measures that should be taken, the water sector is fo-
cusing on the types of infrastructure attacks that could
result in significant human casualties and property
damage or widespread economic consequences. In
general, there are four areas of primary concentration:
• Physical damage or destruction of critical assets,
including intentional release of toxic chemicals;
• Actual or threatened contamination of the water
supply;
• Cyber attack on information management
systems or other electronic systems; and
• Interruption of services from another
infrastructure.
The Strategy also states that water infrastructure
protection initiatives are guided both by the challenges
that the water sector faces and by recent legislation.
Additional protection initiatives include efforts to:
• Identify high-priority vulnerabilities and
improve site security
• Improve sector monitoring and analytical
capabilities
• Improve sector-wide information exchange and
coordinate contingency planning
• Work with other sectors to manage unique risks
resulting from interdependencies
The Drinking Water Needs Survey (EPA, 1997) states
that "community water systems need to invest signifi-
cant amounts of money in infrastructure improvements
if they are to continue providing water that is safe
to drink. Much of the Nation's drinking water infra-
structure suffers from long term neglect and serious
deterioration. Recent events, including waterborne
disease outbreaks and extended boil water notices in
major cities, have focused national attention on the
dangers associated with contamination of public water
supplies. Current needs for minimizing health threats
from microbiological contaminants (those needs as-
sociated with the SWTR and the TCR) are especially
critical. Water systems around the country must make
immediate investments in infrastructure to protect
public health and ensure the availability of safe drink-
ing water."
8.7 Telemetry
Small water utilities typically have their customer and
billing information system computerized (a traditional
Information Technology-IT system) along with some
remote components potentially on a Supervisory
Control and Data Acquisition (SCADA) System (a.k.a.
telemetry). These IT/SCADA systems are vulnerable
to attacks which may disrupt the operations of the util-
ity and potentially damage equipment. The Associa-
tion of State Drinking Water Administrators/National
Rural Water Association document, titled Security
Vulnerability Self-Assessment Guide for Small Drink-
ing Water Systems (ASDWA/NRWA, 2002), suggests
the following:
• password protect all computer access;
• install a firewall protection program;
• consider subscribing to a virus protection update
program;
• back up computers regularly;
The U.S. Department of Homeland Security's website
(www.dhs.gov) provides information on reporting
cyber-security incidents. It specifies that individuals
can report to the United States Computer Emergency
Readiness Team at www.us-cert.gov and federal agen-
cies/department report to www.us-cert.gov/federal.
The DHS website also provides information on current
threats, including the advisory system, advisories, and
information bulletins.
Panguluri et al, (2004), provide an overview of a
utility's computer system infrastructure along with
identifying methods for mitigating cyber-attacks. This
document also has a compilation of sources from
where common vulnerabilities can be identified. An
overview of planning for incident response and busi-
ness continuity is also provided in this document.
8.8 Early Warning Systems for
Drinking Water Systems
According to Online Monitoring for Drinking Water
Utilities (AWWARF-PROAQUA, 2002) "a water utili-
ty's primary responsibility is to consistently produce
and distribute water that will satisfy the customer in
terms of quality and quantity. Water quality in the
distribution system can significantly deteriorate due to
bacterial growth, corrosion, and direct contamination.
Assuring stable, high-quality drinking water depends
on the utility's ability to ensure that the water put into
8-5
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the distribution system maintains its quality until it is
consumed. Online monitoring of a limited number of
variables can substantially contribute to achieving this
goal."
"Water quality monitoring sensor equipment may be
used to monitor key elements of water or wastewater
treatment processes (such as influent water quality,
treatment processes, or effluent water quality) to iden-
tify anomalies that may indicate threats to the system.
Some sensors, such as sensors using biological organ-
isms or measuring radiological contaminants, measure
"surrogate" parameters that may indicate problems in
the system but do not identify sources of contamina-
tion directly, while others, particularly chemical moni-
toring systems measure potential contamination di-
rectly. In addition, sensors can provide more accurate
control of critical components in water and wastewater
systems and may provide a means of early warning
so that the potential effects of certain types of attacks
can be mitigated. One advantage of using chemical
and biological sensors to monitor for potential threats
to water and wastewater systems is that many utilities
already employ sensors to monitor potable water (raw
or finished) or influent/effluent for SDWA or CWA
water quality compliance or process control.
Chemical sensors that can be used to identify poten-
tial threats to water and wastewater systems include
inorganic monitors (e.g. chlorine analyzer), organic
monitors (e.g. total organic carbon analyzer) and
toxicity meters. Radiological meters can be used to
measure concentrations of several different radioactive
species. Monitors that use biological species can be
used as sentinels for the presence of contaminants of
concern, such as toxics. "At the present time, biologi-
cal monitors are not in widespread use and very few
biomonitors are used by drinking water utilities in the
U.S. (EPA, 2005b)." "Proof that the delivered water
meets the quality requirements must be gained during
and after the treatment process. For that reason, online
monitoring of key parameters, in combination with
other tools, will help the system operator to:
• Identify areas in the system that are vulnerable
to water quality deterioration or external
contaminant sources
• Take proper preventive or corrective measures to
improve system integrity
• Substantially increase the capability of early
detection methods for regulated parameters
• Optimize the system in terms of energy
consumption and water supply patterns
• Document that some parameters (disinfectant
residuals, fluoride, etc.) comply with required
concentrations for a specified period of time
(e.g., over 95 percent of operation period)
• Inform customer on water quality (via the
Internet or other communication systems)."
