&EPA
United States
Environmental Protection
Agency
RESEARCH REPORT ON
Investigation of the Capability
of Point-of-Use/Point-of-Entry
Treatment Devices as a
Means of Providing
Water Security
Office of Research and Development
National Homeland Security
Research Center
3w=w -
r> -
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EPA/600/R-06/012
February 2006
Investigation of the Capability
of Point-of-Use/Point-of-Entry
Treatment Devices as a Means of
Providing Water Security
U.S. Environmental Protection Agency
Office of Research and Development
National Homeland Security Research Center
Irwin Silverstein, Ph.D., PE.
AAAS Environmental Fellow
February 2006
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Table of Contents
Acknowledgments vi
Disclaimer vii
Acronyms and Abbreviations viii
Executive Summary ix
Introduction 1
Study Objectives 3
Literature Review on the State of the Art 5
Comparison of POU and POE Treatment Devices 5
Extent of POU/POE Use and Commercialization 5
Use of POU/POE Treatment Devices to Meet Drinking
Water Standards 6
EPA Guidance 6
NSF/ANSI Standards 6
NSF/ANSI Standard 44 - Residential Cation
Exchange Water Softeners 7
NSF/ANSI Standard 53 - Drinking Water
Treatment Units - Health Effects 7
NSF/ANSI Standard 55 - UV Microbiological
Water Treatment Systems 7
NSF/ANSI Standard 58 - RO Drinking
Water Systems 8
NSF/ANSI Standard 62 - Drinking Water
Distillation Systems 8
Federal Regulations 8
Role of the States 9
State-of-the-Art Technologies and Designs 10
Technologies 10
Solid Block Activated Carbon (SBAC) Filters 10
Granular Activated Carbon (GAG) Filters 11
Reverse Osmosis (RO) 11
Microfine Filters 13
Ultrafilters 13
Specialty Media 13
Iron Media and Activated Alumina 14
Nanofilters 14
Ultraviolet (UV) Light 14
Ozone 15
Ion Exchange (IE) 15
Distillation 16
Batch Treatment 16
POU/POE Product Design 16
Prefiltration 16
GAG Treatment Devices 17
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RO Treatment 18
Specialty Media 18
Ion Exchange 18
Portable Purifiers 20
Performance of Current POU/POE Products 20
Arsenic 20
Radium 20
Microbial Issues 20
Chemical Contaminants 21
Mobile Treatment Technologies 21
Next Generation ROWPU-Type Units 21
Technical Support Working Group
(TSWG) Project 21
Potential Water Security Role of POU/POE
Devices 23
Administrative Planning for Possible POU/POE Usage 23
Optimal Design Features of POU/POE Devices for Water
Security Applications 24
POU/POE Treatment in a Proactive Role 24
POU/POE Treatment in Response to a Contamination
Incident (Reactive Mode) 25
General Considerations 25
Specific Scenarios for Reactive POU/POE
Implementation 26
Monitoring and Forensics Roles 27
Practical Considerations for Widespread POU/POE Use 27
Potential Implementation of POE Treatment in a Reactive
Decontamination Role 27
Post-Incident Considerations for POU/POE Treatment
Devices 28
Disposal Considerations and Residuals Management.... 28
Decontamination Study of Post-Service Connections.... 29
Costs of POU/POE Devices 29
Reactive Scenario 29
Proactive Scenario 30
Benefits and Limitations Associated With the
Implementation of POU/POE Treatment for
Water Security 31
Benefits/Applicability of POU/POE Treatment 31
Limitations of POU/POE Treatment 32
Conclusions and Recommendations 33
References 35
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices iii
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List of Figures
Figure 1 Carbon Adsorption Process 10
Figure 2 RO Process 12
Figure 3 Microfiltration Process 13
Figure 4 GAG POU Unit 17
Figure 5 RO POU Unit 18
Figure 6 Specialty Media for POU Arsenic Removal 19
Figure 7 Typical POE IE Installation 19
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List of Tables
Table E-l Most Promising Technologies x
Table E-2 Comparative POU/POE Treatment Costs — Reactive
Scenario xi
Table E-3 Comparative POU/POE Treatment Costs at Household—
Proactive Scenario xi
Table E-4 Comparative POE Treatment Costs at Large Facilities/
Institutions xii
Table 1 Comparative POE Treatment Costs at Large Facilities/
Institutions 31
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices v
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Acknowledgments
The author wishes to express his appreciation for the guidance and
support provided by Ms. Grace Robiou (EPA Office of Ground Water
and Drinking Water, Water Security Division), Mr. Jonathan Herrmann
(EPA Office of Research and Development, National Homeland Security
Research Center), and Mr. Kim Fox (EPA Office of Research and
Development, National Homeland Security Research Center), and by the
American Association for the Advancement of Science.
EPA Reviewers
Matthew Magtiuson Office of Research and Development/National
Homeland Security Research Center
Jeffrey Adams Office of Research and Development/National
Risk Management Research Laboratory
Eric Koglin Office of Research and Development/National
Homeland Security Research Center
Alan Hals Office of Research and Development/National
Homeland Security Research Center
vi WIPD
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Disclaimer
Mention of trade names, products, or services does not convey, and should
not be interpreted as conveying, official EPA approval, endorsement, or
recommendation.
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices vii
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Acronyms and Abbreviations
ANSI American National Standards Institute ORD
AWWA American Water Works Association OW
AwwaRF American Water Works Association POE
Research Foundation POU
AX Anion Exchange QC
CAM Cellulose Acetate Membrane PCB
CX Cation Exchange psi
DBP Disinfection Byproduct RCRA
EPA U.S. Environmental Protection Agency
ETV Environmental Technology Verification RO
Program ROWPU
GAG granular activated carbon
gpd gallons per day SBAC
gph gallons per hour SSCT
gpm gallons per minute SDWA
HPC Heterotrophic Plate Count SOC
HSPD Homeland Security Presidential TDS
Directive TFM
IE Ion Exchange TOC
MCL Maximum Contaminant Level TSWG
MF Microfiltration TWPS
mj millijoules UF
MGD million gallons per day UV
NHSRC National Homeland Security Research VOC
Center WIPD
NPDWR National Primary Drinking Water
Regulations WSD
NRC National Research Council WQA
NSF National Sanitary Foundation
Office of Research and Development
Office of Water
Point-of-Entry
Point-of-Use
Quality Control
Polychlorinated Biphenyl
pounds per square inch
Resource Conservation and Recovery
Act
Reverse Osmosis
Reverse Osmosis Water Purification
Unit
Solid Block Activated Carbon
Small System Compliance Technology
Safe Drinking Water Act
Synthetic Organic Compound
Total Dissolved Solid
Thin Film Membrane
Total Organic Carbon
Technical Support Working Group
Tactical Water Purification System
Ultrafiltration
Ultraviolet
Volatile Organic Compound
Water Infrastructure Protection
Division
Water Security Division
Water Quality Association
viii WIPD
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Executive Summary
Point-of-use (POU) and point-of-entry (POE) water
treatment devices are cited in the United States
Environmental Protection Agency (EPA) Water Security
Research and Technical Support Action Plan as a topic
requiring further research. POU devices are designed to
purify only that portion of incoming water that is being
used for drinking and cooking purposes, while POE
devices treat all the water coming into a house or facility
What are the capabilities of these devices for treating or
capturing the most likely contaminants? How should
such devices be disposed of if they become contaminated?
This paper investigates the use of these devices as a
potential strategy for addressing water security concerns.
Study Objectives
The first objective of this study was to conduct a literature
review regarding the types of devices and technologies
currently available for removing contaminants at the
point of use and/or at the point of entry. The most
promising technologies and combinations of technologies
(e.g., treatment trains) were investigated with regard to
their principle of operation; effectiveness for removing
radiological, biological, or chemical contaminants; and
limitations. Of particular interest was a determination
of a device's efficacy in preventing exposure to biological
agents.
The second objective was to examine the potential
water security role of POU/POE treatment devices. To
fulfill this objective, different implementation strategies
and their ramifications were discussed; issues associated
with disposal and residuals management were addressed;
and costs, benefits, and limitations from a water security
perspective were described.
