i

Water Quality in Small Community

Distribution Systems

A Reference Guide for Operators
ii
Recycled/Recyclable

Printed with vegetable-based ink on

paper that contains a minimum of

50% post-consumer fiber content 

processed chlorine free 

EPA/600/R-08/039

 March 2008

Water Quality in

Small Community Distribution Systems

A Reference Guide for Operators

U.S. Environmental Protection Agency

Offi ce of Research and Development

National Risk Management Research Laboratory

Water Supply and Water Resources Division

Cincinnati, Ohio
ii

Notice

The document was prepared by Shaw Environmental, Inc. (Shaw) under EPA Contract No. EP-C-05-056, 

Work Assignment No. 0-10 and 1-10, with Pegasus Technical Services, Inc. Mr. Radha Krishnan, P.E., 

was the Shaw Program Manager for this contract and Mr. Srinivas Panguluri, P.E. was the Shaw Project 

Leader for this Work Assignment. Dr. Walter Grayman, P.E., and Dr. Robert Clark, P.E., D.E.E. were 

consultants to Shaw on this Work Assignment. Ms. Lucille M. Garner served as EPA Work Assignment 

Manager and Mr. Craig L. Patterson, P.E., served as the Alternate EPA Work Assignment Manager. Mr. 

Roy C. Haught served as EPA Technical Advisor. 

Disclaimer

Any opinions expressed in this document/reference guide for utilities are those of the author(s) and do 

not, necessarily, refl ect the offi cial positions and policies of the U.S. Environmental Protection Agency 

(EPA). Any mention of products or trade names does not constitute recommendation for use by EPA. 

This document has been reviewed in accordance with EPA’s peer and administrative review policies and 

approved for publication.
iii

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, EPA’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 investigation 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 scientifi c 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 EPA’s Offi ce of Research and Development to assist the user community and to link researchers with their clients.

Sally Gutierrez, Director

National Risk Management Research Laboratory
iv

Abstract

The U.S. Environmental Protection Agency (EPA) has developed this reference guide to assist the 

operators and managers of small- and medium-sized public water systems. This compilation provides a 

comprehensive picture of the impact of the water distribution system network on distributed water quality.

This reference guide provides information on the following topics:

• Water supply and distribution process overview

• Distribution system infrastructure 

• Drinking water regulations

• Distribution system water quality issues

• Distribution system monitoring, control and security

• Operational, financial and management strategies to address 

distribution system water quality

In addition, to make this document appeal to a diverse group of small system operators and managers, 

graphical elements such as pictures, tables, blue sidebars, and cartoon illustrations have been used 

throughout the document. Although every water distribution system is different (in terms of specifi c 

layout and operations), all water distribution systems generally have the same components and operate 

under similar principles and operational strategies. To illustrate solutions to some of the common issues 

faced by the small community distribution system operators, an example of a small water distribution 

network (SmallWater, USA) has been included in this document. At the end of many chapters, one 

or more SmallWater problem scenario(s) are presented along with some guidance on resolving these 

problems.

Other related EPA reference guides in this area include the following:

• Small Drinking Water Systems: State of the Industry and Treatment Technologies to Meet 

the Safe Drinking Water Act Requirements. EPA Publication Number: 600-R-07-110

• Water Distribution System Analysis: Field Studies, Modeling and Management – A 

Reference Guide for Utilities. EPA Publication Number: 600-R-06-028

• Small Drinking Water Systems Handbook: Guide to “Packaged” Filtration and Disinfection 

Technologies with Remote Monitoring and Control Tools. EPA Publication Number: 600-

C-03-041
v

Table of Contents

1.0 Introduction ..................................................................................................................................1-1

1.1 Purpose and Scope of the Document ....................................................................................1-1

1.2 Graphical Elements and Cartoon Illustrations........................................................................1-1

1.3 SmallWater, USA - Problem Scenarios ..................................................................................1-2

1.4 Content Development and Description ..................................................................................1-2

2.0 The Supply, Distribution, and Quality of Water: An Overview ......................................................2-1

2.1 Protecting Source Water Quality ............................................................................................2-1

2.2 Water Treatment, Supply and Distribution ..............................................................................2-2

2.3 History of Water Supply and Treatment in the United States .................................................2-3

2.4 History of Water Quality Regulations and Standards in the United States ............................2-3

2.5 Public Water System ..............................................................................................................2-4

2.5.1 Type and Size of Systems ..............................................................................................2-4

2.5.2 Type of Source Water Used ...........................................................................................2-5

2.5.3 Type of Ownership .........................................................................................................2-6

2.6 Common Problems Faced by Small and Medium Utilities .....................................................2-6

2.6.1 Water Quality Problems .................................................................................................2-6

2.6.2 Operational Problems ....................................................................................................2-7

2.6.3 Regulatory/Compliance Problems .................................................................................2-7

2.6.4 Institutional Problems .....................................................................................................2-7

2.7 SmallWater, USA Scenario ....................................................................................................2-7

3.0 Distribution System Infrastructure ...............................................................................................3-1

3.1 The Impact of Distribution System on Water Quality..............................................................3-1

3.2 Distribution System Pipes .....................................................................................................3-2

3.2.1 Pipe Connectivity, Placement and Confi guration ...........................................................3-2

3.2.2 Pipe Material ..................................................................................................................3-3

3.2.3 Common Problems, Troubleshooting and Pipe Repair ..................................................3-4

3.3 Distribution System Pumps ...................................................................................................3-5

3.3.1 Common Problems, Troubleshooting and Maintaining Pumps.......................................3-6

3.4 Distribution System Storage Facilities ...................................................................................3-6

3.4.1 Types of Storage Facilities .............................................................................................3-6

3.4.2 Common Problems, Troubleshooting and Maintaining Tanks .........................................3-7

3.5 Distribution System Valves ....................................................................................................3-8

3.5.1 Gate Valves ....................................................................................................................3-8

3.5.2 Butterfl y Valves ..............................................................................................................3-8

3.5.3 Check Valves .................................................................................................................3-9

3.5.4 Other Valves ...................................................................................................................3-9

3.5.5 Common Problems, Troubleshooting and Maintaining Valves .......................................3-9

3.6 Distribution System Hydrants ..............................................................................................3-10

3.6.1 Common Problems, Troubleshooting and Maintaining Hydrants .................................3-10

3.7 Water Meters and Service Lines ..........................................................................................3-11

3.7.1 Water Meters ...............................................................................................................3-11

3.7.2 Service Lines ...............................................................................................................3-11

3.7.3 Common Problems, Troubleshooting and Repairs .......................................................3-11

3.8 Distribution System Asset Management ..............................................................................3-12

3.9 Distribution System Modeling ..............................................................................................3-13

3.10 SmallWater, USA – Asset Management Problem Scenario .................................................3-16

4.0 Drinking Water Regulations .........................................................................................................4-1

4.1 Highlights of 1974 SDWA and its Amendments .....................................................................4-3

4.1.1 1986 Amendments to SDWA .........................................................................................4-3

4.1.2 1996 Amendments to SDWA .........................................................................................4-3

4.1.3 Variances and Exemptions ............................................................................................4-3

4.2 Regulations to Control Microbial Contaminants .....................................................................4-4
vi

4.3 Regulations to Control Chemical Contaminants ....................................................................4-5

4.4 Public Notification and Consumer Confidence Rules ............................................................4-5

4.5 SmallWater, USA – Regulatory Scenario Problems ..............................................................4-9

5.0 Distribution System Water Quality Issues ....................................................................................5-1

5.1 Taste, Odor, and Color ..........................................................................................................5-1

5.1.1 Taste and Odor Problems ..............................................................................................5-1

5.1.2 Color Problems ..............................................................................................................5-2

5.2 Biofilm ...................................................................................................................................5-3

5.2.1 Factors Aiding Biofilm Growth ........................................................................................5-4

5.2.2 Operational Factors Inhibiting the Growth of Biofilm ......................................................5-4

5.3 Disinfection and Disinfection Byproducts ...............................................................................5-5

5.4 Nitrification .............................................................................................................................5-6

5.5 pH Stability and Scale Formation ..........................................................................................5-6

5.6 Contamination Events ...........................................................................................................5-7

5.6.1 Cross-connections and Backflow ...................................................................................5-7

5.6.2 Permeation and Leaching .............................................................................................5-8

5.6.3 Intrusion and Infiltration ................................................................................................5-8

5.6.4 Storage Facility Contamination .....................................................................................5-8

5.7 SmallWater, USA – Water Quality Problem Scenarios ..........................................................5-9

6.0 Distribution System Monitoring, Control, and Security ................................................................6-1

6.1 Monitoring a Distribution System ...........................................................................................6-1

6.2 Distribution System Hydraulic Monitoring ..............................................................................6-2

6.2.1 Flow and Velocity Monitoring .........................................................................................6-2

6.2.2 Pressure Monitoring .......................................................................................................6-4

6.3 Distribution System Water Quality Monitoring ........................................................................6-5

6.4 Controlling a Distribution System ...........................................................................................6-6

6.4.1 SCADA Instrumentation and Hardware .........................................................................6-6

6.4.2 SCADA Operator Interface .............................................................................................6-6

6.4.3 Communication Media ...................................................................................................6-7

6.4.4 Selection of SCADA Systems ........................................................................................6-7

6.5 Securing a Distribution System ..............................................................................................6-8

6.5.1 Distribution System Vulnerabilities .................................................................................6-8

6.5.2 Operational and Emergency Response Mechanisms ....................................................6-9

6.6 SmallWater, USA – Monitoring, Control and Security Problem Scenarios ..........................6-10

7.0 Strategies to Address Distribution System Water Quality Issues ................................................7-1

7.1 Operational Strategies ...........................................................................................................7-1

7.1.1 Reducing Water Age in the Distribution System ............................................................7-1

7.1.2 Adapting Operations to Meet System-Specific Water Demands ....................................7-2

7.1.3 Changing Disinfectants ..................................................................................................7-2

7.1.4 Implementing Corrosion Control ....................................................................................7-3

7.1.5 Preventing Sedimentation and Scale Formation ...........................................................7-4

7.1.6 Implementing a Flushing Program .................................................................................7-4

7.1.7 Infrastructure Replacement and/or Treatment Upgrades ...............................................7-5

7.2 Financial Strategies ...............................................................................................................7-5

7.2.1 Drinking Water State Revolving Fund ............................................................................7-6

7.2.2 Community Development Block Grants .........................................................................7-7

7.2.3 Rural Utilities System .....................................................................................................7-7

7.2.4 Economic Development Administration .........................................................................7-7

7.2.5 Other Entities and Private Foundations .........................................................................7-8

7.3 Management Strategies .........................................................................................................7-8

7.3.1 Small Systems Working Together ..................................................................................7-8

7.3.2 Change in Ownership and/or Management ...................................................................7-9

7.4 SmallWater USA – Cell Tower Installation .............................................................................7-9

8.0 Bibliography .................................................................................................................................8-1
vii

List of Tables

Table 3.1 Infrastructure Components ..............................................................................................3-1

Table 3.2 Potential Negative Impacts to Water Quality Based on Pipe Material and Changes in 

Water Quality ...................................................................................................................3-3

Table 3.3 Common Problems that Lead to Pipe Failure for Various Pipe Materials ........................3-5

Table 3.4 Listing of Low-cost CADD and GIS Application Software ..............................................3-14

Table 3.5 Available Hydraulic-Water Quality Network Modeling Software Packages ....................3-16

Table 3.6 Hydrant Inventory Information .......................................................................................3-17

Table 3.7 Event Table ....................................................................................................................3-17

Table 4.1 Summary of Regulations Designed to Control Microbial Contamination .........................4-6

Table 4.2 Summary of Regulations Designed to Control Chemical Contamination ........................4-7

Table 6.1 Flow Meters .....................................................................................................................6-3

Table 6.2 Cost of SCADA Implementation at Coalwood, WV. .........................................................6-7

List of Figures

Figure 1.1 “Rogue’s Gallery” of fi ctional characters used in this reference guide. ............................1-1

Figure 2.1 The Hydrologic Cycle or “Water Cycle”............................................................................2-1

Figure 2.2 Multiple Risks to Public Health ........................................................................................2-2

Figure 2.3 A Typical Water Supply System Using Surface Water as Source ....................................2-3

Figure 2.4 A Schematic Representation of a Water Distribution System ..........................................2-3

Figure 2.5 Classifi cation of PWSs in the U.S. ...................................................................................2-5

Figure 2.6 Distribution of PWSs by Size ...........................................................................................2-5

Figure 2.7 Distribution of Small- and Medium-Sized PWSs by Source of Water Used .....................2-6

Figure 2.8 Distribution of Small- and Medium-Sized PWSs by Ownership ......................................2-6

Figure 2.9 SmallWater, USA – Schematic Layout ............................................................................2-8

Figure 3.1 A Branched Distribution System ......................................................................................3-2

Figure 3.2 A Grid/Looped Distribution System .................................................................................3-2

Figure 3.3 NSF-Approved PVC Pipe for Potable Water Use.............................................................3-3

Figure 3.4 Pipe Wall Interactions that Affect Water Quality ..............................................................3-3

Figure 3.5 Storage Tank Volume Design Requirements ...................................................................3-7

Figure 3.6 Gate Valve (side view) .....................................................................................................3-8

Figure 3.7 Butterfl y Valve (top view) .................................................................................................3-9

Figure 3.8 Swing Check Valve (side view) ........................................................................................3-9

Figure 3.9 Dry Barrel Hydrant .........................................................................................................3-10

Figure 3.10 Arenas Valley Pipe Inventory and Main Break Map .......................................................3-12

Figure 3.11 Screen-shot Showing the Results of an Analysis for the SmallWater Distribution 

System ..........................................................................................................................3-14

Figure 3.12 EPS Plots of Tank Water Levels and Flow in a Water Main Over a 2-Day Period. .........3-15

Figure 3.13 Components in the SmallWater Distribution System .....................................................3-17

Figure 3.14 Hydrant locations in part of SmallWater ........................................................................3-17

Figure 3.15 Sample Asset Management Database Design or Schema ...........................................3-17

Figure 4.1 The Evolution of Federal Drinking Water Standards ........................................................4-2

Figure 4.2 Disease-Causing Microorganisms - E. coli, Giardia and Cryptosporidium (not to scale) 4-5

Figure 4.3 Sample Public Notice ......................................................................................................4-8

Figure 5.1 Drinking Water Taste and Odor Wheel.............................................................................5-3

Figure 5.2 Biofi lm Growth Inside the Pipe ........................................................................................5-4

Figure 5.3 Water Age Within SmallWater, USA ..............................................................................5-10

Figure 6.1 Manual Water Quality Sampling and Field Testing ..........................................................6-2

Figure 6.2 Automated Water Quality Monitoring ...............................................................................6-2

Figure 6.3 Hydrant Flow Gages ........................................................................................................6-4

Figure 6.4 Digital and analog pressure meter attached to fi re hydrant .............................................6-5

Figure 6.5 Readout meters for fl ow, water level and pressure from a SCADA system .....................6-5

Figure 7.1 Crowded Cell Tower Installation ....................................................................................7-11

Figure 7.2 A Well-Designed and Constructed Cell Tower Installation .............................................7-11
viii

Acronyms and Abbreviations

AM Asset Management

AMR Automatic Meter Reading

ANSI American National Standards 

Institute

AOC Assimilable Organic Carbon

ARC Appalachian Regional Commission

ASTM American Society for Testing 

Materials

AWWA American Water Works Association

AwwaRF American Water Works Association 

Research Foundation

BAT Best Available Treatment

BDOC Biodegradable Organic Carbon

CaCO3 Calcium Carbonate

CADD Computer-Aided Design and Drafting

CCR Consumer Confi dence Report

CDBG Community Development Block 

Grant

CWA Clean Water Act

CWS Community Water System

DBP Disinfection Byproduct

D/DBPR Disinfectants/Disinfection Byproducts

Rule

DWSRF Drinking Water State Revolving Fund

EDA Economic Development 

Administration

EPS Extended Period Simulation

ERP Emergency Response Plan

EPA United States Environmental 

Protection Agency

FBRR Filter Backwash Recycling Rule

fps Feet per Second

GIS Geographic Information System

gpm Gallons Per Minute

GPS Global Positioning System

GWR Ground Water Rule

GWUDI Ground Water Under Direct Infl uence 

(of Surface Water)

HAA Haloacetic Acids

HDPE High-Density Polyethylene

HPC Heterotrophic Plate Count

IESWTR Interim Enhanced Surface Water 

Treatment Rule

IDSE Initial Distribution System Evaluation

IHS Indian Health Service

I/O Input/Output

IOC Inorganic Compounds

IRS Internal Revenue Service

LCR Lead and Copper Rule

LOS Level of Service

LRAA Locational Running Annual Average

LSI Langelier Saturation Index

LT1ESWTR Long-term 1 Enhanced Surface 

Water Treatment Rule

LT2ESWTR Long-term 2 Enhanced Surface 

Water Treatment Rule

MCL Maximum Contaminant Level

MCLG Maximum Contaminant Level Goal

MCPSD McDowell County Public Service 

District

μg/L Micrograms per Liter

mg/L Milligrams per Liter

NDWC National Drinking Water 

Clearinghouse 

NIPDWR National Interim Primary Drinking 

Water Regulations

NKWD Northern Kentucky Water District

NMEFC New Mexico Environmental Finance 

Center

NPDES National Pollutant Discharge 

Elimination System

NRWA National Rural Water Association

NSDWR National Secondary Drinking Water 

Regulations

NTNCWS Non-Transient Non-Community Water 

System

O&M Operation and Maintenance 

OSHA Occupational Safety and Health 

Administration

PD Positive Displacement

POE Point of Entry

POU Point of Use

PRV Pressure Reducing Valve

PVC Polyvinyl Chloride

PWS Public Water System

RAA Running Annual Average

REM Roentgen Equivalent Man

RTU Remote Terminal Unit

RUS Rural Utilities System
ix

SBREFA Small Business Regulatory 

Enforcement Act

SCADA Supervisory Control and Data 

Acquisition

SCWIE Small Community Water 

Infrastructure Exchange

SDWA Safe Drinking Water Act

SMF Standardized Monitoring Framework

SOC Synthetic Organic Compounds

SSCT Small System Compliance 

Technology

STEP Simple Tools for Effective 

Performance

SWTR Surface Water Treatment Rule

TCR Total Coliform Rule

THM Trihalomethanes

TMDL Total Maximum Daily Load

TNCWS Transient Non-Community Water 

System

TOC Total Organic Carbon

TT Treatment Technique

UF Ultrafi ltration

UL Underwriters Laboratory

USDA U.S. Department of Agriculture

U.S. United States

USA United States of America

VA Vulnerability Assessment

VOC Volatile Organic Compounds

WV West Virginia
x

Acknowledgements

The principal authors of this document, titled “Water Quality in Small Community Distribution Systems 

- A Reference Guide for Operators,” were: Mr. Srinivas Panguluri, P.E., Dr. Walter M. Grayman, P.E., Dr. 

Robert M. Clark, P.E., D.E.E., Mr. E. Radha Krishnan, P.E., Ms. Lucille M. Garner, Mr. Craig L. Patterson, 

P.E., and Mr. Roy C. Haught. 

The authors wish to acknowledge the contributions of the following individuals and organizations towards 

the development of this document:

EPA technical reviews of the document were performed by:

Mr. Thomas Grubbs, P.E., Environmental Engineer, EPA Offi ce of Ground Water and Drinking 

Water (OGWDW)

Mr. Michael Finn, P.E., Environmental Engineer, EPA OGWDW, Standards and Risk Reduction 

Branch 

Mr. Steve Clark, Environmental Health Scientist, EPA OGWDW, Drinking Water Protection Branch

EPA Offi ce of Research and Development (ORD) Quality Assurance, editorial and graphical reviews 

were performed by:

Mr. Stephen M. Harmon, Quality Assurance Manager – Quality Assurance Review

Dr. Jean Dye – Editorial Review

Mr. Patrick Burke – Publishing Review 

Mr. Steve Wilson – Review of Illustrations

Ohio EPA Drinking Water Division staff for coordination of site visits to small water distribution systems 

and providing state perspective on key issues:

Mr. Dan Cloyd, Environmental Specialist 3

Mr. Jeff G. Davidson, Environmental Manager

Mr. Daniel J. Stine, Environmental Supervisor

External technical reviews of the document were performed by:

Mr. Jerry C. Biberstine, P.E., of the National Rural Water Association 

Mr. Gary Burlingame of the Philadelphia Water Department 

Mr. Gary Lynch of the Park Water Company

Mr. Lee Larue with the National Park Service at Mt. Rainer, Washington

Assistance during the conduct of site visits to small water distribution systems:

Mr. Jeremy Fite and Mr. Jason Barger at Williamsburg, Ohio

Mr. Fred Freeman at Blanchester, Ohio 

Mr. Ken Shearwood and Mr. Don Caudel at New Richmond, Ohio

Illustrations and Graphical layout assistance:

Dr. Robert Probst of the University of Cincinnati (UC) Design, Architecture, Art, and Planning 

(DAAP), for arranging the services of DAAP graduate students to prepare the illustrations

Ms. Shereen Puthenpurackal, graduate student at UC-DAAP, for preparing the stand-alone 

illustrations

Mr. Abhijeet Bhattacharya, graduate student at UC-DAAP, for developing the character-based 

illustrations

Mr. James I. Scott of Shaw for performing the document setting and layout
xi

Context-specifi c information and illustrations for inclusion into the document were provided by:

Mr. Ira M. Gabin, Dixon Engineering

Ms. Heather Himmelberger, P.E., New Mexico Environmental Finance Center

Dr. Yeongho Lee, P.E., Greater Cincinnati Water Works

Mr. Adam Levine, Historical Consultant, Philadelphia Water Department

Ms. Charlotte D. Smith, Consultant 

Mr. Gordon W. Thompson, Shaw

Cover Photo Credits (starting from top left clockwise) are as follows:

Rural water tank – photograph by Mr. James I. Scott

Children drinking from a faucet – pictured are Mr. Ravi R. Panguluri and Ms. Isabella M. Panguluri 

– photograph by Ms. Jennifer S. Panguluri

Small town picture – Aerial view of Stowe, Vermont – Royalty-free image from American Spirit 

Images purchased from www.fotosearch.com

Operators fl owing a hydrant – Montgomery County Sanitary Engineering Department Operators 

– photograph by Dr. Walter M. Grayman.
xii
1-1

Chapter 1

Introduction

In the United States, there are thousands of miles of

water distribution pipes which convey drinking water

to consumers. However, there are many changes that

occur within a distribution system that may result in

degraded water quality. Suspended and/or dissolved

solids in fi nished water can settle under low-fl ow conditions and can be re-suspended during high-fl ow conditions. Various disinfection agents (e.g., chlorine,

chlorine dioxide, and chloramines) can react with organic matter contained in the source water and generate potentially harmful byproducts to which consumers 

are exposed. In addition, microorganisms can attach

to pipe surfaces, producing a complex microbiological environment known as “biofi lm.” Contaminants

may infi ltrate a distribution system during pipe breaks 

or through fi nished water storage facilities. Some of

these undesirable water quality changes result in taste, 

odor or red-water problems that can be detected immediately. Potential contamination by pathogens (e.g., E. 

coli or Salmonella) may only be identifi ed by sampling 

and analysis after a contamination event or following

a waterborne disease outbreak. In order to minimize

the degradation of water quality within distribution

systems, the United States Environmental Protection

Agency (EPA) publishes drinking water regulations.

It is important that water distribution system operators 

and water utility managers understand changes occurring in water distribution systems, the related water

quality concepts, and associated regulations in order to 

maintain a high degree of water quality within a distribution system. As emphasized in this document, proper operation and management of distribution system

components is essential to protect the customer against 

both aesthetic and public health threats that may result 

due to undesirable water quality changes in the distribution system.

1.1 Purpose and Scope of the 

Document

EPA has developed this reference guide to assist operators and managers of 

small- and medium-sized 

public water systems

(PWSs). It presents a

compilation of information designed to provide 

small- and medium-sized 

water utility operators

with a comprehensive 

picture of the water distribution system network. Because the technical background level of the target audience (small- to medium-size system operators and decision makers) varies widely, some very basic concepts 

have been included in this document. For the purposes 

of this reference guide, PWSs are interchangeably referred to as water utilities.

1.2 Graphical Elements and 

Cartoon Illustrations

To make this document appealing to a wide audience, 

graphical elements (pictures, tables and blue sidebars) 

and cartoon illustrations have been used throughout the 

document. Many of these graphical elements and cartoons are borrowed or adapted from existing publications (as referenced). Others were developed exclusively for use in this reference guide. Many of the cartoons 

were developed to illustrate basic distribution system 

concepts in a humorous manner but bear no relation to 

any real individuals or organizations.

Figure 1.1 “Rogue’s Gallery” of fi ctional 

characters used in this reference guide.

Bob, a small 

utility operator

Target

Audience

Carl, a utility 

consultant

Fred, a federal 

regulator

Stan, a state 

regulator

Dale, a small utility

decision-maker

Liz, a small utility 

laboratory technician

Reed,

a reporter

Figure 1.1 shows

a “rogue’s gallery” of the characters that populate this 
1-2

Treatment

Storage

Distribution

Source

Distribution System 

Infrastructure

manual and their roles. In addition to these fi ctional

characters, other “stand alone” cartoons are also used

throughout the document as necessary. None of the cartoon illustrations are meant to provide any “real-world”

solutions. The sole purpose of the cartoon illustrations

is to provide humor without offending any race, nationality, gender, politics, or religion.

1.3 SmallWater, USA - Problem 

Scenarios

Every water distribution system is different in terms of 

specifi c layout and operations. However, water distribution systems generally have the same components 

and operate under similar principles and operational 

strategies. SmallWater, USA is an example of a water 

distribution system, utilized in this document to illustrate a drinking water utility serving a small- to medium-sized town. This example system includes all

of the components that 

are typically found

in the majority of

small- and mediumsized PWSs and is

used to illustrate 

many of the issues 

and potential problems facing a small 

water utility. SmallWater, USA problem scenarios 

are used throughout this reference guide to explore a 

number of water quality, operational, regulatory/compliance, and institutional problems faced by many of 

the small- and medium-sized utilities in the nation. 

At the end of each chapter, one or more SmallWater 

problem scenario(s) are presented along with some 

guidance on how to address these problems.

1.4 Content Development and 

Description

Between January and February of 2007, during the 

initial stages of development of this reference guide, 

several of the authors met with the staff at three small 

water utilities to discuss their operational and management procedures. The various utility staff members 

were very helpful in discussing their approaches to 

solving common problems. The authors also met with 

various state regulatory agency personnel to get their 

perspective on the critical issues facing small-community water utility operators and managers. In addition, 

the authors consulted with several technical and editorial reviewers to refi ne the material presented in the 

document to make it suitable for the target audience. 

These individuals are listed in the Acknowledgement 

ly, the process for treating, storing and distributing water is 

described. A brief history 

of water treatment and 

water quality regulations is provided

as it relates to protecting water quality. Summary statistics documenting

the size, source water, 

and ownership of PWSs

is presented. Finally, a listing of 

common problems faced by small- and medium-sized 

water utilities is presented along with the description 

of SmallWater, USA.

Chapter 3 describes distribution system infrastructure 

and how each component can potentially impact water 

quality. Each of the major distribution system components is discussed in this chapter. The fi rst subsection of this chapter discusses distribution system pipes 

and how their functionality varies 

with connectivity, placement and confi guration.

Pipe types and material are also discussed 

along with common

problems, as well

as troubleshooting and pipe repair 

techniques. Options 

for minimizing pipe 

leaks and water loss 

during distribution

system line breaks

are also presented.

This is followed by a discussion on distribution system pumps, storage facilities (tanks), valves, and hydrants. Common problems associated with each of 

these components, along with troubleshooting and 

suggested maintenance techniques for these components, are also presented. Finally, the distribution 

system asset management concept is presented along 

with a SmallWater, USA problem scenario.

section immediately preceding this chapter. The following is a brief description of the content in each of 

the subsequent chapters of this reference guide.

Chapter 2 provides an overview of the water supply 

and distribution process with an emphasis on how the 

distribution system impacts the quality of water supplied to the consumer. First, the concept of “water 

cycle” is illustrated along with strategies employed 

by EPA to protect source water quality. Subsequent-
1-3

Strategy

Additional Information and 

Bibliography

Water Distribution 

Automation

Water Quality

Safe Drinking Water Act

Chapter 4 presents a summary of 

the drinking water regulations. The highlights of 

the 1974 Safe Drinking 

Water Act (SDWA) 

and its subsequent

amendments are discussed. The regulations to control microbial and chemical 

contaminants are tabulated. Public notifi -

cation and consumer 

confi dence rules under the SDWA are discussed. Two SmallWater, USA 

regulatory problem scenarios are presented.

Chapter 5 summarizes various distribution system water quality issues such as taste, odor, and color. The 

concept of “biofi lm” is presented, along with the factors contributing to 

biofilm growth and 

operational factors

that could inhibit the 

growth of biofi lm. 

Subsequently, distribution system water 

quality issues such as 

disinfection byproducts 

(DBPs), nitrifi cation, pH 

stability and scale formation are discussed. These 

sections are followed by a 

discussion on contamination 

events including cross-connections, permeation/leaching, intrusion/infi ltration and reservoir/storage facility 

contamination. Finally, the concept of hydraulic modeling is introduced followed by two SmallWater, USA 

regulatory problem scenarios.

Chapter 6 provides a summary of the 

available methods for monitoring, 

controlling, and securing distribution systems. The physical state of the distribution 

system changes over time and 

techniques for monitoring parameters such as fl ow, velocity, and pressure are presented. Distribution system water 

quality monitoring techniques 

and methods for controlling a 

distribution system are discussed. Common control 

automation equipment such as Supervisory Control and 

Data Acquisition (SCADA) instrumentation, SCADA 

hardware, SCADA interface, and SCADA communication media are presented. This is followed by a discussion on distribution system vulnerabilities, operational 

responses, and emergency response mechanisms. Finally, two SmallWater, USA problem scenarios related 

to monitoring, control and security are presented.

Chapter 7 contains a summary of operational, management and fi nancial strategies to address distribution 

system water quality issues. Operational strategies 

such as reducing water age, 

adapting operations to meet 

demand, initiating or changing disinfectants, and controlling corrosion are presented. Financial strategies 

such as obtaining loans and 

grants through various government and private sources 

are discussed. Management 

strategies such as regionalization and change in ownership are presented. Finally, 

two SmallWater problem scenarios are presented.

Chapter 8 includes a bibliography for this reference 

guide. Some of the documents included in the bibliography are referenced within the text of this guide. The 

references in the bibliography contain additional 

detailed information and provide 

valuable reading material for 

readers who wish 

to pursue any of the 

specifi c topics discussed in this guide in 

greater detail.

In the development of 

this reference guide, care has been taken to keep the 

guide simple, short, and concise. The guide contains 

additional references for supplementary reading material (as necessary and appropriate). Acronyms and abbreviations used in each chapter are defi ned in a separate listing as well as at their fi rst occurrence in each 

chapter. In addition, to help explain many of the concepts, a variety of graphic illustrations, crossword puzzles and example problem scenarios have been utilized 

throughout the document.
1-4
2-1

Chapter 2

The Supply, 

Distribution, and 

Quality of Water:

An Overview

Water is a renewable resource that is in continuous 

movement at the earth’s surface (e.g., rivers, streams, 

and oceans), below the ground in aquifers and in the 

atmosphere. The natural movement of water 

is powered by the sun 

and the earth’s gravity. 

This natural continuous movement of water 

is called the hydrologic 

cycle or the “water cycle.” In this cycle, water precipitates as rain 

and falls onto surface 

storage areas such as

lakes, rivers, streams,

and oceans. The water 

on the land and these surface storage 

areas infi ltrates and recharges underground sources called aquifers. Additionally, the 

water from the surface 

sources and plants evaporates to form rain-bearing 

clouds. Figure 2.1 is a graphical representation of the 

natural water cycle. 

Aquifers (ground water) and rivers (surface water) are 

the main sources of water for utilities in the United 

States (U.S.). 

Figure 2.1 The Hydrologic Cycle or “Water 

Cycle” (Adapted from: EPA, 2002f)

2.1 Protecting Source Water 

Quality

During the natural cyclic movement and storage of water in both surface and subsurface sources, water may 

be exposed to a variety of natural or human activityrelated contaminants. Depending upon the location, the source 

water may be exposed to surface 

or subsurface sources of physical, 

chemical, biological and/or radiological contamination. Examples 

of contamination sources include:

• Rain water run-off collected by storm 

sewers (physical and/or chemical/biological 

contamination)

• Concentrated Animal Feeding Operations 

(biological and chemical contamination)

• Agricultural Pesticide 

and Fertilizer Application 

(chemical contamination)

Regulations

Consumer

Complaints

Water

Cycle
2-2

• Septic Systems and Leaking Sewers (biological 

contamination)

• Construction Activities (chemical 

contamination)

• Wastewater and Industrial Discharges (chemical 

and biological contamination)

• Mining Wastes (chemical and radiological 

contamination)

• Naturally occurring chemical and radiological 

material in contact with underground 

water resources (chemical and radiological 

contamination)

These multiple risks to public health, illustrated in Figure 2.2, are only a few of the potential sources of contamination that can threaten both surface and ground 

water supplies used by the water utilities. EPA mandates various water quality standards and regulations 

that are designed to serve as barriers to the risk of 

source water contamination. 

If the amount (or concentration) of the contaminant 

material present in the source water supply exceeds 

drinking water standards, water utilities are required to 

treat the source water to reduce (or eliminate) the contaminant material to the required standard levels prior 

to distributing the water to their customers. 