(AWAARF, 2002)
8.9 Disinfection in Distribution
Systems
Disinfection of drinking water is considered to be
one of the major public health advances of the 20th
century. Disinfection ensures that dangerous micro-
bial contaminants are inactivated before they can enter
the distribution system. The successful application
of chlorine as a disinfectant was first demonstrated in
England. In 1908, Jersey City (New Jersey) initiated
the use of chlorine for water disinfection in the U.S.
This approach subsequently spread to other locations,
and soon the rates of common epidemics such as
typhoid and cholera dramatically dropped in the U.S.
Today, disinfection is an essential part of drinking
water treatment. Chlorine gas, hypochlorite, chlorine
dioxide, and chloramines are most often used because
they are very effective disinfectants, and residual
concentrations can be maintained in the water distri-
bution system. Some European countries use ozone
and chlorine dioxide as oxidizing agents for primary
disinfection prior to the addition of chlorine or chlo-
rine dioxide for residual disinfection. The Netherlands
identifies ozone as the primary disinfectant, as well as
common use of chlorine dioxide but typically uses no
chlorine or other disinfectant residual in the distribu-
tion system (Connell, 1998).
8.10 Preparedness Assessment
for Handling Threats
The NRWA has customized the Standardized Emer-
gency Management Systems/Incident Command Sys-
tem (SEMS/ICS) training for small systems to man-
age, respond and mitigate real or perceived threats.
SEMS/ICS is based on the use of commonly accepted
terminology that clearly describes needs and expecta-
tions between response agencies. This terminology
is based on the established and accepted common
names for emergency response equipment, organi-
zational units, functions, resources, and facilities. A
SEMS/ICS response organization is based on the type
and size of the incident. Modular organization allows
for the addition and reduction of positions based on
current and future needs. All SEMS/ICS organizations
build from the top down as the incident grows.
SEMS/ICS is made up of five functions: Management;
Operations; Planning; Logistics; and Finance. These
8-6
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functions may, as the incident grows, be organized
and staffed into Sections. Initially, the Director of
Emergency Services may be performing all five func-
tions. Then, as the incident grows, each function may
be established as a Section with several Units under
each Section. Only those functional elements that are
required to meet current objectives will be activated.
Those functions which are needed but not staffed will
be the responsibility of the next higher element in
the organization. Several states mandate the use of
SEMS/ICS when responding to any of the following
emergency operations:
• Single jurisdictional responsibility with multiple
agency involvement
• Multiple jurisdictional responsibility with
multiple agency involvement
The SEMS/ICS provides an efficient tool for the
management of emergency operations. SEMS / ICS is
designed to be adaptable to any emergency or incident.
The system expands in a rapid and logical manner
from an initial response to a major incident call-out.
When organizational needs dictate, the system also
contracts just as rapidly. SEMS/ICS allows for con-
tinuous notification of intelligence from state and local
level agencies to information and alerts from the Of-
fice of Homeland Security, Federal Bureau of Investi-
gation, Environmental Protection Agency, Department
of Energy, Department of Transportation, U.S. Bureau
of Reclamation and the Awareness National Security
Intelligence Reports, as well as the Association of
Metropolitan Water Agencies and the American Water
Works Association.
8.11 Local/State Emergency
Planning Committees
Local Emergency Planning Committees (LEPCs) were
established by the Emergency Planning and Com-
munity Right-to-Know Act (EPCRA), which includes
emergency planning and community right-to-know
requirements. The purpose of the LEPC includes:
• Development, training, and testing of the
hazardous substances emergency response plan
for the community
• Development of procedures for regulated
facilities to provide informational and
emergency notification to the LEPC
• Development of procedures for receiving and
processing requests from the public under
EPCRA
• Provision for public notification of LEPC
activities
A major role for LEPCs is to work with industry and
the interested public to encourage continuous atten-
tion to chemical safety, risk reduction, and accident
prevention by each local stakeholder. The EPA's
Office of Emergency Management (OEM) maintains
a LEPC database (EPA, 2005a) which contains over
3,000 listings. This database can be searched by state,
name address or by zip code. The database is updated
monthly. In addition, the Local Governments Reim-
bursement (LGR) Program provides federal funds to
local governments for costs related to temporary emer-
gency measures conducted in response to releases or
threatened releases of hazardous substances. The pro-
gram serves as a "safety net" to provide supplemental
funding to local governments that do not have funds
available to pay for these response actions. Eligible
local governments may submit applications to EPA for
reimbursement of up to $25,000 per incident.
On February 18, 1998, EPA published a new LGR
regulation that simplifies and streamlines the process
for applicants. EPA has designed the reimbursement
process to be very straightforward. Local govern-
ments obtain and complete a simple LGR application
form that requires a local government to provide basic
information about the incident, document its response
costs by attaching copies of receipts, and certify that
certain program requirements have been met. An ap-
plicant may receive a reimbursement check from the
federal government in as little as three months after
EPA receives the application. Local governments can
take action today to help ensure that they are eligible
to participate in the LGR program in the future.