Drawing on the results of the first two objectives, the
third objective was to offer a set of recommendations for
consideration regarding POU/POE treatment and water
security. The results of this effort were to help identify
the best preventive measures, treatment alternatives, and
post-treatment disposal options regarding the intentional
contamination of drinking water.
Available Technologies
This review produced a comparative study showing
the types of devices that are currently available, the
principles of operation, the types of contaminants that
can effectively be removed and those that cannot, removal
efficiencies, and the anticipated service life. The two
most widely used POU devices are a faucet-mounted
device and a pitcher-style filter. The former is composed
of activated carbon in solid block configuration with
1-micrometer pore space plus an activated agent to
remove lead; the latter uses a sieve filter, granular activated
carbon (GAG), and ion exchange resin in sequence.
POU and POE treatment devices can be used to meet
drinking water standards, but this use is constrained by
EPA guidance, third-party certification by the National
Sanitary Foundation (NSF) International, standards
developed by the American National Standards Institute,
and federal regulations.
Optimal Design Features
Because the type of contaminant threat can be so
variable and unpredictable, a combination of treatment
technologies could be most successful. Desirable
characteristics of these devices include:
having greater than 99 percent removal efficiency
for chemicals and greater than 3 logs for microbial
agents
remaining mechanically sound and maintaining
a consistent performance level over time, despite
variations in intake water characteristics
exhibiting a high level of quality assurance/quality
control by the manufacturer to ensure confidence
by many users
signaling either by sounding an alarm or by
shutting down when the device no longer can
achieve desirable removal efficiencies
being easy to install and maintain to encourage
continued use
having the ability to obtain performance
certification
being readily available and relatively inexpensive
demonstrating an acceptable level of performance
under real-agent exposure conditions
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices ix
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Most Promising Technologies
Activated
Carbon (SBAC)
Granular
Activated
Carbon (GAG)
Reverse Osmosis
(RO)
Ultraviolet (UV)
Light
Microfiltration
(MF)
Ultrafiltration
(UF)
Nanofiltration
no
yes
most
no
some
yes
no
yes
yes
yes
yes
yes
j"°
no
yes
yes
yes
yes
yes
most
most
no
no
some
some
pesticides; can remove methyl tert-
butyl ether and selected disinfection
byproducts; also removes chlorine and
can be formulated to remove metals
Limited removal capability for atrazine,
aldicarb, and alachor; shows promise for
removal of biotoxins; removes chlorine;
and is moderately effective at removing
some metals
Not effective at removing low molecular
weight organic compounds; removes
many metals and radionuclides
Requires prefiltration; used alone or in
combination with other technologies
Used as prefilters in combination with
RO
Cannot remove low-weight (less than
100,000 daltons) organic compounds
Can be configured to remove arsenic
The final characteristic can be accomplished via
extensive testing, using actual contaminants of concern.
Table E-l lists the most promising technologies, their
effectiveness, and their limitations.
Costs
This paper presents comparative costs for different
POU/POE units that could be used in response to
a contamination event. Approximate purchase and
installation costs are summarized in Table E-2, with the
caveat that they do not take into account the uncertainty
regarding the markup in price that could occur during an
emergency.
Approximate amortized costs (7 percent over a
10-year life expectancy) for households that would use
these units in a proactive (i.e.,preventive) manner are
summarized in Table E-3-
A comparison of approximate capital and annual
operating and maintenance (O&M) costs for four
different POE treatment technologies used at large
facilities and institutions is shown in Table E-4. While
two combinations, microfiltration/ultrafiltration (MF/
UF) and reverse osmosis/ultraviolet light/granular
activated carbon (RO/UV/GAC) offer the greatest
protection against the largest variety of potential
contaminants, all four treatment systems have limitations
against certain contaminants. Therefore, cost must be
weighed against the desired level of protection.
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Comparative POU/POE Treatment
Costs — Reactive Scenario
r"
RO POU without UV disinfection
RO POU with UV disinfection
RO/GAC - faucet mount
RO/GAC - under the sink
ROPOE
UVPOE
Specialty media POU - arsenic removal
Cation exchange (CX) POE
GAC POU without UV - faucet mount
GAC POU without UV - under the sink
GAC POU with UV - under the sink
GAC POE with UV
Rented RO POU without UV
$400 - 700
$600 - 900
$50
$300
$5,000 - 20,000
$1,000
$300 - 650
$3,300
$10-30
$500
$750
$3,000
$20 per month
Comparative POU/POE Treatment Costs at
Households — Proactive Scenario
ROPOU
$200 - 400
Rented RO POU
$200 - 300
Specialty media POU
$150-250
Pitcher filters
$75
GAC - under the sink
$100-150
CXPOE
$600 - 650
Rented GAC POU without UV
$250 - 300
Rented GAC POU with UV
$350 - 400
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices xi
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Comparative POE Treatment Costs at
Large Facilities/Institutions
Capital/O&M
Capital/O&M
Capital/O&M
Capital/O&M
50,000
$350,000/$40,000
$250,000/$20,000
$600,000/$40,000
$550,000/$40,000
100,000
$500,000/$50,000
$350,000/$25,000
$750,000/$50,000
$800,000/$50,000
250,000
$900,000/$85,000
$600,000/$40,000
$1,200,000/$80,000
$1,400,000/$75,000
500,000
$1,500,000/$125,000
$1,000,000/$60,000
$2,000,000/$100,000
$2,000,000/$100,000
Benefits and Limitations Associated
With the Implementation of POU/
POE Treatment Water Security
POU/POE treatment devices can contribute to increased
water security, subject to the circumstances of the water
security concern and the limitations described below.
The type of contaminant a terrorist might use cannot
be known ahead of time, but the use of POU/POE
treatment can serve in a protective role. When one of
these technologies is used for other reasons (e.g., aesthetics
or to address a specific problem with the finished water),
there could be an added, serendipitous security benefit if
the device happens to be effective against the contaminant
that was introduced into the distribution system. In
addition, consumers may feel that by using these units,
they are taking an action to increase their security against
an intentional act. This sense of empowerment can also
be a motivating force for installing these devices in the
first place.
Benefits, applicability, and limitations of POU/POE
from a water security perspective are summarized below.
In addition to the water security benefits, POU/POE
treatment may have some collateral beneficial effects on
public health that are not necessarily related to protecting
against intentional contamination of the distribution
system.
Benefits/Applicability of POU/POE
Treatment
The benefits/applicability of POU/POE treatment can be
summarized as follows:
For certain contaminants, POU/POE treatment
devices can play a proactive role and perhaps be
protective of human health.
In an emergency situation, POU devices can
reduce human exposure associated with chronic/
subchronic effects caused by contaminants,
even though these devices would not offer total
protection from acute contaminants and all
exposure pathways, particularly those other than
ingestion.
POE devices using RO plus GAG plus UV
represent a promising technology combination
for a large number, albeit not all, contaminants of
concern.
POE devices may be desirable as a means of
protecting vulnerable or potential target facilities
both proactively and also in reaction to a water
contamination emergency involving these
facilities.
POU devices could serve as an interim measure
until a water treatment system has been
decontaminated or an alternative supply has been
put into service.
POU devices could serve as a polishing step
during the final stages of water treatment system
decontamination.
xii WIPD
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For long-term distribution system leaching
scenarios involving a contaminant that can cause
chronic toxicological and/or aesthetic ill effects,
POU/POE devices may be appropriate.
POU devices placed by utilities at critical
points in the distribution system might play
monitoring and forensics roles in either detecting
a contaminant or in confirming a contaminant
after the fact.
Limitations of POU/POE Treatment
The limitations of POU/POE can be summarized as
follows:
POU is not recommended for use in a post-
contamination mode for infectious agents as these
devices may over time leach trapped, absorbed, or
adsorbed contaminants. This effect is of particular
concern for immunosuppressed individuals and
other sensitive subpopulations.
Nonpathogenic bacteria tend to accumulate in
carbon POU devices and can adversely affect
children and other susceptible individuals,
especially when these devices are not well
maintained.
If POU rather than POE is used, the potential risk
exists of using an untreated tap, especially for an
interval of time during which a contaminant has
been introduced but has not yet been detected.
During a contamination incident, users of POU
devices must be reminded that only the faucet in
their homes that is fitted with the POU device is
safe to use.