Figure 2.2 Multiple Risks to Public Health 

(Adapted from: EPA, 2002f)

2.2 Water Treatment, Supply and 

Distribution

Source water is often treated by unit processes such 

as coagulation, fi ltration, and disinfection to remove/

reduce the contamination, to meet the maximum contaminant levels (MCLs). These treatment processes 

are generally not considered to be part of the distribution system. The fi nished water may be directly 

delivered to the consumer through the distribution 

system or temporarily stored in underground/elevated 

tanks before it is delivered to the consumer through 

the distribution system to faucets in their homes or 

work places. Figure 2.3 is a graphical representation 

of a typical water supply system that uses a surface 

water source. 

A drinking water distribution system is a complex network of pipes, tanks and reservoirs that delivers fi nished 

water to consumers. The consumers of water include: 

residential households, commercial businesses, industrial users, and agricultural users. Collectively, water 

distribution system infrastructure consists of a variety 

of equipment such as pumps, pipes, tanks, valves, hydrants and meters, that are built to deliver water from 

the surface (e.g., river) and/or subsurface source (e.g., 

wells drilled into aquifers) to the customer. Figure 2.4 

shows a schematic representation of a generic water 

distribution system. 
2-3

A more detailed discussion of the distribution system 

components is presented in Chapter 3.0 of this report.

Figure 2.3 A Typical Water Supply System Using Surface 

Water as Source (Adapted from: EPA, 2002f)

Intake

Treatment

Storage

Figure 2.4 A Schematic Representation of a Water 

Distribution System

 	

 


	

2.3 History of Water Supply and 

Treatment in the United States

The fi rst water supply utility was established in the U.S. 

in Boston, Massachusetts in 1652, for the purpose of

providing domestic water and fi re protection. Other

cities followed Boston’s example and established water 

utilities for fi re protection and to provide commercial 

and residential water service. The fi rst water treatment 

plant in the U.S. was constructed in Richmond, Virginia 

in 1832 and the second was constructed in 1855 in Elizabeth, New Jersey. The water treatment system in Elizabeth consisted of a small charcoal sand and gravel fi lter. 

By 1860, only 136 water systems had been constructed 

in the U.S. Because most of the early utilities supplied 

water from springs low in turbidity and relatively free 

from pollution, they were also relatively problem-free. 

By the end of the nineteenth century, however, waterborne disease had become a serious problem in industrialized watersheds. For example, during one year in 

the 1880s, the typhoid death rate was 158 deaths per 

100,000 in Pittsburgh, Pennsylvania. This led to the

more routine use of water treatment; by 1935, the typhoid death rate had declined to 5 per 100,000. Another 

study of typhoid case rates and associated death rates in 

the City of Cincinnati between 1898 and 1928 shows a 

signifi cant decline in these rates after the city initiated 

fi ltration in 1907, and after implementation of chlorination in 1915. Water treatment in the U.S. has proven to 

be a major benefactor to the nation’s public health. The 

use of chlorine in particular has been recognized as a

breakthrough in public health.

2.4 History of Water Quality 

Regulations and Standards in 

the United States

The fi rst federal drinking water regulation was promulgated in 1912 under the Interstate Quarantine Act of 

1893. At that time, interstate railroads provided a common cup for train passengers to share for drinking water 

while on board. The Act prohibited this practice. By 

1962, several sets of federal drinking water standards 

Sorry, honey, the fi rst drinking water 

regulation passed in 1912 under the 

Interstate Quarantine Act of 1893 

specifi cally prohibits the use of a “common 

cup” on carriers of interstate commerce!

(Courtesy: PWD, 2007)
2-4

had been issued, but they applied only to interstate carriers. By the 1960s, each of the states and trust territories had established its own drinking water regulations, although there were many inconsistencies among 

them. Reported waterborne disease outbreaks had declined from 45 per 100,000 persons in 1938-40 to 15 

per 100,000 persons in 1966-70. However, the annual 

number of waterborne disease outbreaks had stopped

declining around 1951 and may have actually increased 

slightly. These conditions, in part, led to the passage of 

the Safe Drinking Water Act (SDWA) of 1974. 

The SDWA defi nes drinking water quality as a measure of 

its suitability for human consumption, based on selected

physical, chemical, and biological characteristics. The 

regulations established under the SDWA became the fi rst 

set of national drinking water regulations. These regulations require that utilities meet specifi c guidelines and/or 

numeric standards for drinking water quality. The SDWA 

defi nes a public water system (PWS) as a system that provides water for human consumption through pipes or other 

constructed conveyances, provided that such a system has 

at least 15 service connections or regularly serves an average of at least 25 individuals daily for at least 60 days out 

of the year. The SDWA established two types of numeric 

standards. The fi rst is an enforceable standard commonly 

referred to as an MCL. The other (non-enforceable) standard is referred to as a maximum contaminant level goal 

(MCLG). MCLGs are set at a level at which no known or 

anticipated adverse human health effects occur. 

Where it is not economically or technologically feasible 

to determine the MCL for a contaminant, an enforceable treatment technique (TT) is prescribed by EPA instead of an MCL. For example, Giardia lamblia is a 

microbial contaminant that is diffi cult to measure. To 

ensure proper treatment, experimental work has been 

conducted by EPA and others to establish optimum 

treatment conditions. EPA and other researchers have 

identifi ed treatment technologies for ensuring proper 

treatment. Therefore, the TT describes a specifi ed pH, 

temperature, and disinfectant concentration along with 

a specifi ed length of “contact time” to achieve a specifi c level of inactivation (or microbial kill). EPA has 

also set operational conditions that systems must meet 

to demonstrate removal by physical removal processes 

(e.g., rapid granular fi ltration, membranes).

The major rules and requirements of interest to smalland medium-system operators are discussed in Chapter 4 

of this document.

EPA has identifi ed several Best Available Technologies 

(BATs) under SDWA for the treatment of drinking water. The identifi ed BATs include: Activated Alumina, Coagulation/Filtration, Direct Filtration, Diatomite Filtration, 

Electrodialysis Reversal, Corrosion Control, Granulated 

Activated Carbon, Ion Exchange, Lime Softening, Reverse 

Osmosis, Polymer Addition, and Packed Tower Aeration. 

Note that using BAT is not the same as employing specifi ed TT. However, BATs can be used for requesting the 

issuance of variance or exemption.

Water quality in the distribution system has been of major 

interest to regulators and drinking water utilities. Maintaining a high level of water quality in the distribution system can pose a major challenge to some drinking water 

utilities because of the age and type of pipes used in their 

system. Corroded and decaying pipes may deteriorate 

water quality signifi cantly during transportation of water 

through the distribution system. Contaminants that can 

potentially increase in a distribution system include lead, 

copper, disinfection byproducts (DBPs), and coliform. 

Cross-connections are another major source of distribution system contamination.

2.5 Public Water System

There are nearly 160,000 water utilities in the U.S. These 

water utilities vary greatly in size, ownership, and type 

of operation. The SDWA defi nes PWSs as consisting of 

community water systems (CWSs), transient non-community water systems (TNCWSs), and non-transient 

non-community water systems (NTNCWSs). A CWS 

is a PWS which serves at least 15 service connections 

used by year-round residents or regularly serves at least 

25 year-round residents. An NTNCWS is a PWS that is 

not a CWS and it regularly serves at least 25 of the same 

persons for more than six months per year. A TNCWS 

is a not a CWS and it does not regularly serve at least 25 

of the same persons for more than six months per year. 

Figure 2.5 shows examples of this classifi cation.

2.5.1 Type and Size of Systems

Of the nearly 160,000 water utilities in the U.S., 33 percent are classifi ed as CWSs, 55 percent are classifi ed as 

TNCWSs, and 12 percent are classifi ed as NTNCWSs. 

PWSs serve 297 million residential, transient, and 

Safe Drinking Water Act

Fix the leak, open the valve, 

fl ush the hydrant, and take the 

water samples by 4:00 pm.
2-5

commercial customers. PWSs serving fewer than 3,300 

people are categorized as small systems and those serving 3,300 to 10,000 people are categorized as medium 

systems. Although a vast majority (98 percent) of systems are categorized as small and medium, they serve 

only about a quarter of the U.S. population. Other size 

classifi cations such as that specifi ed by the Small Business Regulatory Enforcement Act (SBREFA) generally 

defi ne small systems to include all distribution systems 

that serve less than 10,000 people. Figure 2.6 shows a 

distribution of PWSs by size in the U.S.

As shown in Figure 2.6, a very large number of the 

PWSs in the U.S. are represented by small- and medium-size water utilities. The large number of small 

and medium utilities creates a major administrative and 

oversight challenge for state and federal water supply 

regulatory agencies. 

“Consecutive systems” are those PWSs that receive some 

or all of their fi nished water from one or more wholesale 

systems. Delivery may be through a direct connection or 

through the distribution system of one or more consecutive 

systems.

Public

Water System

Community

Water System (CWS)

• Municipal Systems

• Rural Water Districts

• Mobile Home Parks

Non-Transient, 

Non-Community

Water System 

(NTNCWS)

• Office Buildings

• Schools

• Factories

• Daycare Facilities

Transient, 

Non-Community

Water System

(TNCWS)

• Restaurants

• Parks

• Motels

Figure 2.5 Classifi cation of PWSs in the U.S.

Figure 2.6 Distribution of PWSs by Size (EPA, 2007a)

 131,291 

82.2%

19,632

12.3%

3,584 376 4,913 2.2% 0.2% 3.1%

Very Small 25-500 Small 501-3,300

Medium 3,301-10,000 Large 10,001-100,000

Very Large >100,000

2.5.2 Type of Source Water Used

Some utilities rely primarily on surface water supplies, 

while others rely primarily on ground water. Surface 

water is the primary source of 22 percent of the CWSs, 

while ground water is used by 78 percent of CWSs. Of 

the TNCWSs and NTNCWSs, 97 percent are served by 

ground water. In addition, many systems serve communities using multiple sources of supply such as a combination of ground water and/or surface water sources. 

In these systems, the mixing of water in the distribution 

system poses a challenge for managing water quality. 

Figure 2.7 shows a distribution of PWSs by primary 

source of water used. 

As shown in Figure 2.7, the vast majority of small and 

medium water utilities in the U.S. use ground water. 

We have 85 customers and we spent 

1.4 million dollars to build this 

double reverse osmosis system

I sure hope we can buy a spare 

hydrant at the fl ea market, I don’t 

think we can fi x this one again
2-6

11,909

7.6%

143,927

92.4%

Ground Water Systems Surface Water Systems

Figure 2.7 Distribution of Small- and Medium-Sized 

PWSs by Source of Water Used (EPA, 2007a)

2.5.3 Type of Ownership

The ownership of water utilities in the U.S. is also diverse and has a long history of local government control 

over operation and fi nancial management, with varying 

degrees of oversight and regulation by state and federal government. The water utilities serving cities and 

towns are generally administered by departments of 

municipalities or counties (public systems) or by investor-owned companies (private systems). 

Public systems are predominately owned by local municipal governments, and serve approximately 78 percent of the total population. Approximately 82 percent 

of urban water systems (those serving more than 50,000 

persons) are publicly owned. 

About 33,000 privately owned water systems serve the 

remaining 22 percent of people served by CWSs. Private systems are usually investor-owned in the larger 

population size categories, but can include many small 

systems as part of one large organization. These investor-owned utilities are in business to generate profi t for 

their shareholders. In the small-and medium-sized categories, the privately owned systems tend to be owned 

by homeowners, associations, or developers. 

Other types of system owners include several classifi cations of state-chartered public corporations, quasi-governmental units, and municipally owned systems that 

operate differently from traditional public and private 

systems. These systems include special districts, independent non-political boards, and state-chartered corporations. Figure 2.8 shows the distribution of PWSs 

by ownership.

Figure 2.8 indicates that the vast majority of small and 

medium water utilities in the U.S. belong in the private 

ownership category, followed by the local government 

category. The difference in fi nancial structure between 

the government and private entities makes the management of small system operations challenging.

6,610 107,976 4.2% 69.3%

5,417

3.5%

2,26

1.5%

3,787

2.4%

825 28,958

0.5% 18.6%

Federal Government

Local Government

Tribal Government

Private

Public/Private

State Government

Unknown

Figure 2.8 Distribution of Small- and Medium-Sized 

PWSs by Ownership (EPA, 2007a)

2.6 Common Problems Faced by 

Small and Medium Utilities

The problems faced by operators of a small- and medium-sized utility are as diverse as the system statistics 

presented in Section 2.5. However, for the purposes of 

this document, the common problems have been broadly categorized as follows:

• Water Quality

Problems

• Operational 

Problems

• Regulatory/

Compliance 

Problems

• Institutional 

Problems

Key considerations associated with the management 

of these problems for small-and medium-sized utilities 

will be the focus of this document.

2.6.1 Water Quality Problems

Water quality issues faced by small-and medium-sized 

utilities are geographically diverse and complex. The 

common consumer-reported problems include taste, 

odor, and color. These problems generally do not have 

an immediate impact on consumer health or result in 

regulatory non-compliance. However, they must be addressed quickly to retain customer support for the system. Examples of taste and odor issues reported by the 

“Help!”
2-7

customers include:

• earthy smell

• chlorine smell

• rotten egg smell

• petroleum smell

• fi shy smell

• metallic taste

Examples of common color issues reported include:

• red water

• green water

• black water

• milky water

2.6.2 Operational Problems

Common operational problems faced by small-and medium-sized utility operators include:

• pressure problems

• main breaks, leaks

• valve problems

• excessive 

sediments in pipes 

and reservoirs

• cross-connection 

and backfl ow

• replacement and/or repair of tanks and water 

mains

• network and supply expansion

• adequate fi re fl ow

2.6.3 Regulatory/Compliance Problems

Common regulatory and compliance issues faced by 

small-and medium-sized utilities include: 

• Monitoring and 

reporting problems

• MCL exceedances (e.g.,

elevated lead, copper, 

and arsenic levels) 

• Treatment technique 

violations

• Loss of disinfectant 

residual

2.6.4 Institutional Problems

Common institutional issues faced by small-and medium-sized utilities include:

• money constraints (small population and low 

water rates)

• limited asset management

• poorly trained and low-paid operators (even 

volunteers)

• inadequate metering

• unaccounted-for water loss

• lack of system security

To focus on these problems and to evaluate potential solutions, a hypothetical example of a community with a 

small water utility called “SmallWater, USA” has been 

developed. The problems and solutions discussed and 

presented in this document will be related to SmallWater, USA. The following section presents a brief overview of SmallWater, USA.

2.7 SmallWater, USA 

Scenario

SmallWater is a hypothetical rural town in Midwestern 

U.S. The current population is about 2,700 with a small 

commercial downtown area and a small industrial park. 

The original water system was installed in the 1930s using cast iron pipe and was served by a well fi eld on the 

western edge of the town and an adjacent standpipe. The 

town grew with additional development in the 1970s to 

the north of the original town using asbestos-cement 

pipe. In the 1990s, the well supply became inadequate 

and an alternate source was developed in the form of an 

interconnection to the surface water supply for a larger 

“This should take care of 

the smell issue!”

I’m using a miracle fertilizer. 

Hopefully, we’ll have enough money 

to buy a water tank next summer.
2-8

system located to the southeast. The well fi eld was 

maintained as a supplemental and emergency supply. 

At that time, additional development also occurred in 

the form of a subdivision at the eastern edge of the town 

and on the ridge to the north of the town. A pump station was built to serve this high zone (ridge) and a small 

elevated tank was constructed. A commercial development (shopping center) was also added to the system 

and served via a pressure-reducing valve (PRV) from 

the high zone. Polyvinyl chloride (PVC) pipe was used 

for these modifi cations. Figure 2.9 is a schematic of the 

water system in SmallWater, USA.

SmallWater, USA purchases fi nished water from the 

adjacent system via the interconnection. Well water is 

chlorinated without any additional treatment. At the current time, the town uses an average of 210,000 gallons/

day with approximately 70 percent of that total attributed to residential use and the remainder for commercial, 

industrial, and institutional use. Maximum daily usage 

is approximately 400,000 gallons. Total revenue for the 

water utility is approximately $250,000/year. The water system is run by the town water board. Employees 

include a full-time clerk, a full-time water director and 

a part-time assistant. 

Land Use Category

Residential

Industrial

Commercial

Tank

PRV

Pump

School

Trailer Park

Pump

Tank

Industrial Park

Well Field

(Stand pipe)

Inter-Connect

High Zone

Shopping Center

New Subdivision

Old Subdivision

N

Figure 2.9 SmallWater, USA –Schematic Layout

The SmallWater, USA scenario will be used in this reference guide to explore a number of water quality, operational, regulatory/compliance, and institutional problems faced 

by many small- and medium-sized utilities in the U.S.

It says... 

try again! So what is the solution 

to our problem? 
2-9

Crossword solution:

1) Water cycle, 2) TNCWS, 3) NTNCWS, 4) Boston, 5) Biofi lm, 6) Source Protection, 7) CWS, 8) Richmond, and 9) MCL

1

2 3

4

5

6

7

8

9

ACROSS

2 Regulatory acronym for water system serving 

restaurants, parks, motels that serve different 

customers

4 U.S. City where first water utility was established

6 Term for preventing source water contamination

7 Regulatory acronym for utilities serving 25 or 

more people year round

8 U.S. City where first water treatment plant was 

established

9 Regulatory acronym for expressing the 

enforceable limits for a particular contaminant

DOWN

1 Term for natural movement of water from 

rains, to lakes and streams, and evaporation

3 Regulatory acronym for water system 

serving schools, hospitals and factories that 

have their own water supply and serve the 

same people for at least six months in a 

year.

5 Term for microbial organisms that attach to 

interior pipe surfaces

Crossword

The Supply, Distribution, and Quality of 

Water: An Overview
2-10
3-1

Chapter 3

Distribution System 

Infrastructure

Distribution system infrastructure consists of a network 

of pumps, pipes, tanks, valves, hydrants, and meters 

through which fi nished water is supplied to customers. 

This infrastructure is designed to deliver water to the 

customer. The physical integrity of the distribution system, from entry point to the customer’s faucet, is a primary barrier against the entry of external contaminants. 

Figure 2.4, in the previous chapter, showed a schematic 

representation of a typical water distribution system. 

A variety of components and materials make up a drinking water distribution system. These include: (1) pipes, 

including mains and service lines; (2) fi ttings and appurtenances such as crosses, tees, ells, hydrants, valves, 

and meters; (3) storage facilities including reservoirs 

(underground, open, and covered), elevated storage 

tanks, ground level storage tanks, and standpipes; and 

(4) backfl ow prevention devices. 

Table 3-1 provides examples of the infrastructure 

components and the common materials of construction. These components serve as a physical barrier to 

protect the distribution system water quality from external contamination threats. For example, the piping 

material and fi ttings serve to protect the water from external contamination sources such as soil, ground water, sewer exfi ltration, surface runoff, human activity, 

animals, insects, microbial pathogens, and other life 

forms. The premise plumbing and storage facilities 

are designed to protect from air contamination, rain, 

algae, surface runoff, human activity, animals, birds, 

insects and other sources of non-potable water.

Table 3.1 Infrastructure Components (NRC, 2006)

Component Common Materials of Construction

Pipe Asbestos cement, reinforced concrete, steel, lined and unlined cast iron, lined 

and unlined ductile iron, polyvinyl chloride (PVC), polyethylene and high-density polyethylene (HDPE), galvanized iron, copper, polybutylene, and lead

Pipe wrap and coatings Polyethylene, bitumastic, cement-mortar

Pipe linings Epoxy, urethanes, asphalt, coal tar, cement-mortar, plastic inserts

Service lines Galvanized steel or iron, lead, copper, chlorinated PVC, cross-linked polyethylene, polyethylene, polybutylene, PVC, brass, cast iron

Customer building plumbing Copper, lead, galvanized steel or iron, iron, steel, chlorinated PVC, PVC, 

cross-linked polyethylene, polyethylene, polybutylene

Fittings and appurtenances (meters, valves, Brass, rubber, plastic

hydrants, ferrules)

Storage facility walls, roof, cover, vent hatch Concrete, steel, asphalt, epoxy, plastic

Backfl ow prevention devices Brass, plastic, stainless steel

Gaskets and joints Rubber, leadite (a lead substitute), asphalt, plastic

3.1 The Impact of Distribution 

System on Water Quality

Although water entering the distribution system may 

meet the regulatory standards, water quality may degrade during transportation within the distribution 

system before reaching the consumer. Some of these 

undesirable water quality changes such as taste, odor 

or red-water problems can be detected immediately, 

whereas others may only be identifi ed by sampling and 

analysis. A waterborne outbreak caused by organisms 

such as E. coli or Salmonella, for example, may be later 

traced back to accidental contamination of water in the 

distribution system. A variety of components make up 

the physical barrier that protects against the deterioration of water quality in a distribution system. In addition, the proper management of these components is 

essential to protecting the customer against both aesthetic and public health threats to distribution system 

water quality. This chapter presents an overview of the 

key distribution system infrastructure components, the 

common problems associated with these components, 

and some potential solutions to these problems. Specifi cally, the following infrastructure components are 

discussed in this chapter:

• Pipes

• Pumps

• Storage facilities

• Valves

• Hydrants

• Water meters and service lines
3-2

3.2 Distribution System Pipes 

Pipe materials used by the water utilities have changed 

greatly over time. Cast iron pipe (lined or unlined) has 

been largely phased out primarily due to its susceptibility to both internal and external corrosion. Early 

on, ductile iron pipe (with or without a cement lining) took its place because of its durability, strength 

and good resistance to external corrosion from soils. 

However, ductile iron pipe also needs corrosion protection in certain soils and may require multiple types 

of joints. Subsequently, concrete, asbestos cement, 

and polyvinyl chloride (PVC) plastic pipe were used 

to replace metal pipe because of their relatively good 

resistance to corrosion. More recently, high-density 

polyethylene (HDPE) pipe is being used as a replacement because of its ease of installation, toughness, 

fl exibility, and corrosion resistance. 

3.2.1 Pipe Connectivity, Placement and 

Configuration

Distribution system pipe networks consist of water “mains,” also called “primary feeders” or “trunk 

lines.” The mains are generally 12 inches or greater 

in diameter (for small systems, the mains may be only 

6- to 8-inches in size), and carry water from the treatment plant to the local service areas where they are 

connected to smaller-diameter “branches” also called 

“secondary feeders.” The branches that are tied into 

the mains are usually greater than six inches in diameter. At the other end, the branches are tied to other 

smaller diameter pipes (4, 6 or 8 inches) that connect 

with service connections to customers (residential, 

commercial, and industrial). Water pipes are typically 

placed three to six feet below ground level to protect 

them from traffi c, freezing, damage from excavation 

and construction activities. These pipes are placed 

within the public right-of-way so that workers can install service connections for all potential water users. 

Branch and grid/loop are the two basic confi gurations 

used by most water distribution systems. A branch 

system is similar to a tree where smaller pipes branch 

off larger main pipes (similar to a tree trunk) throughout the service area. This type of system is most 

frequently used in rural areas, and generally in this 

type of system, water has only one pathway from the 

source to the consumer. A grid/loop system consists 

of interconnected pipe loops throughout the area to be 

served. In this type of system, there are several pathways that the water can follow from the source to the 

consumer. A grid/loop system is the most widely used 

confi guration in medium-and large-sized utilities. The 

grid/looped systems provide a high degree of reliability should a line break occur, because the break can 

be isolated with little impact on customers outside the 

immediate area. Figures 3.1 and 3.2 depict a branched 

and grid/looped distribution system, respectively.

Figure 3.1 A Branched Distribution System

Figure 3.2 A Grid/Looped Distribution System

Whoops... I should 

have called 811!

The U.S. Federal Communications Commission in 

March 2005 made 811 the universal number for 

coordinating location services for underground public 

utilities. This was required by the Pipeline Safety 

Improvement Act of 2002.
3-3

3.2.2 Pipe Material

Distribution system pipes are generally made of asbestos cement, unlined cast iron, cement-mortar-lined cast 

or ductile iron, plastic (PVC, HDPE), reinforced concrete, steel or fi berglass. Pipes used in water systems 

must be approved for potable water use. NSF International, American National Standards Institute (ANSI), 

American Society for Testing Materials (ASTM), and 

Underwriters Laboratory (UL) are among the organizations that test and approve pipe for potable water applications. Figure 3.3 shows the NSF potable water use 

approval depicted on a PVC pipe. 

The condition of pipe, source water quality, and the soil 

conditions around the buried pipe can negatively impact 

the water quality. Degradation of plastic (PVC or HDPE) 

pipes located in soils contaminated with organic compounds may result in softening of the pipe wall and subsequent permeation of organic matter through the pipe wall, 

leading to contaminated water. Table 3.2 presents a summary of potential negative impacts to water quality based 

on pipe material and changes in source water quality.

As presented in Table 3.2, depending upon the pipe material and relative changes in source water quality, the 

pipe wall interactions may negatively impact the water 

quality. Figure 3.4 depicts the various pipe wall interactions that may adversely affect water quality. 

Figure 3.3 NSF-Approved PVC Pipe for Potable Water 

Use

Table 3.2 Potential Negative Impacts to Water Quality Based on Pipe Material and Changes in Water 

Quality (Adapted from AwwaRF, 2005)

Pipe Material Changes in Water Quality Potential Negative Impacts

Unlined cast iron, steel, or old 1) pH increase or decrease, or May result in discolored water

galvanized steel 2) Alkalinity decrease, or

3) Dissolved oxygen increase or decrease

Chlorine residual increase May mobilize iron and/or manganese 

oxides and result in discolored water

Cement-mortar lined ductile iron 1) pH decrease, or May trigger localized pH and alkalin2) Alkalinity decrease ity increases with associated negative 

impact of discolored water

Asbestos cement (Transite) 1) pH decrease, or May trigger localized pH and alkalin2) Alkalinity decrease ity increases and increased levels of 

asbestos fi bers in water

All pipe types including fi ber glass Chlorine residual decrease May result in increase in microbiological 

population such as HPCa and possibly 

coliformb levels

aHeterotrophic Plate Count —A bacterial counting procedure used to estimate bacterial density in a water sample. Other names for the procedure 

[within the water industry] include total plate count, standard plate count, or plate count.

bColiform - A specifi c class of bacteria found in the intestines of warm-blooded animals and people. The presence of coliform bacteria in water 

indicates that there is a possibility, but not a certainty, that disease-causing organisms may also be present in the water.

Figure 3.4 Pipe Wall Interactions that Affect Water 

Quality (Adapted from: MSU, 2005)

Additional Information

Pipe Material Voluntary 

Standards

AWWA - M9, Concrete Pressure Pipe, Second Edition, 

1995

AWWA - M11, Steel Pipe—A Guide for Design and Installation, Fourth Edition, 2004

AWWA - M23, PVC Pipe—Design and Installation, Second Edition, 2002

AWWA - M41, Ductile-Iron Pipe and Fittings, Second 

Edition, 2003

AWWA - M55, PE Pipe—Design and Installation, First 

Edition, 2006
3-4

3.2.3 Common Problems, Troubleshooting and 

Pipe Repair

Excessive scale buildup, corrosion, pipe leaks and main 

breaks are the most common pipe-related problems

faced by water utilities. Excessive scaling in pipe results 

in loss of delivery capacity over time. Internal corrosion 

of pipes can result in discolored water or high lead and 

copper levels. For example, reddish-brown water is the 

result of corrosion of iron pipes, bluish stains on fi xtures 

are the result of corrosion of copper lines, and black water generally results from sulfi de corrosion of copper or 

iron lines, or can be the result of precipitation of natural 

occurring manganese in water. External corrosion leads 

to pipe leaks and water main breaks. There are several 

types of leaks, including valve leaks and service line 

leaks, but in most cases the largest amount of water is 

lost through water main leaks. Leaks occur due to factors such as pipe material, pipe composition, pipe age, 

fi nished water quality, temperature, pressure, and pipe 

joining methods. External conditions, such as contact 

with other structures (that can cause movement or electrical current fl ow), stray electric currents, traffi c load, 

aggressive soils, vibrations, and frost conditions can 

also contribute to leaks. Pipes also break due to factors 

such as water freezing, traffi c load, and corrosion. In 

addition, pipes may be defective, installed improperly, 

or simply not strong enough to handle pressure surges.

Pipe Leak Management by a Small System (EPA, 2002c)

Gallitzin, a small town in western Pennsylvania (population ~2,000), services approximately 1,000 connections. 

The system was experiencing water losses exceeding 70 

percent. In November 1994, the system was using an average of 310,000 gallons per day. Gallitzin experienced a 

peak usage in February 1995 of 500,000 gallons per day. 

The water authority identifi ed fi ve major problems in the 

system: 1) high water loss, 2) recurring leaks, 3) high overall operational costs, 4) low pressure complaints and 5) unstable water entering the distribution system.

The water utility decided to implement a comprehensive 

program for water leak detection. For this purpose, the 

utility fi rst developed accurate water production and distribution records using 7-day meter readings at the plant 

and pump station. A system map was then created to locate leakage. Through the use of a leak detector, the utility 

was able to identify approximately 95 percent of its leaks. 

Thereafter, the utility initiated a leak repair program and 

a corrosion control program at the Water Treatment Plant. 

Gallitzin was one of the fi rst systems to receive technical 

assistance from the Pennsylvania Department of Environmental Protection Small Water Systems Outreach Program. 

The training helped the authority repair distribution system 

leaks, replace inaccurate meters, and improve customer 

billing. Accuracy of water meters is critical for determining water loss as part of a good leak management program. 

By November 1998, 4 years after implementation of the 

program, the system delivered an average of 128,000 gallons per day to the town—down from 310,000 gallons per 

day in November 1994. Unaccounted-for water dropped 

to only 9 percent. The fi nancial savings from the program 

have been highly benefi cial. The city saved $5,000 on total 

annual chemical costs and $20,000 on total annual power costs between 1994 and 1998. The signifi cant savings 

helped the utility keep water rates down.

Additional Information

Leak Detection and Water 

Loss

A National Drinking Water Clearinghouse (NDWC) Tech 

Brief on leak detection and water loss control can be obtained online from: http://www.nesc.wvu.edu/ndwc/pdf/

OT/TB/TB_LeakDetection.pdf

AWWA - M36, Water Audits and Leak Detection, Second 

Edition, 1999

3.2.3.1 Minimizing Leaks and Water Loss

Leakage results in loss of revenue to a utility. Larger 

leaks are usually detected faster, because they usually 

lead to water reaching the surface which results in quick 

identifi cation, isolation and repair. Small undetected 

leaks can often lead to large amounts of water loss over 

time. Leak detection methods usually involve sonic or 

ultrasonic leak-detection equipment, which identifi es 

the sound of water escaping a pipe. These devices include pin-point listening devices that make contact with 

valves and hydrants, or geophones that listen directly 

to sound moving through the ground. In addition, there 

are other devices that can listen at two locations simultaneously to correlate “leak” sounds and determine 

the exact leak location. Leak detection efforts should 

focus on the portion of the system where the greatest 

problems are expected. These problem areas generally 

include areas with excessive leak and break rates, highpressure areas, and areas where pipes are old. As a general guideline, a water conservation and leak detection 

Somebody get me a 

pipe clamp, quick!
3-5

program should be implemented when the “unaccounted-for” water (water produced – metered water usage at 

customer locations) exceeds 15 percent.

3.2.3.2 Distribution System Line Breaks

Distribution system pipes can break for a variety of 

reasons such as excessive traffi c load, extremely cold 

temperatures, accidents during excavation/construction 

activities, pressure surges, and corrosion. Procedures 

for dealing with major main breaks are usually outlined 

in a utility’s emergency response plan (ERP). If a utility suffers a major main break, law enforcement, fi re 

protection, and city offi cials should be notifi ed since the 

leak may pose signifi cant hazard to life or property. Affected customers should be notifi ed since valves must 

be shut off to isolate the break and to perform needed 

repairs. For smaller leaks, it is preferable to perform the 

repair without shutting off the water service. Allowing 

a line to remain under pressure prevents back siphoning 

and back pressure that can cause contaminants to enter 

into the pipe. In some cases, nearby hydrants can be 

opened to lower the water pressure to facilitate the repair. If the pipe break is small, it can be repaired using 

a pipe clamp or sleeve that serves as a “bandage.” For 

larger breaks, portions of pipe are cut off and replaced 

by new sections. As a general rule when conducting 

repairs, safety precautions are necessary with regard to 

trenching and shoring, in addition to following proper 

procedures for pipe installation and repair.

Table 3.3 summarizes some of the common problems 

that lead to pipe failures for pipes of differing materials. These include some of the principal factors, but 

they are not the only factors that act individually or in 

combination to cause a main break. Other factors could 

include a street excavation that accidentally disturbs a 

water main or the misuse of fi re hydrants. 

Table 3.3 Common Problems that Lead to Pipe Failure for Various Pipe Materials (NRC, 2006)

Pipe Material (common sizes) Common Problems

PVC and Polyethylene (4−36 in.) Excessive defl ection, joint misalignment and/or leakage, leaking connections, exposure 

to sunlight, high internal water pressure or frequent surges in pressure, exposure to 

solvents, manufacturing fl aws

Cast/Ductile Iron (4−64 in.)

(lined and unlined)

Internal corrosion, joint misalignment and/or leakage, external corrosion, leaking connections, casting/manufacturing fl aws

Steel (4−120 in.) Internal corrosion, external corrosion, excessive defl ection, joint leakage, imperfections 

in welded joints

Asbestos-Cement (4−35 in.) Internal corrosion, cracks, joint misalignment and/or leakage, small pipe can be damaged during handling or tapping

Concrete (12−16 to 144−168 in.)