EPA's LGR Program HelpLine can be reached by call-
ing 800-431-9209 or via e-mail at lgr.epa@epamail.
epa.gov.
8.12 Alternative Drinking Water
Supplies in the Event of an
Incident
Public water systems may at some time need to utilize
an alternate source of water. This need may arise due
to drought, contamination of the primary source, or
failure at the source (e.g. a dam). Use of an alternate
source of water can be complex, and will require
advance approval by the state agencies. Prior to sub-
mitting an application for approval, the PWS should
perform a preliminary evaluation to assess the difficul-
ty of locating pipes to transport water on a temporary
basis, obtaining right-of-way or access rights, and se-
curing financing to construct temporary or permanent
structures. If a PWS anticipates the need to utilize
an alternate source of raw water and the preliminary
evaluation indicates that the project can be accom-
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plished, the PWS should proceed by contacting the
regulating state agency to obtain approval. Typically,
a state agency will require basic information, such as
identification of proposed alternate source(s), surface
and ground, including location and name of source. In
addition, specific information on each proposed alter-
nate source is usually required, such as estimated days
of water available and potential sources of contamina-
tion within the vicinity of each proposed source (e.g.,
domestic or hazardous waste sites, oil and gas wells,
abandoned wells, mining operations, discharges from
sewage treatment plants, industrial discharges). Also,
depending upon the size and location of the alternative
source, there may be many other requirements that a
PWS must meet to be able to utilize that source. Fur-
thermore, alternate sources of raw water must be tested
(for evaluating the water quality), evaluated against
available treatment techniques, and finished water
testing must be performed in order to ascertain that the
water provided to the public will meet all regulatory
requirements.
If an alternate source(s) is(are) approved, the results
of the raw water testing are typically used in part to
determine the amount of testing necessary for the fin-
ished water. Other factors would include the operation
and maintenance of the treatment plant and the water
treatment practices in place to remove contaminants if
they are encountered. Typically, at a minimum, testing
is required for total coliform bacteria in the treated wa-
ter. Continued use of the alternate sources will also be
subject to routine monitoring requirements. In many
cases it may be more economical and practical to
contract with a neighboring water supplier and form a
partnership for sharing raw and/or finished water dur-
ing emergencies. If such sources are not available, the
PWS should implement other appropriate emergency
water conservation measures outlined in their ERP
8.13 Key Questions
• Are information sources adequate for small
systems? Can information dissemination be
improved through cooperation with NRWA?
• Are emergency response procedures/protocol
adequate? Are small systems satisfied with
these procedures?
8.14 References
ASDWA/NRWA. Security vulnerability self-assess-
ment guide for small drinking water systems, http://
www.doh. wa.gov/ehp/dw/Security/Security _Vulner-
ability.pdf. 2002.
AWWARF-PROAQUA, Online monitoring for drink-
ing water utilities. American Water Works Association,
Denver, CO. 2002.
World Bank. World Development Report: Develop-
ment and the Environment. Oxford University Press,
New York, NY, 1992.
Connell, G.F. European water disinfection practices
parallel U.S. treatment methods, http://www.clo2.
com/reading/waternews/european.html. 1998.
DHS. National strategy for the physical protection of
critical infrastructures and key assets, http://www.dhs.
gov/interweb/assetlibrary/Physical_Strategy.pdf. 2003.
EPA. Drinking water infrastructure needs survey, first
report to congress. Washington, DC http://www.epa.
gov/safewater/needssurvey/pdfs/1997/report_needssur-
vey_1997_cover.pdf, 1997.
EPA. Strategic plan for homeland security. http://www.
epa.gov/epahome/downloads/epa_homeland_secu-
rity_strategic_plan.pdf. 2002.
EPA. Interim final response protocol toolbox: Plan-
ning for and responding to contamination threats to
drinking water systems. Washington, DC http://cfpub.
epa.gov/safewater/watersecurity/home.cfm?program_
id=8#response_toolbox, 2003.
EPA. Response protocol toolbox: Response guidelines.
Washington, DC http://www.epa.gov/safewater/water-
security/pubs/rptb_response_guidelines.pdf, 2004.
EPA. Local emergency planning committee database.
Accessed: August 5, 2005. Last Update: April 2005.
http://www.epa.gov/ceppo/lepclist.htm. 2005a.
EPA. Sensors for monitoring chemical, biological,
and radiological contamination. Accessed: August 5,
2005. Last Update: March 8, 2005. http://www.epa.
gov/watersecurity/guide/chemicalbiologicalandradio-
logicalsensoroverview.html. 2005b.
EPA. Water security. Accessed: August 5, 2005. Last
Update: June 24, 2005. http://cfpub.epa.gov/safewater/
watersecurity/index.cfm. 2005c.
Field, M, Development of a counterterrorism pre-
paredness tool for evaluation risks to Karstic spring
water, in US Geological Survey Karst Interest Group
Proceedings, Shepherdstown, WV. 2002.
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NSF International World Health Organization, Provid-
ing safe drinking water in small systems: Technology,
Operations, and Economics. Lewis Publishers, Boca
Raton, FL. 1999.
Panguluri, S., W.R. Phillips, and R.M. Clark, Cyber
Threats and IT/SCADA System Vulnerability, in Mays
L., editor. Water Supply Systems Security. McGraw
Hill, New York, NY. 2004.