Many POU/POE treatment devices are not
effective against all possible contaminants.
Choosing the appropriate device must be done
carefully and would be assisted by accurate
knowledge of the contaminant identity.
There is limited historical information available
on the performance of POU/POE treatment
devices using chemical or biological agents or their
simulants or surrogates.
Except in small communities, distributing POU
or POE devices that require several hours to install
in a post-contamination mode may take too long.
POE treatment trains can be expensive ($5,000
to $20,000); POU devices generally cost $500 to
$1,000 per unit, as discussed above.
Widespread installation as a response action
would likely not be done until flushing,
hyperchlorination, and the use of bottled water
were deemed impractical or inadequate.
Bottled water may offer a higher confidence
alternative to consumers during an emergency
incident but would not address other uses for
water.
Additional technicians and installers may be
needed for possible widespread installation
scenarios.
Conclusions and Recommendations
POU/POE treatment devices can provide some water
security benefits, especially if selectively deployed. For
example, POE treatment devices could be employed at
certain high-risk or sensitive facilities such as hospitals,
military bases, police stations, and fire stations. While
widespread proactive use of POU treatment devices
is not recommended, they could have a water security
application under circumstances in which a limited
population has been affected, the type of contamination
is well understood, and the POU treatment technology
has demonstrated effectiveness against that type of
contamination. Prefiltration, RO, carbon adsorption,
and UV disinfection represent the most promising
combination of technologies that would likely be effective
against the vast majority of potential contaminants,
especially during an acute incident.
The following short-term considerations should be
taken into account when weighing the risks and benefits
for the particular situation:
Consider the installation of POE devices that use
SBAC, RO, and UV for all facilities that would be
of critical value during an attack (e.g., hospitals,
fire departments, police stations) and all high-
risk targets (e.g., government buildings, military
bases).
Continue testing POU/POE treatment devices
against actual contaminants of concern. This
testing will help inform the Agency and the
general public regarding which devices are
effective in either a proactive or reactive manner.
Compile and periodically update an informational
database, reflecting the test results on the
efficacy of each type of device against various
contaminants. This information would provide
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices xiii
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guidance regarding the use of devices with the
highest likelihood of success.
Compile and periodically update an inventory
database of manufacturers and distributors
of various POU and POE treatment devices,
including production capacity, number of devices
and replacement cartridges in stock, delivery time
estimates, and, if available, testing and certification
status for contaminants or classes of contaminants
of concern.
Include a distribution plan as part of local
emergency response preparation for POU
treatment devices to provide short-term protection
in the event an incident occurs in the community.
This distribution plan would be dependent upon
the informational database developed as part of
the previous recommendation.
The following strategies should be considered,
but further analysis is required to determine whether
implementation of the strategy is to be recommended:
Investigate whether POU devices may have some
value being readily attachable to a faucet and
being available for engagement by the homeowner
once a warning has been issued about a potential
or confirmed emergency. To prevent use of the
device in non-emergency situations that would
raise maintenance costs and concerns, there could
be a carefully considered lockout feature.
Consider the potential benefits of a proactive and
random distribution of POU treatment devices
from a post-contamination forensics perspective.
If technology permits, there is the potential
for these devices to provide sensing points for
collection and transmission of water quality
data in the distribution system as part of a more
extensive contamination warning system.
Develop a consumer kit that could provide a
bridge response action during an emergency.
This kit would contain different modular units,
employing various treatment technologies. For
example, there would be a prefiltration module,
an SBAC module, an RO module, and possibly
a UV module as well. The kit would also include
adaptors so that the modules could be properly
attached to a faucet. The parts of the kit would
not be used until the responsible authority
specified what module or combination of modules
should be used in the short term. Consumer
use of the modules on a routine basis could be a
drawback to this strategy.
Consider the implications of decontamination
and disposal of treatment devices once they have
served their purpose. Issues to consider include
routine versus incident-specific use, the type
of contaminant captured or retained, and the
most effective methods for decontamination and
disposal of the device and its contents.
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Introduction
Terrorist acts are not directed solely toward individuals
but also toward a country's key resources and critical
infrastructure, such as the nation's drinking water
and wastewater systems. Government institutions,
water utilities, state and local water agencies, public
health organizations, emergency responders, technical
assistance providers, academia, and the private sector
across the country can all be affected. The Public
Health Security and Bioterrorism Preparedness and
Response Act (Bioterrorism Act) of 20021 placed the
responsibility for protecting the country's drinking water
supply under the purview of the U.S. Environmental
Protection Agency (EPA). This mandate was reinforced
by Homeland Security Presidential Directive (HSPD)72,
"Critical Infrastructure Identification, Prioritization, and
Protection, " which reinforced the role of the Agency as
the sector-specific lead for water infrastructure security.
To meet these responsibilities, the Agency's Office of
Research and Development (ORD) officially established
the National Homeland Security Research Center
(NHSRC) in February 2003- In addition, the Agency's
Office of Water (OW) established the Water Protection
Task Force, which was formally organized as the Water
Security Division (WSD) in August 2003- ORD and
OW collaborate to provide research and technical support
to the drinking water and wastewater sectors.
NHSRC's Water Infrastructure Protection
Division (WIPD), formerly the Water Security Team,
conducts applied research to obtain reliable and credible
documentation of data for use by a variety of individuals
and organizations. WIPD is responsible for developing
analytical tools and procedures, technology evaluations,
models and methodologies, decontamination techniques,
technical resource guides and protocols, and risk
assessment methods for carrying out EPA's mission. All of
this applied research is done in close cooperation with the
OWs WSD and the responsible water representatives in
each of the Agency's ten regional offices.
To meet the charge of the Bioterrorism Act and
HSPD 7, ORD and OW developed the Water Security
Research and Technical Support Action Plan in March
2004 to "identify critical research and technical support
projects in the areas of physical and cyber infrastructure
protection; contaminant identification; monitoring
and analysis; treatment, decontamination, and disposal;
contingency planning; infrastructure interdependencies;
and risk assessment and communication."3 While the
primary objective of the Action Plan is to protect the
infrastructure of source water, drinking water, and
wastewater from terrorist threats, once a distribution
system has been compromised, a better understanding
of response options to a contamination incident is
required. Accordingly, Chapter 3, Section 3-4.1(c)(6)
of the Action Plan cites the need for further research
regarding the capabilities of point-of-use (POU) and/or
point-of-entry (POE) devices "for treating or capturing
the most likely contaminants and disposal procedures for
such devices should they become contaminated." POU
treatment devices are designed to purify only that portion
of incoming water that is being used for drinking and
cooking purposes. POE treatment devices are designed to
purify all the water coming into a house or facility via its
placement within the water supply line.
The Action Plan was reviewed by the National
Research Council (NRC), and NRC supplied comments
with regard to POU/POE technology as a means of
providing water security4 While acknowledging that
this technology could play a role during a persistent
distribution system contamination incident, NRC
concluded that its widespread application throughout
communities would be daunting with regard to
logistics, installation, and expense. NRC also expressed
reservations that without a rigorous testing program
against potential terrorist agents, it is unknown how
such devices would perform during a distribution system
contamination incident. Furthermore, some types of
units could eventually release trapped contaminants back
into the water and produce a delayed impact on the
user. However, NRC did see some merit in considering
the application of this technology to protect critical,
vulnerable, and potentially targeted facilities such as
hospitals, military bases, and police and fire stations.
Overall, the NRC comments point to the need
to study the role of POU/POE devices in more detail.
Another report pointing toward such an investigation
was prepared by the General Accounting Office (GAO)
in 20035 on how future federal spending could best be
spent to improve security. This report cited improved
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 1
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treatment technologies as one of the nine priorities
warranting federal funding and support. Some of
the experts who provided input to the GAO report
recognized the need for more research and development
of POU/POE treatment devices, which would provide
additional security against contamination. Specifically
cited were treatment technologies using ultraviolet (UV)
systems and improved reverse osmosis (RO) techniques.
The Government Accountability Office reinforced
concerns regarding contaminant introduction into the
distribution system in its testimony on September 30,
2004, before the House Subcommittee on Environment
and Hazardous Materials, Committee on Energy and
Commerce.6
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Study Objectives
The implementation of POU/POE treatment requires
further investigation for consideration as a water security
strategy with regard to drinking water infrastructure
contamination. This study has three objectives, each
designed to elucidate different aspects of the potential
water security role of these treatment devices.