(prestressed or reinforced)

Corrosion in contact with ground water high in sulfates and chlorides, pipe is very heavy, 

alignment can be diffi cult, settling of the surrounding soil can cause joint leaks

Additional Information

Line Repair and 

Rehabilitation

A NDWC Tech Brief on repairing distribution line breaks 

can be obtained online from: http://www.nesc.wvu.edu/

ndwc/articles/OT/SP04/TechBrief_LineBreaks.pdf

AWWA - M28, Rehabilitation of Water Mains, Second 

Edition, 2001

AWWA - M22, Sizing Water Service Lines and Meters, 

Second Edition, 2003

3.3 Distribution System Pumps 

Within a distribution system, pumps are used to discharge water under pressure to the pipe network, to 

boost pressure within a system and also to lift water 

to a higher elevation where it can then be delivered by 

gravity (e.g., elevated water storage tanks). Pumps can 

be classifi ed into two basic groups: positive displacement and variable displacement pumps. A positive 

displacement pump delivers the same volume or fl ow 

of water against any “head” within its operating capacity. Head is the vertical distance between a pump and 

water outlet, usually measured in feet or converted and 

expressed in equivalent pressure scale. Examples include: piston pumps, screw pumps, diaphragm pumps 

and gear pumps. Variable displacement pumps deliver 

water with the volume or fl ow varying inversely with 

the operating head (i.e., the greater the head, the less 

the volume of the fl ow). Examples include: centrifugal 

pumps, jet, and airlift pumps. Appropriate pumps are 

selected based on the desired application. 

Centrifugal pumps are used widely in water distribution 

systems because of several advantages including: 1) 

low cost and small footprint for a given capacity, 2) a 

rotary mechanism that allows for adaptability to highspeed driving mechanisms such as electric motors and 

gas engines, 3) simple mechanism, easy for operations 

and repair, and 4) safety against damage from highpressure because of limited maximum pressure that can 

be generated.
3-6

Many brands of centrifugal pumps are available in the 

U.S. with capacities ranging from a few gallons per 

minute (gpm) to several thousand gpm. Working heads 

can range between 5 to 700 feet, but the effi ciency of 

each pump is limited to a narrow range of discharge 

fl ows and head. Careful consideration must be given to 

these factors prior to pump selection. 

3.3.1 Common Problems, Troubleshooting and 

Maintaining Pumps

During startup, centrifugal pumps require “priming.” 

Priming is a procedure in which the pump is fi lled with

water before turning the switch on. The unit does not 

operate effi ciently if it is not properly primed. In general, pumps have an adjacent priming chamber that draws 

water when the pump is turned on to keep the impeller 

submerged. After priming, the pump must be started 

with the discharge valve fully closed. Thereafter, the 

discharge valve must be opened slowly to allow any air 

in the system to escape and prevent water hammer or 

pressure surges. A surge of pressure occurs when a valve 

is suddenly closed or opened. This surge can cause the 

pipes to vibrate or create a hammering noise. Also, at 

shutdown or during power failures, the discharge valve 

must be programmed to close in order to avoid backfl ow 

and prevent the impellers from running in reverse.

Because of the variety of pumps available, individual 

procedures for proper operation of each pump vary by 

manufacturer. A utility operator should refer to manufacturer instructions while operating and troubleshooting the pumps. Centrifugal pumps require regular inspection and maintenance. Bearings on the motor may 

become worn and must be checked and kept well-lubricated. The packing seals must be examined for wear 

due to friction that can result in pump leakage. Bearing 

and motor temperature must be monitored for excessive 

heat. If a surface is substantially hotter than normal, 

the unit must be shut down and examined for the cause. 

Any unusual noises or vibrations from the pump should 

also be thoroughly investigated by shutting down the 

unit fi rst. Prior to performing any maintenance activity 

on the pump, the pump must be shut down and drained 

of all liquids before servicing. Electrical safety procedures must also be followed while servicing motors. 

All safety instructions provided by the manufacturer 

must be followed during the performance of maintenance activities.

3.4 Distribution System Storage 

Facilities 

Distribution system storage facilities (tanks and reservoirs) are necessary to accommodate peak fl ow (equalizing storage), emergency demand, and fi refi ghting 

capabilities. In addition, they help maintain uniform 

pressure and allow for reduction in the size of distribution mains that would otherwise be much larger to 

accommodate peak fl ow requirements. Storage also reduces pumping costs under peak energy periods. Generally, these storage facilities are designed and located 

such that they can provide water at the required pressure to the farthest location in the service area. 

3.4.1 Types of Storage Facilities

Ground level reservoirs and tanks, elevated tanks and 

hydro-pneumatic tanks are designed for multiple uses 

including: equalizing storage, maintaining pressure 

in the system, and providing fi refi ghting capabilities. 

Equalizing storage is necessary when the source pump 

capacity is less than the peak system demand. This 

storage is also essential for water production facilities 

to run at a constant rate. Smaller distribution systems 

with wells and relatively fl at topography may use a 

hydro-pneumatic tank to maintain water pressure. A 

hydro-pneumatic tank is an air-pressurized water tank. 

The air in the tank acts as a cushion that can exert or 

absorb pressure as required. The two common methods 

employed for air-charging the tanks are: motor-driven 

air compressors and hydraulic-powered air chargers. 

Additional Information

Pumps

AWWA - Water Transmission and Distribution: Principles 

and Practices of Water Supply Operations, 3rd edition, 

2003

AWWA- Design and Construction of Small Water Systems, 2nd edition, 1999

We got the pump, and the 

horses to power it!
3-7

The storage volume requirements for tanks are classifi ed by function: operating, equalizing, fi re and/or emergency, and dead storage volume. The typical minimum 

municipal fi re fl ow requirement for a single-family residential area is 500 to 1,000 gpm for two hours, which is 

equivalent to a minimum storage requirement of 60,000 

to 120,000 gallons. For commercial and industrial areas, the fi re fl ow requirement ranges between 2,000 and 

8,000 gpm for several hours which is equivalent to a 

storage requirement of ~500,000 gallons to over a million gallons. Some local fi re and state agencies allow 

for combining fi re and emergency storage requirements. 

Figure 3.5 illustrates the typical storage tank volume design parameters.



	







	





	








	






	









 


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"

#





Figure 3.5 Storage Tank Volume Design Requirements

Depending upon the size and location-specifi c requirements, tanks may be constructed using steel (welded or 

bolted, carbon or stainless), concrete, fi berglass, or plastic (polyethylene, polypropylene). The type of material 

used for the tank depends upon many factors including: 

1) location of the water tank (indoors, outdoors, above 

ground or underground), 2) volume (larger tanks are 

generally made of steel), 3) temperature and wind in 

the area where water will be stored (concern for freezing and structural strength requirements). In addition 

to selecting appropriate tank material, all piping, joints 

and fi ttings should conform to regulatory design specifi cations. Steel tanks are most widely used by water 

utilities in the U.S. Steel tanks are required to be painted 

and to have cathodic protection to resist corrosion.

Additional Information

Storage Tanks

AWWA - M25, Flexible-Membrane Covers and Linings 

for Potable-Water Reservoirs, Third Edition, 2000

AWWA - M31, Distribution System Requirements for Fire 

Protection, Third Edition, 1998

AWWA - M42, Steel Water-Storage Tanks, First Edition, 

1998

3.4.2 Common Problems, Troubleshooting and 

Maintaining Tanks

Water storage facilities (tanks) must have covers or 

hatches that keep out birds, rodents, insects, dust and 

surface runoff. They must also have a screened vent 

which allows air to enter and leave as the water level 

drops or rises in the tank. Outside access to the storage facility must be lockable and weather-tight. Lack 

of proper hatches and vents may result in dead animals 

and/or birds fl oating in the tank which can create serious 

health problems. Tanks should be routinely inspected 

(for corrosion and structural integrity) and cleaned. Water tanks are confi ned spaces and a confi ned-space warning label must be placed on tank access. Confi ned-space 

entry procedures must be followed by anyone entering 

the tank. For larger tanks, commercially trained divers 

and/or remotely controlled underwater robotic systems 

can be used for inspection and/or cleaning. The use of 

divers and/or robotic devices requires special precautions and procedures, especially if the tank is allowed to 

remain in service during inspection/cleaning procedures.

Tanks that are improperly operated can lead to excessive 

“aging of water” or areas of poor circulation. Excessive 

storage time can lead to a loss of disinfectant residual 

(chlorine/chloramine) which can result in bacterial reI am thankful that you guys 

approved our funding request 

to perform some minor repairs 

to this tank. 
3-8

Cover your ears dear... he is 

closing the valve real fast, he 

is sure to produce a bang!

growth. In addition, the disinfectant can react with naturally occurring organic matter to form greater levels of 

undesirable byproducts that may pose long term health 

problems. Poor circulation can lead to “dead” or static zones where the water may be much older than the 

average age in the storage facility. Stratifi cation is an 

example of poor mixing where the water age and characteristics vary in the vertical direction in the tank. This 

is most common in tall standpipes and in tanks where 

there is insuffi cient energy in the infl ow during the fi ll 

cycle to create a well-mixed tank. Water aging can be 

reduced by changing the tank operation so that there is 

a greater exchange of water between the tank and the 

distribution system. Mixing problems can frequently

be relieved by modifying the inlet-outlet confi guration 

and/or increasing the infl ow rate and velocity.

3.5 Distribution System Valves 

Valves are critical for management of the distribution 

system. Valves control fl ow/pressure, and isolate portions of the water distribution system for servicing. If 

valves are properly placed, distribution system pipe repairs and maintenance can be conducted with minimal 

loss of service to the customer. Most valves require 

some mechanical or externally devised system to open/

close or change the position of the valve. Manually operated actuators, or electromechanically actuated mechanisms are installed on valves to allow proper operation. 

In newer installations, it is common to use automatic 

valves. The valve types generally used in water distribution systems include: gate, butterfl y, check, control, 

pressure reducing, pressure relief, altitude, and air-andvacuum relief. A brief overview and general function 

of the most commonly used valves are presented in the 

following sections. 

3.5.1 Gate Valves

Gate valves are used to isolate distribution system sections. A sliding gate is moved up or down to block the 

fl ow. The purpose of the valve is to completely stop 

the fl ow and not to regulate it. These valves should not 

be opened or closed too rapidly. Rapid valve operation 

can cause a phenomenon known as “water hammer” or 

pressure surge that can seriously damage distribution 

system components. Water hammer is caused by the 

sudden increase in pressure of water caused by the conversion of the kinetic energy of the water in motion to 

static energy when it is forced to stop. Under extreme 

conditions, this pressure surge may cause the pipes to 

vibrate and/or create a hammering noise. Figure 3.6 

illustrates a gate valve.

 

 





Figure 3.6 Gate Valve (side view)

3.5.2 Butterfly Valves

A butterfl y valve consists of a round disk attached to 

a shaft in the pipe. Rotating the shaft by 90 degrees 

(one quarter turn) opens or closes the valve. In the 

open position, the disk is parallel to the fl ow of water. 

These valves are commonly used for larger diameter 

pipes. Similar to gate valves, these valves should not 

be opened or closed too rapidly in order to avoid water 

hammer. Figure 3.7 illustrates a butterfl y valve.
3-9

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&

 

 





Figure 3.7 Butterfl y Valve (top view)

3.5.3 Check Valves

Check valves are designed to allow flow in only one direction. One common application of this valve is on the 

discharge side of a pump to prevent backfl ow when it is 

shut down. A variety of devices (e.g., weights, springs, 

motors) are available to dampen the closing of valves to 

minimize water hammer. Figure 3.8 illustrates a swing 

check valve.

 





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% 

Figure 3.8 Swing Check Valve (side view)

3.5.4 Other Valves

Control valves are used to regulate fl ow between a fully opened and a fully closed position. Control valves 

are almost always equipped with some sort of actuator 

mechanism to provide ease of operation. 

There are many types of pressure regulating and fl ow

control valves. For example, a pressure sustaining

valve tries to maintain a constant upstream pressure, 

whereas a pressure reducing valve maintains a constant 

downstream pressure. An altitude valve is a self contained pressure regulating valve that is used to control 

the fl ow into a tank in order to prevent water overfl ow. 

These valves are balanced to use the line water pressure 

as the operating motive. For example, when the tank 

level rises to a specifi ed upper limit, the valve closes to 

prevent any further fl ow from entering, thus eliminating 

overfl ow. When the fl ow trend reverses, the valve reopens. In some places, high- and low-level tank indicators are also used to control fl ow. 

Pressure relief valves are installed to relieve excessive 

internal pressures (such as surge pressures) in a hydropneumatic tank as the excessive pressure may lead to 

ruptures. 

Air and vacuum valves, commonly referred to as air 

release/vacuum breaker valves, are used to remove 

air from system components. For example, deep-well 

pumps are equipped with air release valves to exhaust 

large quantities of air very rapidly from a deep-well 

pump column when a pump is started.

3.5.5 Common Problems, Troubleshooting and 

Maintaining Valves

Valves in constant use have parts that wear out and require routine maintenance. In addition, valves that are 

not used regularly may not function when the need 

arises. Valves can stick (due to deposition or rust formation and growth of biofi lm on the operating surface) and even break (weakened by corrosion) if neglected. A valve exercise program is a necessary part 

of water distribution system maintenance. 

In cases where there is a high-pressure drop through 

a valve, it can lead to a number of immediate problems such as cavitation, fl ashing, choked fl ow, high 

noise levels and vibration. Over the longer term, 

it degrades system effi ciency and results in higher 

pumping costs.

We have initiated a valve 

exercising program
3-10

Additional Information

Valves

A NDWC Tech Brief on valves can be obtained online 

from: http://www.nesc.wvu.edu/ndwc/pdf/OT/TB/OT_

TB_Su02.pdf

AWWA - M44, Distribution Valves: Selection, Installation, 

Field Testing, and Maintenance, Second Edition, 2006

AWWA -M49, Butterfl y Valves: Torque, Head Loss, and 

Cavitation Analysis, First Edition, 2001

AWWA - M51, Air-release, Air/Vacuum and Combination 

Air Valves, First Edition, 2001

3.6 Distribution System Hydrants 

Two types of hydrants are used in a distribution system: 

fl ush hydrants and fi re hydrants. Flush hydrants are 

generally installed in a pit and have nothing projecting 

above ground. These hydrants are placed at the end of 

lines to remove accumulated corrosion products from 

dead-ends. Flush hydrants should also be installed 

throughout the system to provide for periodic fl ushing to maintain high water quality. Sometimes, fl ush 

hydrants are mistaken for fi re hydrants. Fire hydrants 

are larger in size. Fire hydrants are classifi ed into two 

basic categories: wet barrel and dry barrel. Wet barrel hydrants are designed to be used only in areas of 

the country where the temperature never drops below 

freezing, since these units are always charged with 

water. Dry barrel hydrants are predominantly used in 

the U.S., and designed to automatically drain water 

after the water is turned off. Figure 3.9 illustrates a 

dry barrel hydrant.

'






(




)

*



	

+ 



	

*



$


+ 

 ,


#


Figure 3.9 Dry Barrel Hydrant

Fire Hydrant History (Adapted from Rader, L. undated):

In colonial America, cisterns were used to store water 

for early fi re fi ghting purposes. Around the time of the 

American Revolution, several American communities had 

built water distribution systems. These early systems used 

wooden main lines that workers had built using bored-out 

logs. The logs were fi tted together and buried. When fi re 

fi ghters needed water, they uncovered the wooden line and 

bored a hole in the pipe wall. They used the water that 

collected around the pipe for fi ghting the fi re. After the 

fi re was put out, a tapered wooden plug was driven into 

the hole in the pipe wall and the location of the hole was 

marked with the “fi replug.” Later, when cast iron became 

the material of choice for water lines, it became harder to 

bore the hole. However, water systems installed tees with 

wooden plugs at convenient locations and the wooden fi replug continued for several more years. The hydrant’s evolution included a standpipe that fi re fi ghters shoved into 

the tee after they removed the fi replug. It conveyed water 

above ground to a hose connection and a ball valve, and 

it fi nally made the wooden plug obsolete. This setup was 

the forerunner of the dry-barrel compression hydrant. Cisterns continued to be used even after the introduction of the 

hydrant in many cities. As late as 1861, the city of Louisville, Kentucky employed 124 cisterns but no fi re hydrants. 

Cisterns are still used today for fi refi ghting.

Additional Information

Hydrants

A NDWC Tech Brief on how to begin a fi re hydrant operation and maintenance program can be obtained online 

from: http://www.nesc.wvu.edu/ndwc/pdf/OT/TB/OT_

HowTo_f02.pdf

3.6.1 Common Problems, Troubleshooting and 

Maintaining Hydrants

Hydrants should be opened and closed slowly to avoid 

water hammer effect. Dry barrel hydrants should always be fully opened because operation of the drain 

mechanism is linked to the main valve. A partially 

opened hydrant causes water to leak through the base 

which can cause erosion around the base of the hydrant. 

Dry barrel hydrants need a supply of air to drain properly. Therefore, the caps should not be tightened until 

the unit fi nishes draining. Hydrants should be inspected on a routine basis for operability and leaks. Many 

different brands and models are available in the U.S. It 

is important that parts provided or recommended by the 

manufacturer be used for servicing each unit. Hydrant 
3-11

repair requires specialized tools that are available from 

the manufacturer; using other tools may result in unnecessary damage and lead to the early failure of the unit.

3.7 Water Meters and Service 

Lines

Water meters are generally considered to be the last connection in the portion of the distribution system owned 

by a utility before water is delivered to the customer. 

They are extremely important because they measure the 

customer’s water usage and are the basis for billing customers for money to support the utility’s operation. In 

larger utilities, wastewater charges are frequently based 

on water meter readings. A service line carries water 

from the main to the water meter and/or curb stop or to a 

customer’s building plumbing. Meters are generally the 

property of the water utility, but there are wide differences across the country with regard to the ownership of 

service lines. Residential or building plumbing is almost 

always the property of the home or building owner.

3.7.1 Water Meters

A water meter is a device used to measure the volume 

of water usage. Water meters are used at the service line 

inlet to a residential and commercial building in a PWS. 

Water meters can also be used at the water source, well, or 

throughout a water system to determine fl ow through that 

portion of the system. Water meters in the U.S. typically 

measure and display total usage in cubic feet, or U.S. gallons on a mechanical or electronic register. Water meters 

are also used to generally defi ne ownership and responsibility. For example, maintenance and repair of pipes on 

the “street side” of the water meter is the responsibility of 

the PWS, and the customer/property owner is responsible 

for the maintenance and repair of pipes and plumbing on 

the “customer side” of the water meter.

There are several types of water meters in common use. 

Selection is based on different fl ow measurement methods, the type of end user, the required fl ow rates, and 

accuracy requirements. In U.S., standards for manufacturing of water meters are made by the American Water 

Works Association. Positive Displacement (PD) meters 

are most commonly used and are generally very accurate at low to moderate fl ow rates typical of a residential 

user and a small commercial user. Common PD meters 

are sized between 5/8 and 2 inches. Because these meters rely on water fl owing through the meter to “push” 

the measuring element, they are generally not practical 

in large commercial applications requiring high fl ow 

rates or low pressure loss. See Section 6.2.1 for other 

types of fl ow meters.

PD meters normally have a built-in strainer to protect 

the measuring element from rocks or other debris that 

could stop or break the measuring element. PD meters 

normally have bronze, brass or plastic bodies with internal measuring chambers made from molded plastics 

and stainless steel. Most meters in a typical water distribution system are designed for cold potable water 

only. There are other water meters manufactured for 

specifi c uses. For example, hot water meters are designed with special materials that can withstand higher 

temperatures. Meters for reclaimed water have special 

lavender register covers to signify that the water is nonpotable and should not be used for drinking.

Water meters are generally owned, read, and maintained 

by the PWS. In some cases, an owner of a mobile home 

park, apartment complex or commercial building may 

be billed by a utility on one meter, and the cost of the bill 

is shared among the tenants. In these cases, the complex 

owner may purchase private water meters to separately 

track usage of each unit in what is called submetering. 

3.7.2 Service Lines

A service line carries water from the main to the water 

meter and/or curb stop. A curb stop box refers to the 

enclosure which houses a valve. In case of an emergency or service disconnection, this valve is used to shutoff water service to the individual customer. Most curb 

stop boxes are not boxes, but cast iron housings with 

a pipe that extends to the ground level with a removable cover. The valve is accessed with a special wrench 

which is slid down the pipe and turns the valve off and 

on. A meter stop is a valve placed on the street side of 

the water meter to isolate the water meter for installation or maintenance. Many codes require a gate valve 

on the customer side of the meter to shut off water for 

performing customer plumbing repairs. 

3.7.3 Common Problems, Troubleshooting and 

Repairs

Water meters are generally well built, and require minimal maintenance if installed correctly. If a meter is in 

need of repair, it will generally under-register rather than 

over-register the customer’s water use. Because they 

are very accurate, they can be used to identify leaks in 

a customer’s plumbing. For example, if a customer reports excess usage bill, the fi rst step would be to shutoff 

all water use in the building and observe if the meter is 

still moving. In case the meter registers usage, it is very 

likely that the customer plumbing contains a leak. The 

customer should be recommended to obtain the services 

of a licensed plumber to isolate and correct the problem. 

Even small leaks over time can result in signifi cant water loss and resulting cost to the customer.

The majority of water leaks in a distribution system 

occur in service lines, service fi ttings, and connections 

including ferrules, curb stops, valves and meters. In
3-12

addition, customer’s plumbing and service lines have 

longer residence times, more stagnation, lower fl ow 

conditions and elevated temperatures than normally 

found in distribution systems and can have a negative 

effect on the quality of water supplied to the customer. 

Therefore, service lines and their fi ttings provide the 

greatest potential for intrusion and subsequently for

outside contamination to enter the distribution system. 

Compared to the main water distribution systems, less 

is known about the types and causes of service-line failures than for other components of the distribution system. Some possibilities include:

• Internal and external corrosion

• Poor installations such as improper backfi lling 

techniques and materials

• Damage during handling

• Improper tapping

Many times during landscaping of the home, the curb

stop access is buried or damaged. The cover lid can also

be damaged, allowing debris to block access to the valve. 

Locating and marking the curb stop on a customer’s

property line can save time and money during an emergency when water needs to be shut off. The curb and

meter stop valves are not designed for frequent use and

can be ruined in a short time if used very frequently.

Because of the wide variation in ownership service 

lines, it is diffi cult to identify the party that should take 

responsibility for their maintenance. This lack of clear 

responsibility can complicate the extent to which service lines are inspected, replaced, and repaired. In most 

cases, a drinking water utility only assumes responsibility for the quality of water delivered to the curb stop or 

water meter. For the portion of the service line owned 

by customers, the responsibility and cost of repairs falls 

on the customer.

Service Line/Water Meter Repair (NRC, 2006)

A recent report published by the National Research Council of the National Academies highlighted the issue of service lines and residential plumbing and their contribution to 

the deterioration of water quality. A waterborne disease 

outbreak that occurred in Cabool, Missouri, in the winter 

of 1989-1990 was partially attributed to the need to replace 

a large number of water meters in the distribution system at 

the same time as the sewage overfl ow occurred. The town 

had a population of approximately 2,100 people. A total 

of 243 cases of E. coli O157:H7 was reported, with 32 hospitalizations and four deaths. It was the fi rst documented 

waterborne outbreak of E. coli O157:H7 ever reported.

3.8 Distribution System Asset 

Management

Distribution systems typically represent a water utility’s 

largest capital investment. In order for a distribution system to operate at peak performance, its status must be 

continuously assessed. The Asset Management (AM) 

concept has emerged as an important mechanism for 

tracking and evaluating distribution system operation 

and maintenance (O&M) needs. The key focus of asset management is to minimize the amount of money 

necessary to own, operate, and maintain a distribution 

system asset (e.g., pumps, pipes, hydrants, and tanks) 

over its useful life. One key feature of an AM system is 

to track the installed life of a distribution system asset. 

Asset Management (NMEFC, 2007)

In 2005, the New Mexico Environmental Finance Center 

(NMEFC) conducted an AM study for the Arenas Valley 

water distribution system in New Mexico. The Arenas valley water system purchases fi nished water from Silver City. 

The primary distribution system assets included: relatively 

new PVC pipe installed in the 1980’s (approximately 20 

miles of pipe), approximately 430 service connections, 25 

hydrants and 100 valves. When the study was initiated, the 

utility was concerned that a substantial portion of the system’s PVC pipe had degraded/failed and needed replacement. During the process of developing a comprehensive 

AM database, a pipe break event map was created depicting the 26 breaks previously recorded. Figure 3.10 shows 

the pipe break event map, which indicates that the majority 

of the breaks were service-line leaks and two of the 26 

breaks were caused by a service-line tap. This pipe break 

map allowed the utility board to see that these pipes were 

not degrading as originally suspected, and therefore did 

not need replacement. Also, a better grasp on assets and 

Level Of Service requirements allowed the utility board to 

see that it was more valuable to install new pipe that would 

create some loops in the distribution system, improving 

both service and possibly water quality. 

Figure 3.10 Arenas Valley Pipe Inventory and Main 

Break Map
3-13

The “expected useful lives” of distribution system components are theoretically known and depend upon construction material, location, and environmental conditions. For example, the expected useful life of distribution 

system components is as follows: pipes – 35 to 50 years; 

hydrants – 40 to 60 years; valves – 35 to 40 years; storage 

tanks – 30 to 60 years; pumps – 10 to 15 years. Though 

these are typical values for expected useful life, there are 

always exceptions and it is not unusual, for example, to 

fi nd some 100-year old pipes that are still in good condition. Generally speaking, when a specifi c asset begins 

to exceed its “useful life,” it needs to be inspected periodically and reevaluated for replacement. For example, 

if the average age of the hydrants is documented as 50 

years in the AM database, it is likely that a majority of the 

hydrants are near the end of their useful lives and would 

need to be replaced fairly soon or evaluated on a regular 

basis. Basically, a good AM system contains a comprehensive equipment inventory, and is closely linked to the 

Level of Service (LOS) concept. LOS clearly defi nes 

performance goals and can be periodically used to defi ne 

where, when, and how resources must be expended. The 

LOS defi nes a utility’s commitment to the customer and 

its goals must be measurable. For example, a water utility 

might defi ne its LOS as follows:

• Main breaks will be repaired within 8 hours of 

initiation of repair 90 percent of the time.

• Regulatory water quality requirements will be 

met 100 percent of the time.

• Monthly water losses will be kept to less than 

15 percent .

• Customer complaints will be responded to 

within 24 hours. 

These LOS requirements make it possible for a utility 

to prioritize its O&M activities in order to meet these 

goals. For example, if monthly water losses average 

greater than 20 percent, the utility would initiate some 

type of water audit and leak detection program.

The heart of any utility AM system is a complete inventory of the pipes, tanks, pumps and other facilities that 

make up the distribution system, coupled with a system 

for recording and tracking the status of those assets. 

Historically, information on distribution system assets 

has been kept in the form of maps and paper records. 

In recent years, many larger water utilities have moved 

to computerized mapping and database management 

systems. Commercial AM software packages are now 

readily available. However, most small- to mediumsized water utilities continue to use paper records as 

the primary method for tracking assets. In many cases, 

electronic AM takes a backseat to other utility functions such as electronic billing and electronic reporting 

(which may be required by regulations). Expenditures 

for commercial AM software packages and their associated labor costs are generally perceived as being too 

expensive for most small- and medium-sized systems. 

The resulting lack of effective tracking often results in 

a delay or deferment of needed repair and maintenance 

of distribution systems. 

An economical solution to AM inventory and recordkeeping is the use of general spreadsheet or database 

management software typically available on most personal computers. These systems can be augmented 

by mapping software (Geographic Information System [GIS] or Computer Aided Design and Drafting 

[CADD]). As an alternative, a utility may continue to 

use paper-based maps.

CADD and GIS are more advanced geographic-based 

computer systems that allow the user to store, display 

and analyze spatial data. Historically, CADD packages 

have been used by engineers and draftsmen in the design 

of facilities. GIS grew out of the planning and mapping 

fi elds as a means of constructing maps and analyzing 

spatial data. The two fi elds have moved closer together 

in terms of concepts and software and both are used 

today as a basis for designing, analyzing and displaying 

water distribution systems. 

Table 3.4 provides a listing of the popular low-cost 

CADD and GIS mapping software.

3.9 Distribution System Modeling

Distribution systems are designed to provide customers with needed fl ow at an acceptable pressure level. 

Some questions frequently asked regarding the design 

and operation of a distribution system are as follows:

The missing fi re hydrant serial number obtained from 

your asset management database helped us catch the 

crooks trying to sell it on the Internet.”
3-14

• How is a distribution system designed and 

operated to satisfy the acceptable fl ow and 

pressure objectives? 

• How can one determine the fl ow available to 

fi ght a fi re in a particular neighborhood on a hot 

summer day? 

• How can one determine the consequences 

of taking a tank out of operation to perform 

maintenance activities such as painting? 

• If an extension to the water system is built to 

serve a new development, what will be the 

pressure and will there still be an acceptable 

chlorine residual in the water delivered to the 

new service area? 

Table 3.4 Listing of Low-cost CADD and GIS Application Software

CAD Mapping Software GIS Mapping Software

Product Virtual Drafter IntelliCAD TurboCAD GRASS V6.2 JUMP V1.2 Map Window Forestry GIS Manifold Tatuk GIS Editor 

V2.2 Deluxe V14 GIS V4.4 V1.0 System V6.5 V1.8

Vendor Softsource IintelliCAD IMSI/Design GRASS Vivid Solution Map Window Forest Pal Manifold.Net TatukGIS

Technology Technology Open Source 

Consortium Consortium Team

Web site http://www. http://www. http://www. http://grass. http://www. http://www. http://www. http://www. http://www.

vdraft.com/ intellicad.org/ turbocad. itc.it/ vividsolutions. mapwindow. forestpal. manifold.net/ tatukgis.com/

vdraft.html com/ com/ org/ com/Toolbox. products/Editor/

html Editor.aspx

Cost $250 Basic - $149, Deluxe - Price Free (Open Free (Open Free (Open Free; Version Personal $350, Free 

w/ Service Varies from Source) Source) Source) of software is - $245/$295; Viewer Available

Contract $249 $100-$150 frozen in time Professional 

Pro Version 

- $349

- $295/$345

Ease of Use Medium Easy/Medium Easy/Medium Difficult Difficult Medium/Hard Medium Medium/Hard Medium/Hard

Operating Microsoft Microsoft Microsoft Microsoft Microsoft Microsoft Microsoft Microsoft Microsoft 

systems Windows 95, Windows Windows XP Windows Windows 2000, Windows 95, Windows 95, Windows 95, Windows 95, 98, 

supported 98, ME, NT, 2000, XP and and Vista, 2000, XP, Mac XP, Mac 10+, 98, ME, NT, 98, ME, NT, 98, ME, NT, ME, NT, 2000, XP 

2000 and XP Vista Macintosh 10+, Linux Linux 2000 and XP 2000 and XP 2000, XP and and Vista

10.4+ Vista

Computerized network models can assist in providing answers to these questions. These models are also 

referred to as distribution system models or hydraulic and water quality models. Computerized network 

models perform calculations based on mathematical 

descriptions of fl ow and pressure. The basic formulation of these models dates back to the work of Professor Hardy Cross in the 1930s. Today, these models 

are packaged in an interactive graphical format that 

makes the data entry and analysis of results relatively 

easy. Figure 3.11 is a computer screen shot depicting 

the results of an analysis of the SmallWater distribution 

system using the EPANET software package (available 

from EPA). Color coding and arrows are displayed in 

order to show fl ow magnitude and direction, and pressure at junctions. Figure 3.11 Screen-shot Showing the Results of an 

Analysis for the SmallWater Distribution System

A distribution system is represented as a network 

model of links and nodes. Links represent pipes, while 

nodes represent junctions, sources, tanks or reservoirs. 

Valves and pumps are represented as either nodes or 

links depending on the specifi c software package. In 

order to “build” a network model, the location and connectivity between each network component must be 

known. Additionally, the following basic information 

is required for the various types of components:

• Pipe: length, diameter, roughness

• Junction: elevation, water use

• Tank: diameter or dimensions, elevations

• Reservoir: water level
3-15

• Pump: head-discharge curve, intial status

• Valve: type, settings

There are two types of hydraulic analyses that may be 

conducted using a drinking water distribution system 

network model: steady-state and extended period simulation (EPS). In a steady-state analysis, all water demands and operations are treated as constant over time 

and a single solution is generated. Steady state analysis 

is useful for assessing a distribution system under a particular set of circumstances. For example, a steady state 

model could be used to estimate the amount of water 

available to fi ght a fi re and the resulting pressures in a 

particular neighborhood on a hot summer day. 

In the EPS mode, variations in demand, tank water levels and other operational conditions are simulated by a 

series of steady-state analyses that are linked together 

in order to represent the changes in fl ows and pressures over time. EPS can be used to investigate distribution system operation, study the behavior of tanks 

and pumps, assess energy usage, and serve as the basis 

for water quality modeling. Figure 3.12 illustrates plots 

from an EPS model of SmallWater showing the variation in tank water levels and fl ow in a water main over 

a 2-day period. EPS models are “built” starting with 

a steady-state model. Additional information that is 

needed for an EPS model include: variation in water use 

(demands) over the course of a day, operating rules that 

describe how pumps and valves are operated and minimum and maximum allowable water levels for tanks. 