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Chapter 9
Remote Monitoring
and Control
9.1 Introduction
Drinking water regulations require all conventional
drinking water treatment system operators to provide
water quality monitoring to ensure that good quality
water is provided to the consumers (EPA, 1996). Most
treatment systems/technologies can be equipped with
sensors and operating devices that can be monitored
from remote locations. Remote monitoring and con-
trol technology can be used to improve monitoring/re-
porting and reduce operation and maintenance (O&M)
costs. Remote monitoring and control technologies or
remote telemetry systems are also known as Supervi-
sory Control and Data Acquisition (SCADA) systems.
A SCADA system consists of three key components:
monitoring/control device(s) (e.g., a sensor/analyzer
that measures and reports the desired parameter, a vari-
able frequency drive pump the speed of which can be
controlled remotely), data transmission equipment/me-
dia (e.g., phone, wire and radio), and data collection
and processing unit (typically a central computer that
analyzes the reported parameter value and program-
matically decides what controls, are warranted based
on the reported value). For example, when a tank level
sensor reports that a remote reservoir is full, this infor-
mation is processed by the SCADA central computer
which instructs the associated pump to shut down. For
small packaged treatment systems, such equipment
could easily double the purchase cost. However, oper-
ational payback can be quickly realized through lower
use of chemicals, low residue generation (disposal),
and increased reliability. Also, the cost of subsequent
networking of multiple package plant sites or water
quality monitoring devices is also decreased after the
initial cost for installing the basic SCADA equip-
ment has been incurred. It has been demonstrated
that various remote monitoring technologies are being
appropriately designed for small systems and these
will ultimately produce a better quality of drinking
water, accommodate the resources of small systems,
increase the confidence level of the customer, opera-
tor and regulator, and comply with the monitoring and
reporting guidelines.
SCADA systems are not always used to their fullest
potential by small systems due to complex operating
systems and control (software and hardware) that usu-
ally require specially trained computer programmers
or technicians and costly service agreements. In the
last few years, SCADA vendors have changed the way
they design and fabricate their systems, thus making
them more accessible and affordable to small drinking
water treatment operators.
9.2 Rationale for Online Monitoring
The application of SCADA to operate, monitor,
and control small systems from a central location is
believed to be one mechanism that can reduce viola-
tions of MCLs as well as Monitoring/Reporting (M/R)
violations. Through the application of SCADA, EPA
has demonstrated that filters could be operated more
efficiently for particle removal, disinfectant doses
altered in real-time in response to varying raw water
conditions, and routine maintenance and chemical
re-supply can be scheduled more efficiently. Small
independent systems could contract with an off-site
O&M firm or join with other small system communi-
ties or utilities to either work out schedules to monitor
via SCADA or hire an O&M services provider, while
maintaining ownership. This type of approach would
provide the small system the economies-of-scale that
the medium and larger systems have in purchasing
supplies, equipment, and power.
EPA has been evaluating a variety of "small" SCADA
systems that would allow a single qualified/certified
operator to monitor and control the operation of sev-
eral small treatment systems from a central location.
The use of a SCADA system results in optimum utili-
zation of time for onsite inspections and maintenance,
thus allowing the operator to visit only the problematic
systems/sites and better schedule the maintenance of
these systems. The expected results from an appro-
priately designed and successfully deployed SCADA
system are (Panguluri et al., 2005a):
• enhanced security and control,
• improved water quality,
• regulatory compliance, and
• reduced overall maintenance costs
9.3 Selection and Implementation
of Supervisory Control and
Data Acquisition (SCADA)
Systems
It is important to understand the treatment system
operation, location and other environmental factors
when engineering and designing a SCADA system
for remote operation and maintenance. The treatment
system operation, location and site-specific factors (the
site-specific factors are discussed later in this section)
will determine the need and the basic design of the
SCADA system. These factors will also help to deter-
9-1
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mine if the system will complement the needs of the
treatment system and the utility services. Retrofitting
a treatment system for remote operations can be cost
prohibitive; many of the small treatment systems cur-
rently in use were not originally designed for remote
operations. Rural areas have little or no electronic
hardware to communicate with a SCADA system.
Thus, the cost of upgrading the treatment system for
remote operations could be significant. Therefore, it is
essential that the treatment system be fairly amenable
to automation. Table 9.1 identifies the current amena-
bility of small package plant treatment technologies to
SCADA.
Many of these treatment technologies are available as
package plants with some degree of automation de-
signed specifically for small systems. The membrane
technologies are extremely amenable to automation
and remote control and also provide efficient removal
for a wide range of drinking water contaminants.
Federal regulations require all small PWS operators to
provide monitoring to assure quality of the treatment
processes. Constant remote monitoring of the water
quality has the potential to provide savings in costs
of time and travel for O&M. It has been determined
that remote telemetry can support regulatory reporting
guidelines by providing real-time continuous monitor-
ing of the water quality and reporting the information
electronically. However, current guidelines are not
available on how to interpret the online data. For ex-
ample, if the data shows that for a period of 5-minutes
(in a particular month) the measured chlorine levels
Table 9.1 Amenability of treatment
technologies to remote monitoring used for
small water (EPA, 2003).