The first objective of this study was to conduct
a literature review regarding the types of devices and
technologies currently available for removing distribution
system contaminants at the point of use and/or
point of entry. The most promising technologies and
combinations of technologies (e.g., treatment trains) were
investigated with regard to their principle of operation;
effectiveness for removing radiological, biological, and
chemical contaminants; and limitations. Of particular
interest was a determination of a device's efficacy in
preventing exposure to biological agents.
The second objective was to examine the potential
water security role of POU/POE treatment devices. To
fulfill this objective, different implementation strategies
and their ramifications were discussed; issues associated
with disposal and residuals management were addressed;
and costs, benefits, and limitations from a water security
perspective were described.
Drawing on the results of the first two objectives,
the third objective was to offer a set of recommendations
for consideration regarding POU/POE treatment and
water security. The recommedations are intended to
help identify the best preventive measures, treatment
alternatives, and post-treatment disposal options
regarding the intentional contamination of drinking
water.
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 3
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Literature Review on the
State of the Art
A literature review of currently available POU/POE
treatment devices was conducted. The results of this
review are organized into several topic areas relevant to
POU/POE operation:
comparison of POU and POE treatment devices
extent of POU/POE use and commercialization
use of POU/POE treatment devices to meet
drinking water standards
state-of-the-art technologies and designs
This review produced a comparative study showing
the types of devices that are currently available, the
principles of operation, the types of contaminants
that can and cannot effectively be removed, removal
efficiencies, and maintenance considerations.
Comparison of POU and
POE Treatment Devices
POU treatment devices are designed to purify only that
portion of incoming water used for drinking and cooking
purposes. These devices can be configured in a flow-
through mode so that they are, for instance, attached to
a faucet, placed on top of a counter, or installed within
the plumbing beneath the kitchen sink. POU treatment
can also be free-standing, whereby water is placed into
and treated by the device on a batch basis. Batch POU
treatment could also include adding treatment chemicals
to a volume of water and then filtering it prior to use.
POE treatment devices, on the other hand, are designed
to purify all the water coming into a house or facility.
The major differences between POU and POE units
with regard to their applications are as follows:
Many households use POU treatement devices
on only one tap, as opposed to using a POE
device to treat all incoming water, so occupants
are more vulnerable to water contamination,
whether accidental or intentional, because other
unprotected taps may be used.
POE units are inherently more expensive and
require more maintenance because they are
treating all the water entering the household;
however, if multiple tap POU devices were used
instead of one POE unit, sampling and analysis
costs associated with drinking water regulations
would be higher.
Regarding disposal, there may be some economy
of scale in disposing of a few larger units (POEs)
versus many smaller units (POUs).
Consumer behavior is a consideration regarding
maintenance because a device that is in the
basement and out of sight (POE) might be less
well maintained than a unit that is visible in the
kitchen (POU).
A discussion of the major differences between POU
and POE units as they relate to drinking water regulations
begins on page 6.
Extent of POU/POE Use and
Commercialization
Information gathered by the AWWA Research
Foundation (AwwaRF)7 and from a survey conducted
in February 2004 by the Water Quality Association
(WQA)8 of approximately 2,000 adults living in private
households provides some insight regarding the current
sales and use of POU and POE treatment devices in the
United States. Such sales were estimated at more than a
billion dollars by a January 2003 survey report prepared
by the market research firm of Frost and Sullivan.9 These
sources indicated that the two most widely used POU
devices are a faucet-mounted device and a pitcher-style
filter. The former is comprised of activated carbon in solid
block configuration with 1-micrometer (um) pore space
plus an activated agent to remove lead; the latter uses a
sieve filter, granular activated carbon (GAG), and ion
exchange (IE) resin in sequence. Detailed descriptions of
these technologies begin on page 10. Additionally, the
WQA survey results indicated:
Faucet-mounted POU filters are thought by
consumers to be of the same quality as bottled
water and refrigerator filters (a type of in-line
device integral to the refrigerator that uses
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 5
-------
treatment technologies similar to faucet-mounted
POU devices).
Many consumers are unaware of the differences
between the various POU devices and the relative
effectiveness of the technologies used.
Taste is the predominant driving factor for
consumer use of filtered or bottled water.
Sixty-eight percent of the respondents purchase
bottled water, and twenty-eight percent use POU
devices (mostly faucet-mounted and pitcher-style
products).
Faucet-mounted devices are the most popular.
A phone survey of four commercial vendors indicated
that POE technologies are currently in use at all types
of facilities described earlier as vulnerable or potentially
targeted, e.g., hospitals, military bases, and police and fire
stations. POE technologies were not installed in all such
facilities, and it is uncertain whether the decision to install
these technologies was made for water security purposes.10
Types of POE treatment trains include primarily RO and
GAG for commercial and residential buildings, with UV
and micro-, ultra-, and nano-filtration mainly in use at
residences. RO systems can be used at potential target
facilities for flow rates from 15,000 gallons per day (gpd)
to greater than 1 million gallons per day (MGD). UV
systems are limited because of the need for significant
pretreatment of the water and because flow rates generally
do not exceed 10 to 30 gallons per minute (gpm) unless a
number of units are used in a parallel configuration.
Use of POU/POE Treatment
Devices to Meet Drinking
Water Standards
The use of POU and POE treatment devices to meet
drinking water standards is constrained by EPA guidance
and regulations, third-party certification by the National
Sanitary Foundation (NSF) International, standards
developed by the American National Standards Institute
(ANSI), and federal laws and state involvement.
Furthermore, the use of POU treatment on only one
tap raises regulatory concerns regarding nonresidential
taps and associated health risks. A discussion of these
constraints is presented below.
EPA Guidance
In 1986, EPA established the "Guide Standard and
Protocol for Testing Microbiological Water Purifiers."
This document provides a protocol for testing treatment
systems that claim microbial purification of drinking
water, specifically with regard to removing, killing,
or deactivating bacteria, viruses, and protozoan cysts.
For a device to be federally registered as a "purifier,"
data must be gathered in accordance with specific
protocols. The guide provides technology-specific
test protocols for halogenated resins, UV treatment
systems, and ceramic candles. In addition, the guide
presents a general framework for developing specific
testing protocols for other technologies. For example,
the framework specifies the makeup of the challenge
water so that it is representative of worst-case source
water. Such characteristics include pH extremes, varying
temperatures, and elevated amounts of turbidity, total
dissolved solids (TDSs), and total organic carbon (TOG),
depending on the technology to be tested.11
The guide requires that a minimum percent
reduction of bacteria, viruses, and cysts be achieved. For
bacteria, the challenge organism is Klebsiella terrigena
and the influent concentration to be used is 10 million
organisms per 100 milliliters. A minimum reduction
of 99-9999 percent (6 logs) is required. For viruses, the
combined challenge organisms are polio and rotavirus
and the influent concentration is 10 million per liter of
each virus. A minimum reduction of 99-99 percent (4
logs) is required. Alternatively, MS2 bacteriophage may
be used with an influent concentration of 20 million
per milliliter, and a minimum reduction of 4 logs is
required. In the case of protozoans, either Giardia or
Cryptosporidium at an influent concentration of 1 million
cysts per liter, or 3-um microspheres at an influent
concentration of 10 million per liter is used. A reduction
of 99-9 percent (3 logs) is required; however, if NSF/
ANSI Standard 53 (see below) is used, a 99-95 percent
reduction is required.
NSF/ANSI Standards
NSF International (http://www.nsf.org) is an
independent testing organization for many products
related to public health. Certification is accredited by
ANSI and indicates that a product has met specific
criteria related to materials, design, construction, and
performance. NSF International standards are developed
6 WIPD
-------
with the active participation of public health and other
regulatory officials, users, and industry. See below for a
description of NSF/ANSI Standards 53, 55, 58, and 62.