Water quality models use the output from hydraulic 

models in conjunction with additional inputs to predict the temporal and spatial variability of a variety of 

constituents within a distribution system. These constituents include:

• the fraction of water originating from a 

particular source

• the age of water (i.e., duration since leaving the 

treatment plant)

• the concentration of a non-reactive tracer 

compound either added to or removed from the 

system (e.g., fl uoride or sodium)

• the concentration of a reactive compound 

including the concentration and loss rate 

of a secondary disinfectant (e.g., chlorine 

or chloramines) and the concentration and 

growth rate of disinfection by-products (e.g., 

trihalomethanes [THMs]) 

EPANET was initially developed in 1993 as a distribution system hydraulic-water quality model to support research efforts at the EPA. The development of 

the EPANET software has also satisfi ed the need for 

a comprehensive public sector hydraulic/water quality 

distribution system model. It has been a key component in providing the basis for water quality modeling 

incorporated into many commercial models and has 

been used by many utilities throughout the country. 

In addition to EPANET, there are several commercial 

software packages that are widely used in the United 

States and internationally. Many of these packages 

are based on the EPANET formulation and include 

value-added components that increase the capability of 

the software. Table 3.5 provides a summary listing of 

available commercial software and a Web link where 

additional details may be obtained on specifi c features, 

current versions, availability and pricing.

I need some fresh pictures for my portfolio, I have 

a new hydraulic modeling gig coming up!

Figure 3.12 EPS Plots of Tank Water Levels and Flow in 

a Water Main Over a 2-Day Period.

Tank Water Level

Time (hours)

0 4 8 12 16 20 24 28 32 36 40 44 48

Head (ft) 364.0

362.0

360.0

358.0

356.0

354.0

352.0

Flow for Link 42

Time (hours)

0 4 8 12 16 20 24 28 32 36 40 44 48

Flow (GPM) 200.0

100.0

0.0

-100.0

-200.0
3-16

3.10 SmallWater, USA – 

Asset Management 

Problem Scenario

SmallWater has been experiencing a rapid turnover of 

operators. Often, during these personnel changes, one 

operator has left before another is fully trained. Consequently, much of the on-duty operator’s time has been 

spent in locating seemingly misplaced maintenance 

records. Repair problems seem to be increasing. The 

utility’s managers are increasingly concerned that the 

loss of trained operators, personnel turnover and misplaced records are jeopardizing the utility’s ability to 

meet long-term water quality goals, to develop an O&M 

plan, and to meet their overall LOS requirements. 

Issues to Consider

SmallWater does not have an AM system in place. It has 

limited fi nances to purchase commercially available AM 

software and is limited in its ability to provide training 

to operators for developing an in-house AM system.

Guidance

In order to solve these problems, it is recommended that 

the utility investigate the use of a simple spreadsheetor database-based AM system. Prior to selecting an 

AM system to track inventory and event data, the utility 

staff should examine its needs and determine which AM 

system provides the best fi t. If utility personnel are not 

familiar with the use of spreadsheet or database management software, there are many readily available resources that can help provide training. These resources 

include local software specialists, community colleges, 

and vendors. Also, there are many books that can provide a good overview of available software packages. 

Once data are entered into a spreadsheet or database 

management system, the data can be sorted or fi ltered 

and custom reports can be generated. To be effective, 

this system should be viewed as a means for effi cient 

O&M, not merely a recordkeeping tool.

The key to successful inventory and recordkeeping is

the identifi cation of all distribution system assets and 

assignment of a unique identifi er to each separate asset 

component. Figure 3.13 shows the SmallWater distribution system with each component color coded. Each 

component type is assigned a letter (or letters) and within that component type, individual items are assigned a 

unique number. For example, T-2 refers to tank number 

2 and P-30 refers to pipe number 30. Individual pipes 

are categorized as continuous “runs” between junctions, 

where pipe characteristics (diameter or material) may 

(or may not) change at other important locations such as 

a tank, pump or major water users.

For each component, additional information of interest 

can be collected and stored in the database. For example, the following information would likely be stored for 

pipes:

• Pipe number

• Street name

• Diameter

• Length

• Material

• Date installed or replaced

Other types of information could easily be stored. For 

example, in addition to the components shown in Figure 3.13, inventory data on hydrants and isolation valves 

could be kept. Figure 3.14 shows the location of hydrants 

in parts of SmallWater and the accompanying Table 3.6 

contains useful hydrant inventory information. This 

type of data could be useful and provide the basis for an 

inventory of assets. It is usually referred to as static data 

since it remains relatively constant over time. 

Other data that can be collected and stored in a data base 

include information on pipe breaks, valve exercising, 

hydrant fl ushing, hydrant fl ow tests, water quality events 

such as “red water,” or any other distribution system 

events or activities of interest. This type of O&M information is especially useful for evaluating the performance of assets and making decisions on future repair and 

Table 3.5 Available Hydraulic-Water Quality Network Modeling Software Packages

Network Modeling Software Company Website

AQUIS 7-Technologies http://www.7t.dk/company/default.asp

EPANET U. S. EPA http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html

InfoWater H2ONET/H2OMAP MWHSoft http://www.mwhsoft.com

InfoWorks WS Wallingford Software http://www.wallingfordsoftware.com/

MikeNet DHI http://www.dhisoftware.com/mikenet/

Pipe2000 Univ.of Kentucky http://www.kypipe.com/

PipelineNet TSWG, SAIC http://www.tswg.gov/tswg/ip/PipelineNetTB.htm

STANET Fisher-Ulrig Eng. http://www.stanet.net

SynerGEE Water Advantica http://www.advantica.biz/

Wadiso GLS Eng. Software http://www.wadiso.com

WaterCAD/WaterGEMS Bentley Systems http://www.bentley.com
3-17

replacement programs. Table 3.7 shows a portion of an 

event table for SmallWater. 

The inventory and event tables serve as a permanent repository for information on all actions taken related to 

the distribution system. Figure 3.15 presents an example schema (structure) that can be used to design such 

a system within a spreadsheet or database management 

system. The solid boxes show the elements in the water 

system. The dashed boxes refer to maintenance events 

for various elements, and the dashed lines show the relationship between the elements and the maintenance 

events. This schema can be modifi ed, based on the specifi c needs of the utility. Some types of information may 

not be of immediate interest to some utilities and other 

data may be added as needed.

Table 3.6 Hydrant Inventory Information

Hydrant 

No.

Year 

Installed Address Pipe No. Available Flow (gpm) Notes

H014 1996 202 Main St. P-3

H015 1996 224 Main St. P-5

H016 1996 248 Main St. P-17 1100

H017 1996 286 Main St. P-17

H043 1952 140 Spring St. P-16

H044 1952 110 Spring St. P-9 375

H045 ? 78 Spring St. P-8

H046 ? 95 Spring St. P-8

H047 2005 112 Lincoln St. P-12

H048 1968 82 Lincoln St. P-13 420

Table 3.7 Event Table

Component 

Type ID Date of Event Type of Event Notes

Pipe P-4 2/5/03 Break

Valve V-55 2/5/03 Flow Test Valve cannot be closed

Valve V-55 6/14/03 Replaced

Hydrant H016 8/07/06 Flush

Hydrant H047 9/12/06 Replaced

Figure 3.13 Components in the SmallWater Distribution 

System

Figure 3.14 Hydrant locations in part of SmallWater

PIPE

Pipe ID

Diameter

Length

Material

Year installed

PUMP

Pump ID

Pump station

Pump name

Manufacturer

Design flow

Design head

Year installed

TANK

Tank ID

Diameter

Height

Max level

Min level

Year installed

CONT. VALVE

Valve ID

Valve type

Setting

Diameter

Year installed

ISOL. VALVE

IsolValve ID

Pipe ID

Turn direction

Year installed

HYDRANT

Hydrant ID

Pipe ID

Elevation

Fire Flow

Material

Year installed

VALVE MAINT.

IsolValveID

Date

Maintenance

Active?

HYDRANT MAINT.

Hydrant ID

Date

Maintenance

Active?

PIPE BREAK

Pipe ID

Date

Action

Active?

PIPE

Pipe ID

Diameter

Length

Material

Year installed

PIPE

Pipe ID

Diameter

Length

Material

Year installed

PUMP

Pump ID

Pump station

Pump name

Manufacturer

Design flow

Design head

Year installed

PUMP

Pump ID

Pump station

Pump name

Manufacturer

Design flow

Design head

Year installed

TANK

Tank ID

Diameter

Height

Max level

Min level

Year installed

TANK

Tank ID

Diameter

Height

Max level

Min level

Year installed

CONT. VALVE

Valve ID

Valve type

Setting

Diameter

Year installed

CONT. VALVE

Valve ID

Valve type

Setting

Diameter

Year installed

ISOL. VALVE

IsolValve ID

Pipe ID

Turn direction

Year installed

HYDRANT

Hydrant ID

Pipe ID

Elevation

Fire Flow

Material

Year installed

HYDRANT

Hydrant ID

Pipe ID

Elevation

Fire Flow

Material

Year installed

VALVE MAINT.

IsolValveID

Date

Maintenance

Active?

HYDRANT MAINT.

Hydrant ID

Date

Maintenance

Active?

PIPE BREAK

Pipe ID

Date

Action

Active?

Figure 3.15 Sample Asset Management Database 

Design or Schema
3-18

Crossword solution:

1) Pumps, 2) Centrifugal, 3) Pipes, 4) PVC, 5) Valves, 6) Hydrant, 7) Loop, 8) PW, 9) Priming, 10) Asset Management, 11) Check valve

1

2

3

4 5

6

7 89

10

11

ACROSS

3 The longest components of a distribution 

system infrastructure

4 Abbreviation for a commonly used plastic pipe 

in U.S. water distribution systems

7 Configuration of distribution system that 

provides a higher degree of reliability of 

service to customers in case a main break 

occurs

9 Centrifugal pumps require this at startup

10 Term for keeping an inventory of distribution 

system components

11 Type of valve that allows flow in one direction 

only

DOWN

1 Mechanical device that moves water from 

surface to elevated storage tanks

2 Types of pumps most commonly used in 

distribution systems

5 Can be a “turn on” or a “turn off” for water 

utilities

6 Provides a water connection for fire-fighters

8 Two letters of the NSF logo designating pipe 

approved for potable water use

Crossword

Distribution System Infrastructure
4-1

Chapter 4

Drinking Water 

Regulations

Drinking water regulations are designed primarily to 

protect public health. As discussed in Section 2.4, the 

Safe Drinking Water Act (SDWA) was passed by the 

U.S. Congress in 1974 to protect public health by regulating the Nation’s drinking water supplies. The 1974 

SDWA and its amendments established the following 

four key elements:

• a framework (including schedule and 

procedures) for developing drinking water 

standards

• drinking water standards designed to include 

health-based goals, known as Maximum 

Contaminant Level Goals (MCLGs) 

• technically achievable enforceable standards 

known as Maximum Contaminant Levels (MCLs)

• use of treatment techniques (TTs) instead of the 

MCLs (as necessary) 

The SDWA works in conjunction with the Clean Water 

Act (CWA), which controls the discharge of pollutants 

into lakes, rivers and streams. The CWA regulations are 

designed to protect the source water, whereas SDWA 

regulations are designed to protect water quality supplied to the general public (consumer) by public water 

systems (PWSs).

Even though CWA and SDWA generally work in conjunction with each other, some confl icts may arise between the two acts as they have separate and distinct 

measures of water quality. As mentioned previously, the 

CWA prescribes Total Maximum Daily Loads (TMDLs) 

for different pollutants based on the designated use of a 

water body, whereas the SDWA prescribes MCLs. 

Clean Water Act (EPA, 2002a)

The 1977 amendments to the Federal Water Pollution 

Control Amendments of 1972 are commonly known as the 

CWA. The goal of the CWA is to eliminate the releases of 

toxic amounts of pollutants into waters of the United States 

(e.g., rivers, lakes, streams). The CWA established the following three major programs:

• National Pollutant Discharge Elimination System 

(NPDES) Program – A system for granting and 

regulating discharge permits which regulates both 

point (industrial) and non-point (agricultural) 

discharges into waters of the U.S. 

• Total Maximum Daily Load (TMDL) Program – A 

TMDL is the sum of the allowable loads of a single 

pollutant from all contributing point and non-point 

sources to a water body (e.g., river, stream, lake). 

The TMDL calculation includes a margin of safety 

to ensure that the receiving water body can be used 

for the state-designated purposes (e.g., drinking 

water supply, swimming, fi shing). The TMDL 

calculation also accounts for seasonal variation in 

water quality.

• State Water Pollution Control Revolving Fund 

– To assist municipalities in creating wastewater 

treatment plants that were capable of meeting the 

standards, the CWA established a system to provide 

federal fi nancial assistance. Initially, funding was 

provided in the form of construction grants. This 

mechanism was modifi ed several times and later 

replaced by the State Water Pollution Control 

Revolving Fund in 1987.

In response to the CWA, EPA fi nalized effl uent guidelines 

that regulate water pollution from 56 industrial categories. 

It also established pretreatment requirements for industrial 

users contributing wastewater to Publicly Owned Treatment Works. It is estimated that these EPA regulations are 

responsible for preventing the discharge of nearly 700 billion pounds of pollutants each year.

Regulated by

Safe Drinking Water Act

Regulated by 

Clean Water Act Clean Water Act
4-2

From a compliance perspective, PWS operators who 

discharge wastewater and/or storm water (during construction activities) from their facilities need to ensure 

that the applicable requirements of CWA are met. However, the focus of this reference guide is distribution 

system water quality; therefore, only SDWA-related 

regulations are discussed in this chapter. A summary 

of the evolution of federal drinking water regulations 

since the passage of the 1974 SDWA is presented in 

Figure 4.1. 



	

			


	


	

	

			


	






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Figure 4.1 The Evolution of Federal 

Drinking Water Standards

(Adapted from EPA, 2005a)

The regulations presented in Figure 4.1 are designed to: 

control microbiological contamination, control chemical/radioactive contamination, and establish procedural 

requirements for meeting MCLs. The following three 

factors determine if a specifi c regulation or rule applies 

to a utility’s operations:

• classifi cation and size of the utility

• type of source water used (e.g., surface water, 

ground water, or ground water under the 

infl uence of surface water)

• type of water treatment used by the utility (e.g., 

fi ltration, disinfection)

Based on these factors, if it is determined that a particular rule applies, the utility must then meet the sampling, 

monitoring, reporting, treatment, and management 

practices as outlined in the regulation. These applicability decisions are typically made by the state regulatory agencies. Failure to meet these requirements 
4-3

constitutes a violation under the SDWA and can lead 

to enforcement actions and penalties. The following 

sections present a summary of the key regulations that 

apply to small- and medium-sized utilities.

4.1 Highlights of 1974 SDWA and 

its Amendments

Between 1975 and 1976, EPA adopted a set of National Interim Primary Drinking Water Regulations 

(NIPDWR). The NIPDWR provided the basis for the 

fi rst national drinking water standards. These standards included limits for ten inorganic chemicals, six 

organic pesticides, turbidity and fi ve radionuclides. 

In addition, the NIPDWR established standards for 

microbiological contamination based on total coliform organisms. In order to ensure that the water 

quality supplied to the public met these standards, 

the SDWA required that utility operators routinely 

monitor drinking water by sampling and testing the 

water entering the distribution system for most contaminants and in their distribution system for other 

contaminants. The SDWA also required utilities to 

notify their customers if the standards or sampling 

requirements were not met. State regulatory agencies were given the primary enforcement responsibility (“primacy”) over their water supply systems, provided the individual State program met the national 

criteria. Furthermore, the SDWA required EPA to 

assume the enforcement responsibility in case a State 

was unable or unwilling to do the job of enforcing the 

national standards. 

4.1.1 1986 Amendments to SDWA

In 1986, the SDWA was amended and the NIPDWR 

standards were declared to be fi nal. In addition, the 

1986 amendments required EPA to:

• regulate 83 contaminants within three years after 

enactment 

• regulate an additional 25 contaminants every 

three years

• mandate disinfection for all PWSs

• mandate fi ltration for surface water systems 

• designate best available technology for each 

contaminant regulated

• allow for TT instead of MCL

The non-community water systems were subdivided 

into transient and non-transient systems. States with 

primacy were required to adopt these regulations and 

begin enforcing them 18 months after they were published by EPA.

4.1.2 1996 Amendments to SDWA

The SDWA was amended again in 1996 to address these 

concerns and provide funds for PWS infrastructure and 

state program management. The 1996 amendments 

made the following changes to the SDWA:

• allowed EPA to establish a process for selecting 

contaminants to regulate based on scientifi c 

merit and eliminated the need to regulate an 

additional 25 contaminants every three years

• established the Drinking Water State Revolving 

Fund (DWSRF) to help PWSs fi nance the costs 

of drinking water infrastructure needs

• added an emphasis on source water protection 

and enhanced water system management

• allowed for fl exibility of regulations and 

monitoring for small systems

• required EPA to conduct cost-benefi t analyses of 

new regulations and analyze the likely effect of 

the regulations on the viability of the utility to 

implement them cost-effectively

• provided all systems additional time to come 

into compliance, plus allowed up to two more 

years if capital improvements were required

• established consumer confi dence reporting 

requirements

4.1.3 Variances and Exemptions

Each drinking water regulation includes provisions for 

states to issue variances and exemptions. Affordability-based variances are available for small-to-medium 

systems (serving fewer than 10,000 people) that allow 

utilities to deviate from MCL or TT requirements under 

Hmm... maybe it’s time for 

us to amend the SDWA!

?
4-4

certain conditions. Exemptions are designed to give

utilities additional time to comply with the new regulations. To use these variances and exemptions, the utility 

must fi rst prove that the requested variance or exemption does not pose an unreasonable risk to public health 

as determined by EPA. Also, variances and exemptions 

are not allowed for meeting the regulatory requirements 

for controlling microbial contaminants.

General Variance A general variance from meeting an 

MCL requirement can be requested if the utility cannot

comply with the MCL because of the characteristics of the 

source water. This variance is granted only if the utility 

has already installed the EPA-designated Best Available 

Technology (BAT) for treatment to remove the contaminant for which the MCL is being exceeded. In addition, 

the variance should not result in an unreasonable risk 

to public health, and the state agency must prescribe a 

schedule for compliance when granting this variance.

Small System Variances States can grant small-system 

variances to systems serving fewer than 3,300 people 

without EPA approval. However, they must get EPA 

concurrence for variances to systems serving between 

3,300 and 10,000 people. EPA needs to identify affordable variance technology for each regulation based on 

affordability criteria. As of 2005, no such small-system 

variances have been granted because EPA has not identifi ed any affordable small-system variance technology.

Exemptions States may exempt PWSs from an MCL 

or TT requirement if the following three conditions are 

met:

• The utility is unable to comply because 

of compelling factors, which may include 

economic factors.

• The exemption must not result in unreasonable 

risk to public health.

• The system was in operation as of January 1, 

1989, or, if it was not, no reasonable alternative 

source of drinking water is available to the new 

system.

In summary, the variances and exemptions are temporary. Only under an extreme condition should a utility 

consider these as options.

The EPA Regulatory Process (EPA, 2003b)

To continually increase the effectiveness of the multiple 

barrier approach and protect drinking water customers, 

EPA develops regulations as new scientifi c or health information becomes available. Each new regulation strengthens or adds a needed barrier at one or more stages of the 

water supply process. After an extensive review of scientifi c and health information, EPA works with stakeholders 

and concerned citizens to draft a proposed regulation. The 

proposed regulation is published for public comment. EPA 

considers all comments and revises the regulation, if appropriate. A fi nal regulation is then published. A listing 

and details on specifi c current and proposed standards can 

be found on the EPA website at: http://www.epa.gov/safewater/standards.html

4.2 Regulations to Control 

Microbial Contaminants

Disease-causing microbial contaminants such as fecal 

coliform (e.g., E. coli), Giardia, and Cryptosporidium

are frequently found in surface waters and groundwaters under the infl uence of surface water. Figure 

4.2 shows microscopic photographs of the diseasecausing microorganisms E. coli, Giardia, and Cryptosporidium. Some of the major rules that are intended 

You don’t think this could qualify 

as an Affordable Small System 

Variance Technology...

Dad, I heard you talking about affordable virus 

removal technology. This tool is guaranteed to 

remove all viruses, and best of all it’s free!
4-5

to control these microbial contaminants include:

• Total Coliform Rule (TCR)

• Surface Water Treatment Rule (SWTR)

• Interim Enhanced SWTR (IESWTR)

• Long-term 1 Enhanced SWTR (LT1ESWTR)

• Filter Backwash Recycling Rule (FBRR)

• Long-term 2 Enhanced SWTR (LT2ESWTR)

• Ground Water Rule (GWR)

Table 4.1 presents a summary overview of each of these 

regulations and its applicability to small- and mediumsized systems, along with the associated monitoring, 

treatment, and management practice requirements. 

The information presented in the table is only meant 

to provide a general overview of the regulation. EPA 

has developed many regulation-specifi c factsheets and 

guidance documents that are much more thorough and 

cover the nuances of each regulation.

E. coli Giardia Cryptosporidium

Figure 4.2 Disease-Causing Microorganisms - E. coli, 

Giardia and Cryptosporidium (not to scale)

4.3 Regulations to Control 

Chemical Contaminants

Some of the major rules under the SDWA that are intended to control chemical contaminants include:

• Arsenic Rule

• Lead and Copper Rule (LCR)

• Stage 1 Disinfectants/Disinfection Byproducts 

Rule (Stage 1 D/DBPR)

• Stage 2 Disinfectants/Disinfection Byproducts 

Rule (Stage 2 D/DBPR)

• Radionuclides Rule

• Radon Rule

Table 4.2 presents a summary overview of each of 

these regulations and its applicability to small- and medium-sized systems, along with the associated monitoring, treatment, and management practice requirements. 

The information presented in the table is only meant 

to provide a general overview of the regulation. EPA 

has developed many regulation-specifi c factsheets and 

guidance documents that are much more thorough and 

cover the nuances of each regulation. 

Additional Information

Regulatory Guidance 

Documents

EPA has prepared many rule-specifi c guidance documents 

for public use. A has prepared the following guides which are tailored for small system operators:

1. Small Systems Guide to Safe Drinking Water Act 

Regulations: The First STEP to Providing Safe and 

Reliable Drinking Water - One of the Simple Tools 

for Effective Performance [STEP] Guide Series.

2. Complying with the Ground Water Rule: Small 

Entity Compliance Guide - One of the Simple Tools 

for Effective Performance (STEP) Guide Series.

These and the other rule-specifi c regulatory guidance documents can be downloaded for free from the EPA website 

at: http://www.epa.gov

In addition, EP

4.4 Public Notifi cation and 

Consumer Confi dence Rules

Public notifi cation is intended to ensure that consumers will know if there is a problem with their drinking 

water. PWSs must notify their customers if: the level 

of a contaminant in the water exceeds EPA/state drinking water regulations; there is a waterborne disease 

outbreak or any other situation that may pose a risk to 

public health; the water system fails to test its water 

as required; or the system has a variance or exemption 

from the regulations. Depending on the severity (tier) 

of the situation, PWSs have a time limit of 24 hours to 

one year to notify their customers. The three EPA designated tiers are as follows:

1. Tier 1, for MCL violations and situations with 

signifi cant potential to have serious adverse 

effects on human health as a result of short-term 

exposure. Notice is required within 24 hours 

of the violation. A consultation with the state 

agency is also required within 24 hours.

2. Tier 2, for other violations and situations with 

potential to have serious, but not immediate, 

adverse effects on human health. Notice is 

required within 30 days, or as soon as possible, 

with extension of up to three months for 

resolved violations at the discretion of the state 

or primacy agency. 
4-6

Table 4.1 Summary of Regulations Designed to Control Microbial Contamination (Adapted from AWWA, 2006a)

Rule/Applicability to Small-andMedium Systems Rule Overview/Objective Related General Monitoring 

Requirements Related Treatment Requirements Related Management Practice Requirementsa

Total Coliform Rule – Applies to all 

PWSs.

Coliforms are abundant in the feces 

of warm-blooded animals. In most 

instances, coliforms themselves 

are not the cause of sickness, but 

they are easy to culture and their 

presence is used to indicate that 

other pathogenic (disease-causing) organisms of fecal origin may 

be present which can cause serious illnesses. 

Sampling is required. The number 

and frequency of samples is based 

on population served by the PWS 

and results of the sanitary survey. 

Repeat samples are required within 

24 hours if a positive total coliform 

sample is found. Furthermore, the 

positive samples must be analyzed 

for E. coli (a fecal coliform). Certain strains of E. coli are known to 

cause illness in humans.

The rule does not mandate any 

specific treatment. However, if 

monitoring indicates the presence 

of coliform, treatment may need to 

be added or modified as necessary to resolve the issue.

The rule does not mandate any 

specific management practices. 

However, management practices 

may need to be adjusted to meet 

the problems uncovered during 

monitoring.

Surface Water Treatment Rule 

– Applies to all PWSs that use surface water or ground water under 

the influence of surface water.

Disease-causing microorganisms 

such as Giardia and Legionella are 

present in most surface waters. 

This rule establishes criteria for 

determining if both filtration and 

disinfection are required for removal of these organisms.

Unfiltered systems need to monitor turbidity every 4 hours (source 

water), residual disinfectant concentration continuously (finished 

water), maintain distribution system disinfectant residual, and the 

total coliform levels (source water) 

1-3 times per week, depending 

upon the population served.

Filtered systems need to monitor 

turbidity at least every 4 hours and 

residual disinfectant concentration 

continuously (finished water).

Systems may avoid filtration if 

they have low coliform and turbidity in source water and meet 

other site-specific criteria. Systems that do not meet this criteria must install filtration treatment 

and the state must determine 

that filtration in combination with 

disinfection achieves the desired 

Giardia (99.9% removal) and virus 

(99.99% removal) removal/inactivation efficiency.

Unfiltered systems are required to 

meet source water quality criteria 

and maintain a watershed control 

program. They are also subject to 

annual inspection and watershed 

control program evaluation.

Interim Enhanced SWTR and 

Long-term 1 Enhanced SWTR.

This regulation builds upon the 

SWTR to address Cryptosporidium - a microorganism that can 

spread due to contamination of 

water from human or animal feces 

leading to severe diarrheal illness.

Continuous turbidity monitoring is 

required for each conventional and 

direct filtration process, with values recorded every 15 minutes.

States are required to perform 

sanitary surveys.

Combined filter effluent must be ≤ 

0.3 NTU for 95 percent of monthly 

readings and may at no time exceed 1.0 NTU.

Systems requiring compliance 

must establish disinfection profile 

and benchmark. Any changes to 

disinfection practice must be approved by the state.

Long-term 2 Enhanced SWTR 

– Applies to all PWSs that use surface water or ground water under 

the influence of surface water.

This regulation builds upon the 

SWTR, IESWTR and LT1ESWTR to 

address Cryptosporidium - a microorganism that can spread due 

to contamination of water from 

human or animal feces leading to 

severe diarrheal illness.

Required to initially monitor E. 

coli for a year and if the annual 

mean concentration in the source 

water exceeds specified levels, 

Cryptosporidium monitoring is 

required.

Depending upon the initial monitoring results, the PWS is further 

classified into four “bins” (Bin 1 < 

0.075 oocyst/L, Bin 2 - between 

0.075 and 1.0 oocyst/L, Bin 3 - 

between 1.0 and 3.0 oocyst/L, and 

Bin 4 > 3.0 oocyst/L). Each bin 

(except Bin 1) requires the PWS to 

install a treatment technology and 

establish a monitoring schedule 

based on contamination levels in 

the source water. The treatment 

options range from improving 

watershed control, reducing influent concentrations and additional 

pre-treatment to membranes and 

advanced oxidation.

The rule does not mandate any 

specific management practices. 

However, management practices 

may need to be adjusted to meet 

the problems uncovered during 

monitoring.

Filter Backwash Recycling Rule 

– Applies to all PWSs that use surface water or ground water under 

the influence of surface water; if 

they employ conventional or direct 

filtration, and recycle spent filter 

backwash water, thickener supernatant, and liquids from dewatering process.

Spent filter backwash water, thickener supernatant, and liquids from 

dewatering process can contain 

microbial organisms such as 

Cryptosporidium. This rule minimizes the risks associated with 

recycling these types of water.

The FBRR requires utilities to submit a plant schematic showing 

recycle flow and plant flow to the 

regulatory authority. They must 

also retain any records on recycle 

practices to document that the recycling of the regulated streams is 

performed correctly. 

The recycle streams must be sent 

to a point where they will pass 

through all the treatment process 

steps before entering the distribution system. The PWSs can 

request approval for an alternate 

location.

The rule does not mandate any 

specific management practices. 

However, management practices 

may need to be adjusted to meet 

requirements of the regulation.

Ground Water Rule – Applies to all 

PWSs that use ground water.

This rule is designed to protect the 

consumers of ground water from 

bacteria and viruses. It also seeks 

to identify defects through sanitary 

surveys in water systems that 

could lead to contamination.

Systems not achieving mandated 

level of microbial removal/inactivation must, after a positive total 

coliform result, take a source 

water sample and conduct further 

tests (e.g., for E. coli, enterococci, 

or coliphage). States also conduct 

hydro-geological assessments to 

identify if a particular source is 

sensitive to such contamination 

in which case further monitoring 

requirements are applicable.

Systems that detect fecal contamination would be required to take 

corrective action that may include 

disinfection, removal of the contamination source, or switching 

sources.

The rule does not mandate any 

specific management practices. 

However, management practices 

may need to be adjusted to meet 

deficiencies noted in the sanitary 

survey requirements of the regulation.

a

All of the rules have recordkeeping and reporting requirements associated with the monitoring, treatment and/or management requirements.
4-7

Table 4.2 Summary of Regulations Designed to Control Chemical Contamination (Adapted from AWWA, 2006a)

Rule/Applicability to 

Small-and-Medium 

Systems

Rule Overview/Objective Related General Monitoring 

Requirements Related Treatment Requirements Related Management Practice Requirementsb

Arsenic Rule – the revised 

rule is called -Arsenic and 

Clarifications to Compliance and New Source Contaminants Monitoring Rule. 

All CWSs and NTNCWSs.

The revised Arsenic Rule reduced the MCL from 

0.05 mg/L to 0.01 mg/L. Arsenic is shown to 

cause cancer and other health effects.

The rule makes monitoring requirements 

of arsenic consistent with those for other 

inorganic compounds (IOCs) regulated under the standardized monitoring framework 

(SMF)‡.

The rule specifically lists BATs and 

small system compliance technologies (SSCTs). The SSCTs including 

Point-of-Use (POU)/Point of Entry 

(POE) technologies most likely to be 

used by small systems include: activated alumina treatment, reverse osmosis, and modified lime softening.

The rule does not mandate 

any specific management 

practices. However, systems employing treatment 

for the first time to meet 

the MCL need to focus 

and develop appropriate 

technical, managerial and 

financial capacity. Systems employing POU/POE 

systems must maintain 

excellent customer relationship.

Lead and Copper Rule – All 

CWSs and NTNCWSs.

This rule establishes a 90th percentile action level 

for lead at 15 micrograms/L (μg/L) from the 50 

μg/L previous level and copper action level of 1.3 

mg/L. Lead is a toxic metal that can cause a range 

of health effects including learning disabilities in 

children. Long-term (more than 14 days) exposure to copper in drinking water at levels higher 

than 1.3 mg/L may cause kidney and liver damage in infants.

The number of samples required (ranging 

between 5 and 60 for small- and mediumsized systems) depends upon the system 

size. Sampling frequency is annual, every 

3 years, or every 9 years (depending upon 

the system size and previous monitoring 

results). If lead or copper concentrations 

exceed the specified action levels in more 

than 10% of customer taps sampled, the 

PWS must undertake a number of additional 

actions to control corrosion. 

Corrosion control treatment is required unless the monitoring data 

indicates levels below the action 

level for two consecutive 6-month 

sampling periods. Source water 

monitoring and treatment may be 

required if the action levels are exceeded because of elevated levels 

in source water. If the service lines 

are the cause of the exceedance and 

the problem is not corrected by corrosion control, service lines must be 

replaced.

The rule does not mandate 

any specific management 

practices. However, management practices may 

need to be adjusted to 

meet the problems uncovered during monitoring.

Stage 1 Disinfectants/ Disinfection By-products (D/

DBPs) Rule – All CWSs and 

NTNCWSs that add chemical disinfectant to water 

during the treatment process. Certain requirements 

apply to TNCWSs that use 

chlorine dioxide.a

DBPs result from a reaction between the disinfectant (such as chlorine) and the organic and 

inorganic compounds present in water. The rule 

sets MCLs for haloacetic acid 5 (HAA5) at 0.060 

mg/L, chlorite (chlorine dioxide by product) at 1.0 

mg/L, bromate (ozone byproduct) at 0.010 mg/L, 

and total trihalomethanes (TTHMs) at 0.080 mg/L. 

It also sets maximum residual disinfectant levels 

(MRDL) for chlorine (4.0 mg/L), chloramines (4.0 

mg/L) and chlorine dioxide (0.8 mg/L). DBPs can 

potentially cause cancer and impact reproductive 

health of humans.

For small and medium systems, 1 sample 

per plant annually are required for THMs and 

HAAs, generally in the warmest month, or 

quarterly. Plants using ozone are required to 

monitor monthly, and chlorine dioxide plants 

are required to monitor daily at the entrance 

to distribution system and monthly within 

the distribution system. For systems using 

conventional filtration, monthly sampling is 

required for total organic carbon (TOC) and 

alkalinity which are precursors that impact 

the DBP formation.

Systems that use surface water or 

ground water under the influence of 

surface water and employ conventional filtration must remove a specified percentage (15 to 50%) of TOC 

using either enhanced coagulation or 

enhanced softening. The specific % 

requirement depends upon TOC concentration and alkalinity of source 

water.

The rule does not mandate 

any specific management practices. However, 

management practices 

may need to be adjusted 

to balance the need for 

disinfection while minimizing the potential for DBP 

formation.