Amenability for
Automation/Remote
Technology Monitoring & Control*
Air Stripping
Oxidation/Filtration
Ion Exchange
Activated Alumina
Coagulation/Filtration
Dissolved Air Flotation
Diatomaceous Earth Filtration
Slow Sand Filtration
Bag and Cartridge Filtration
Disinfection
Corrosion Control
Membrane Filtration Systems
Reverse Osmosis/Nanofiltration
Electrodialysis Systems
Adsorption
Lime Softening
4-5
1 -2
3-4
1 -2
1 -2
1 -2
3-4
3-4
3-4
4-5
3-4
3-4
4-5
4-5
3-4
1 -2
"A rating scale of one to five (1 to 5) is employed with one (1) being
unacceptable or poor and five (5) being superior or acceptable.
were below the regulated levels does that constitute a
violation? Additionally, states do not have a mecha-
nism to accept large quantities of data There is need
for developing guidance on how to interpret the online
monitoring data both from compliance and security
perspectives.
Long-term real-time remote monitoring can provide
data that can be used to significantly enhance treat-
ment system operation and reduce system downtime.
Real-time remote monitoring (Clark et al., 2004; EPA,
2003; Haught, 1998; Haught and Panguluri, 1998) has
the following advantages:
• Can lead to improved customer satisfaction,
improved consumer relations and other health
benefits.
• Can be used to satisfy regulatory recordkeeping
and reporting requirements.
• Can reduce labor costs (associated with time and
travel) for small system operators.
• Provides the capability to instantly alert
operators of undesirable water quality and/or
other changes in treatment system(s).
• Reduces downtime and increases repair
efficiency; troubleshooting can be performed
remotely.
• Can identify monitored parameter trends and
adjust operating parameters accordingly.
• Can provide an attractive alternative to fixed
sampling and operation and maintenance
schedules.
The following questions must be addressed before
purchasing a SCADA System (Clark et al., 2004; EPA,
2003; Haught, 1998; Haught and Panguluri, 1998):
• Does the water treatment system justify the
requirement for a SCADA system (is it remotely
located)?
• Is the treatment system amenable (can water
quality instrumentation and operational
controls "send and receive" data in real-time) to
automation?
• What types of communication media can be
used (phone, radio, cellular, etc.)? See Figure
9.1
• How much automation and control is available
on the treatment system?
• What type of SCADA system is needed (is the
goal to monitor, control or both)?
9-2
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• How many parameters are going to be monitored
and/or controlled?
• What are the specific regulatory monitoring and
reporting requirements?
Figure 9.1 shows the possible schematic layout of a
remote monitoring network.
9.4 Fundamentals of SCADA
As discussed previously, the three key components
of SCADA are: monitoring/control device(s), data
transmission equipment/media, and data collection and
processing unit. This equipment is briefly discussed in
the following sub-sections of this report.
9.4.1 Monitoring Equipment
In general, monitors can be categorized by the types of
parameters (contaminants, agents, characteristics) that
the monitor is used to measure. For establishing water
quality, the monitors are designed to measure one or
more parameters that represent physical, chemical and/
or biological characteristics of the system. The online
remote monitoring devices are fairly complex devices
that are designed to automatically measure, record.
and display specific physical, chemical or biological
parameters. Online monitoring equipment can be the
most expensive component of a SCADA system. The
sensors used in a SCADA system may vary widely.
depending upon the parameters that need to be moni-
tored. The cost for these devices can range from $ 300
to $ 85,000. The costs associated with maintenance
and calibration of the monitoring equipment should be
considered when planning the acquisition and imple-
mentation of a SCADA network. The basic types of
monitoring devices that may be employed in a water
distribution system for monitoring water quality are
discussed below.
9.4.1.1 Physical Monitors
Physical monitors are used to measure physical
characteristics of the water. They include a variety
of instruments that measure various characteristics.
such as flow, velocity, water level, pressure and other
intrinsic physical characteristics of water. Examples
of intrinsic physical characteristics include: turbidity.
color, conductivity, hardness, alkalinity, radioactivity.
temperature and oxidation-reduction potential. In gen-
eral, physical monitors tend to be relatively inexpen-
sive, quite durable, and readily available.
9.4.1.2 Chemical Monitors
Chemical monitors are used to detect and measure
inorganic or organic chemicals that may be present in
the water. A wide range of chemicals may be of inter-
est and a large variety of technologies can be used. A
specific technology or multiple technologies must be
properly selected for a particular chemical or group of
chemicals. Examples of chemical monitors include:
Chlorine analyzer, nitrate sensor, Total Organic Car-
Remote
Location
Central
Office
Radio (RF) Communication
OR
Direct Wire
Figure 9.1 Possible layout of remote monitoring system (EPA, 2003).
9-3
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bon (TOC) analyzer, etc. Typically, the same general
type of technology may be available for either auto-
mated online monitoring capability or for manual grab
sample analysis.
9.4.1.3 Biological Monitors
Biological monitors (biomonitors) include bio-sensors
and bio-sentinels. Bio-sensors detect the presence of
biological species of concern, such as some forms of
algae or pathogens. The general operating principles
of bio-sensors may include: photometry, enzymatic
and/or some form of bio-chemical reaction. The
bio-sentinels use biological organisms as sentinels to
determine the likely presence of toxicity in a water
sample. In general, bio-sentinels cannot be used to
identify the presence of a specific toxic contaminant
- rather only that there is some form of toxic contami-
nant present. Most bio-sentinels operate by observ-
ing the behavior of selected organisms. Examples of
such organisms include: fish, mussels, daphnia and
algae. When the sentinel organism senses the pres-
ence of toxic contaminant(s), the organism reacts in
some manner. The bio-sentinel instruments respond
to these reactions and note that some form of event is
occurring.