NSF International developed a certification for
microbiological water purifiers known as NSF Protocol
P231 by combining the EPA "Guide Standard and
Protocol for Testing Microbiological Water Purifiers" with
several NSF/ANSI standards for evaluating materials,
structural integrity, and requirements for product
literature. A new comprehensive NSF/ANSI standard for
microbial contaminants is currently in development. Cyst
reduction is covered by Standard 53, while Standards
55 and 62 address other microbial issues. Standard 55
was recently updated, using MS2 bacteriophage as a
surrogate for validation of UV units. In addition, Bacillus
subtilis is used as a surrogate to validate the capability of
the distiller in Standard 62.n Testing, evaluation, and
performance standards relevant to POU/POE treatment
are summarized below.
NSF/ANSI Standard 44 - Residential Cation
Exchange Water Softeners
This standard applies to the use of cation exchange
resins to remove calcium and magnesium ions, which
are responsible for hardness in water. These cations
are replaced with sodium and potassium ions during
the exchange process. Although water softeners are
primarily designed to remove calcium and magnesium,
other divalent ions are exchanged, some of which (lead,
beryllium, cadmium, and radium) are regulated under
the Safe Drinking Water Act (SDWA). According to
data presented at a February 2003 NSF International
conference, there were 3 companies making a total of 43
POE products that met this standard.12
NSF/ANSI Standard 53 - Drinking Water
Treatment Units - Health Effects
This standard applies to both POU and POE units.
The substances covered by this standard include
asbestos, cysts (based on the use of microspheres or
Cryptosporidium parvum oocysts), barium, cadmium,
hexavalent and trivalent chromium, copper, fluoride,
lead, mercury, nitrate, nitrite, selenium, radon,
turbidity, and total trihalomethanes. A number of
volatile organic compounds (VOCs), such as synthetic
organic compounds (SOCs), chlordane, toxaphene,
and polychlorinated biphenyls (PCBs), are also covered.
Typically, the testing done by NSF International requires
that to be certified, the device must reduce the influent
challenge concentrations to below the maximum
permissible concentration of a contaminant in drinking
water as established by a recognized regulatory agency,
such as the EPA or Health Canada. A given product may
be certified under this standard for removal of some of the
challenge substances. For example, activated carbon filters
covered by this standard are not intended to be used with
water that is microbiologically unsafe or of unknown
quality unless there is adequate disinfection before and
after the carbon treatment component. Products that
use activated carbon adsorption would be certified in a
way that indicates it has achieved acceptable reduction
regarding a partial list of the substances cited above.
In other words, a product may be certified under this
standard to remove lead and asbestos, but not VOCs.
Although the current universe of certified devices
is ever-changing, data presented at the February 2003
NSF International conference12 on public drinking water
compliance using POU and POE treatment devices
indicated that there were about 80 companies making a
total of about 800 products that meet this standard for
all or some of the contaminants of concern. With regard
to specific contaminants, 12 companies make 61 media
filter products that were certified to remove asbestos,
23 companies make 101 media filter products that
were certified to remove lead, and 10 companies make
37 media filter products that were certified to remove
mercury. Also, 16 companies make 58 products certified
to achieve SOC reduction by VOC surrogate test, and
2 companies make 20 products certified to achieve
acceptable chlordane, PCBs, and toxaphene reduction.
Currently, there is at least one POU adsorptive media
unit that has been certified under this standard for arsenic
removal (in addition to other contaminants) and there are
numerous GAC-containing POU units that are certified
for removal of SOCs (in addition to other contaminants).
No POE units have been tested and certified by any of
the testing agencies for SOC, VOC, or radon reduction.
NSF/ANSI Standard 55 - UV Microbiological
Water Treatment Systems
This standard is applicable when the treatment train uses
UV light energy to disinfect water in a Class A system
(designed to disinfect microbiologically contaminated
water that is nonturbid, without any interfering
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 7
-------
turbidity, to meet all public health standards) or reduce
the heterotrophic plate count (HPC) bacteria in water
in a Class B system (designed to reduce normally
occurring nonpathogenic or nuisance organisms only).
Units certified for Class B are offered only for aesthetic
improvement, not disinfection. According to data
presented at the February 2003 NSF International
conference, 6 companies make a total of 32 products that
meet this standard. Of these products, all treat water at
the point of entry12
NSF/ANSI Standard 58 - RO Drinking Water
Systems
The certification associated with this standard would
apply to a list of substances (all or some) as follows:
arsenic (V) [arsenate], barium, cadmium, copper,
chromium (III) and chromium (VI), fluoride, lead,
nitrate, nitrite, radium 226/228, selenium, TDS, and
cysts. According to data presented at the February 2003
NSF International conference, about 70 companies
make a total of about 560 products that meet this
standard. Most inorganic compounds of health concern
are removed by certified RO devices. In particular, 23
companies make 86 products that were certified to
remove most of these inorganic compounds.12
NSF/ANSI Standard 62 - Drinking Water
Distillation Systems
The certification associated with this standard would
apply to a list of substances such as arsenic, barium,
cadmium, chromium, copper, lead, nitrite, and selenium,
which are tested by chemical reduction with TDS as a
surrogate. Mercury and fluoride must be tested separately
to make the reduction claim. Typically, VOCs are not
removed by this process as they are carried with the water
vapor and show up in the condensate. Certified distillers
adequately remove all inorganics, with the exception
of asbestos and radium, which are not covered by this
standard. According to data presented at the February
2003 NSF International conference, 3 companies make a
total of 31 products that meet this standard.12
Federal Regulations
After the establishment of EPA in 1970, concerns about
waterborne diseases and chemical contamination led to
the passage of the Safe Drinking Water Act (SDWA)
in 1974. This act authorized the Agency to promulgate
regulations to protect the public health. The first set of
these regulations, known as the National Interim Primary
Drinking Water Regulations, was passed in 1975- These
regulations became effective in 1977 and established
maximum contaminant levels (MCLs) for 10 inorganic
contaminants, 6 organic contaminants, turbidity,
coliforms, radionuclides, and radioactivity. The states are
responsible for establishing and enforcing state drinking
water standards that are at least as stringent as the federal
standards. The states' role also includes identifying and
resolving significant violations that are detected, keeping
the EPA informed about compliance assurance and
enforcement activities, and requesting assistance when
necessary from EPA to achieve timely and effective
enforcement.
A series of amendments and rules were added to
the SDWA between 1986 and 2002. The 1986 SDWA
amendments required EPA to apply future National
Primary Drinking Water Regulations (NPDWR)to
community and nontransient noncommunity water
systems. Challenges facing small water systems, defined
as serving 10,000 or fewer people, were a major focus
of the 1996 SDWA amendments. At that time, the
U.S. Congress directed EPA to explicitly allow the use
of POU/POE devices to achieve compliance with some
of the MCLs established by the NPDWR. As a result
of the 1996 amendments, SDWA regulates the design,
management, and operation of POU and POE treatment
devices used to achieve such compliance. One important
aspect of this change is that certain POU/POE devices are
specifically listed as small-system compliance technologies
(SSCTs). For example, both activated alumina POU and
RO POU devices are listed as SSCTs for compliance with
the revised arsenic standard of 0.01 milligrams per liter
(mg/L); ion exchange POU and RO POU devices are
listed as SSCTs for radionuclides. A technology may have
met NSF/ANSI certification requirements but may not
be acceptable with regard to the SDWA as an SSCT (e.g.,
a distillation product may be certified to remove arsenic
but this technology is not currently listed as an SSCT or
in a rule for arsenic).13 Similarly, there are technologies
that are recognized as effective for removal of certain
contaminants, but they have not yet gone through a
formal NSF/ANSI certification process and therefore
could not be considered an SSCT.12' 13
Using POU/POE devices to meet MCLs also adds
administrative burden and cost and raises a number of
concerns, including sabotage, disposal of wastes associated
8 WIPD
-------
with spent materials, and vandalism. These concerns
can be pronounced when transient populations are
involved because of a reduced sense of ownership and
empowerment.
Additional concerns include a lack of utility
personnel with expertise to manage and coordinate
sampling and maintenance, and the presence of
unprotected taps if a household has only one POU unit.
Furthermore, the following restrictions apply regarding
the use of POE/POU devices in meeting MCLs:13
Only POE treatment devices can be used
to achieve compliance regarding microbial
contaminants or indicators of microbial
contaminants.