Stage 2 D/DBPs Rule – All 

CWSs and NTNCWSs that 

add chemical disinfectant 

(other than UV light) to 

water during the treatment 

process or deliver water 

that has been disinfected.a

The rule builds upon the Stage 1 D/DBP Rule. The 

covered PWSs are required to perform an initial 

distribution system evaluation (IDSE) to identify 

monitoring locations for eventual compliance with 

the current standards for TTHM and HAA5. Very 

small systems (serving fewer than 500 people) 

may seek waiver from IDSE. The other option 

is to obtain a “40/30” certification. The term 

“40/30” refers to a system that under the Stage 

1 D/DBP monitoring shows all samples < 0.040 

mg/L for TTHMs and 0.030 mg/L for HAA5.

The IDSE determines the monitoring site 

locations. The frequency of monitoring is 

based on both source water type and system size. Generally, for small to medium 

systems it is 2 samples per quarter or year.

Changes in treatment may be required to remove the DBP precursor (TOC) for the reduction of DBP 

concentrations. Systems should 

explore operational changes, distribution system modifications, and 

alternative disinfection strategies as 

necessary.

The rule does not mandate 

any specific management practices. However, 

management practices 

may need to be adjusted 

to balance the need for 

disinfection while minimizing the potential for DBP 

formation.

Radionuclides Rule – All 

CWSs

This rule builds upon the MCLs for combined radium-226/228 of 5 pico curies/liter (pCi/L), gross 

alpha particle activity 15 pCi/L, and beta particle 

and photon activity of 4 millirem†/year. It adds a 

uranium MCL of 30 pg/L. These radionuclides 

are known to cause cancer and death at elevated 

levels of exposure.

Monitoring of the radionuclides other than 

beta particle and photon emitters is consistent with the SMF‡. Monitoring is required 

at each entry point to the distribution system. Monitoring of beta particle and photon 

emitters is not required for most CWSs. If 

the system is designated by the state as 

“vulnerable” or “contaminated,” monitoring of beta particle and photon emitters is 

required.

The small system compliance technologies listed in the rule are green 

sand filtration, co-precipitation with 

barium sulfate, electrodialysis, activated alumina and ion exchange 

POU/POE devices. Special consideration for spent media or cartridge 

disposal may be required.

The rule does not mandate 

any specific management 

practices. However, management practices may 

need to be adjusted to 

meet requirements of the 

regulation.

a

 Stage 1 D/DBP Rule compliance is based on running annual average (RAA), monitoring is plant-based. Stage 2 D/DBP Rule compliance is based on locational running annual average (LRAA), 

monitoring is population-based.

bAll of the rules have recordkeeping and reporting requirements associated with the monitoring, treatment and/or management requirements.

‡ The Standardized Monitoring Framework (SMF) was finalized by EPA in 1991 to simplify and consolidate monitoring requirements across contaminant groups. The SMF increases public health 

protection by simplifying monitoring plans and synchronizing monitoring schedules leading to increased compliance with monitoring requirements. The SMF reduces the variability within monitoring 

requirements for chemical [inorganic compounds (IOCs), volatile organic compounds (VOCs), and Synthetic organic compounds (SOCs)] and radiological contaminants across system sizes and 

types. Monitoring for asbestos, fluoride, nitrate and nitrite are different from monitoring requirements for other IOCs because these chemicals have unusual characteristics. The SMF established a 

9-year “compliance cycle” composed of three 3-year “compliance periods.” Newly regulated contaminants will be subject to the SMF. During the initial monitoring period, the rule requires PWSs to 

sample four consecutive quarters for each contaminant at each entry point to the distribution system. Depending upon the results, systems may be able reduce their monitoring frequency to annually 

or once every 3, 6, or 9 years. The SMF allows states to waive all monitoring requirements for all contaminants except nitrate (MCL of 10 mg/L) and nitrite (MCL of 1 mg/L).

† millirem is a unit of radiation dose equivalent to one-thousandth of a rem. Roentgen equivalent man (rem) - A unit used to express different types of ionizing radiations on a common 

scale to indicate its relative biological effects. For beta and gamma radiations: Exposure to 1 Roentgen delivers a dose of 1 Rad, which is equivalent to 1 Rem.
4-8

3. Tier 3, for all other violations and situations not 

included in Tier 1 and Tier 2, such as monitoring 

and reporting violations. Notice is required 

within 12 months of the violation, and may be 

part of a single annual report, including, in some 

cases, the annual consumer confi dence report 

(CCR) already required by EPA.

EPA sets strict requirements on the form, manner, 

content, and frequency of public notices. Figure 4.3 

contains a sample public notice. Public notifi cation 

is provided in addition to the annual water quality 

report (or CCR), which provides customers with a 

more complete picture of drinking water quality and 

system operations for the preceding year. The annual 

CCR informs consumers what is in their water, where 

it comes from, and where they can obtain additional 

information.

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER 

Tests Show Coliform Bacteria in [System] Water 

The Jonesville water system routinely monitors for coliform bacteria. 

During the month of July, 7 percent of our samples tested positive. 

The standard is that no more than 5 percent of samples may test 

positive. 

What should I do? 

• You do not need to boil your water or take other corrective 

actions. However, if you have specific health concerns, consult 

your doctor. 

• You do not need to use an alternate (e.g., bottled) water supply. 

• People with severely compromised immune systems, infants, and 

some elderly may be at increased risk. These people should seek 

advice about drinking water from their health care providers. 

General guidelines on ways to lessen the risk of infection by 

microbes are available from EPA's Safe Drinking Water Hotline at 

1-800-426-4791. 

What does this mean? 

This is not an emergency. If it had been, you would have been notified 

immediately. Coliform bacteria are generally not harmful themselves. 

Coliforms are bacteria which are naturally present in the environment 

and are used as an indicator that other, potentially-harmful, bacteria 

may be present. Coliforms were found in more samples than allowed 

and this was a warning of potential problems. 

Usually, coliforms are a sign that there could be a problem with the 

system's treatment or distribution system (pipes). Whenever we detect 

coliform bacteria in any sample, we do follow-up testing to see if other 

bacteria of greater concern, such as fecal coliform or E. coli, are 

present. We did not find any of these bacteria in our subsequent 

testing.

What was done? 

We took additional samples for coliform bacteria which all came back 

negative. As an added precaution, we chlorinated and flushed the 

pipes in the distribution system to make sure bacteria were eliminated. 

This situation is now resolved. 

For more information, or to learn more about protecting your drinking 

water please contact John Jones at 555-1212. 

Please share this information with all the other people who drink this 

water, especially those who may not have received this notice directly 

(for example, people in apartments, nursing homes, schools, and 

businesses). You can do this by posting this notice in a public place or 

distributing copies by hand or mail. 

This is being sent by the Jonesville Water System. 

State Water System ID#1234567. Date Distributed: 8/8/06 

2) When the 

violation

occurred 

3) Potential 

health

effects

6) Actions 

consumers

should take 

7) What is 

being done to 

correct the 

violation

10) Required 

distribution

language

9) Phone 

number for 

more

information

5) The 

population

at risk

4) Should alternate 

water supplies 

be used

1) Description 

of the 

violation

8) When the 

system will 

return to 

compliance

5) The

population

at risk

4) Should alternate

water supplies be

used

Figure 4.3 Sample Public Notice (EPA, 2007c)

“Hi Stan. Our contractor dropped his 

cell phone into the fi nished water tank. 

Is this a Tier 1, 2 or 3 violation?”
4-9

System Type Minimum Frequency

Noncommunity water system Every 5 years

Community water system Every 3 years

Community water system with Every 5 years

outstanding performance based 

on prior sanitary surveys

Sanitary Surveys (EPA, 1999)

A sanitary survey is an on-site survey of the water source, facilities, equipment, operation, and maintenance of the PWS for 

the purpose of evaluating the adequacy of such source, facilities, equipment, operation, and maintenance for producing and 

distributing safe drinking water. They are used to prevent and 

correct sanitary defi ciencies and are indispensable for ensuring 

the delivery of safe water on a sustainable basis. When conducted 

properly and with appropriate follow-up, sanitary surveys fulfi ll 

the following objectives:

• Reduce the risk of waterborne disease;

• Provide an opportunity to educate system operators;

• Identify systems needing technical or capacity 

development assistance; and

• Identify candidates for enforcement action. 

Sanitary surveys have been a critical component of state drinking water programs for decades. States regulatory agencies are 

required to complete sanitary surveys for all surface water systems and systems using ground water under the direct infl uence of 

surface water (GWUDI) on the following schedule:

The recent ground water rule extends sanitary survey requirements to ground water systems. Sanitary surveys may also be required when compliance problems arise. The PWSs are required 

to cooperate with their regulatory agency and provide supporting 

information when requested by the agency. Sanitary surveys can 

be very useful for small utilities and provide them outside assistance to identify weaknesses in the system before they cause serious problems. They can also help the utility regain control and resolve current weaknesses and avoid repeat compliance problems. 

Sanitary surveys help evaluate the following issues:

• The capability of the PWS to monitor and manage water 

quality data

• System management and operational weaknesses

• Regulatory compliance weaknesses

• The integrity of supply sources

• Treatment adequacy and operational weaknesses

• Potential impacts of pumping

• Integrity of storage facilities, and 

• Distribution system weaknesses

After the sanitary survey is completed, the inspector generally 

provides a follow-up report addressed to the PWS manager or 

chief operator. The purpose of the report is to summarize any 

problems that have been identifi ed, as well as recommendations 

for necessary improvements. The report generally discusses each 

of the items listed above in detail and provides dates by which the 

defi ciencies (if any) should be corrected. Sanitary surveys can be 

a preventive tool, helping water utilities address weaknesses. 

4.5 SmallWater, USA – 

Regulatory Scenario 

Problems

Problem #1 Scenario

As previously presented in Section 2.7, in the 1990s, 

the well (ground water) supply in SmallWater became 

inadequate. Therefore, an alternate source was developed in the form of an interconnection to the surface 

water supply from a larger system located to the southeast. The well fi eld was maintained as a supplemental 

and emergency supply. What regulations would currently apply?

Issues to Consider

1) Is the source considered a surface water source 

from a regulatory standpoint because it has 

switched supply from ground water wells to 

purchased surface water?

2) If the ground water source is used for 

supplementing for peak summer demand, what 

compliance issues are raised?

3) Since SmallWater is buying treated surface 

water from another source which is in 

compliance with all surface water source 

requirements, does SmallWater have any 

compliance requirements?

Regulatory Guidance

SmallWater should fi rst contact its state (primacy) 

regulatory authority and present the entire operating 

scenario. From a regulatory standpoint, SmallWater is 

considered as the supplier to the customers who live in 

the SmallWater service area. At the point where the 

bulk purchase takes place, it is SmallWater’s responsibility to ensure that the water quality supplied to the 

consumer meets the surface water requirements mandated by the SDWA.

If ground water is used as a supplement to meet summer 

demand, the supplier has to comply with both ground 

and surface water treatment requirements. SmallWater 

should consult the state regulatory agency to make sure 

the mixed water supply meets all regulatory requirements.

Problem #2 Scenario

Last July, one of the three required monthly routine 

total coliform samples in SmallWater showed positive 

results. This triggered a series of actions including notifi cation to the state, additional testing, and public notifi cation. 
4-10

Issues to Consider

1) What is the procedure to identify if 

contamination is isolated to the plumbing 

system of an individual building from where the 

routine sample was drawn, or if contamination 

was in the distribution system itself?

2) What should be done if a repeat sample is total 

coliform-positive?

3) How is the overall monitoring schedule affected 

by this event?

Regulatory Guidance

In response to the notification of positive total coliform 

sample, SmallWater was required to take action within 

24 hours. This response includes collection of a set of 

three repeat samples to assess the extent of the problem. 

For water systems that collect one or fewer samples per 

month, a fourth repeat sample is required. One of the 

repeat samples must be collected from the original sample tap, one within fi ve service connections upstream, 

and one within fi ve service connections downstream. 

This pattern of repeat sampling helps to determine the 

extent of contamination and potential cause of the positive sample. If a repeat sample is total coliform-positive 

at the same service connection, but negative at upstream 

and downstream service connections, the state may investigate to determine if it is appropriate to waive the 

total coliform-positive sample as being a plumbing system problem in the individual building.

If any routine or repeat sample is total coliform-positive, 

the positive sample is tested either for the presence of 

fecal coliforms or E. coli. The test is done automatically 

by the lab and does not require an additional sample. A 

potential urgent health risk exists if any sample, routine 

or repeat, tests positive for fecal coliform/E. coli. When 

notifi ed by the laboratory that one of the samples tested 

positive for fecal coliforms or E. coli, SmallWater was 

required to notify the state by the end of the day. This 

notifi cation is required on or before the end of the next 

business day if the state offi ce is closed. The occurrence 

of a positive routine and repeat sample in conjunction 

with a positive fecal or E. coli sample creates an acute 

violation of the MCL. In addition to notifying the state, 

SmallWater is also required to notify the public within 

24 hours by television, radio, hand delivery, or other 

methods approved by the state, and consider advising 

their customers to boil their water. 

A less serious but still signifi cant potential health risk 

exists if more than one sample (routine and/or repeat) 

in a month is total coliform-positive. This creates a 

monthly MCL violation. When SmallWater is notifi ed 

by their laboratory of the repeat or second routine total 

coliform-positive sample results, they are required to 

notify the state by the end of the next business day and 

to notify the public within 30 days by mail, hand delivered notices, or other methods approved by the state.

In the month following detection of total coliforms in 

any routine or repeat sample, SmallWater is required to 

collect fi ve routine samples. If none of these tests are 

positive for the presence of total coliforms, they may 

resume collecting their usual three routine samples the 

next month. A total coliform-positive sample is cause 

for concern. However, if a set of repeat samples that 

month and fi ve routine samples the next month are all 

negative, and their other multiple barriers to contamination are adequate, SmallWater should have confi dence 

that their water is safe.

Beyond the strict requirements for responding to a positive coliform sample, SmallWater may also consider the 

following progressive steps to avoid further problems.

1. The sample-tap and sample collection 

procedures should be examined and reviewed. 

Coliform bacteria can come from unclean 

faucets, biofi lm in the premise plumbing, and 

poor sample collection and handling procedures 

such as sample bottles sitting in melted ice in a 

cooler. Sample collectors may need to take more 

care in the collection process and sample faucets 

may need to be repaired and sanitized.

2. Local water main conditions should be 

reviewed. If the water system is chlorinated, 

chlorine test results should be evaluated to 

ensure that there is adequate chlorine residual. 

Local main breaks, fl ushing, unusual fl ow 

reversals, valve and hydrant operations can all 

stir up or dislodge coliforms from sediments or 

biofi lms.

3. Storage facilities that infl uence the water 

provided to the sample location from which the 

positive coliform sample was taken should be 

checked for possible contamination.
4-11

1

2

3

4

5

6 7

ACROSS

3 The action level for this compound is 15 μg/L 

under the Lead and Copper Rule

4 A microbial contaminant that is used as a 

general indicator of the presence of other 

disease-causing organisms

6 Acronym for the regulation designed to control 

Cryptosporidium in drinking water

DOWN

1 Time period within which a notice is required 

to the regulatory agency in case of a Tier 1 

violation

2 Term for special allowances by the regulators to exempt small systems from meeting 

the regulatory MCL or treatment technique 

requirements

5 Abbreviation for the act passed by congress 

to protect drinking water in 1974

7 Acronym for the sum of four disinfection 

byproducts formed due to reaction of 

chlorine with naturally occurring organic 

matter

Crossword Solutions

TTHM 1) 24 hours, 2) Variances, 3) Lead, 4) Coliform, 5) SDWA, 6) LT2ESWTR, 7) 

Crossword

Drinking Water Regulations
4-12
5-1

Chapter 5

Distribution System 

Water Quality Issues

Drinking water exiting the water treatment plant enters 

a distribution system which is a complex network of 

pipes, tanks and reservoirs designed to deliver fi nished 

water to consumers. Although water entering a distribution system may meet drinking water standards, the 

quality of the transported water may degrade within 

the distribution system before it reaches the consumer. 

Some of these undesirable changes such as objectionable taste, odor or color can often be detected immediately, whereas other changes in quality such as the 

intrusion of dangerous pathogens may only be noticed 

after a waterborne disease outbreak. Some of these 

pathogens include Salmonella and E. coli. Therefore, 

proper distribution system management is essential to 

protect consumers from both aesthetic and public health 

threats due to deteriorating water quality. The following 

sections in this chapter discuss common water quality 

issues faced by water utilities, including small- and medium-sized systems. These issues include taste, odor, 

and color; biofi lm formation; disinfection and disinfection byproducts (DBPs); nitrifi cation; pH stability and 

scale formation; and contamination events.

5.1 Taste, Odor, and Color 

In most cases, taste and odor do not pose a public health 

threat, and color in water can stain household appliances and plumbing fi xtures. These aesthetic problems can 

result due to various factors including the following: 

poor source water quality, inadequate treatment, initiating disinfection of well with iron or manganese, changes in water quality in the distribution system, and external contamination events. The Safe Drinking Water Act 

(SDWA) established National Secondary Drinking Water Regulations (NSDWR or secondary standards) that 

are non-enforceable guidelines regarding contaminants 

that may cause cosmetic effects (such as skin or tooth 

discoloration) or aesthetic effects (such as taste, odor, 

or color) in drinking water. EPA recommends secondary standards for water systems, but does not require 

these systems to comply. However, states may choose 

to adopt them as enforceable standards and may require 

monitoring and reporting. 

All customers want their water to look, taste and smell 

good; therefore, the utility operator should investigate 

customer complaints and try to resolve these issues. 

When complaints are fi led, as a fi rst step, the utility operator should try to identify if the water quality problem 

has occurred in the customer’s plumbing or is due to 

poor source water quality or treatment and/or changes 

in the distribution system that can be controlled by the 

utility operator. If more than one customer has reported 

similar problems, it is likely that the issue is related to 

source water, inadequate treatment or distribution system problems. The following sections discuss typical 

customer concerns, their most common causes and basic troubleshooting techniques.

5.1.1 Taste and Odor Problems

Petroleum, gasoline, turpentine, fuel or solvent odor

Generally, the source of these types of odors is external 

contamination (e.g., leaking underground fuel storage 

tanks). Therefore, it is recommended that the utility 

perform on-site investigations to isolate and remediate the problem. Contaminated soil or ground water 

can enter a well or it can permeate through plastic pipe 

buried in a contaminated area. Small systems that lack 

resources and expertise for tackling this problem should 

notify the state agency.

Sulfur or rotten egg odor These types of odors are 

commonly caused by bacteria growing in a sink drain 

or in a water heater in the customer’s home. In some 

cases, the smell may be caused by naturally occurring 

hydrogen sulfi de. As a fi rst step, it is recommended that 

the utility ask the customer to collect a small amount of 

water in a cup, step away from the odor-causing sink, 

swirl the water around inside the cup and smell it. If the 

water has no odor, the likely source is bacteria in a sink 

drain. If the water continues to have an odor, a possible 

source is the customer’s water heater. This problem can 

occur 1) if the hot water has not been used for a long 

time, 2) if the heater has been turned off for a while, or 

Do you have anything that will mask a 

“rotten egg” smell in drinking water?
5-2

3) if the thermostat on the heater is set too low. If the 

sink drain and the water heater have been eliminated as 

the potential source of the problem, additional investigations will be needed. Sulfur odors can also originate 

from unmaintained household water treatment devices 

and from stagnant plumbing. Sulfur odors can appear 

in dead-end mains or through a backfl ow event and 

the distribution system piping may require fl ushing to 

remove the odor-causing material. If the problem is 

system-wide, additional water treatment (such as carbon fi ltration) prior to distribution may be necessary to 

eliminate organic compounds in the source water that 

may be causing the problem.

Moldy, musty, earthy, grassy or fi shy odor These 

odors can also be caused by bacteria growing in a sink 

drain or stagnant water. As indicated in the previous 

section, the customer should be requested by the water 

utility to collect a small amount of water in a cup, step 

away from the tap, swirl the water around inside the 

container and smell it. If the water has no odor, the 

likely cause is bacteria in the sink drain. If the water 

continues to have an odor, the source is most likely algal bloom in the main water. Although generally harmless, it may result in abnormal odor at very low concentrations. Temporarily, this problem can be alleviated 

by fl ushing (running the faucet for several minutes). 

However, it is possible that the distribution system may 

require fl ushing to remove the odor-causing material. 

If an algal bloom in the surface water source is determined to be the cause, additional water treatment (such 

as ozonation or carbon fi ltration) prior to distribution 

may be necessary to eliminate the problem.

Chlorine, chemical or medicinal odor These types 

of odors are usually caused by the presence of excess 

chlorine in the water. Chlorine odors can result from 

disinfection of new pipe installations or due to poor control of chlorine residual. Chemical or medicinal odors 

may occur due to the interaction of excess chlorine with 

organic matter present in source water or the distribution system piping. If the organic matter in the source 

water is not a problem and there are no nearby customers reporting similar problems, it is recommended that 

the customer contact a licensed plumber and have the 

building pipes cleaned or replaced. If organic matter in 

the source water is found to be causing the problem, additional water treatment (such as carbon fi ltration) prior 

to distribution may be necessary to resolve the issue.

Salty taste This type of taste is usually caused by naturally occurring sodium, magnesium or potassium compounds that are present in a coastal area where sea water 

may be affecting the fresh water supply. Naturally occurring high levels of total dissolved solids (e.g., Colorado 

River water) can also cause this problem. A utility should 

work with the state, and additional site investigation may 

be required to isolate and remediate the problem.

Metallic taste Metallic tastes may be caused by metals, such as aluminum, zinc, iron, copper or manganese 

that leaches from distribution system piping as corrosion byproducts, or arise from the source water, or a 

residual chemical contaminant from water treatment. 

Possible sources of these tastes are treatment process 

chemicals (e.g., coagulants or corrosion inhibitors) or 

the source water. The corrosive potential of the fi nished 

water must be evaluated to determine if the distribution 

system piping could be a source (see Section 5.5, pH 

Stability and Scale Formation, for additional details). 

Appropriate sampling and analysis may be required to 

isolate the problem. Once the problem is identifi ed, 

corrective techniques can be applied which may include 

modifi cation of the treatment process.

5.1.2 Color Problems

Green or blue water Corrosion of copper plumbing will 

frequently cause a bluish-green stain on porcelain fi xtures. The cause of this problem is generally in the customer’s piping or due to corrosive water supplied by the 

utility. Copper corrosion can sometimes appear in new 

building plumbing. Also, backfl ow of carbon dioxide 

or other corrosive chemicals can cause copper corrosion 

in plumbing. The corrosive potential of water should be 

checked and, if necessary, adjustments need to be made 

during treatment such that the water supplied is not corrosive. Phosphate is commonly added to reduce corrosion in the distribution system. If the water supplied by 

the utility is not corrosive, the customer should contact a 

licensed plumber and possibly have the residential pipes 

replaced. A short-term acute exposure (above the maximum contaminant level (MCL) of 1.3 mg/L) can cause 

gastrointestinal distress. Long-term acute exposure can 

result in liver or kidney damage. People suffering from 

Wilson’s disease should consult their doctor if the copper in their water exceeds the MCL. 

Brown, red, orange or yellow water Rusty water can 

cause brown, red, orange or yellow water due to corroding galvanized iron, steel or cast iron pipes in building plumbing or in the distribution system pipes. Local 

water main conditions (valve operating, fl ow reversals, 

and fl ushing) can upset corroded iron mains and stir 

up rust. While unpleasant and potentially damaging to 

clothes and fi xtures, iron in drinking water is not an immediate human health concern. The SDWA has a (nonenforceable) secondary standard of 0.3 mg/L for iron. 

The corrosive potential of water should be checked by 

the utility and, if necessary, appropriate adjustments 

should made during treatment. Phosphate addition and 

pH adjustment are commonly used to reduce corrosion 

in the distribution system. 
5-3

I’m feeling a bit fl ushed... 

I think it is more than just 

iron rust contamination

Black or dark brown water Manganese or other pipe 

sediment can cause a black or dark brown color but 

generally clears up without further action after the 

sediment settles in the water main. Flushing of cold 

water faucets and toilets is recommended. Manganese 

does not pose a threat to human health. The SDWA has 

a (non-enforceable) secondary standard of 0.05 mg/L 

for manganese. The utility should investigate to determine if the household is located in an area with chronic 

low-fl ow issues that could lead to pipe sediments and 

deposits. If the problem is caused by the presence of 

manganese in source water, additional treatment

or to distribution may be required to resolve the

priproblem.

Milky white or cloudy water Entrapment of air bubbles can result 

in milky or cloudy water. The 

customer should fi ll a clear 

glass with water and set it on 

a flat surface. If the water 

starts to clear at the bottom of the glass fi rst, the 

cloudy or white appearance is a natural occurrence. Presence of air 

bubbles is not a health 

threat and should clear in 

about fi ve minutes. If the 

water does not become 

clear, additional studies 

should be conducted to 

isolate and remediate the

problem. Galvanized pipe 

(zinc coating) or aluminum

oxide can also make the water 

appear milky. 

Figure 5.1 depicts a taste and odor 

wheel that can assist troubleshooting

activities.

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Figure 5.1 Drinking Water Taste and Odor Wheel (adapted from AWWA, 2004)

5.2 Biofi lm 

Biofi lm consists of microbial organisms that attach 

to the interior surfaces (e.g., pipes, tanks) of water 

distribution system pipes and tanks. These organisms excrete a slimy glue-like substance that allows 

them to adhere to the piping or other water distribution system components. Figure 5.2 shows a picture 

of biofi lm growth inside a pipe. Generally, biofi lm 

in distribution system piping contains various species 

of bacteria: most commonly coliforms, heterotrophic 

and nitrifying bacteria. However, biofi lm can contain 

fungi, algae, protozoa, dead cells, corrosion products, 

organic, and inorganic matter. Typically, biofi lms are 

benign and do not cause health problems. However, 

in many cases, their excessive growth leads to various 

types of problems and requires control. For example, 

biofi lms can shield disease-causing microorganisms 

such as mycobacteria, aeromonads and Legionella

from residual disinfectants. In addition, biofi lms can 

allow the growth of bacteria to reach a level that interferes with total coliform compliance testing or 

support the growth of coliform organisms to a level 

that jeopardizes compliance with the total coliform 
5-4

Just like the “fi re triangle,” 

for the biofi lm to grow it 

needs three key nutrients....

monthly standard. Furthermore, biofi lms can also

produce taste- and odor-causing compounds, especially after initiation of disinfection, leading to consumer 

complaints. Therefore, it is important to understand 

the factors that promote biofi lm growth and the operational techniques that can be employed to minimize 

biofi lm growth as discussed in the following subsections.

Figure 5.2 Biofi lm Growth Inside the Pipe

5.2.1 Factors Aiding Biofilm Growth

Drinking water is not sterile. Thus, bacteria in water 

will form biofilm as water always has enough nutrients 

(carbon, nitrogen and phosphorous) to allow biofi lm 

growth to occur. However, the rate of biofi lm growth is 

infl uenced by the fi nished water quality and other contributing factors such as disinfectant type, residual disinfectant concentration, pipe material, system hydraulics, 

corrosion activity and distribution system maintenance 

practices. The basic process begins with the seeding of 

the microbial organism in the system and the growth 

rate is a function of nutrient availability and other contributing factors which are discussed in this section.

The overall composition of the biofi lm in a distribution system depends upon the organisms that initiate 

the growth. For example, water main construction and 

repair activities can create an opportunity for some 

undesirable organisms to enter the system and act as 

“seeds” for growth. Thereafter, the availability of nutrients in the fi nished water is a key factor in biofi lm 

growth. The key nutrient that impacts biofi lm growth 

is total organic carbon (TOC) in water. Some research 

has pointed to specifi c components of TOC, notably assimilable organic carbon (AOC) and biodegradable organic carbon (BDOC), as the key factors in infl uencing 

biofi lm growth. However, there is still much uncertainty 

associated with the biofi lm growth process. 

Biofi lm growth is amplifi ed by factors such as fl ow, 

high temperature, corrosion, and low residual disinfectant levels. In general, low fl ow conditions tend to 

favor formation of biofi lms. Higher temperatures favor 

the development of biofi lms and increase the diversity of microorganisms present in the biofi lm. A ruleof-thumb is that water temperature at or above 15°C 

(~60°F) tends to experience greater bacterial activity. 

Corroded pipes are more supportive of biofi lm growth 

than non-corroded pipes, because the corrosion deposits 

and tubercles (blister-like growth of iron oxides) can act 

as a shelter to the organisms to protect them from the 

disinfectant. Most disinfectants are effective in controlling the organisms that comprise a biofi lm provided that 

it comes in contact with the organisms. However, the 

dead cells, extra cellular molecules, and other components of a biofi lm react with the disinfectant to limit 

their destructive ability. The type of disinfectant used 

can also affect biofi lm growth. In some instances, the 

use of chloramines may yield better biofi lm control.

5.2.2 Operational Factors Inhibiting the 

Growth of Biofilm

Biofilm growth in distribution system piping is inevitable, given that small quantities of microorganisms 

are always present in source water and pass through 

treatment or can be introduced accidentally during construction and repair activities. Operational techniques 

can be implemented to inhibit biofi lm growth by the 

following: reducing available nutrients, optimizing disinfectant dosage, controlling corrosion and periodic 

fl ushing. 

Reducing nutrient availability As mentioned in the 

previous section, TOC is usually the key nutrient that 

impacts biofi lm growth in drinking water systems. 

Utilities should consider treatment techniques such as 
5-5

I wonder if the new disinfectant 

soap we are using for handwashing 

causes any disinfectant byproducts 

to form on our hands...

enhanced coagulation and/or activated carbon fi ltration 

in conjunction with source water protection measures 

to reduce the overall TOC levels in water. For some 

utilities, another option is to move the point of disinfection (to a point after the fi ltration process). This allows 

bacteria to grow in the fi lter media and consume the 

biodegradable fraction of TOC, even though the overall TOC levels are not signifi cantly reduced. In some 

systems, nitrogen may be the limiting nutrient factor. 

Ammonia, nitrate or nitrite removal technologies may 

be employed by the operator to reduce nitrogen availability. For systems using chloramines, careful control 

of ammonia addition may help to reduce residual free 

ammonia in the fi nished water.

Optimizing disinfectant dosage Disinfectants can reduce the growth of biofi lm in a distribution system. 

However, residual disinfectant must be available 

throughout the distribution system. In many cases, it 

may not be practical to maintain residual levels based 

on disinfection at one central location. Distributed 

booster chlorination stations may be more effective in 

maintaining residual levels in areas of low-fl ow and 

stagnation, especially during warmer water temperature months.

Corrosion control As discussed previously, corrosion 

deposits and tubercles can act as a shelter to help protect biofi lm from a disinfectant. In moderate to severely corroded iron pipes, the exposed surface may take up 

a vast majority of the available disinfectant. Proactive 

corrosion control practices may result in better control 

of biofi lm growth. Water main rehabilitation or replacement is another option.

Flushing Flushing at velocities greater than 2 feet/second can physically remove some biofi lm by scouring. 

Flushing can also remove accumulated debris and corrosion products that shield the biofi lm from disinfection. Flushing is only a temporary measure; the underlying conditions that support biofi lm growth need to be 

addressed simultaneously.

5.3 Disinfection and Disinfection 

Byproducts

All utilities using surface water sources are required 

by EPA to disinfect the water prior to delivery to their 

consumers. The intent of this requirement is to provide a barrier against disease-causing microorganisms. 

The process which destroys or removes disease-causing 

organisms is termed “disinfection.” Chlorine and chloramines are the most commonly used disinfectants in 

the U.S. Furthermore, it is necessary that a residual 

disinfectant be maintained throughout the distribution 

system. Loss of disinfectant residual is one of the most 

common water quality concerns. The availability of a 

disinfectant residual is a function of time and rate of decay or loss caused by consumption of disinfectant at the 

pipe wall and in the bulk water. Excess disinfectant levels lead to undesirable changes in water quality when 

the disinfectants react with naturally occurring organic 

matter or compounds, such as TOC or bromide, in the 

source water/distribution system to form DBPs.

This automated antibiotic 

drip system is designed to 

control Biofi lm
5-6

If you paid attention in your 

chemistry class, you would know 

they stand for nitrite and nitrate!

Although studies are ongoing to determine the longterm health effects of exposure to DBPs, EPA has 

already set monitoring requirements and MCLs for 

some of the more common DBPs including: trihalomethanes (THMs), haloacetic acids (HAAs), 

bromate, and chlorite. If DBPs are a problem, the 

utility should carefully evaluate the key variables 

that impact their formation including: residual disinfectant levels, water age in the distribution system, 

TOC concentration, pH, and water temperature. A 

DBP problem scenario is described in Section 5.7 at 

the end of this chapter.

5.4 Nitrifi cation

Nitrifi cation in drinking water distribution systems is 

the transformation of ammonia to nitrate. In this process, ammonia is fi rst transformed to nitrite by bacteria 

and subsequently, nitrite is transformed to nitrate as a 

bacteriological process or simply in the presence of 

oxygen. Nitrifying bacteria are slow-growing organisms, and nitrifi cation problems usually occur in large 

reservoirs or low-fl ow sections of distribution systems. Ammonia is present in drinking water through 

either naturally-occurring processes or through the 

addition of ammonia during disinfection to form chloramines. Given similar levels of TOC and temperature 

in the source water, chloramines form less DBPs than 

chlorine. Therefore, chloramine use is expected to increase as a direct result of more stringent DBP MCLs 

associated with the Stage 1 and Stage 2 D/DBP Rules 

(see Chapter 4). 

Nitrate and nitrite levels in water are required to be 

monitored at the entrance to the distribution system. 