While bio-sensors can be directly applied in distri-
bution systems, the bio-sentinels are typically used
in source waters. This is because most organisms
are sensitive to the presence of chlorine (or other
disinfectants) in the water. Therefore, if a bio-sen-
tinel is proposed to be used for distribution system
monitoring, the water must be de-chlorinated prior to
entering the bio-sentinel instrument. Also, the bio-
sentinels require a protected housing environment
along with some sort of nutritional supply to keep
the sentinel organism alive and healthy. The use of
bio-monitors is ideally more suitable for security
issues.
9.4.2 Control Equipment
Control equipment such as switches and controllers
are used widely in SCADA systems. Cost of the con-
trol units such as pumps or shut-off valves are gener-
ally less expensive (Panguluri et al., 2005a) compared
to the monitoring equipment.
9.4.3 Data Collection and Processing Unit(s)
Depending upon the system design requirements,
there can be more than one central data collection
and processing unit. The SCADA system can be de-
signed in a way such that the field SCADA units are
"dumb" units that simply collect and transmit data
to the central station for analysis and action. Alter-
natively, field SCADA units can be "smart" and be
automated to perform some of the control decisions
locally and interact with the central station as neces-
sary for additional analysis and support.
9.4.4 Communication Media and Field Wiring
Depending upon availability, cost, user preference, and
the relative location of the sensors to the data acquisi-
tion system, the communication media can be either
wired (e.g., direct, phone line) or wireless (e.g., radio,
cellular). Infield environments, distributed input/out-
put is typically employed. A remote data acquisition
hardware unit employed at the field location performs
the appropriate signal conditioning and transmits the
data to a central hub (Clark et al., 2004; EPA, 2003;
Haught, 1998; Haught and Panguluri, 1998; Pollack et
al., 1999). More recently, mesh or grid computing sys-
tems are used in remote locations to add redundancy
in cases of link failures. The field wiring between the
sensor and the remote data acquisition hardware unit is
typically direct wire.
Typically, direct wire and phone line (including cel-
lular) communication media are the most inexpensive.
The primary limitations associated with selecting
the communication media include installation and
operating costs, which can vary between $200 (for a
simple telephone or cellular modem) to several hun-
dred dollars for a satellite-based system per location.
Ongoing monthly operating costs can range from $25
for a phone line to approximately $200 per month for
satellite-based services within the U. S (per monitored
location). The overall costs for individual SCADA
components are summarized in Table 9.2 (EPA, 2003).
For a small system, it is expected that (except for the
sensor instrumentation) the actual costs will be on the
lower side of the presented ranges in Table 9.2.
9.5 Remote Telemetry Applications
for Small Systems
Over the years, EPA has funded several remote
monitoring applications in the field. The very first
field implementation for a small system was in West
Virginia and the most recent implementation was in
Puerto Rico. A brief summary of these case studies is
presented in this section.
9.5.1 West Virginia Remote Monitoring Case
Study
In May 1991, EPA provided funding to support a
research project titled "Alternative Low Maintenance
Technologies for Small Water Systems in Rural Com-
munities" (Goodrich et al., 1993). This project in-
volved the installation of a small drinking water treat-
ment package plant in a rural location in West Virginia.
The primary objective of this study was to evaluate
the cost-effectiveness of package plant technology in
9-4
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Table 9.2 Cost estimates ofSCADA system components (Updated from EPA, 2003).
SCADA System Component Component Option Range of Costs, $
Hardware
Software
Communication Medium
Instrumentation
Main Computer
SCADA Unit
Operating System
Telemetry System
Data Collection & Loggers
Telephone
Cellular
Radio
Satellite
Valves
Switch
Sensor
1 ,000 - 3,500
500 - 30,000
250 - 750a
500 - 30,000b
250 - 8,000
75-125c
250 - 500d
200 - 3,500e
200 - 700f
25 - 1 ,5009
25 - 3009
350 - 85,000h
aOperating system software is usually included in the purchase price of a computer.
bSCADA software is usually included in the purchase price of the hardware.
'Monthly service charges are estimated.
dActivation, roaming, and monthly service are estimated and included.
eUpdated: Equipment cost + transmission cost unlicensed frequency ($0), other vary by radio frequency.
'Updated: Starband satellite system monthly cost ~ $200, dish and installation ~ $500.
sCost per valve and/or switch.
hCost per individual sensor or sensor system.
removing microbiological contaminants. The second-
ary objectives of this project included: remote moni-
toring and automation of the system to minimize the
O&M costs, assessment of the community's accept-
ance of such a system, ability to pay, and the effect of
the distribution system on water quality at the tap. The
following is a brief summary of the overall project.