POU and POE treatment devices must be owned,
controlled, and maintained by the public water
utility or by a contractor hired by the utility to
ensure their proper operation and maintenance
and compliance with the MCLs. The utility
must retain oversight of device installation,
maintenance, and sampling, and is responsible for
the quality and quantity of water provided to the
community.
POU and POE treatment units must be equipped
with a warning device (e.g., an alarm, a light) to
alert the consumer that it is no longer functioning
properly. Alternatively, there must be an automatic
shutoff feature.
Only units that have met NSF/ANSI standards
may be used. If they are covered by these
standards, they must be independently certified
according to these standards by an accredited
laboratory.
The SDWA does not specify the technologies and/or
designs (see "State-of-the-Art Technologies and Designs,"
beginning on page 10) to be used in POU/POE devices,
except for the following:
Only the arsenic rule and the radionuclides rule
list POU devices as acceptable SSTCs.
A proposed radon rule lists GAG POE treatment
as the only SSCT.
Ion exchange POU units (radium, uranium,
and beta and photon activity only) and RO
POU units are acceptable SSCTs regarding
radionuclides.
POU devices cannot be used to treat water for
radon or VOCs.
Role of the States
When the use of POU/POE devices is regulations driven,
the water utility bears the responsibility to properly
install, maintain, and monitor the device, subject to
state approval. For example, the state must approve a
monitoring plan prepared by the water utility when a
POE device is installed for regulatory compliance. It can
be challenging to obtain a statistically valid sample because
deployment of the units will be decentralized and limited
in number. This is not typically a problem for monitoring
of municipal water supplies. EPA guidance allows the
annual collection of samples at 1/9 of homes that employ
these devices or a statistically valid sample with regard to
meeting regulatory monitoring requirements. The state
must also require adequate certification of performance
and field-testing for POE devices. In addition, a state may
require a feasibility study to justify a water utility's selection
of a POU or POE technology instead of an alternative
means of meeting an MCL. Furthermore, the state may
want a detailed engineering study that verifies how a POU
or POE device will perform regarding MCL compliance.
Finally, plumbing and electrical codes must be considered
to ensure the proper installation of these devices.
Despite the amendments to the SDWA that allow
implementing POU/POE treatment as a means of
meeting the NPDWR, some states prohibit or restrict a
utility from doing so. Pennsylvania is one of the states that
does not allow POU treatment devices to be used to meet
compliance requirements. Some states allow POU/POE
treatment devices for a restricted list of contaminants.14
Of the 24 states that responded to an AwwaRF survey,24
only Delaware, Kansas, Missouri, and Washington had
systems currently using POUs for SDWA compliance, and
only New York, Pennsylvania, and Wisconsin had systems
using POEs for compliance to address microbial and
VOC contaminants. Only nine states (Arizona, California,
Florida, Idaho, Massachusetts, New York, Pennsylvania,
Vermont, and Washington) indicated that POUs/POEs
could be used to meet arsenic compliance regulations.
Eight states (Alaska, Arizona, Illinois, Massachusetts,
New York, Virginia, Washington, and Wisconsin) plan to
conduct further study regarding SDWA compliance using
POUs/POEs. A recent report by the Arizona Department
of Environmental Quality indicated that for small water
systems with a dispersed population of users, POU
treatment devices may be an appropriate means to meet
the new arsenic standard.15
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 9
-------
State-of-the-Art
Technologies and Designs
POU/POE devices on the market today rely on various
types of basic technology Each of these basic treatment
technologies is discussed in more detail below. Although
these technologies are first discussed separately, often
they are used in combination. A discussion of some of
the designs of POU/POE systems begins on page 16.
Performance of current POU/POE treatment products,
mobile treatment technologies, and costs are discussed in
subsequent sections.
Technologies
Solid Block Activated Carbon (SBAC) Filters
All types of carbon filters effect the removal of organic
substances by adsorption onto the carbon surface as
shown in Figure 1. The filter in this device consists of
extremely small particles of activated carbon that are fused
together into a solid block with uniform pore size. If the
carbon block configuration is properly constructed, the
pore size may be uniformly 0.5 micrometer (um), which
would be effective at removing asbestos fibers, protozoan
cysts (e.g., Cryptosporidia, Giardia), and some bacteria
(e.g., Escherichia coli, Bacillus anthmcis). SBAC filters are
less prone than GAG filters to channeling and can also
be effective at removing organic contaminants such as
some insecticides and pesticides and chlorinated solvents.
In addition, some SBAC devices are certified by NSF
International for removal of methyl tert-butyl ether and
selected disinfection byproducts (DBPs) such as total
trihalogenated methanes. Furthermore, they can remove
chlorine and can be formulated to remove metals such as
mercury and lead.12'16
With regard to limitations, SBAC filters typically will
not remove most heavy metals, viruses, small bacteria,
arsenic, fluoride, iron, or nitrates. These filters also tend
to harbor bacteria that grow on trapped organic matter,
and the bacteria can migrate from the filter to the water
at a later time. Most manufacturers recommend that the
filters be replaced about every six months, even though
the adsorptive capacity may not yet be totally exhausted.
However, replacement may be required sooner depending
on the quality of the incoming water and the amount of
usage. Replacement filters generally cost $30 to $50.17
Figure 1
Carbon Adsorption Process
Image was reproduced with permission from Home Water Treatment
(NRAES-48), 1995, Natural Resources, Agriculture, and Engineering Service,
Cooperative Extension, Ithaca, N.Y., http://WWW.nrttes.org
Purified
Water
Contaminated
Water
Activated
Carbon Filter
10 WIPD
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Granular Activated Carbon (GAC) Filters
GAG is extremely porous and can have a surface area
of about 1,000 square meters per gram (equivalent
to 125 acres per pound). Many organic compounds,
such as chlorinated and nonchlorinated solvents, select
SOCs, naturally occurring organic matter, some gasoline
components, and trihalomethanes, can be adsorbed onto
the GAC surface. For some pesticides, such as atrazine
and alachlor, GAC has a very low adsorptive ability.
This material is also effective for removal of chlorine
and moderately effective for removal of some heavy
metals and metals that are bound to organic molecules.
In addition, activated carbon processes show promise
for removal of biotoxins and other potential organic
contaminants of concern.13
Typically, GAC is a viable treatment technology for
those compounds with a Freundlich K value greater than
200 ug/g (L/ug)l/n. The Freundlich K is defined as a
constant generated during adsorption isotherm studies
in which the mass of material adsorbed is plotted against
an equilibrium concentration; for a log-log plot, log
K represents the Y-intercept. While this rule of thumb
may be helpful, the adsorption of some compounds is
difficult to predict when the Freundlich K value is near
that threshold. However, many SOCs have Freundlich K
values in the thousands, enabling their ready adsorption.
When a Freundlich K value is not known, it can be
predicted typically within an order of magnitude from
the molecular weight, density, and solubility values.18 The
error in this prediction becomes important for weakly
adsorbing compounds.
From a regulatory perspective, GAC POU units, as
well as SBAC POU units, have been identified as small-
system compliance technologies for SOCs (except as
noted above), and GAC and SBAC POE units are under
investigation as small-system compliance technologies
for SOCs. GAC is a recognized technology for removal
of many VOCs, and GAC POE treatment has been
identified as a small-system technology in the proposed
radon rule. Regardless of the design, GAC filters are
subject to clogging and, like all types of activated carbon
filters, provide an environment for bacterial growth.
When obtaining a variance under SDWA to allow the use
of this technology at the point of use or point of entry to
meet the National Primary Drinking Water Regulations,
post-device disinfection (e.g., UV, discussed below) to
address HPC bacteria must be considered.13 The variance
consideration applies despite the April 2002 opinion by
the World Health Organization that the presence of HPC
growth in POU/POE treatment devices does not indicate
a health risk, provided the entry water is biologically
safe.19 Backwashing can improve long-term effectiveness
for removal of organic compounds and provide some
control of bacterial growth, but it does not improve radon
removal efficiency.
GAC is not effective at removing fluoride, chloride,
nitrate, hardness (calcium and magnesium), or most
metal ions and is not recommended at the point of
use for removal of radon or VOCs. GAC is also not
as effective as SBAC, especially with regard to removal
of chlorine, taste-causing substances, or halogenated
organic compounds. Maintenance considerations
include replacement of spent cartridges and particulate
prefilters, if used, and periodic backwashing when GAC is
employed at the point of entry.