If the levels are greater than one-half of the MCL, 

additional proactive monitoring and troubleshooting 

should be performed. Nitrate and nitrite have direct 

health implications. Nitrate is transformed to nitrite 

in the human digestive system. The nitrite ion oxidizes iron in the hemoglobin of the red blood cells to 

form methemoglobin, which lacks the oxygen-carrying ability of hemoglobin. This creates the condition 

known as methemoglobinemia (commonly referred 

to as “blue baby syndrome”), in which blood lacks 

the ability to carry suffi cient oxygen to the individual body cells causing the veins and skin to appear 

blue. Infants under 6 months of age and older persons 

with genetically impaired enzyme systems are unable 

to reduce toxic methemoglobin to oxyhemoglobin. 

Therefore, ingestion of nitrite and nitrate can be fatal 

in these susceptible population groups. To protect the 

susceptible population, EPA has mandated the MCL 

for nitrate to be 10 mg/L (measured as nitrogen) and 

1 mg/L for nitrite (measured as nitrogen). Most individuals over one year of age have the ability to rapidly 

convert methemoglobin back to oxyhemoglobin. 

It is important to recognize that nitrate and nitrite may 

come from sources other than nitrifi cation. It has been 

found that 93 percent of all U.S. water supplies contain 

less than 5 mg/l nitrate, but these values may be changing as a result of the increased use of nitrate-containing fertilizers that enter source waters. Increased use 

of chloramination may also result in higher levels of 

nitrate in drinking waters because of partial nitrifi cation 

in the distribution system. The nitrifi cation process in 

a distribution system can be controlled by utility operators by controlling the presence of ammonia, minimizing the low-fl ow areas in distribution systems and 

controlling the growth of biofi lm that may contain the 

nitrifying bacteria.

5.5 pH Stability and Scale 

Formation 

It is important to maintain a stable pH as part of maintaining distribution system water quality. Excessive 

changes in pH can lead to water quality problems. For 

example, low pH values (less than 7.0) can accelerate 

the internal corrosion of metallic pipes, and can lead 

to leaching of lead and copper in pipes and plumbing 

fi xtures. Therefore, a certain level of scaling in metallic pipes is helpful in passivating the pipe by depositing a protective carbonate layer on it. However, 

higher pH (greater than 9) can cause excessive scale 

formation which can signifi cantly reduce the carrying 

capacity of a pipe and provide a shelter for biofi lm 

growth. Scales in pipes are formed due to the precipi-
5-7

tation of mineral constituents in water onto the pipe 

walls. Scale formation is a complicated process that 

depends on a variety of system-specifi c physical and 

chemical conditions and pH is only one of the factors. 

Scale-forming potential is often measured by the Calcium Carbonate Precipitation Potential or the Langelier Saturation Index (LSI). 

Langelier Saturation Index (LSI) (CD, undated)

In order to calculate the LSI, it is necessary to know the 

alkalinity (mg/l as calcium carbonate [CaCO3]), the calcium hardness (mg/l Ca2+ as CaCO3), the total dissolved 

solids (mg/l), the actual pH, and the temperature of the 

water (°C).

LSI = pH – pHs

Where: pH is the measured water pH and pH is the pH at s

saturation in calcite or calcium carbonate and is defi ned as: 

pH = (9.3 + A + B) – (C + D) s

Where: 

A = (Log10 [total dissolved solids] – 1) / 10 

B = –13.12 x Log10 (°C + 273) + 34.55 

C = Log10 [Ca2+ as CaCO3] – 0.4 

D = Log10 [alkalinity as CaCO3] 

A negative LSI value indicates that there is no potential for 

scaling to occur, the water will dissolve CaCO3. A positive 

LSI indicates that scaling can result from CaCO3 precipitation. An LSI close to zero is the desirable in most cases.

5.6 Contamination Events 

Drinking water distribution systems are vulnerable to 

external contamination from cross-connections, permeation/leaching, intrusion/infi ltration and reservoir/storage facility contamination. These problems are briefl y 

discussed below.

5.6.1 Cross-connections and Backflow

Almost all distribution systems contain locations 

where accidental cross-connections between potable drinking water and non-potable water can occur. 

These cross-connections can provide a pathway for 

backfl ow of non-potable water (i.e., contaminated 

water into potable supplies). Backfl ow occurs either 

because of reduced pressure in the distribution system 

(termed backsiphonage) or due to the presence of increased pressure from a non-potable source (termed 

backpressure). Backsiphonage may be caused by a variety of circumstances, such as main breaks, fl ushing, 

pump failure, hilly terrain, limited pumping capacity, 

high demand by consumers, or emergency fi refi ghting 

water drawdown. Backpressure can occur when heating/cooling, waste disposal, or industrial manufacturing systems are connected to potable supplies and the 

pressure in these external systems exceeds the pressure in the distribution system. In both cases, the direction of water fl ow is reversed, causing non-potable 

and potentially contaminated water from industrial, 

commercial, or residential sites to fl ow back into the 

distribution system through a cross-connection. 

The risk posed by cross-connection and backfl ow can 

be minimized. For example, it can be prevented by 

installing backfl ow prevention devices and assemblies 

and through formal programs to seek out and correct cross-connections within the distribution system. 

Some water systems have programs to identify crossconnections or the potential for cross-connections 

in individual service connections. Some corrective 

measures include activities such as fl ushing and cleaning a distribution system after an incident. 

There is no easy way to detect and monitor for the occurrence of cross-connection and backfl ow. Also, there 

are no national reporting requirements for backfl ow incidents, and no central repository exists for backfl ow 

incident information. Some states have detailed requirements and other states have minimal requirements 

for cross-connection control. The number of reported 

incidents is believed to be a small percentage of the total number of backfl ow incidents that actually occur in 

the U. S. There is a lack of general awareness about 

the threat posed by cross-connections and backfl ow 

through illegal and unprotected taps. PWS operators 

should be aware that there is a potential for intentional 

contamination of a distribution system through such 

cross-connections. 

The extensive scaling has reduced 

the pipe diameter to 20% of design 

capacity. If we adjusted the pH and 

cleaned the pipes, we could meet the 

new demand in this service area.
5-8

5.6.2 Permeation and Leaching 

Permeation of piping materials and non-metallic joints 

is defi ned as the passage of contaminants external to 

the pipe, through porous, non-metallic materials, into 

the drinking water and is generally limited to plastic 

and other non-metallic materials. Volatile organic compounds present in the ground can permeate plastic piping and gaskets. 

Leaching is defi ned 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, metals 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. Vinyl chloride can leach from PVC 

pipe manufactured prior to 1977. The SDWA has established an MCL of 0.002 mg/L (2 μg/L) for vinyl chloride; 

however, no instances of MCL violations have been cited 

in connection with PVC pipe manufactured after 1977. 

Permeated plastic piping must be replaced since the 

piping retains its swollen porous state after permeation. Operators of small PWSs using non-metallic pipes 

should be aware of permeation and leaching problems 

and address them appropriately. Operators should avoid 

placing plastic pipes (mains or service lines) in soils 

and ground water environments that may be contaminated with organic solvents and petroleum products.

5.6.3 Intrusion and Infiltration 

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 valve 

is closed rapidly, it suddenly stops water fl owing in a 

pipeline and the associated pressure energy is transferred to the valve and pipe wall. Similar action can 

occur when a pump is shut off rapidly, as may happen 

with a power outage. Shock waves circulate within the 

distribution system and pressure waves sometimes produce a banging noise as it travels back and forth. A less 

severe form of water hammer is called a surge where 

a slow motion mass oscillation of water is caused by 

internal pressure fl uctuations in the system. If these 

pressure transients are not controlled, they can damage 

pipes, fi ttings, and valves, causing leaks and shortening 

the life of the system. The production of this transient 

low- and negative-pressure creates the opportunity for 

contaminated water to intrude and infi ltrate the pipe 

from outside. Such pressure transients can back-siphon 

environmental water in soil (or fl ooded valve and meter 

pits) into the mains through leaking joints or cracks.

5.6.4 Storage Facility Contamination 

Reservoirs and neglected finished water storage facilities such as reservoirs and tanks can be a dangerous 

source of contamination. When unchecked, animals, 

birds and pests can inhabit and contaminate these facilities. If these facilities are improperly maintained, 

they can quickly spread the contamination throughout 

a distribution system. Storage facilities should be thoroughly inspected on a regular basis.

Storage Tank Contamination (Clark et al., 1996)

In December 1993, a Salmonella outbreak was identifi ed in 

the Gideon, Missouri, municipal water system. This outbreak affected around 486 of the 1,104 residents and caused 

seven deaths among nursing home residents. Ensuing EPA 

investigations supported by other federal, state and local authorities concluded that all the affected residents had consumed municipal water. The investigations revealed that a 

large municipal storage tank was in a state of disrepair with 

bird parts and other fl oating debris which was determined 

to be the source of contamination. During November 1993, 

the residents of Gideon reported objectionable tastes and 

odors in the drinking water supply. The utility superintendent initiated an aggressive and comprehensive fl ushing 

program and fl ushed the hydrants in the system. Unfortunately, the fl ushing program resulted in water being drawn 

from the municipal tank that was severely contaminated 

with Salmonella which dispersed throughout the network. 

This preventive action led to a major waterborne disease 

outbreak. Initially, it was suspected that the sediments in 

the tank owned by the private company also connected to 

the distribution system and was the source of the outbreak. 

However, a pressure test confi rmed that the backfl ow prevention valve connecting the private tank to the Gideon 

network was functioning properly. A modeling analysis 

confi rmed that the earliest reported cases of disease were 

found to be from areas receiving water predominantly from 

the contaminated municipal tank. 

Looks like we have 

a storage facility 

contamination problem!
5-9

Additional Information

Taste, Odor, Flushing, DBP, 

Nitrifi cation and Crossconnection

NESC. Tech Brief: Taste and Odor Control. 2006.

AWWA. Water Supply Operations: Flushing and Cleaning 

- DVD. 2006.

AWWA. Cost and Benefi t Analysis of Flushing. 2004.

EPA. Technologies and Costs for Control of Disinfection 

By-Products. October, 1998

EPA. Nitrifi cation. August 15, 2002.

EPA. Cross-Connection Control Manual. February, 2003.

5.7 SmallWater, USA – 

Water Quality Problem 

Scenarios

Problem #1 DBP Scenario

SmallWater purchases water from another supplier and 

has discovered a compliance problem with DBPs (particularly THMs and HAAs) in its purchased water. The 

supplier chlorinates the water and the long travel time to 

SmallWater and within the SmallWater distribution system frequently leads to the formation of excess DBPs.

Issues to Consider

Elevated DBP levels can be a diffi cult problem to alleviate. This is especially true in this situation where 

SmallWater purchases most of its water from another 

utility and has little control over the source water and 

treatment process. Issues that should be considered include:

• Does the water comply with DBP levels in the 

new Stage 2 DBP Rule?

• If it is not in compliance, what are the primary 

causes for the elevated DBP levels? Potential 

problems could be high levels of DBP 

precursors in the source water coupled with 

insuffi cient or incorrect treatment, long travel 

times for the fi nished water to reach the town, 

and/or excessive travel times from the entry 

points into the town until the water reaches the 

town’s customers. 

Regulatory Guidance

The initial question that SmallWater should address is 

whether or not the elevated DBP levels are due primarily to the characteristics of the source water and treatment. Another question is whether or not excessive water age has led to high levels of DBP formation during 

the time when the water is traveling to SmallWater and 

within the SmallWater distribution system. 

Sampling data showed that THM levels at the point of 

entry to the town were in compliance and typically averaged around 40 to 50 μg/L while samples within the 

SmallWater distribution system frequently exceeded 80 

μg/L and, in some cases, exceeded 100 μg/L. This suggested that THM formation within the town was the primary cause of the elevated DBP levels. A quick calculation of the travel time for the water from the treatment 

plant to the town for the purchased water showed that, 

under average conditions, it took about 20 hours. This 

was compared to the map of maximum water age (from 

the entry points to the town) that the town’s consultants 

produced from their hydraulic model.

Figure 5.3 indicates that maximum travel times within 

the town were typically in the range of 1 to 5 days. This 

far exceeded the 20-hour travel time for the purchased 

water to reach the town. Both the sampling data and 

the travel time calculations clearly indicated that the 

primary problem leading to excessive DBP levels was 

the operation of SmallWater’s water distribution system 

rather than the source water/treatment. SmallWater’s 

consultant was asked to work with the town’s water 

staff to determine operational changes for reducing the 

water age within the town. 

Problem #2 Contamination Scenario

SmallWater has received several sporadic complaints 

over the past year from the residents in the trailer park 

in the southwestern part of town about water that occasionally tastes and smells bad. The water system operator has visited the area on a few occasions and has 

not found any obvious problems. There haven’t been 

any positive coliform samples in the town for the past 

year. Recently, one resident mentioned that both their 

children and elderly mother have experienced severe 

stomach aches. 

Issues to Consider

The patterns of complaints in the trailer park suggest 

that there may be some intermittent contamination 

occurring in the distribution system serving this area. 

Since the complaints are from more than a single residence, it is likely that the location of the contamination 

is in the distribution system itself or possibly within the 

customer’s plumbing that has then migrated through 

the distribution system. Also, since the trailer park is 

served by a single connection to the main part of the 

distribution system, it is likely that the contamination 

usually will stay in the trailer park piping rather than 

move more widely into the distribution system. There 

are no Total Coliform Rule (TCR) sampling sites in the 
5-10

trailer park which may explain why there have been no 

positive coliform readings. 

Regulatory Guidance

The town has fulfi lled the sampling requirements associated with the TCR and has not experienced any 

positive readings. However, the repeated complaints 

within a small area and especially the recent indications 

of possible gastrointestinal illness should alert the town 

to a potential serious problem. SmallTown offi cials 

should contact the state primacy and health agency and 

solicit its assistance. Other activities should include (1) 

a cross-connection investigation in the trailer park area; 

(2) additional coliform sampling in the trailer park area; 

and (3) medical testing of the sick residents for possible 

exposure to disease-causing coliforms such as E. coli. 

Tank

Pump Station

School

Trailer Park

PRV

Reduced Zone

Stand pipe

Industry

Downtown

Well Field

Old Subdivision

New Subdivision

Inter-Connect

Age

24

48

72

96

hours

Figure 5.3 Water Age Within SmallWater, USA
5-11

Crossword Solutions

1) Scales, 2) Brown Red, 3) Green Blue, 4) Sulfur, 5) Backfl ow, 6) Disinfection, 7) Permeation, 8) Cloudy, 9) Water Hammer, 

10) Nitrifi cation, 11) Black Brown

1

2

3 4

5

6

7

8

9

10

11

ACROSS

4 Odor commonly caused by bacteria growing 

in a sink drain

7 Plastic pipes are susceptible to contamination 

from surrounding soils when this occurs

8 Water appearance caused by entrapment of 

air bubbles

9 Shock-waves caused by abrupt changes in 

velocity and direction of water

10 Technical term for process that converts 

ammonia to nitrate in distribution system

11 Water colors associated with manganese or 

other pipe sediments

DOWN

1 Forms due to precipitation of minerals in 

water on to the pipe walls

2 Water colors associated with corroding iron 

pipes

3 Water colors associated with corrosion of 

copper plumbing

5 A result of a cross-connection where 

nonpotable water contaminates drinking 

water distribution system

6 Common technique used for biofilm control 

which can sometimes lead to undesirable 

byproducts

Crossword

Distribution System

Water Quality Issues
5-12
6-1

Chapter 6

Distribution System 

Monitoring, Control, 

and Security

There are many questions that arise when attempting to monitor, control and/or secure a distribution 

system. Some of these questions include the following: 

• What is happening at any moment in the 

underground pipes, elevated tanks, pump 

stations and other components that make up 

the distribution system? 

• Are pressures sufficient to meet customer 

demands, prevent infiltration, and provide fire 

flow? 

• Is there sufficient chlorine residual to protect 

the water in the distribution system? 

• Is there enough water in the tank in case of a 

major fire? 

• Has a contaminant entered the water system 

that could lead to a waterborne disease 

outbreak? 

• When opening a hydrant, how much flow is 

available? 

• Does the distributed water quality meet the 

standards set by EPA and the state regulatory 

agency?

In order to answer these questions with some degree of accuracy and reliability, data must be collected and reviewed periodically by the utility personnel from a variety of sources. If any problems 

are observed, corrective actions must be taken by 

the utility personnel. Utility managers may want 

to consider automated monitoring for operating and 

controlling a distribution system. Automation assists 

in obtaining a continuous set of records that can be 

examined for improving system operations. A distribution system is one of the most vulnerable aspects 

of a water utility because its components are geographically dispersed, making it difficult to ensure 

physical integrity. However, some key distribution 

system components, such as finished water storage 

tanks, can be adequately secured. Automation may 

therefore help improve the overall security of the 

distribution system. This chapter discusses options 

for monitoring, controlling and securing a distribution system.

6.1 Monitoring a Distribution 

System

Monitoring can be broadly categorized as measuring 

the hydraulic state of the water in a distribution system, or measuring water quality parameters. These 

two aspects of distribution system monitoring are 

discussed further in Sections 6.2 and 6.3. Hydraulic 

state monitoring includes: measuring fl ow rate, water 

pressure, velocity and/or water levels within a tank 

or reservoir. Water quality monitoring involves measurement of the intrinsic characteristics of the water. 

For example, a representative sample of water may be 

analyzed for temperature, conductivity, and pH. In 

addition, the water can be analyzed for specifi c water quality parameters such as chlorine residual and 

coliform. 

Specific monitoring procedures may range from simple manual sampling to a highly automated process of 

sample collection and analysis. In manual sampling, a 

water sample is taken from the distribution system and 

is either analyzed in the fi eld (Figure 6.1) or transported for analysis in the laboratory. Automated monitoring typically requires more sophisticated and costly 

equipment, but provides savings in labor costs and the 

added benefi t of a greater number of measurements. 

Historically, small water utilities have generally relied 

upon manual sampling procedures in order to avoid the 

capital investments associated with automated equipment. However, as technology costs decrease, there 

are many cases where automated monitoring equipment is cost-effective for smaller utilities. Figure 6.2 

shows an example schematic of an automated sampling 

unit that measures and analyzes the sample in the fi eld 

and sends the information back to a central offi ce for 

assessment.

Doc, the sampling guide said to grab 

a sample and store at 39°F

t-t-til the t-t-time of analysis!
6-2

Figure 6.1 Manual Water Quality Sampling and Field 

Testing

Figure 6.2 Automated Water Quality Monitoring 

(GCWW, 2007)

Since monitoring activities are expensive, they are usually performed to meet a specifi c objective or multiple 

objectives. These objectives may include:

• Regulatory requirement – Taking samples of 

water to determine if it meets the requirements 

established by federal or state agencies

• Process control requirement – Providing realtime information that assists in operating the 

system

• Baseline data collection – Establishing normal 

ranges for data values from the system

• Contaminant identifi cation – Detecting the 

presence of a contaminant that has intentionally, 

accidentally or naturally entered the water 

system

• Computerized model calibration – Collecting 

hydraulic or water quality data to be used in 

adjusting a hydraulic and/or water quality model 

of the distribution system

• Improving system performance – Collecting 

real-time information that may be used to 

understand and improve system performance

In the following sections, various available options for 

distribution system state and water quality monitoring 

are discussed. 

6.2 Distribution System Hydraulic 

Monitoring

As water moves through a distribution system and its 

various components, hydraulic characteristics such as 

fl ow, velocity, and pressure change over time. In order 

to understand a system’s operation, to identify potential 

problems, or to operate the system more effi ciently, it is 

useful to monitor these characteristics. Measurements 

may be made continuously at key locations using automated monitors (if affordable) or be measured manually 

at selected locations and times. 

6.2.1 Flow and Velocity Monitoring

Flow is an important factor in understanding the operation of a distribution system. Low fl ows in some pipes 

may indicate a constriction or closed valve. High fl ows 

can result in high velocities which cause large friction 

losses and even damage to the pipe. Water sold to customers is typically billed based on fl ow. Therefore, understanding fl ow is important to the proper operation and 

maintenance of a water distribution system. 

Meters are used to measure fl ow rates and velocities in 

an open channel or closed pipe. They may be permanently placed in the distribution system or in a treatment 

plant to provide continuous measurements. They may 

also be temporarily installed as part of a testing program 

to provide measurements over a period of a few days 

or weeks. They may also be used manually to measure 

fl ow from a hydrant as part of a system calibration or fi re 

fl ow analysis. Flow meters can provide continuous fl ow 

measurements and/or totalized volumes over a period 

between readings. 

There are several different types of fl ow meters. Most 

meters can be broadly classifi ed based on the following 

operating principles: differential pressure, positive displacement (PD), velocity measurement and level measurement. Differential pressure meters and velocity meters 

are most commonly used in the water industry. Within 

each of these categories, there are alternative methods for 

achieving these measurements. Table 6.1 illustrates several different types of fl ow meters and the basic principle 

upon which each is built. More detail on the limitations 

and advantages of each type of meter can be found in 

American Water Works Association’s (AWWA’s) M33 

Manual of Water Supply Practices “Flowmeters in Water 

Supply” (second edition published in 2006). 
6-3

Table 6.1 Flow Meters (Partially adapted from AWWA, 2006b) 

Meter Type Diagram Principles of Operation

Venturi Meter A constricting section is placed in the pipe causing 

an increased velocity and corresponding pressure 

drop. Pressures are measured at the upstream end 

of the constriction and within the constriction. Flow 

is calculated from the square root of the measured 

pressure differential multiplied by a meter factor 

that accounts for dimensional units and discharge 

coeffi cient.

Turbine and Propeller In turbine and propeller fl owmeters, fl owing water 

Meters strikes rotor blades that rotate at a rate proportional 

to the fl ow velocity. The turbine wheel of a turbine 

meter generally fi lls the cross-section of the pipe 

and is mounted to spin freely between two central 

bearings supported in the pipe wall. The propeller 

of a propeller meter is mounted on bearings at the 

downstream end of the pipe and does not fi ll the 

meter cross-section.

Transit Time Ultrasonic A pair of transceivers is positioned diagonally across 

Flow Meter the meter body. The transceivers transmit and receive an ultrasonic pulse in the direction of fl ow, followed by a return pulse against the direction of fl ow. 

The time difference between the two pulse transmissions through the stream is a function of fl uid velocity and, by computation, the rate of fl ow. 

Averaging Pitot Flow Multiple ports in an insertion tube face upstream 

Meters into the fl ow to provide sampled pressures at 

selected points along the vertical pipe diameter to 

provide an averaged pressure over the pipe crosssection while ports facing downstream register 

static pressure. The device produces a differential 

pressure reading which is used to calculate velocity 

(proportional to the square root of the pressure 

differential).

Insertable Averaging Multiple magnetic fi elds are generated by electroMagnetic Flowmeter magnetic coils placed inside a sensor inserted in 

the pipe section through a tap connection. Water 

passing around each sensor encounters the magnetic fi eld, which induces a small electric charge 

that is proportional to the velocity of the water in 

the magnetic fi eld. The electric charge is sensed by 

multiple pairs of electrodes in contact with the water 

adjacent to each of the electromagnets. Each coil 

and pair of electrodes becomes an electromagnetic 

velocity sensing point along the sensor.

Variable Area Flow Also known as a rotameter, the area through which 

Meter the liquid fl ows is permitted to vary so that a constant differential pressure is maintained. The basic 

elements are a vertical conical tube and a cylindrical fl oat that is free to rise and fall in the tube. The 

greater the entering volumetric fl ow, the larger the 

required fl ow through area, and the higher the fl oat 

rises. Therefore, the rise of the fl oat is proportional 

to the rate of fl ow.
6-4

Flow measurements may also be taken at hydrants 

and used to estimate fi re fl ow availability (or as part 

of a distribution system model calibration study). Pitot 

gages are typically used to measure hydrant fl ow and 

are available in three forms: hand held, clamp-on, or in 

combination with diffusers (see Figure 6.3). They are 

all based on the principle that virtually all of the velocity head in the hydrant fl ow is converted to pressure head 

that is read by the pitot gage. Pressure measurements 

can then be converted to hydrant discharge rates based 

on the diameter of the hydrant port, the characteristics 

of the port and the specifi c instrument.

(a) Hand-held

(b) Clamp-on

(c) Integrated with diffuser

Figure 6.3 Hydrant Flow Gages

Water Meters and Automation

Positive displacement (PD) water meters are normally 

used to measure usage in residences and commercial 

buildings. Other types of fl ow meters can also be used 

at specifi c locations in a distribution system to determine 

fl ow through that portion of the system. These fl ow meters utilize a variety of fl ow measurement methods and are 

generally selected for specifi c use based on the type of end 

user, the required fl ow rates, and accuracy requirements.

PD meters employ oscillating pistons or a nutating disk to 

measure fl ow. Both methods rely upon the physical displacement of the measuring element in direct relation to 

the amount of water passing through the meter. The piston 

or disk moves a magnet that drives the register. PD meters 

are generally very accurate at low to moderate fl ow rates 

typical of residential and small commercial users, and are 

common in sizes from 5/8 to 2-inch pipe-size. However, 

this measuring methodology is not practical in large commercial applications that experience high fl ow rates or low 

pressure loss. A velocity type meter is commonly employed for higher fl ows where the velocity is converted 

into volume. Common velocity-based meters include: jet 

meters (single-jet and multi-jet), turbine meters, propeller 

meters, and magnetic meters. 

Manufacturers have now developed pulse or encoder registers to produce electronic output for radio transmitters, 

reading storage devices, and data logging devices that 

are employed with Automatic Meter Reading (AMR). In 

AMR technology, the usage data is automatically collected 

from customer water meter and transferred to a central database for billing and/or analyzing. AMR systems provide 

customers and utilities a more accurate way of tracking 

and billing of actual water usage rather than depending 

on a fl at rate system or an estimate. AMR technologies 

include handheld, mobile and network technologies based 

on wired, wireless, or radio frequency transmission.

6.2.2 Pressure Monitoring

Pressure measures the amount of internal energy within 

water at any location in the distribution system. Most 

importantly, pressure serves as an important indicator of 

how a water system is operating and is closely related to 

hydraulic integrity. Routine low pressures in a distribution system indicate design defi ciencies or operational 

problems in the system. Unusually low pressures may 

indicate a problem such as a main break, closed valve 

or low water levels in a tank. Therefore, pressure is 

frequently monitored to assess system operation and 

integrity.

Pressure can be monitored continuously using pressure meters installed in the system or can be measured 

manually at hydrants or any faucet in the distribution 
6-5

system. Permanently installed continuous monitors 

are frequently connected to a Supervisory Control and 

Data Acquisition (SCADA) system (See Section 6.4 

for an overview on SCADA and automation). These 

pressure values are transmitted to a central control 

room. Pressure meters may also be used to measure 

tank water levels. Figure 6.4 shows a pressure gage 

attached to a fi re hydrant. Figure 6.5 shows typical 

SCADA readouts of the distribution system hyraulic 

measurements.

Figure 6.4 Digital and analog pressure meter attached 

to fi re hydrant

Figure 6.5 Readout meters for fl ow, water level and 

pressure from a SCADA system

6.3 Distribution System Water 

Quality Monitoring

Water utilities strive to deliver water that meets or 

is better than the Safe Drinking Water Act (SDWA) 

standards and is aesthetically acceptable. Other goals 

may include minimizing treatment costs and delivering a product that is consistent in quality for all uses. 

Water quality monitoring serves as the mechanism for 

measuring how well the utility meets these goals and 

may serve multiple purposes including: 

1. Satisfying regulatory compliance requirements

2. Assisting in process or operational control

3. Identifying contaminants in the water

4. Characterizing the water quality for use in future 

decisions

Because water quality monitoring can be expensive, 

most small utilities emphasize its use only in meeting 

regulatory compliance requirements. However, additional monitoring can frequently pay off in terms of 

an improved product and lower treatment and chemical costs. Routine or automated online monitoring can 

also assist in screening for the possible occurrence of: 

loss of disinfection residual, pathogen contamination, 

disinfectant byproduct formation, nitrifi cation, metal 

accumulation, and intentional (e.g., terrorist) contamination.

Design of a monitoring or sampling program involves 

the following decisions:

1. What constituents should be monitored?

2. Where should the monitoring locations be 

placed?

3. What type of sampling (continuous, composite 

or grab) should be employed?

4. How often should sampling occur?

5. What type of analytical procedures should be 

used?

6. Is the sampling routine, seasonal, or being 

conducted for a special study?

My dad put automatic water meters and 

valves throughout the house and the 

shower shuts off after 15 gallons use!
6-6

For compliance monitoring, the answers to most of 

these decisions are spelled out in the regulations and 

operating permits. However, for other types of monitoring, the water utility is responsible for designing the 

monitoring program that meets its specifi c needs and 

fi ts within its budget.

6.4 Controlling a Distribution 

System

The smaller utilities have historically limited the use 

of SCADA to control the treatment process. However, 

SCADA is routinely employed by larger utilities to monitor and control distribution system operations. A SCADA 

system consists of three components: instrumentation 

and hardware, a software program or operator interface, 

and communication media. In the past, most small systems could not afford SCADA systems because the initial 

equipment cost was high and it required a highly trained 

technical person to effectively operate the SCADA on a 

routine basis. However, with more sophisticated technology updates, costs have become more reasonable. Furthermore, the degree of sophistication (and customization of the programming) allows for a less skilled person 

to operate the system effectively. The implementation 

of appropriate automation and control technology (e.g., 

SCADA) can greatly enhance operations and maintenance activities for small utilities. The key components 

of SCADA systems, along with some basic selection criteria, are described in the following subsections.

6.4.1 SCADA Instrumentation and Hardware

Instrumentation and hardware are generally the most 

expensive components of a SCADA system. In order 

for an instrument to be connected to a SCADA system, 

it must generate an output signal that the SCADA can 

read. Sophisticated monitoring instruments generally 

have a local display and an optional standard external 

analog or digital output. The analog output is usually a 

direct current output of 1 to 5 volts or 4 to 20 milliamperes which can be interfaced with standard SCADA 

input/output (I/O) hardware. Through calibration, this 

signal can then be directly related to the instrument 

reading, such as chlorine concentration in milligrams 

per liter or turbidity in nephelometric turbidity units. 

Similarly, a pump’s operating state would have a predefi ned digital output (e.g., 1 or 0) where the value returned would directly correspond to the operating state 

of the pump (i.e., 1 = off and 0 = on, or vice versa).

Information also travels in the opposite direction 

through the SCADA system. In this case, the central 

system sends an analog or digital signal to the instrument in order to initiate some action by the instrument. 

The digital signals are used to control all system components from relays to motor starters. The analog signals are used to control variable frequency drives and 

other variable speed pumps and motors. 

The analog and digital I/O values are aggregated, computed and communicated by fi eld SCADA devices such 

as programmable logic controllers or micro-processor 

based remote terminal units (RTUs). Field RTUs may 

be connected to other master RTUs or computing devices such as a personal computer that contains customized 

software which provides the human machine interface 

or the SCADA operator interface. The cost of the RTUs 

can range between $200 and $20,000, depending upon 

the features and complexity desired. 

6.4.2 SCADA Operator Interface

The price of commercially available customizable 

SCADA software usually depends on the number of 

I/O channels licensed for use along with the number 

of computers or workstations from which the system is 

operated. The cost of SCADA software has decreased 

Honestly ma’am, the computer 

virus ate our monitoring and 

compliance records!

Would we be able to send an alarm to 

our vendor when the cookie supplies are 

running low on the vending machine?
6-7

over the past few years and the ease of customizing 

SCADA software has improved dramatically. The most 

sophisticated packages, designed to work with a variety 

of hardware, are relatively expensive (between $1,000 

and $20,000 for a utility with I/O channels numbering 

between 50 and 1,000) and generally require a trained 

programmer for the initial setup. For less complicated uses, such as by a small water utility with minimal 

staffi ng, a package arrangement (where the software 

is included with the hardware and basic programming 

setup) is usually suffi cient.

6.4.3 Communication Media

Generally, SCADA equipment that is located within 

a treatment plant is hard-wired. Distribution system 

components, such as tanks and pumps that are scattered 

throughout the distribution system, need alternative 

communication media such as leased lines or wireless 

transmission capability. Small systems that are relatively compact should explore the use of standard industrial wireless radio modem connectivity where possible. Other hard-wired and wireless options available 

to commercial carriers (such as the phone company) 

require a monthly fee that may range between $20 and 

$200 per month, depending upon the selected solution 

and required data bandwidth requirement. Table 6.2 Cost of SCADA Implementation at 

Coalwood, WV.

Computer, Instrumentation, Software, and $6,000

Upgrades

Communication Modem and Phone Line $1,000

Data Collection and Transportation Terminal $5,200

Instrumentation for Monitoring and Control $21,000

Setup and Installation $1,800

Total Capital Cost $35,000

Remote Monitoring – Coalwood, West Virginia (EPA, 2003d)

In 1992, EPA, in collaboration with the McDowell County Public 

Service District (MCPSD), installed a prefabricated semi-automated ultrafi ltration (UF) drinking water treatment package plant 

in Coalwood, West Virginia (WV). The UF system was located 

approximately 12 miles from the MCPSD offi ce in the Appalachian Mountains. The UF system has been in operation since 

1992, and has been providing water of good quality to the community. However, upon completion of the two-year project, it became apparent that the MCPSD would be unable to meet the WV 

Department of Health monitoring and reporting guidelines. These 

regulations require that the treatment operator(s) maintain daily 

records of specifi c operating and treatment parameters. Routine 

monitoring of the water distributed from the UF treatment process 

was resulting in signifi cant costs for associated time and travel. 