The treatment system was located in rural Coalwood
(McDowell County), WV, approximately 12 miles
from the McDowell County Public Services Division
office in Appalachian Mountain terrain. Prior to 1994,
an aerator combined with a slow sand filter was being
used for water treatment at this site. This combined
unit had been operational for over 30 years and needed
substantial repairs. The water flowed by gravity from
an abandoned coal mine to an aerator built over a
six-foot diameter slow sand filter. A hypochlorina-
tor provided disinfection to the treated water, and
the water flowed by gravity through the distribution
system to the consumer. The volume of water from
the mine was considered sufficient for the small rural
community.
Based on a review of existing technology, EPA de-
termined that a packaged ultrafiltration (UF) system
would be ideally suited for this location. In 1992, a UF
unit was purchased and installed at this site. In 1996,
EPA developed, installed, and tested a remote monitor-
ing system at the site. The system used commercially
available hardware along with proprietary EPA-devel-
oped software. The software was not user-friendly and
the overall cost of ownership was very high. Therefore,
in 1998, EPA updated the SCADA system with a scal-
able commercially available off-the-shelf user-friendly
SCADA system. The total cost (including instrumenta-
tion, technical support, training, and set-up) was about
$33,000. After the success of this project in 2000,
EPA installed similar SCADA systems at Bartley and
Berwind sites in McDowell County, WV, for remote
monitoring of the water quality.
9.5.2 Puerto Rico Remote Monitoring Case
Study
For small system operators, depending upon surface
water sources, various environmental factors heavily
impact system operations. For example, in tropical ar-
eas, storm events can be followed by extreme turbidity
swings in surface waters (especially during the rainy
season). While the turbidity increase may be short-
lived, the high solids loading following a storm event
can overwhelm the treatment capacity of the system.
Frequent occurrence of these events may lead to high
maintenance costs or, at worst, premature equipment
failure. Thus, knowledge of the watershed and source
water conditions prior to the influx of high-turbidity
water to a treatment system is expected to provide an
operational advantage. Online remote monitoring of
smaller systems located in remote areas has the poten-
tial to solve these operational issues and enhance the
quality of water delivered to the consumer.
In early 2005, EPA funded the field implementation
of a web-based remote monitoring system in San
German, Puerto Rico. An overview of the treatment
system is presented in Figure 9.2 (Panguluri et al.,
2005b).
The system-specific challenges included:
• Topography - Steep mountainous region with
dense vegetative cover and significant distance
between system components
9-5
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Figure 9.2 Schematic layout of the small
sytstem in San German, Puerto Rico
(Panguluri et al., 2005b).
Data Processing Center
& Remote Monitoring
via Internet
• Source Variability - 200 inches of rain/year
results in flooding events and source water
turbidity swings, lack of water under drought
conditions
• Other - Lack of electric power and vandalism
Phase 1 of the implementation was completed in
April 2005. In this phase, a solar powered real-time
web-based remote monitoring system was installed
at the source water (dam) location and at the distribu-
tion system location. The monitoring systems at both
locations are equipped with sensors (multi-parameter
sondes) that monitor various water quality parameters
(e.g., pH, temperature, and turbidity),. During periods
of high-turbidity (>25 NTU) at the source water (dam)
location, the system is designed to close an automatic
control valve to protect the horizontal-flow gravel pre-
filter (HFGP). The source water monitoring location
has a built-in option for weather monitoring. In Phase
2 of this implementation, EPA plans to install weather
sensors and evaluate alternative water treatment tech-
nologies.
The equipment installed at the project site during
Phase 1 include: met-tower (without sensors), solar
panels, storage batteries, water quality/level sensors
(sondes), SCADA units (controller and controlled
units) and an automatic control valve. The controller
Table 9.3 Puerto Rico remote monitoring
system component costs (Panguluri et al.,
2005b).
Monitoring System Component Total Cost, $
Towers, antenna, solar panel, and batteries
YSI Sondes (2 units)
Automated control valve
Two SCADA units (one equipped with radio
and other with radio and cellular access)
Website hosting, data warehousing, and
digital cellular service
$3,000
$6,000
$2,000
$7,000
$300/month
9-6
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and controlled SCADA units communicate using radio
frequency and data is transmitted to a central location
via a cellular access at the master location to a central
web-site for operator or user access. Table 9.3 shows
the costs for system components.
Prior to the installation of the remote monitoring
equipment several repairs to the treatment system
were performed. The repairs included: cleaning and
replacing of the sand filter and gravel filter. The
overall Phase 1 installation and repair cost (excluding
the equipment costs shown in Table 9-3) was approxi-
mately $30,000.
9.6 General Security Issues with
Remote Monitoring
Because SCADA systems can provide automatic
control of a system, system security is an important
consideration. The primary security vulnerabilities
for SCADA systems are the communication links, the
computer software, and power sources for the various
system components. A brief discussion about security
considerations for communications and software are
provided in Chapter 8 of this document. Protection of
power sources for individual system components will
be dependent on the power sources used in the system.
However, security can be improved by ensuring that
there are backup power systems for emergency situa-
tions.
9.7 Contamination Warning
Systems
EPA's WSWRD is providing technical support to
NHSRC at the T&E Facility to research and develop
monitoring systems that measure relatively standard
parameters, such as TOC, pH, turbidity, conductivity,
chlorine, oxidation-reduction potential and tempera-
ture. For both water quality- and security-related
monitoring, the instrument response time is critical.