Reverse Osmosis (RO)
This type of POU/POE treatment relies on water pressure
to force only "clean" water to migrate through the pores
of a semipermeable membrane (see Figure 2). The effect
of the applied pressure is to reverse the tendency of
dissolved materials in water from moving naturally via
osmosis from a solution of lower concentration to one of
higher concentration. The membrane or filter typically
will have a pore size between 0.00025 and 0.001 um,
which will allow water and molecules less than 200
daltons in size to pass. The liquid on the other side of
the membrane that contains the retained contaminants
is conveyed away as waste. For POU/POE treatment,
typical clean water production rates are 10 to 30 gpd,
while the wastes, usually 70 to 75 percent of the influent
water, are discarded.
The two most common RO membrane types are thin
film membranes (TFMs) made of polyamide polymers
and cellulose acetate membranes (CAMs). CAMs are
hydrophilic and are less prone to fouling than TFMs.
One inherent weakness of a CAM is that it is subject
to being degraded by microorganisms. While CAMs
are more chlorine-resistant, TFMs are more widely
used because they are more durable and can tolerate a
higher range of pH. Also, their performance is better,
especially in low-pressure water systems. Both these types
of membranes have pores small enough to remove high
molecular weight organic compounds, as well as many
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 11
-------
Figure 2
RO Process
Image was reproduced with permission from Home Water Treatment
(NRAES-48), 1995, Natural Resources, Agriculture, and Engineering Service,
Cooperative Extension, Ithaca, N.Y., http://WWW.nrttes.org
Water Stream
to Storage Tank
Feed Water
Under Pressure
*•!
Treated Water
(Diluted)
Rejected Contaminants
(Concentrate)
Semipermeable
Membrane
Waste Stream
to Drain
low molecular weight anionic species by electrostatic
repulsion because the membrane acquires a slight
negative charge at drinking water pHs. Typical inorganic
contaminants removed include a number of metals,
chlorides, fluoride, and sulfates. RO is not effective
for removal of low molecular weight (less than 100
daltons) organic compounds such as trichloroethylene,
trihalomethanes, and some pesticides, although removal is
dependent on both molecular weight and geometry20
While these filters will effectively remove viruses,
membranes are subject to tearing, which could allow
viruses and other microbes to pass through. Leakage
can occur around seals of the assembled device, which
can allow contaminants to short-circuit the membrane
barrier. In addition, RO membranes are subject to
biological fouling, and strong oxidants, such as chlorine,
can damage the membranes. The presence of salts in the
influent can lead to membrane scaling problems, and
exposure to air can lead to the precipitation of elemental
sulfur or metallic sulfides on the membrane. The waste
stream from POE RO units may have special disposal
requirements and may require pH adjustment to prevent
corrosive wear on piping. Furthermore, the introduction
of waste liquid into the wastewater collection system
could disrupt processes at the wastewater treatment plant.
RO membrane filtration requires more maintenance
than SBAC filters and many other POU/POE
technologies. Maintenance considerations include
cleaning of the storage vessel and replacement of spent
or worn membranes, particulate prefilters, and post-
treatment GAG polishing filters. RO filtration is more
costly than SBAC filtration and produces less water
(only a few gallons of treated water per day in POU
applications). Also, since POE filters rely on high
pressures—a minimum of 40 pounds per square inch
(psi)—they will not function in an emergency involving
a power outage, unless there are standby generators.
Offsetting these disadvantages is the fact that RO may be
able to remove many more types of contaminants. From
a regulatory perspective, RO POU is an acceptable SSCT
for antimony, arsenic, barium, beryllium, cadmium,
chromium, copper, lead, fluoride, radium, selenium,
thallium, and uranium. An RO POE unit is not an
SSCT, but it is recognized as a removal technology for
arsenic, copper, lead, fluoride, nitrate, SOCs, radium,
uranium, and microbials.
12 WIPD
-------
Figure 3
Microfiltration Process
Image was reproduced with permission from Home Water Treatment
(NRAES-48), 1995, Natural Resources, Agriculture, and Engineering Service,
Cooperative Extension, Ithaca, N.Y., http://WWW.nrttes.org
Untreated
Water
Filtered
Water
Suspended solids
accumlate on the
filter material.
Filtered water contains
particles too small to be
trapped by the filter.
Filter housing
Microfine Filters
Microfiltration (MF) membranes have pore sizes that
typically range from about 0.1 to 0.2 um. These filters
are capable of removing bacteria and cysts and typically
can retain particles down to 0.1 um in size. For example,
Cryptosporidium oocysts range from 4 to 7 um in size.
Ceramic and SBAC are commonly used to provide MF.
The former has an advantage over the latter because it can
be cleaned and reused a number of times before requiring
replacement. Microfilters also can be configured as flat-
sheet, spiral-wound elements; hollow-fiber modules;
or tubular modules. An example of a hollow-fiber
arrangement in which the untreated water passes through
the filter in a cross-flow manner is shown in Figure 3- In
addition, microfilters are used as prefilters in combination
with RO treatment devices.20
Ultrafilters
The implementation of ultrafiltration (UF) membranes
for POU treatment is similar to that of MF membranes.
However, UF membranes have pore sizes that range from
about 0.01 to 0.04 um and are capable of preventing
the passage of particles greater than 100,000 daltons,
including proteins and suspended solids. Smaller particles,
such as mono- and di-saccharides, salts, amino acids,
low-weight organic compounds, inorganic acids, and
sodium hydroxide, are not removed. UF membranes
can, however, remove viruses, bacteria, and cysts. These
filters can also be configured in flat-sheet, hollow-fiber, or
tubular arrangements.13'21
Specialty Media
Specialty chemical adsorbents, in a configuration similar
to GAG POU treatments described earlier, are being
used to remove one type of contaminant or group of
contaminants at the point of use and the point of entry.
Removal of inorganic contaminants such as arsenic
and fluoride can be accomplished by using activated
alumina (e.g., hydrated aluminum oxide), granular
ferric hydroxide, and other specialty iron-based media;
these typically consist of ferric oxide or ferric hydroxide
granules, activated alumina coated with iron, or natural
materials substantially impregnated with ferric hydroxide.
These media will require periodic replacement when
spent, and periodic backwashing and occasional cleaning
of a storage tank will be necessary when used at the point
of entry.
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 13
-------
Iron Media and Activated Alumina Various designs
and materials have been investigated to improve the
removal efficiency for specific contaminants. With regard
to arsenic removal, the iron-based media perform longer
than activated alumina before media replacement is
required. While activated alumina primarily removes
fluoride and arsenic (V) [arsenate] and does perform
better at a lower pH (best between 5.6 and 6), iron-based
media generally are more effective at removing both
arsenic (III) [arsenite] and arsenic (V) [arsenate], although
oxidation of arsenite to arsenate prior to filtration can
increase its removal efficiency, depending on pH. In
addition, activated alumina is more likely to experience
interference affecting arsenic removal from competing
ions such as silica, fluoride, phosphate, and sulfate than
iron-based media. Although it is feasible to regenerate
both types of media, albeit less practical for POU/POE
applications, granular ferric hydroxide and ferric oxide
cannot be regenerated. When used to meet arsenic
removal requirements in a POU unit, activated alumina
cannot be regenerated and must be taken off-site for
disposal. Furthermore, both types of media also remove
selenium and chromium. From a regulatory perspective,
specialty media using activated alumina is a recognized
POE technology only for removal of arsenic, fluoride,
and uranium, and is considered an SSCT for the final
arsenic rule in a POU mode. However, activated alumina
is undergoing further investigation in a POU mode for
fluoride and selenium.12
Nanofilters Nanofilters can remove particles in the
0.001 to 0.005 um range, which include some dissolved
organic compounds, as well as viruses, bacteria, and cysts.
Nanofilters are also capable of arsenic removal. Two types
of nanofilters are described below.