Furthermore, during inclement weather conditions, completion 

of these routine tasks became extremely diffi cult. Similar monitoring requirements at other remotely located sites also required 

MCPSD to dedicate a considerable amount of staff time to complete these routine tasks. Therefore, in 1998, the EPA extended 

the research project by installing and testing an off-the-shelf userfriendly Windows-based SCADA system. The SCADA system 

selected was fairly inexpensive, smart, user-friendly and scalable. 

The total cost for the hardware and software for setting up the 

SCADA system at the WV test site was $35,000. Table 6.2 provides a breakdown of the SCADA system costs:

The remote capability allowed the utility to save on labor and 

mileage for performing daily monitoring. A simple cost-benefi t 

(return-on-investment) analysis showed the advantages of such 

a system. The site was approximately 24 miles round trip from 

MCPSD headquarters and it took the operator one hour per day to 

perform this task. The annual labor savings (based on an operator 

labor rate of $15/hour) amounted to: $15 per hour X 1 hour/day 

X 365 days/year = $5,475. In addition, the vehicle cost savings at 

the rate of $0.40 per mile amounted to: $0.40 per mile X 24 miles/

day X 365 days/year = $3,504. In total, a minimum of $8,979 

in annual savings to the utility was achieved immediately for 

this site. A direct payback, based on cost savings to satisfy daily 

monitoring requirements, was achieved in less than 4 years. This 

simplifi ed cost model was based on direct operating costs only 

and assumed that the cost of upkeep of monitoring instrumentation was similar to other laboratory devices used by the operator. Additional benefi ts included the ability to maximize the effi -

ciency of the water treatment operations, creation of an advanced 

knowledge of the systems condition prior to performing any site 

visits for troubleshooting and repair, improving the security of the 

system, and improving regulatory monitoring compliance.

6.4.4 Selection of SCADA Systems

If a small system operator is considering the installation 

of a new SCADA system, the following factors should 

be carefully considered:

• Does the treatment and distribution system 

justify the need for a SCADA system (is 

it spatially dispersed and are its various 

components diffi cult to access)?

• Is the treatment plant and the distribution system 

amenable to automation? 

• What types of communication media can be 

used (phone, radio, cellular, etc.) at the critical 

locations in the system?

• How much existing automation and control 

instrumentation is available in the system that 

could be incorporated into the SCADA system?

• What type of SCADA system is needed (is the 

goal to monitor and /or control operations)?

• How many parameters need to be monitored 

and/or controlled?

• Are there any specifi c regulatory monitoring and 

reporting requirements that can be met by using 

a SCADA system?

• Can the selected SCADA system be made 

compatible with existing or future use of AMR?
6-8

• Can the SCADA system be classifi ed as a capital 

improvement project and acquired through 

outside sources of funding such as grants and 

interest-free loans?

• What is the return-on-investment or labor cost 

savings resulting from installing a SCADA 

system? 

Considering these factors will help a utility determine 

the need, affordability, and the basic design of a SCADA 

system. These factors will also help to determine if the 

SCADA system will complement general utility operations. Retrofi tting a treatment and distribution system for 

a SCADA system can be cost-prohibitive because many 

currently operating small utilities were not originally designed for remote operations. Therefore, they have little or no existing electronic instrumentation or hardware 

that can be integrated into a SCADA system, and the cost 

of upgrading the utility for remote operations could be 

signifi cant. It is essential that a cost-benefi t analysis be 

performed prior to such implementation. 

6.5 Securing a Distribution System

The Public Health Security and Bioterrorism Preparedness Act of 2002 mandated that drinking water utilities 

serving more than 3,300 persons conduct vulnerability 

assessments (VAs) and develop emergency response 

plans (ERPs). EPA provided funding or training assistance to utilities to assist in compliance with the 

Act. The compliance schedule was staggered based 

on system size. The last scheduled date for preparing 

a certifi ed ERP was December 31, 2004, for systems 

serving between 3,300 and 50,000 persons. For systems serving fewer than 3,300 persons, EPA developed 

a guidance document titled, “Drinking Water Security 

for Small Systems Serving 3,300 or Fewer Persons.” 

There are a variety of guidance documents and tools 

available on the Internet for addressing small systems 

security that were collaboratively developed and funded by a variety of organizations including: EPA, state 

environmental agencies, Department of Homeland Security, National Rural Water Association, and the Rural 

Community Assistance Program. Small water utilities 

are strongly encouraged to use these sources as much 

as possible.

The VA process identifi es the critical water utility assets that may be subject to potential threats. If these 

assets are successfully targeted, the consumer’s health 

could be compromised or there could be severe infrastructure and economic damage. The ERPs address the 

risks associated with these vulnerabilities and contain 

procedures that eliminate, minimize, and/or manage 

these security breaches. An overview of distribution 

system vulnerabilities, operational and emergency response mechanisms is presented in the following subsections. 

6.5.1 Distribution System Vulnerabilities

Distribution systems and their components are vulnerable to two types of attacks. In one scenario, the system 

component could be physically destroyed or disabled; 

in the other scenario, the component may be contaminated with a chemical and/or biological threat agent. In 

Our security budget only had 

enough money to buy these signs. 

Go ahead and post them... they 

might discourage the vandals.

Under this new water rate plan, anyone can reduce 

their current water bills by 10%... if they take 

showers and cook during off-peak hours!
6-9

addition to security threats, distribution system components are vulnerable to aging and corroded pipes. Pipes 

located below the water table provide an opportunity for 

intrusion of water and contaminants (e.g., animal and 

human wastes) if low or negative pressure conditions 

occur. Maintaining the hydraulic integrity (positive 

pressure) of a water distribution system is important, 

given that insuffi cient pressure can lead to infi ltration 

or backfl ow through cross-connections (see Chapter 

5). Infi ltration or backfl ow can occur during fl uctuating 

water use patterns (e.g., fi re prevention activities/fi re 

hydrant use, power outages, and fl ushing exercises). 

Post-treatment contamination can occur during the storage of drinking water. Storage facilities are particularly 

vulnerable to contamination due to the failure of protective covers or barriers, or open hatches and vents. 

Birds, insects, animals, rain, and microorganisms can 

even contaminate covered fi nished water storage tanks. 

Routine inspections and maintenance are necessary to 

address this vulnerability.

6.5.2 Operational and Emergency Response 

Mechanisms

EPA strongly recommends that utilities develop a formal ERP that contains the following eight core elements:

1. System-Specifi c Information – At a minimum, 

identify the utility staff and contact person(s) 

with the location of critical documents, such as 

distribution system maps, as-built drawings, site 

plans, source water locations, current equipment 

inventory and operations manual(s).

2. Community Water System Roles and 

Responsibilities – The plan should designate an 

Emergency Response Lead with an alternate. 

This person should be designated as having 

the responsibility for evaluating incoming 

information, managing resources and staff, and 

deciding on appropriate response actions. This 

person should also have the lead responsibility 

of coordinating emergency response efforts with 

fi rst responders.

3. Communication Procedures: Who, What, 

and When – The plan should clearly identify 

communication channels for utility staff and 

personnel, external non-utility entities (such as 

other city, state and federal agencies), and the 

public/media. The plan should contain internal 

and external notifi cation lists with information 

on all appropriate entities to be contacted, 

including their names, titles, mailing addresses, 

e-mail addresses, all applicable land line and 

cellular phone numbers, and pager numbers. 

These lists should be updated as necessary.

4. Personnel Safety – During an emergency, 

personnel may be at risk of harm, injury, or 

even death. Therefore, protecting the health 

and safety of the utility, fi rst responders, and 

the surrounding community should be a key 

priority. An ERP should provide direction to 

personnel on how to safely implement a variety 

of response actions.

5. Identifi cation of Alternate Water Sources – The 

plan should contain information on the amount 

of water needed to address both short-term 

(hours to days) and long-term (weeks to months) 

outages. The ERP should identify potential 

alternate water supplies that can be quickly 

mobilized during both types of outages.

6. Replacement Equipment and Chemical Supplies 

– The plan should identify the location of the 

current equipment inventory that contains the 

listing of equipment, repair parts, and chemicals 

that would be needed to respond adequately 

to a particular vulnerability. The utility should 

consider establishing mutual aid agreements 

with other nearby water utilities to address any 

defi ciencies. These agreements should identify 

the equipment, parts, and chemicals available to 

the utility under the agreement.

7. Property Protection – Protecting the utility 

facilities, equipment and vital records at the 

utility is essential to restoring operations once 

a major event has occurred. Therefore, the 

ERP should identify measures and procedures 

that include: “Lock down” procedures; access 

control procedures; establishing a security 

perimeter following a major event; evidence 

protection measures for law enforcement 

(should the major event also be declared a crime 

scene); securing buildings against forced entry; 

and other property protection procedures and 

measures.

8. Water Sampling and Monitoring – The ERP 

should clearly identify water sampling and 

monitoring requirements. To the extent 

possible, the ERP should identify and address 

special water sampling and monitoring issues 

that may arise during and after a major event. 

Some water sampling and monitoring issues to 

consider include: identifying proper sampling 

procedures for different types of contaminants; 

obtaining sample containers; determining the 

quantity of required samples; identifying who 

is responsible for taking samples; identifying 

who is responsible for transporting samples (in 

time-sensitive situations); confi rming laboratory 

capabilities and certifi cations; and interpreting 

monitoring or laboratory results.
6-10

An ERP containing these eight core elements provides 

the necessary information to effectively coordinate and 

respond to an emergency event. In addition, the utility staff should be trained on procedures and conditions 

that necessitate the activation of the ERP. Thereafter, 

operational actions must be implemented to identify the 

source of contamination, to isolate the source (if possible), and to determine the operational changes necessary for containing the damage to public health and the 

distribution system. Finally, steps must be undertaken 

to discharge or transport the contaminated water to a 

location where it can be effectively treated for disposal. 

An ERP should be viewed as a “living document” that 

is frequently updated as changes are made in the system, its operation and its personnel. 

6.6 SmallWater, USA – 

Monitoring, Control 

and Security Problem 

Scenarios

Problem #1 Monitoring and Control

Water samples from the distribution system indicate 

that SmallWater has had trouble maintaining residual 

chlorine levels in the distribution system. Residual 

chlorine levels were frequently near zero at the most 

distant locations (supplied by the elevated tank) in the 

distribution system. SmallWater is considering booster 

disinfection at the tank and installing a continuous chlorine monitor to collect data for optimal disinfectant dosage and to control the chlorine dosage rate.

Issues to Consider

Maintaining adequate residual disinfectant levels is essential from a compliance perspective and to ensure 

a safe water supply. However, the cost of installing a 

booster chlorine station and an online chlorine monitor 

with an analyzer can be quite costly. Costs may range 

between $1,000 and $2,000 for the monitor and connecting it to a SCADA interface to control the booster 

dosage of chlorine will require additional funds (new 

SCADA remote terminal unit ~$2,500, installation and 

testing ~$3,000). Additional funds are required for the 

chlorine storage unit and the injection pump.

Guidance

In order to take better advantage of the costs associated with the booster chlorination station, other uses of 

the SCADA at this location should be investigated. The 

utility may achieve some operational effi ciency if the 

operation of the tank can be optimized by using the tank 

level indicators and integrating them with the SCADA 

system for booster chlorination. Understanding tank hydraulics and mixing processes within the tank and their 

potential impact on loss of chlorine residual may result 

in further effi ciencies and better performance. Online 

residual chlorine data are also useful if there is a great 

deal of variation in the regular weekday, weekend and 

seasonal data.

Problem #2 Security Scenario

Security at the elevated tank has been an ongoing issue. 

The tank property is not fenced and has been broken 

into several times. Birds, animals and insects have periodically contaminated the tank and dead species have 

been found in traps at access locations.

Guidance

First and foremost, the tank access must be physically 

secured. Barriers (e.g., doors, wire mesh or iron bars) 

and locks must be placed on all hatches, vents, gates, 

and other points of entry to prevent access by unauthorized personnel, birds, animals and insects. Dead 

bolt locks and lock guards are fairly inexpensive and 

provide additional security at minimal cost. A daily 

check of critical system components enhances security 

and ensures that there has been no unauthorized entry. 

Doors to critical facilities, and their hinges, should be 

constructed of heavy-duty reinforced material. Hinges 

on all outside doors should be located on the inside.

To further enhance security, SmallWater should consider installing access alarms on all points of entry utilizing the SCADA system (see Problem #1). Integrating 

SCADA with security and monitoring/compliance requirements is extremely cost-effective. 

We only have $100 in our emergency 

communications budget but I got a 

great deal on 5 miles of string.
6-11

Crossword Solutions

1) Monitoring, 2) PD, 3) ERP, 4) Differential, 5) Eight, 6) Ultrasonic, 7) SCADA, 8) Lockdown

1

2 3

4

5

6

7

8

ACROSS

4 Type of commonly used pressure-based 

flowmeter

6 Flowmeter using sound waves to measure 

flow

8 A term for protecting utility property from 

tampering

DOWN

1 Term for periodic measurement of water 

quality in distribution system

2 Abbreviated term for most commonly used 

water meters for residential applications

3 Acronym for a plan to address risks associated with vulnerabilities

5 Recommended number of core elements of 

an Emergency Response Plan

7 Acronym for Supervisory Control and Data 

Acquisition System

Crossword

Distribution System Monitoring, 

Control, and Security
6-12
7-1

Chapter 7 

Strategies to Address 

Distribution System 

Water Quality Issues

In the U.S., a concept called the “multiple barrier approach” (as discussed in Chapter 2) has been applied 

widely to drinking water treatment. This includes the 

use of both disinfection and fi ltration to treat surface 

water prior to supplying it to the consumer. However, 

under the Safe Drinking Water Act (SDWA) and its 

amendments, this concept has been expanded by EPA to 

include source water protection and distribution system 

integrity. The 1996 Amendments to the SDWA emphasized source water protection; more recently, EPA has 

focused on drinking water distribution systems. The 

most recent “report card” issued by the American Society of Civil Engineers addressing the nation’s drinking water infrastructure reveals that distribution system 

infrastructure improvements will require a tremendous 

investment if they are to provide an effective barrier in 

protecting the nation’s drinking water. 

Many small- and medium-sized distribution systems 

built prior to World War II (especially those serving rural areas) have received little or no recent capital investment. Some of these systems are facing water quality 

problems that are associated with aging infrastructure. 

In addition, some utilities are experiencing a higher 

rate of pipe failures and problems with specifi c pipes 

manufactured during a certain period of time, or when 

they are subjected to certain environmental conditions. 

Common problems include: corrosion, biofi lm growth, 

frequent breaks and leaks, and diffi culty in minimizing disinfectant loss and disinfection byproduct (DBP) 

levels. Cross-connection and backfl ow issues are also 

frequently observed in these systems. To address these 

issues and fi nd long-term solutions, small- and medium-sized utilities need to step back from a “crisis management mode” and engage in strategic planning. For 

example, when a water quality problem is discovered 

and the cause isolated, the utility must address immediate problems related to public health. However, utility mangers should also explore strategies that address 

long-term issues. Some of these changes may require 

long-term, phased infrastructure investment. This chapter provides an overview of these operational, fi nancial 

and management strategies.

7.1 Operational Strategies

Operational changes are generally less expensive and 

easier to implement than changes that require signifi -

cant infrastructure investment. For example, if DBPs 

are an issue, the utility should consider actions that 

minimize DBP formation in the distribution system. 

The utility might consider reducing water age and/or 

changing disinfectants (e.g., chlorine to chloramine) or 

both. Switching disinfectants to chloramine will likely 

require some capital investment. In some cases, these 

operational changes may only provide temporary relief 

and eventually an infrastructure investment may be necessary. The utility may need to fi nd an alternative source 

of water or treat the water in such a way as to lower 

the total organic carbon (TOC) content in the fi nished 

water. A summary of available operational strategies 

is presented in the following sections of this chapter. 

Some of these operational strategies are not presented 

in detail here as they have been previously described 

within various chapter-specifi c problem scenarios (see 

Chapter 4 and 5).

7.1.1 Reducing Water Age in the Distribution 

System

There are several indicators of excessive water age including: taste and odor complaints, discoloration, low 

disinfectant residual concentration, elevated DBP level, 

elevated bacterial count, and elevated nitrite or nitrogen 

levels. “Old” water, especially in warm environments, 

promotes the growth of microorganisms. Such microorganisms impart taste and odor issues or enhance nitrifi cation. Low-fl ow and dead-end areas within a distribution system generally accumulate sediments; during 

high-demand periods, these sediments may be stirred 

up, resulting in discolored water. 

From an operational perspective, tanks, valves, main 

size and pumping rates have a direct impact on water 

age. Finished water storage facilities may exhibit poor 

mixing conditions because tank turnover is limited by 

minimum fi re-fi ghting capacity requirements. Tank 

mixing can also be optimized either by cycling the tanks 

periodically or installing mechanical devices, such as 

Ah! here is the quarterly compliance 

report for SmallWater. I knew they 

were cutting back on mail costs.
7-2

diffusers and nozzles to achieve higher velocities which 

results in better mixing. Valve settings and pumping 

rates determine water velocities and fl ow direction. Velocity, in turn, impacts hydraulic pathway and retention 

time. In some cases, operators can adjust system pressures and position the valves in such a way as to induce 

fl ow within the distribution system in a direction that 

can minimize water age. The utility can also initiate 

fl ushing programs to displace “old” water. 

7.1.2 Adapting Operations to Meet System-

 Specific Water Demands

Water demand is a driving force that affects all public 

water system (PWS) operations. However, water demands vary signifi cantly and system operators must 

have a good understanding of the amount of water being used, where it is being used, and how this usage 

varies with time. For example, for most PWSs, the 

ratio of daily average to daily maximum water demand 

ranges from 1.2 to 3.0, and the ratio of the daily average to the peak hourly demand ratio may vary between 

3.0 and 6.0. Seasonal variations may make these ratios even more extreme. Fortunately, these demand 

values are system-specifi c and can be quantifi ed based 

on experience. Demands are generally classifi ed as 

follows: 

• Baseline demands - Corresponds to consumer 

demands and unaccounted-for water associated 

with daily average operating conditions.

• Seasonal Demand - Water use typically 

varies over the course of the year with higher 

demands occurring in the warmer months, due 

to watering of lawns and recreational use (e.g., 

swimming pools).

• Fire demands – Typically, the most important 

consideration for water system design.

• Diurnal (daily) demand variations - 

Continuously varying demands which are 

inherent in a PWS and typically increase during 

the daytime hours.

As discussed previously, water distribution systems are 

basically a networked conveyance mechanism in which 

pumps move water through the system, control valves 

allow water pressure and fl ow direction to be regulated, and storage facilities such as reservoirs and tanks 

smooth out the effects of fl uctuating demands (fl ow 

equalization). Storage facilities also provide reserve 

capacity for fi re suppression and other emergencies. 

Generally, pumping operations are optimized based on 

cost of electricity and demand requirements. A utility 

might consider operational changes based on overriding demand type in an attempt to minimize water age. 

For example, a storage tank might normally be cycled 

to only 50 percent of its capacity because of fi re-fi ghting needs. The utility could consider a change in strategy in which it cycles the tank to utilize 65 percent of 

its capacity and then make arrangements to meet the 

additional 15 percent fi re-fi ghting demand from alternate sources such as other tanks, or even the purchase 

of bulk water from a nearby utility.

7.1.3 Changing Disinfectants

If DBP formation or nitrifi cation is a problem, the utility could consider switching disinfectants on a periodic 

or permanent basis. For example, a drinking water utility that normally uses chloramines might temporarily 

switch to free chlorine as a preventative nitrifi cation 

control measure. This switch to chlorination would be 

accomplished system-wide by simply turning off the 

ammonia feed facilities. However, to switch to free 

chlorine in an isolated pressure zone or storage facility, enough chlorine must be added to exceed the breakpoint and thereby achieve a free chlorine residual. If 

strategies such as adjustments in chlorine to ammonia 

ratio, increased turnover, or fl ushing have not solved 

the problem, breakpoint chlorination is a commonly 

utilized approach in storage tanks.

Utilities that normally chlorinate could consider a temporary switch to chloramines. Recently, many utilities 

have switched from chlorine to chloramines because 

chloramines are more stable and associated DBP formation is lower. Whether disinfectant changes are long- or 

short-term, utilities should be aware that these changes 

may have implications for protecting public health, especially during an intrusion event. Chloramine is a less 

powerful disinfectant than chlorine and may be inadequate for protection against microorganisms entering 

the distribution system. Giardia cysts and enteric viruses 

are known to be less easily inactivated by chloramines 

than chlorine. However, any signifi cant intrusion event 

Hold it, young drop... this is a “dead-end” of 

the distribution system; I have been here for 

almost 8 days now — that is roughly 120 in 

water droplet years, so I’m next to be used!
7-3

will likely overwhelm either types of residual disinfectant. In addition, the utility should inform dialysis 

centers that chloramines are being used so that they can 

have their water treatment system enhanced to remove 

chloramine. In addition to chloramines, other substances found in tap water can also interfere with dialysis. 

For example, copper, fl uoride, sulfate, nitrate, zinc and 

aluminum also impact dialysis operations. Remember, 

chlorine and chloramines are both toxic to fi sh. Generally, the operators of dialysis centers and fi sh breeders 

know that disinfectants in tap water must be removed 

before being used in their facilities. Therefore, utilities 

changing disinfectant techniques must notify the public 

of the change, contact kidney dialysis facilities, and fi sh 

breeders. Disinfection changes may also cause a change 

in pH levels in a distribution system resulting in temporarily elevated lead or copper levels. 

7.1.4 Implementing Corrosion Control

Corrosion in drinking water systems can be controlled by adjusting pH, alkalinity or by introducing

corrosion inhibitors. Increase in pH is one of the 

effective methods for reducing lead and copper corrosion. According to research studies, the optimal 

pH for lead and copper control falls between 7.5 and 

9.5 (the value depends upon the system and inhibitor 

used). The higher pH level can also help reduce iron 

concentrations. However, high pH can also result in 

precipitation and scale on the pipe that signifi cantly 

impact the hydraulics of a distribution system.

Increasing alkalinity can also assist in corrosion control, and the optimal alkalinity for lead and copper 

control lies between 25 and 75 mg/L as calcium carbonate. Higher alkalinity levels (>60 mg/L as calcium 

carbonate) are favorable for controlling iron corrosion 

and result in better buffer intensity, which in turn provides a stable pH. 

Phosphate- and silicate-based corrosion inhibitors are 

often used by water utilities. The most commonly 

used inhibitors include orthophosphate, polyphosphate and sodium silicate, with or without zinc. Orthophosphate and zinc orthophosphate have reportedly been successful in reducing lead and copper levels; 

polyphosphates are reported to prevent iron corrosion. 

Sodium silicate has been shown to reduce lead and 

copper levels. It should be noted that sodium silicate 

is basic and always results in pH increases. Therefore, 

it is diffi cult to determine if reductions in lead or copper are due to the use of sodium silicate or higher pH 

levels. Nevertheless, sodium silicate has been shown 

to be an effective inhibitor. Utilities using inhibitors 

should periodically monitor the inhibitor concentration within the distribution system. 

Use of corrosion inhibitors and pH and/or alkalinity 

adjustments to control lead, copper and/or iron levels 

in drinking water should be employed with caution. 

Pilot studies should be conducted to determine the effectiveness of a specifi c control method. 

Changing Disinfectants (AwwaRF, 2006b)

In November 2003, the American Water Works Association Research Foundation (AwwaRF) sponsored a 

project to evaluate the long-term effects of disinfection 

changes on distribution system water quality. The research team evaluated 19 utilities that had changed their 

primary and/or secondary disinfectants. Specifi cally, 

seven utilities changed from chlorine to chloramines, 

six changed from chlorine to ozone, two changed from 

chlorine to chlorine dioxide, two changed from chlorine to ultraviolet disinfection, and two added booster 

chlorination. The study concluded that, in general, the 

results were positive. The following specifi c improvements in the distribution system water quality were observed as a result of changing disinfectants: 

• Better microbial quality - lower coliform levels 

and heterotrophic plate counts 

• Lower DBPs - reduced levels of trihalomethanes 

and haloacetic acids

• Reduced numbers of customer complaints 

regarding red water or discolored water 

• Reduced numbers of customer complaints 

regarding tastes and odors

Despite the positive effects of changing disinfectants, 

there was one participating utility that experienced an 

increase in lead levels. Therefore, a utility should carefully evaluate the effect of making such changes.

Mommy, I cleaned the fi sh 

bowl and fi lled it with tap 

water. Nobody told me using 

tap water with disinfectants 

would kill my fi sh!
7-4

7.1.5 Preventing Sedimentation and Scale 

Formation 

Under low velocity conditions, suspended solids may 

deposit on the pipe surface. Scale and mineral deposits 

may accumulate on pipe surfaces if the mineral content 

in the water is high and the pH/alkalinity of the water 

is supportive of scale formation (as addressed previously in Section 5.5). The accumulated sediment and 

scale reduces the carrying capacity of the pipe and can 

also create a more favorable environment for microbial 

growth. Although sediments and scales themselves do 

not necessarily pose a serious health risk, they can cause 

water quality deterioration, taste and odor problems, or 

discoloration. Furthermore, the deposited solids may 

be re-suspended by sudden changes in fl ow. Signifi cant 

changes in fl ow (velocity and direction) can scour sediments, tubercles, and scale deposits from pipe walls and 

result in degradation of water quality. It is possible that 

these re-suspended particles may contain adsorbed contaminants such as arsenic and other metals that originated in the source water. Rapid changes in velocity 

and fl ow direction can occur during main breaks, when 

service reservoirs are being fi lled or drained, when 

pumps are going on or off line, or during hydrant fl ushing activities. 

As metal pipes corrode, roughness tends to increase, 

and cross-sectional area tends to decrease. Microbial 

slimes can also result in a decrease in the hydraulic carrying capacity of water mains. This loss in carrying 

capacity can result in a water system that cannot deliver 

necessary fi re fl ow. Increases in pumping rates may be 

necessary to overcome the increasing friction losses and 

local defi ciencies in system pressure. These increased 

pumping requirements can overload motors and result 

in a signifi cant increase in energy consumption, and in 

operating and maintenance costs. Furthermore, the additional pressure can over-pressurize weaker portions 

of the distribution system, potentially increasing the 

number of leaks and breaks. To avoid these negative 

consequences, utilities should operate their distribution systems in a manner that minimizes sedimentation 

and scaling by maintaining appropriate fl ow and water 

chemistry (e.g., pH and alkalinity levels) throughout 

the distribution system.

7.1.6 Implementing a Flushing Program

Flushing involves moving water through the distribution system at a high rate, and then discharging it 

through hydrants or blow-off ports. A fl ushing program is designed with one or more specifi c objectives 

such as replacing aged water, removing loose deposits 

and sediments, and/or scouring internal pipe surfaces. 

Utilities typically implement a fl ushing program in response to consumer complaints. Terms such as “directional fl ushing” or “unidirectional fl ushing” are used to 

describe the operation of valves during a fl ushing program to maximize velocity and control fl ow direction, 

starting with the largest mains and moving to the smallest. Flushing is usually accomplished by opening one 

or more hydrants in a planned pattern. A good rule of 

thumb for fl ushing is to start at the location with “best“ 

water quality in the system and move outwards. 

Residual disinfectant concentration in a distribution 

system can be reestablished or stabilized by displacing 

“old” water and replacing it with fresh water containing 

a measurable residual disinfectant. Flushing can also 

remedy or prevent nitrifi cation in systems that utilize 

chloramines for disinfection. Water that has elevated 

levels of ammonia is replaced with water containing a 

higher disinfectant residual. However, fl ushing is not 

required by all state agencies. Of 34 states responding 

to a survey by the Association of State Drinking Water 

Administrators, only 11 require fl ushing/cleaning/pigging, with 20 others encouraging the practice.

The new prototype pressurized fl ush system 

SP17 fl ushes pipes up to 1,000 feet long. 

We could save thousands of gallons of water 

during routine fl ushing operations.

Flushing Velocities (AwwaRF, 2004b)

AwwaRF sponsored a project to evaluate a range of sitespecifi c fl ushing velocities. The study report indicates that 

utilities which had previously never fl ushed their systems 

benefi ted signifi cantly from a high velocity (~5 feet per 

second [fps]) unidirectional fl ushing program. Utilities 

that had fl ushed within the last 4 to 6 years could receive 

approximately the same benefi t (and save water) by fl ushing at a lower velocity (2 to 4 fps). The AwwaRF study 

also determined that loose particles, including corrosion 

particles, iron sludge, sand, and iron fl oc, are removed 

from smooth or slightly tuberculated pipes at lower fl ushing velocities (2 to 4 fps). In most cases, distribution system lines should be fl ushed until the water is clear.
7-5

Some systems may choose to clean pipelines that are 

suspected of contributing to the decay of disinfectant 

residuals in fi nished water. A variety of cleaning methods are available which include:

• swabbing

• scraping

• pigging

• chemical cleaning, and

• jet fl owing

Swabbing, scraping, and pigging refer to methods that 

remove scale and deposits from the inside of the pipes. 

Chemical cleaning involves the injection of chemical cleaners. Jet fl owing uses a high-pressure method 

to wash the inside of the pipe. Each technique has its 

benefi ts and disadvantages and should be tailored to a 

specifi c site. In addition, depending upon the age of the 

pipes, some utilities may want to consider pipe lining 

or replacement. 

7.1.7 Infrastructure Replacement and/or 

Treatment Upgrades

Proper treatment methods, tailored to the utility’s source 

water characteristics, can also solve potential problems 

in the distribution system. If optimum treatment is employed, it can greatly improve the biochemical stability 

of the fi nished water. Biochemical stability is closely 

related to the amount and kind of organic matter present 

in the water. Problems associated with the formation of 

DBPs increase with the amount of organic matter left 

in the water. Treatment to remove organics, inorganics, 

and turbidity will also curb chlorine decay. The most effective treatment methods for maintaining biochemical 

stability include:

• enhanced coagulation

• biological fi ltration

• ultrafi ltration/nanofi ltration

• granular activated carbon treatment

Water main breaks commonly occur in older or in poorly designed systems. Main breaks are disruptive and 

expensive to fi x. Furthermore, for rusting and aging 

pipes and fi nished water storage facilities, replacement 

may be the only viable option. Therefore, utility operators and managers must develop a long-term strategy 

for timely maintenance and replacement. However, 

these types of infrastructure replacement and treatment 

upgrade projects require a signifi cant amount of fi nancial resources and time. Possible fi nancial strategies 

designed to accomplish these goals are discussed in the 

next section of this document.

7.2 Financial Strategies

Small- and medium-sized systems face unique fi nancial challenges because they cannot take advantage of 

the economies of scale associated with larger drinking 

water systems. For example, in a small system, a piece 

of equipment costing $1,000 may be spread over a customer base of 100 to 1,000 customers. In a larger system, the cost of this same piece of equipment may be 

spread over 10,000 to 100,000 customers. Simply put, 

any capital investment for smaller systems is generally 

higher on a per customer basis or per capita basis than 

in a larger system. 

Financial Strategy (EPA – EFAB, 2005)

In rural and developing areas, back-end loading could be 

used in fi nancing water projects where hook-up fees and 

user charges only begin to fl ow after a project is completed. Infrastructure projects in such areas are often judged 

unaffordable because the debt associated with the capital 

investment needed for new facilities cannot be immediately serviced by user charges. In fact, new hook-ups/connections often occur slowly. As connections are made and the 

service area rate base increases, user charge revenues grow 

to support debt repayment. Back-end loading can enable 

projects to proceed because it solves immediate environmental needs by deferring fi nancial issues of “affordability” of debt repayment to a later time.

This approach has proven to be valuable for San Benito, 

Texas, along the US-Mexican border. The North American 

Development Bank guaranteed a bond issue for San Benito 

with a highly skewed amortization schedule that allowed 

for the build-out of the system and the build-up of operating revenues to sustain long-term debt service. In this 

case, the new water system would enjoy the very low interest rates provided by the bank guaranty until such time as 

the system revenues could provide substantial debt service 

coverage.

In cases where the price of water cannot be simply 

passed on to the customer, small- and medium-sized 

utilities can apply for grants and low-interest loans. A 

grant is a form of fi nancial assistance that is given to a 

utility which does not have to be repaid. Loans must be 

repaid along with the appropriate interest. These terms 

are defi ned more carefully in the following paragraphs:

• Grant Programs: Grants are generally awarded 

to states, local governments or other nonprofi t 

organizations. The primary advantage of grants 

is that the recipients do not have to use their 

own resources to pay the costs that the grant 

covers. Applying for grants, however, can 

require a signifi cant commitment of time by 

utility personnel. In addition, the availability 
7-6

and timing of the grant award may not match 

the utility’s needs. Most grant programs have 

limited funds, and usually there is signifi cant 

competition for this type of funding. Grants also 

have project eligibility requirements, and some 

programs may specify that the grantee contribute 

a share of the total project funds.

• Loan Programs: Loans are available from 

governments, banks or other fi nancial 

institutions and the application process can be 

relatively quick. Commercial interest rates are 

generally higher with less favorable pay back 

rules than government loans. State programs 

generally have better rates and terms for those 

systems that do not qualify for conventional 

types of fi nancing. The terms of loans vary 

signifi cantly and the utility should carefully 

evaluate these terms before a loan is secured.

Some of these fi nancial options (both grants and loans) 

are briefl y summarized in the following sections.

Sustainable Pricing (EPA, 2005b)

Individual customers are the most important source of revenue for a drinking water system. The income provided 

by customers is critical to ensuring that systems are operated properly and effi ciently both in the present and in 

the future. Charging customers the actual cost of service 

ensures that water systems guarantee themselves a stable 

source of funds that is suffi cient to cover the cost of operation (including treatment, storage, and distribution costs). 