Therefore, online monitors are typically used in these
types of applications. The parameters monitored may
vary widely depending upon the type of process and
security monitoring. Currently, WSWRD is assisting
in the development of a database repository based on
bench-and-pilot-scale experiments that reveal how
these traditional parameters, if monitored online, can
serve as triggers for contamination events. This meas-
ured information can then be automatically analyzed
to determine (1) whether there is an indication of
unusual contamination in the sample; and (2) what
the likely contaminant is based on the water quality
signature of these parameters. The interpretation of
online data is currently an important research topic
and a number of companies are offering data min-
ing software or analytical engines to help identify a
contamination event.
The American Society of Civil Engineers (ASCE),
in concert with other leading organizations, entered
into a cooperative agreement with the EPA to develop
standards documents and guidance aimed at enhanc-
ing the physical security of the Nation's water, and
wastewater/storm water systems. Under this agree-
ment, ASCE is leading the effort to develop guide-
lines for designing an online contaminant monitoring
system (OCMS). The Interim Voluntary Guidelines
for Designing an OCMS were published in Decem-
ber 2004. This document provides comprehensive
information on several topics including: rationale for
OCMS and system design basics, selection and siting
of instruments, data analysis and use of distribution
system models.
9.8 Key Questions
• What is the current status of Remote Telemetry
usage?
• What types of SCADA systems can small
systems afford, operate, and maintain?
• If affordable, what parameters can currently be
monitored and is there room for improvement?
• What is the purpose: Security or water quality?
• What are the main maintenance issues for on-
line monitoring systems?
9.9 References
Clark, R., S. Panguluri, and R. Haught, 2004. Remote
Monitoring and Network Models: Their Potential for
Protecting US Water Supplies, in Mays L., editor.
Water Supply Systems Security. McGraw Hill, New
York, NY.
EPA. Drinking water regulations and health advisories.
EPA-822-B-96-002, Office of Water, Washington, DC,
1996.
EPA. Small drinking water systems handbook: A guide
to packaged filtration and disinfection technologies
with remote monitoring and control tools. EPA/600/R-
03/041, National Risk Management Research Labora-
tory, Cincinnati, OH, 2003.
Goodrich, J., J. Adams, and B. Lykins. Ultrafiltration
membrane application for small systems. National
Risk Management Research Laboratory, Cincinnati,
OH, 1993.
9-7
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Haught, R., 1998. The use of remote telemetry to
complement the operations and maintenance of a small
treatment system, in AWWA Annual Conference, Dal-
las, TX.
Haught, R., and S. Panguluri, 1998. Selection and
management of remote telemetry systems for moni-
toring and operation of small drinking water treat-
ment plants, in Proceedings of the First International
Symposium on Safe Drinking Water in Small Systems,
Washington, DC.
Panguluri, S., R. Haught, C. Patterson, E. Krishnan,
and J. Hall, 2005a. Real-time remote monitoring of
drinking water quality, in Proceedings of ASCE World
Water and Environment Resources Conference, An-
chorage, AK.
Panguluri, S., R. Haught, C. Patterson, R. Krishnan, R.
Sinha, and J. Hall, 2005b. EPA small system initia-
tives: Real-time remote monitoring of small drink-
ing water systems, in Improved monitoring for safe
and secure water supplies: An integrated approach to
emerging information technologies, University of Il-
linois, Urbana IL.
Pollack, A., A. Chen, R. Haught, and J. Goodrich,
1999. Options for remote monitoring and control of
small drinking water facilities. Battelle Press, Colum-
bus, OH.
9-8
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Chapter 10
Summary
improve technical support to small systems. We also
hope that these key questions will be useful to other
organizations as they move forward with research to
support small systems.
10.1 Introduction
The challenges facing small drinking water treatment
systems are numerous. Research at EPA must focus
resources on the most pressing issues that apply to as
many systems as possible. The sheer number of small
systems and the degrees to which they vary make this
a difficult task. Research in treatment technology
and monitoring/reporting must be sensitive to cost
restrictions which tend to play a much greater role
in small systems compared to large systems (serv-
ing greater than 10,000 people). Furthermore, future
research must be adaptable to upcoming challenges.
These factors result in the fact that this Small System
Research Strategy Document must be considered as
a "living document"; one that has the capability of
being flexible to meet new challenges. While search-
ing for breakthroughs in the latest technologies, future
work must always consider applicable, affordable
technologies. This document attempts to assess the
current status of small systems with the primary goal
of informing decision-makers so that resources can be
brought to bear on the most pressing issues concern-
ing small systems. It will be crucial to consider input
from small systems personnel and the public at every
stage.
10.2 Memorandum of
Understanding (MOD) with
the National Rural Water
Association (NRWA)
In an effort to focus resources where they are most
needed, EPA-WSWRD will work with the NRWA
through a MOU. The NRWA offers an enormous
amount of resources concerning access at the grass
roots level with small systems across the country. It is
hoped that through cooperation with NRWA, WSWRD
will be able to provide research results to meet the
most pressing needs for small systems.
10.3 Chapter-Specific Key
Questions
At the ends of the chapters in this document, a list of
key questions is presented. These questions are meant
to stimulate research in subjects that are of importance
to small systems in the United States. The questions
will also serve in the prioritization of research in EPA-
ORD. We hope to work closely with the NRWA in
discussing and prioritizing future areas of research to
10-1
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