This policy also allows for the acquisition of funds for infrastructure investments. Asking customers to pay for a 

commodity or service sends a signal about the value of 

the product or service they are purchasing. Fees and other 

charges that refl ect the full cost of water service help customers recognize the value of water service. Customers 

also become more aware of how much water they use and 

how they use it. To support this approach, EPA has developed a sustainable infrastructure initiative which is based 

on the following four pillars:

• Better Management – Similar to asset management, 

environmental management systems, consolidation, 

and public-private partnerships can offer signifi cant 

savings for small water utilities.

• Full-Cost Pricing - A key consideration in 

constructing, operating, and maintaining 

infrastructure is ensuring that there are suffi cient 

revenues in place to support the costs of doing 

business. Sensible pricing can also have the added 

benefi t of encouraging effi cient water use.

• Effi cient Water Use - One way to reduce the 

need for costly infrastructure is effi cient use of 

water. There are many options for enhancing 

water effi ciency including metering, water reuse, 

water-saving appliances, landscaping, and public 

education.

• Watershed Approaches to Protection - In 

addressing infrastructure needs for the purposes 

of water supply and water quality, it is important 

to look at water resources in a coordinated way. 

Directing resources towards high priorities, such as 

permitting on a watershed basis, and water quality 

trading are all means of ensuring that investments 

achieve the greatest benefi t.

7.2.1 Drinking Water State Revolving Fund

Congress established the Drinking Water State Revolving Fund (DWSRF) as part of the 1996 SDWA Amendments to provide states with a fi nancing mechanism to 

ensure safe drinking water for the public. EPA, through 

the various state agencies, administers the DWSRF in 

order to provide fi nancial resources to upgrade and replace drinking water infrastructure. PWSs can receive 

loans with very low or zero percent interest rates with 

repayment periods of up to 20 years. However, in some 

cases, drinking water utilities in disadvantaged communities may fi nd even low-interest loans unaffordable. In 

these types of cases, states can provide DWSRF funds 

at a negative interest loan rate, or under a principal forgiveness loan with an extended repayment period of up 

to 30 years. Each state has specifi c eligibility criteria to 

determine funding priorities. Funding requests under 

the DWSRF program are allocated based on the following order of priority:

• Requests that address the most serious health 

risks to consumers

• Requests necessary to comply with SDWA 

standards

I have solved our fi nancial crisis, 

here is a “cash cow” and a 

“goose that lays the golden egg!”
7-7

• Requests that assist water systems which are 

most in need, on a per-household basis (as 

determined by the state affordability criteria)

Similar funding assistance is also available to Indian 

tribes in the U.S. 

7.2.2 Community Development Block Grants

The U.S. Department of Housing and Urban Development administers a Community Development Block 

Grant (CDBG) program through the individual states. 

The program provides small communities with resources to address a wide range of needs. The program 

gives each state the opportunity to administer CDBG 

funds for “non-entitlement areas.” Generally speaking, 

“non-entitlement areas” are cities with populations of 

less than 50,000 and counties with populations of less 

than 200,000. The primary objective of this CDBG 

program is to develop viable communities by providing 

decent housing and a suitable living environment. This 

general objective is achieved by prioritizing activities 

which benefi t low- and moderate-income families or 

aid in the prevention or elimination of slums or blight. 

Under unique circumstances, states may also use their 

funds to meet urgent community development needs. 

A need is considered urgent if it poses a serious and 

immediate threat to the health or welfare of the community and has arisen in the past 18 months. Local 

governments have the responsibility to consider local 

needs, prepare grant applications for submission to the 

state, and carry out the funded community development 

activities. The list of eligible activities under this program includes construction or reconstruction of water 

and sewer facilities. 

7.2.3 Rural Utilities System

One of the six basic mission areas of the U.S. Department of Agriculture (USDA) is the Rural Utilities System (RUS). Under the RUS umbrella, USDA provides 

a variety of water loan and grant programs. Along with 

EPA and other federal agencies, USDA supports organizations such as the National Rural Water Association 

(NRWA) and the Rural Community Assistance Partnership. The USDA’s RUS issues contracts to NRWA for 

providing rural water circuit rider technical assistance. 

In addition to supporting these national organizations, 

USDA provides emergency community water assistance grants to rural communities that have experienced 

a signifi cant decline in the quantity or quality of drinking water. Grants are provided to rural areas and cities 

or towns with low income and a population of fewer 

than 10,000. Grants can cover up to 100 percent of 

project costs. The maximum grant is $500,000 when 

a signifi cant decline in quantity or quality of water occurred within two years, or up to $150,000, to make 

emergency repairs and replace facilities in existing systems. 

7.2.4 Economic Development Administration

The U.S. Department of Commerce provides grants 

through the Economic Development Administration’s 

(EDA) Public Works and Development Program. Applications must be submitted to the state economic development agency; states are authorized to administer 

the funds. A drinking water project must be located in 

a community or county determined to be economically 

distressed, and the project must be directly related to 

future economic development. Some restrictions apply 

when grants are provided in conjunction with other fi -

nancial assistance. The combined funding is generally 

limited to 80 percent of the total project cost. 

Creative Funding (Hudson, 2007)

Recent SDWA revisions to reduce the Arsenic Maximum 

Contaminant Level (MCL) to 0.010 mg/L affected approximately 80 small Indiana PWSs. As a result, many small 

utilities needed assistance to comply with the new standard. A majority of these affected systems were rural (serving fewer than 500 people) and the Indiana DWSRF Loan 

Program estimated that the average arsenic remediation 

project would cost $44,000. Unfortunately, this amount 

was too small to justify a DWSRF loan. If a utility cannot 

justify a project under the DWSRF, these funds cannot be 

used for small systems. To solve this problem, the Indiana 

DWSRF created the Arsenic Remediation Grant Program 

in May 2006. By combining DWSRF set-aside funds for 

planning and design costs and state monies for construction costs, the DWSRF Loan Program was able to offer 

grants up to $100,000 to small PWSs to cover the entire 

cost of arsenic remediation projects.

I received your application for loan, I 

am afraid we need more information 

than what you currently have provided 

for us to process this application.

1) Project 

Description:

 Need a new 

water tank.

2) Supporting 

Financial 

Information:

 We are broke!
7-8

7.2.5 Other Entities and Private Foundations

Appalachian Regional Commission (ARC) ARC supports qualifying applicants in the designated Appalachian Regions of 13 states. The ARC’s local development 

districts provide assistance in preparing an applicant’s 

proposal. Priority funding is determined each year by 

the state governors, Appalachian district personnel, 

and ARC members. All projects that qualify for grant 

funding must be directly related to economic development, housing development, or downtown revitalization 

and improvement. Drinking water projects are among 

the types of projects eligible for assistance. It should 

be noted that ARC grants are limited to 50 percent of 

project costs and require the recipients to supply the 

other 50 percent. An exception is made for economically distressed counties, which can receive 80 percent 

and must supply only 20 percent. To raise the remaining 20 percent of funds, owners of small systems in distressed counties should innovatively and aggressively 

seek other sources of funding. 

Indian Health Service (IHS) IHS is a part of the Department of Health and Human Services, and provides 

grants for projects undertaken by American Indians and 

Alaska Natives. In 1959, Congress passed the Indian 

Sanitation Facilities Act to provide improved health 

conditions by improving sanitation, sewer, solid waste, 

and drinking water facilities. IHS grants support public 

health rather than economic development or environmental preservation and do not include funding for operation and maintenance. No matching funds are necessary, and IHS grants can be consolidated with those 

from other agencies. 

Small Community Water Infrastructure Exchange 

(SCWIE) SCWIE is a network of water funding offi -

cials. Under the auspices of the Council of Infrastructure Financing Authorities, a group of public and nonprofi t environmental funding and technical assistance 

offi cials combined their efforts to create SCWIE. 

Private Foundations Private foundations are another 

possible source of funding for small- and medium-sized 

PWSs. These are often overlooked by small PWS managers. Information about smaller foundations can be obtained from a local Internal Revenue Service (IRS) offi ce. The IRS annually collects Form 990-PF (Return on 

Private Foundations) from foundations of all sizes, and 

compiles information about the foundations’ interests, 

restrictions, application procedures, and deadlines. 

7.3 Management Strategies

If the operational and fi nancial strategies currently available to a utility do not have long-term sustainability, a 

utility should consider management and institutional 

changes. Some options to consider are merging with a 

larger utility, or changing ownership and/or management 

of the water utility (from private to public or vice versa). 

7.3.1 Small Systems Working Together 

In general, state and federal regulatory agencies encourage small water systems to work together if it makes 

fi nancial sense. Working together generally results in 

a regulatory agency having more effective control over 

water quality and regional development. Furthermore, 

the economies of scale associated with working together 

tend to ensure the long-term fi nancial viability of a system. One challenge in working together is the diffi culty 

in servicing a geographically diverse distribution system 

from a central location. In such cases, remote monitoring and reporting is recommended to ensure prompt local 

service even if bulk water is purchased from a larger utility. Each manager of a small- and medium-sized utility 

should consider the pros and cons of working together, 

for developing regional water usage rates and/or centralized purchasing. In addition to concerns of fi nancial viability, managers should consider the geographical spread 

and type of source water of the combined systems. The 

number one concern of the partners is the potential impact of the combination on the quality of the water served 

to the consumer. Again, remote monitoring and reporting 

is recommended to ensure the quality of the water in the 

combined distribution system. EPA’s Community Water 

System Survey, conducted in the year 2000, indicated 

that there was a continued decline in the number of systems serving fewer than 3,300 people, while the number 

serving more than 3,300 people grew by 20 percent. 

Additional Information

More information on the DWSRF is available at: http://

www.epa.gov/safewater/dwsrf/index.html

More information on state CDBGs is available at: http://

www.hud.gov/local/index.cfm

More information on RUS assistance is available at: http://

www.usda.gov/rus/water/programs.htm

More information on EDA assistance is available at:

http://www.eda.gov/InvestmentsGrants/Investments.xml

More information on ARC assistance is available at: http://

www.arc.gov/index.do?nodeId=101

More information on IHS assistance is available at: http://

www.ihs.gov/

More information on SCWIE assistance is available at: 

http://www.scwie.org/ContactSearch.asp

A commercial source of private foundation listing online 

is: http://foundationcenter.org/
7-9

7.3.2 Change in Ownership and/or 

Management

In general, there are four options to consider when 

changing ownership and/or management of water utilities including:

• Effi ciency Improvement Program: Implementing 

operational and management changes to improve 

effi ciency.

• Municipalization: The assets, operations 

and ownership of private water systems are 

transferred to a public entity.

• Privatization: The assets, operations, and 

ownership are transferred to a private entity

• Public-Private Partnership: In general, the 

public retains the ownership and control 

of the system, but privatizes operation and 

maintenance. 

Private utilities are generally perceived as being profi toriented and hence more effi cient than public or municipal utilities. Because they are for-profi t entities 

there is a perception that they may fail to invest in longterm growth which may lead to poor system maintenance and upgrade practices. Municipalities, because 

they are non-profi t entities and represent the people, are 

perceived as likely to invest in the system and have a 

plan for long-term growth. On the other hand, because 

municipal systems are non-profi t entities, there is concern that there are ineffi ciencies built into the system 

which may increase costs to the consumer. The general 

perception about public-private partnerships is that they 

represent the “best” of both municipal and private systems. These perceptions are generally anecdotal and 

based on individual cases where information is available. There are no long-term data or analyses that conclusively support any of these general perceptions.

Utility Merger (KEPPC, 2006)

The Northern Kentucky Water District (NKWD) was 

formed in 1997 from the merger of water districts in 

Kenton and Campbell counties. In recent years, it has also 

acquired the Newport and Taylor Mill water utilities. By 

2006, NKWD had 78,000 retail customers in Campbell 

and Kenton counties and provided wholesale water service 

to the Pendleton County, Bullock Pen water districts, and 

to the city of Walton.

In 2003, the Kentucky Public Service Commission granted 

NKWD a rate adjustment that equalized the water rates in 

the former Kenton and Campbell county districts. In 2004, 

PSC granted rate adjustments to equalize water rates in 

Newport with the rest of the district. In 2006, the PSC 

granted a rate adjustment to equalize the rates for customers in Taylor Mill. The 2006 rate increase was estimated to 

raise the quarterly bill for the average NKWD residential 

customer consuming 18,000 gallons/quarter, from $78.65 

to $83.70 (an increase of $5.02, or 6.4 percent). It is estimated that the 2006 rate increase will increase NKWD’s 

annual revenues from water sales by 6.8 percent, to $36.3 

million.

7.4 SmallWater USA – 

Cell Tower Installation

Problem #1 Water Storage Tank Antenna 

Scenario 

Several telephone companies approached SmallWater, 

USA offi cials and made fi nancial offers to the town if 

they were permitted to install cell phone antennas on the 

top of the elevated tank in the northern part of the water 

system. It sounded like a good source of needed funds 

but the offi cial wanted to make sure that there would 

not be any problems. He talked to an engineering fi rm 

that specialized in tank construction and maintenance 

procedures. Following is a summary of the information 

that he received from the engineer.

Issues to Consider

The rapid expansion of wireless communication services throughout the United States has resulted in the 

construction of many cellular antenna towers. To save 

on the cost of erecting these towers, communications 

companies look for existing structures that are suitable 

for locating their antennas. Also, in some areas, zoning 

restrictions have severely limited the ability of cellular 

companies to locate their towers. For these reasons, water storage tanks are prime sites for antennas. Existing 

tanks are often the highest structure in a community and 

usually have pre-existing Federal Aviation Authority 

and zoning approvals.

Leasing revenue from antenna installations has been 

a welcome development for hard-pressed water utility 

budgets. Leasing rates range from a few hundred dollars 

to over $1,000 per month depending on the location and 

suitability of the storage tank. Since tanks usually have 

room for multiple antenna installations, leasing revenue 

can be doubled or tripled by adding cellular carriers. 

In some cases, it is possible to pay for all future tank 

maintenance and painting with these revenues. While 

the income provided to water utilities from placement 

of antennas is certainly worth considering, care must be 

taken to avoid the adverse effects of these installations.

Guidance (Source: Gabin, I.M., 2007)

Many problems have occurred from antenna installations that were improperly designed and constructed. 

Many installers have viewed the tank as simply a plat-
7-10

form for their antennas, without understanding the important function that the tank serves and the purpose of 

tank appurtenances. Problem areas include:

1. Structural damage

2. Coating and corrosion damage

3. Occupational Safety and Health Administration 

(OSHA) violations

4. Restriction of access to ladders, manholes and 

hatches with resultant confi ned space and safety 

concerns

5. Contamination of water supply through 

improperly sealed penetrations

6. Potential for interference with future painting

7. Poor aesthetic appearance

A few basic steps should be followed by storage tank 

owners to avoid these problems. First, the cellular 

company should be required to provide a drawing of 

its complete installation including site utilities, ground 

structures, equipment panels, cable routing, and antenna structures. Secondly, a qualifi ed engineering fi rm experienced with both storage tanks and antenna installations should be retained to inspect the tank, and review 

the drawings, welding procedures and coating repair 

specifi cations. Structural analysis should be performed 

to ensure that the tank can safely support the antennas. 

Also, care must be taken that the new installation does 

not interfere with existing cellular or utility antennas.

Only after all necessary drawing and specifi cation revisions are completed should the installer be allowed to 

begin. Keys to the tank or tank site should be returned 

when the project is fi nished. It is not recommended that 

antenna companies be allowed to access the tank to 

service their equipment without utility personnel providing authorization and access.

The fi nal step is inspection of the completed installation. The same fi rm that reviewed the drawings should 

inspect the entire installation including the interior paint 

repairs. In some cases, paint repairs can only be completed during low demand times of the year. In other 

cases, the repairs must wait for warmer weather. This 

will require coordination with the cellular company to 

ensure that the interior paint is properly repaired.

When negotiating a lease with the cellular company, the 

design review and inspection services should be included in the contract at the company’s expense. Most cellular companies are very cooperative in including these 

services in the lease. It is a minimal expense and also 

provides them with the assurance that their equipment 

will be properly installed. A number of other legal and 

financial considerations should be carefully evaluated 

including length of contract, cost of living adjustments, 

access, liability, exclusivity clauses, and future painting 

expenses. Since many utilities already have antenna installations, it would be worthwhile to inquire about their 

leases and hopefully benefi t from their experience.

Water storage tank antennas are certainly worth investigating. By following these steps, one should be able to 

obtain the benefi t of this new source of revenue while 

avoiding the problems that can be caused by defi cient antenna design and installation. Figures 7.1 and 7.2 show 

pictures of bad and good cell-tower designs, respectively. The crowded design shown in Figure 7.1 could lead 

to operational, maintenance and structural problems.

Problem #2 Operational Changes to Reduce 

Water Quality Degradation in Storage 

Tank 

During the past summer, SmallWater, USA offi cials 

received frequent taste and odor complaints from residents in the trailer park located near the old standpipe. 

Discussions with the town consulting engineer led to 

the likely conclusion that these taste and odor problems 

were probably due to water quality degradation in the 

standpipe. Some options for dealing with this problem 

were discussed and will be tried out next summer.

Issues to Consider

Because water sometimes spends a large amount of 

time in a storage tank, it is susceptible to degradation 

of water quality. Some specifi c forms of water quality 

degradation can include: loss of disinfectant residual, 

regrowth of bacteria, formation of DBPs, nitrifi cation 

and sedimentation. In all of these phenomena, the degradation is associated with two physical processes in a 

tank: aging of water and mixing within the tank.

Guidance

Since it is not uncommon for water to spend several 

days or sometimes even weeks in a storage facility, 

tanks are prime candidates for potential water quality 

problems. There is no fi xed standard for allowable water age, but some experts suggest that 3 to 5 days is a 

reasonable maximum residence time within a tank. Allowable water age varies based on the chemical content 

of the water and the type of disinfectant that is utilized. 

An approximate value for the average residence time 

can be easily calculated based on the turnover within 

the tank using the following equation:

Average Residence time (days) =

Average water volume in tank (gallons) ÷

Average daily infl ow (gallons per day)
7-11

The standpipe typically contains about 150,000 gallons 

of water. Based on Supervisory Control and Data Acquisition (SCADA) records, the daily infl ow is about 

75,000 gallons per day. Using this equation, the average residence time in the standpipe was calculated as 

150,000 ÷ 75,000 = 2 days. This was considered to be 

reasonable.

Mixing is another issue in tank operation and design. 

Distribution system storage tanks should be designed to 

encourage good mixing - namely, the water that is entering the tank during the fi ll cycle should mix well with 

the water that is already in the tank. A poorly mixed 

tank can result in zones or pockets of older, deteriorated 

water. In some cases, the tank may become stratifi ed 

(poor vertical mixing), primarily when the infl ow water 

is colder than the water in the tank. Tall tanks, such as 

the SmallWater, USA standpipe, are especially susceptible to mixing and stratifi cation problems. Good mixing will generally occur if 1) the infl ow “jet” enters at 

a relatively high velocity (at least 1 foot per second), 2) 

the inlet is oriented to encourage mixing with the water 

in the tank, 3) the water level in the tank is allowed to 

fl uctuate over a range of several feet over the course of 

each day, and 4) the water temperature of the infl ow is 

approximately the same as the temperature of the water 

in the tank. The average infl ow velocity for the standpipe was calculated by dividing the average infl ow rate 

(100 gpm) by the cross-sectional area of the 16-inch 

inlet. This showed a typical infl ow velocity of only 0.16 

feet per second (fps) - far less than the recommended 

velocity of 1 fps. 

Based on this analysis, the engineer suggested that no 

modifi cation in operations was needed but that some 

minor modifi cations in the standpipe inlet confi guration should be made. The primary recommendation was 

that a “reducer” be placed on the inlet-outlet line where 

it entered the standpipe so that the effective diameter 

would be reduced from 16 to 6 inches. Other situations 

may require the addition of more complex inlet-outlet 

designs or the use of mechanical mixers to encourage 

circulation in the tank. There are a variety of modeling 

and monitoring procedures that can be used to assess 

whether there are mixing problems in a tank and to test 

alternative schemes for improving mixing in a tank. 

Figure 7.1 Crowded Cell Tower Installation

Figure 7.2 A Well-Designed and Constructed Cell 

Tower Installation
7-12

Crossword Solutions

1) DWSRF, 2) Municipality, 3) Flushing, 4) Chloramine, 5) Loans, 6) Age, 7) Grant, 8) Phosphate

1

2

3

4

5 6

7

8

ACROSS

4 Type of disinfectant that can be more toxic to 

fish

5 Financial assistance that must be repaid with 

the applicable interest

7 Financial assistance that does not have to be 

paid back

8 Commonly used base-chemical for corrosion 

inhibition

DOWN

1 Acronym for EPA-established financing 

mechanism

2 Term for a publicly-owned non-profit water 

utility

3 Common procedure for removing loose 

sediments and deposits in pipes

6 Reduce “this” in distribution system to 

control DBP formation

Crossword

Operational, Financial, and Management 

Strategies to Address Distribution 

System Water Quality Issues
8-1

Chapter 8

Bibliography

The references included in this bibliography contain 

additional detailed information for readers who wish to 

pursue, in greater detail, the specifi c topics discussed 

in this guide. Many of these references (especially the 

EPA references) are freely available on the Internet. 

The references are listed alphabetically, based on 

the last name of the fi rst author(s). In cases where 

there are two or more works by the same author (e.g., 

AWWA, AwwaRF, and EPA), the entries are listed by 

the year, with the most recent document listed fi rst. 

The reverse chronological order makes it easy for the 

reader to look up the most recent publication fi rst.

American Society of Civil Engineers (ASCE). 

“Report Card for America’s Infrastructure, Drinking 

Water,” ASCE, Reston, Virginia. 2005.

American Water Works Association (AWWA). Field 

Guide to SDWA Regulations. Technical Editors 

- Lauer, W.C., Scharfenaker, M. and J.M. Stubbart. 

Published by AWWA, Denver, Colorado. 2006a.

AWWA. M33 Manual of Water Supply Practices 

“Flowmeters in Water Supply.” Second Edition. 

Published by AWWA, Denver, Colorado. 2006b.

AWWA. AWWA Water Operator Field Guide. 

Published by AWWA, Denver, Colorado. 2004.

AWWA. M31 Distribution System Requirements for 

Fire Protection, Third Edition. Published by AWWA, 

Denver, Colorado. 1999.

American Water Works Association Research 

Foundation (AwwaRF). Asset Management Planning 

and Reporting Options for Water Utilities. 2006a.

AwwaRF. Long-Term Effects of Disinfection Changes 

on Water Quality. 2006b.

AwwaRF. Development of Distribution System Water 

Quality Optimization Plans. 2005.

AwwaRF. External Corrosion and Corrosion Control 

of Buried Water Mains. 2004a.

AwwaRF. Establishing Site-Specifi c Flushing 

Velocities. 2004b.

Bhardwaj, V. Pumps - A Tech Brief. Published by the National Drinking Water Clearinghouse at the West Virginia 

University, Morgantown, West Virginia. Summer 2003.

Bhardwaj, V. Reservoirs, Towers, and Tanks: Drinking 

Water Storage Facilities - A Tech Brief. Published by 

the National Drinking Water Clearinghouse at the West 

Virginia University, Morgantown, West Virginia. Fall 

2001.

Bowman, L. Comparison of Water and Wastewater 

System Financing through the Rural Utilities Service 

and State Revolving Funds. Published by National Rural 

Water Association (NRWA), Duncan, Oklahoma. 2004.

Braden, J.B., Lee, M.Y., Jaffe, M. Building Technical, 

Financial, and Managerial Capacity for Small Water 

Systems: The Role of Consolidation, Partnership, 

and Other Organizational Innovations. Published 

by Midwest Technology Assistance Center (MTAC) 

for Small Public Water Systems. MTAC Publication 

TR07-01. Undated.

Brenda, L. Water System Operator’s Guide. Published 

by the U.S. Department of Agriculture (USDA) 

Forest Service - National Technology & Development 

Program. Publication ID: 0623 1802- San Dimas 

Technology and Development Center (SDTDC). June 

2006.

California Department of Health Services (CDHS) 

and Environmental Protection Agency (EPA). Small 

Water System Operation and Maintenance – A Field 

Study Training Program. Fourth Edition. Published by 

California State University, Sacramento Foundation. 

2002.

Canadian Federal-Provincial-Territorial Committee on 

Drinking Water. Corrosion Control in Drinking Water 

Distribution Systems. Document prepared for Public 

Comment. April 2007.

Clark, R.M., E.E. Geldreich, K.R. Fox, E.W. Rice, 

C.H. Johnson, J.A. Goodrich, J.A. Barnick, F. 

Abdesaken, J.E. Hill and F.J. Angulo. A waterborne 

Salmonella typhimurium outbreak in Gideon, 

Missouri: results from a fi eld investigation. 

International Journal of Environmental Health 

Research 6:187-193. 1996.

Clark, R.M., J.A. Goodrich, and J.C. Ireland. Cost 

and Benefi ts of Drinking Water Treatment, Journal of 

Environmental Systems, Vol. l4(l), pp. l-30, l984-85.

Corrosion Doctors (CD). Langelier Saturation Index 

(LSI) available at their website: http://www.corrosiondoctors.org. Undated.
8-2

Cowan, C., Mescher, A., Miller, J., Pettway, K. and 

Pink, B. A Framework for Evaluating Water System 

Ownership and Management Alternatives. Group 

Project Report. University of California, Santa 

Barbara, California. April 2005.

EPA. Small Drinking Water Systems: State of the 

Industry and Treatment Technologies to Meet the Safe 

Drinking Water Act Requirements. EPA Publication 

Number 600-R-07-110. September 2007a.

EPA. Complying with the Ground Water Rule: Small 

Entity Compliance Guide. One of the Simple Tools 

for Effective Performance (STEP) Guide Series. EPA 

Publication Number 815-R-07-018. July 2007b.

EPA. Revised Public Notifi cation Handbook - Figure 

1: The Required Elements of a Public Notice. EPA 

Publication Number 816-R-07-003. March 2007c.

EPA. Cross-Connection Control: A Best Practices 

Guide. EPA Publication Number 816-F-06-035. 

September 2006a.

EPA. Distribution Systems: A Best Practices Guide. EPA 

Publication Number 816-F-06-038. September 2006b.

EPA. Complying With the Stage 1 Disinfectants and 

Disinfection Byproducts Rule: Basic Guide. One of 

the Simple Tools for Effective Performance (STEP) 

Guide Series. EPA Publication number 816-B-05-004. 

March 2006c.

EPA. Setting Small Drinking Water System Rates 

for a Sustainable Future. One of the Simple Tools for 

Effective Performance (STEP) Guide Series. EPA 

Publication Number 816-R-05-006. January 2006d.

EPA. Water Distribution System Analysis: Field 

Studies, Modeling and Management – A Reference 

Guide for Utilities. EPA Publication Number 600-R06-028. December 2005a.

EPA. Case Studies of Sustainable Water and 

Wastewater Pricing. EPA Publication Number 816-R05-007. December 2005b.

EPA. Drinking Water Security for Small Systems 

Serving 3,300 or Fewer Persons. One of the Simple 

Tools for Effective Performance (STEP) Guide Series. 

EPA Publication Number 817-R-05-001. September 

2005c.

EPA. Taking Stock of Your Water System - A Simple 

Asset Inventory for Very Small Drinking Water 

Systems. EPA Publication Number 816-K-03-002. 

October 2004.

EPA. Strategic Planning: A Handbook for Small 

Water Systems - One of the Simple Tools for Effective 

Performance (STEP) Guide Series. EPA Publication 

Number 816-R-03-015. September 2003a.

EPA. Small Systems Guide to Safe Drinking Water 

Act Regulations. The First STEP to Providing Safe 

and Reliable Drinking Water - One of the Simple Tools 

for Effective Performance [STEP] Guide Series. EPA 

Publication Number 816-R-03-017. September 2003b.

EPA. Asset Management: A Handbook for Small 

Water Systems. One of the Simple Tools for Effective 

Performance (STEP) Guide Series. EPA Publication 

Number 816-R-03-016. September 2003c.

EPA. Small Drinking Water Systems Handbook: 

Guide to “Packaged” Filtration and Disinfection 

Technologies with Remote Monitoring and Control 

Tools. EPA Publication Number 600-C-03-041. May 

2003d.

EPA. Cross-Connection Control Manual. EPA 

Publication Number 816-R-03-002. February 2003e.

EPA. Federal Water Pollution Control Act as amended 

through P.L. 107–303, November 27, 2002a.

EPA. Complying With the Revised Drinking Water 

Standard for Arsenic: Small Entity Compliance Guide. 

One of the Simple Tools for Effective Performance 

(STEP) Guide Series. EPA Publication Number 816-

R-02-008A. August 2002b.

EPA. Cases in Water Conservation: How Effi ciency 

Programs Help Water Utilities Save Water and Avoid 

Costs. EPA Publication Number 832-B-02-003. July 

2002c.

EPA. Sources of Technical and Financial Assistance 

for Small Drinking Water Systems. EPA Publication 

Number 816-K-02-005. July 2002d.

EPA. Radionuclides in Drinking Water: A Small Entity 

Compliance Guide. EPA Publication Number 815-R02-001. February 2002e.

EPA. Safe Drinking Water - Protecting America’s 

Public Health Poster. EPA Publication Number 816-

H-02-001. January 2002f.

EPA. Guidance Manual for Conducting Sanitary 

Surveys of Public Water Systems; Surface Water and 

Ground Water Under the Direct Infl uence (GWUDI). 

EPA Publication number 815-R-99-016. April 1999.
8-3

EPA - Environmental Financial Advisory Board 

(EFAB). Letter to Mr. Stephen L. Johnson, EPA 

Acting Administrator, from L.A. Gray and S. Meiburg. 

March 16, 2005.

Gabin, I.M. Water tank cell-tower case study and 

images provided by Mr. Gabin of Dixon Engineering. 

2007.

Greater Cincinnati Water Works (GCWW). Water 

quality monitoring images provided by Y.H. Lee. 2007.

Hall, E.L., and Dietrich, A.M. A Brief History of 

Drinking Water. Opfl ow, Published by AWWA, Vol. 

26, No. 6. June 2000.

Holmes, M. Water Audit Manual for Utilities - A step 

by step guide to accurately measure water use and 

water loss. Published by New Mexico Rural Water 

Association. 2006.

Hudson, S. Creatively Funding Arsenic Remediation 

in Indiana, Indiana Finance Authority, Indianapolis. 

2007.

Jesperson, K. Safe Water Should Always Be on 

Tap. Published by the National Drinking Water 

Clearinghouse at the West Virginia University, 

Morgantown, West Virginia. Undated.

Kentucky Environmental and Public Protection 

Cabinet (KEPPC). PSC grants rate hike to Northern 

Kentucky Water. Press Release dated: April 28, 2006.

Lahlou, Z.M. Valves - A Tech Brief. Published by 

the National Drinking Water Clearinghouse at the 

West Virginia University, Morgantown, West Virginia. 

Summer 2002.

MacPhee, M.J. Distribution System Water Quality 

Challenges in the 21st Century: A Strategic Guide. 

Published by AWWA, Denver, Colorado. 2005.

Montana State University (MSU) Center for Biofi lm 

Engineering. Image provided by P. Dirckx. 2005.

National Research Council (NRC). Drinking Water 

Distribution Systems: Assessing and Reducing Risks, 

the National Academies Press, Washington DC. 2006.

National Rural Water Association (NRWA). 

Ownership and Management Options for Small and 

Rural Water Systems. Published by NRWA, Duncan, 

Oklahoma. 2004.

New Mexico Environmental Finance Center 

(NMEFC). Asset Management - Three Case Studies 

in New Mexico. NMEFC, 901 University Blvd. SE, 

Albuquerque, NM. April 2007.

NMEFC. Asset Management: A Guide for Water and 

Wastewater Systems. NMEFC, 901 University Blvd. 

SE, Albuquerque, NM. 2006.

Ottem, T., Jones, R., and Raucher, R. Consolidation 

Potential for Small Water Systems — Differences 

Between Urban and Rural Systems. Published by 

NRWA, Duncan, Oklahoma. 2004.

Philadelphia Water Department (PWD). Cartoon from 

the archives of the PWD Historical Collection – Image 

provided by A. Levine. 2007.

Pontius, F.W. Compounding Effects of Drinking 

Water Regulations on Small Water Systems. Published 

by NRWA, Duncan, Oklahoma. 2004.

Rader, L. How to Begin a Fire Hydrant Operation 

and Maintenance Program. Published by the National 

Drinking Water Clearinghouse at the West Virginia 

University, Morgantown, West Virginia. Undated.

Rural Community Assistance Corporation (RCAC). 

Financial Planning: A Guide for Water and Wastewater 

Systems. Published by RCAC, 3120 Freeboard Drive, 

Suite 201, West Sacramento, California. 2006.

Satterfi eld, Z. Locating Distribution Lines. Tech Brief 

Published by the National Environmental Services 

Center (NESC). NESC, West Virginia University, 

Morgantown, West Virginia. Winter, 2006.

Smith, C.D. Distribution System Assessment 

Workbook. Undated.

Symons, J.M., Bradley, L.C., and Cleveland, T.C. The 

Drinking Water Dictionary. Published by AWWA. 

2001.

Vaswani, R.T. Synopsis of U.S. EPA’s Drinking Water 

State Revolving Loan Fund. Published by Rural 

Community Assistance Program. Undated.

Wallace, Floyd, Associates Inc. Task 18.20: A History 

of the Development of the Metropolitan District 

Commission Water Supply System. September, 1984.

Washington State Department of Health (WSDOH). 

Color, Taste and Odor Problems in Drinking Water, 

WSDOH PUB. #331-286. April 2005.