One manufacturer has produced a nano alumina
electropositive filter consisting of heavily aggregated
fibers that are primarily boehmite (A1OOH). These fibers
are 2 nanometers (nm) in diameter, tens to hundreds
of nm long, and are distributed over a microglass
fiber (0.6 um) matrix. The manufacturer has reported
that this filter is capable of retaining viruses, bacteria,
and other pathogens. For example, the manufacturer
reported that a greater than 6-log reduction was achieved
for bacteriophage MS2, greater than 6-log for the
enterobacteria Klebsiella terrigena, greater than 5-log for
Cryptosporidium, as well as greater than 99-5 percent for
DNA and greater than 99-96 percent for endotoxins.
No other test results were reported regarding removal
efficiencies for other potential biological contaminants.22
In an EPA Phase I research project that investigated
arsenic removal capabiltity to meet the 0.01 mg/L
drinking water standard, the manufacturer23> 24 first
evaluated a nonwoven fibrous nano alumina fiber filter
previously used in pathogen challenge testing and then a
filter comprised of granular forms of nano alumina/iron
hydroxide composites (primarily FeOOH and A1OOH,
with small amounts of MnOOH). Based on experimental
data evaluating this hydroxide composite sorbent bed as
a function of challenge concentration and flow, it was
projected that a conventional POU cartridge 2.75 inches
in diameter and 12 inches in length can contain sorbent
in excess of what is necessary to meet a 2,000-gallon
test conducted under EPA's Environmental Technology
Verification Program (http://www.epa.gov/ett>).
Accordingly, there is sufficient volume in the cartridge
to add components such as a biological (including
virus) filter or activated carbon for chlorine removal. For
example, one option is to use the nano alumina fiber
electropositive filter in combination with the granular
hydroxide composite to achieve acceptable microbial
and arsenic removal efficiencies. The nanofibers can also
absorb trace heavy metals, as initial data showed that
they absorb low ppb levels of arsenate and chromium
(III). Another variation on these filters showed some
promise regarding removal rates for chromium (VI).
An additional option is to mix GAG directly with the
granular hydroxide composite to remove chlorine and
halogenated methanes (e.g., DBPs).
Ultraviolet (UV) Light
This technology uses UV radiation to inactivate microbes.
The UV spectrum is divided into four regions, defined by
wavelength expressed in nm: UV (100 to 200 nm), UV-
C (200 to 280 nm), UV-B (280 to 315 nm), and UV-A
(315 to 400 nm). For application in POU/POE devices,
an effective and practical germicidal wavelength range is
200 to 300 nm. UV light deactivates microbes by causing
dimers (i.e., a molecule composed of two identical
subunits, such as thymine, which is one of the DNA
base units) to form within the organism's DNA, thereby
making it difficult for survival unless the organism is
able to repair this damage.25 The effective UV dosage as a
function of irradiance in milliwatts per area multiplied by
14 WIPD
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time in seconds is expressed as an energy flux. An energy
dosage of 15 to 30 millijoules per square centimeter
(mj/cm2) is effective for killing bacteria, 8 to 20 mj/cm2
for Cryptosporidium, 40 mj/cm2 for Giardia, while it takes
60 mj/cm2 to achieve a 4-log reduction in most viruses.
In the case of adenoviruses, however, a dosage of
60 mj/cm2 will achieve only a 0.5-log reduction and
it takes 120 mj/cm2 to achieve a 4-log reduction. The
reason for the high dosage required for adenoviruses is
that they have the ability to repair the dimers caused by
the radiation. Adenoviruses are on the EPA Contaminant
Candidate List (http://www.epa.gov/safewater/ccl/ccl2.
html), the list from which future regulated drinking water
contaminants may be selected. The actual design for UV
devices may include a safety factor of three to four, which
is not reflected in the values above, to ensure enough
energy per area reaches the target organisms.26
A benefit to using UV treatment is that it has
not been shown to produce regulated DBFs at levels
of concern. With regard to limitations, this type of
treatment is energy intensive, does not address organic
or inorganic contaminants, and typically requires the
use of 1- to 5-um prefilters to remove particulate matter
that would interfere with the effectiveness of the process.
There are other types of media filters that can remove
color-causing substances, such as tannins, that can also
interfere with UV performance. Periodic maintenance
(e.g., UV bulb replacement and the cleaning of the
bulb housing) is important to prevent UV lamps from
becoming fouled from substances occurring naturally
in the source water. Fouling results in an increase in the
required energy dosage 26 and may make it impossible to
achieve the desired level of disinfection.
Ozone
Ozone is generated at its point of use by passing air
or oxygen gas between two electrodes separated by a
dielectric material and a discharge gap. When voltage
is applied to the electrodes, oxygen molecules are
dissociated, leading to the formation of ozone molecules.
Ozone is a strong oxidizing agent that can break down
many inorganic and organic compounds found in water.
It also acts as a disinfectant by breaking apart the cell
wall of a microorganism and then destroys enzymes,
proteins, and nucleic acids, causing the organism to die.
The contact time necessary to achieve the disinfecting
effect is relatively brief in comparison with chlorine, and
no chlorinated DBFs will result. However, if the bromide
ion is present in the source water, its reaction with ozone
can form brominated DBFs. Ozone can also react with
organic matter in water to form aldehydes, ketones, and
acids.27
Ozone is recognized as a treatment technology
for destroying microbial contaminants but is not
considered as an SSCT at the point of entry. A typical
system involves an ozone injection/contact step
followed by mechanical filtration to remove solids that
may precipitate. In some cases, it is used as part of a
more elaborate FOE treatment train involving other
technologies such as GAG and RO. While it is an
effective disinfecting technology, the results are mixed
with regard to the destruction of organic contaminants
because harmful byproducts (e.g., formaldehyde and
bromate) may result.27'28
Ion Exchange (IE)
IE resins are used primarily to address the presence of
inorganic contaminants by removing contaminant ions
in water and replacing them with relatively harmless
ions. Ion exchange can involve anion exchange (AX) or
cation exchange (CX), typically with the ionic exchanger
immobilized on a synthetic polymer backbone. From
a regulatory perspective (POU units only), AX is an
SSCT for antimony, chromium, fluoride, selenium, and
uranium, while CX is an SSCT for barium, beryllium,
cadmium, copper, lead, radium, and thallium. AX and
CX are also used in FOE treatment units for removal of
arsenic, fluoride, nitrate, and uranium (AX) and copper,
lead, and radium (CX) but are not SSCTs for those
contaminants in the POE mode.
CX resins can be either the strong acid or weak acid
type, and devices with CX resins are sometimes referred
to as water softeners. Strong acid resins are more common
because they are regenerated with sodium chloride
rather than with hazardous chemicals. This type of
water softener can also remove hazardous metals such as
barium, cadmium, chromium III, copper, lead, mercury,
radium, and zinc, but is not very effective against organic
or biological contaminants. Some limitations of these
devices include susceptibility to fouling, channeling
that allows the short-circuiting of untreated water, the
introduction of waste brine to the wastewater system or
septic tank during regeneration, and the introduction
of additional sodium into the drinking water supply to
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 15
-------
a household, thereby affecting those members on strict
low-sodium diets. No CX POU units have been certified
by NSF/ANSI, but a CX POE unit has been certified for
radium removal (Standard 44).
When IE is used at the point of use, periodic
replacement of spent resin cartridges and particulate
prefilters is required. When used at the point of entry,
periodic backwashing is required as an additional system
component. Also, the salt used for resin regeneration
needs to be replaced, and if a storage tank is used, it
should be periodically cleaned.
Distillation
This principle of operation involves applying a heat source
to evaporate the water to be treated and condensing the
vapors into a receiving vessel or trap. However, a VOC
trap is needed to remove VOCs that evaporate off with
the water as a secondary step. Inorganic contaminants
will be left behind during the evaporation process. In
principle, heating the water to boiling temperature
should kill biological contaminants; however, it is
important to verify that there is a sufficient combination
of temperature and boiling time so that spores such as
Bacillus anthrads are also killed. These devices typically
produce 1 gallon of water per 3 kilowatt-hours of
electricity29 Their design is typically configured to contain
aerosols produced during evaporation. The aerosols can
contain harmful substances.
With regard to limitations, distillation effectiveness
for organic contaminants is dependent upon the
performance of the VOC trap. The traps are highly
energy dependent and will not work if there is a power
outage and no backup power available. Those powered
by solar energy can operate intermittently. The cost is
about $0.35 of electrical energy per gallon of production
(typically taking 5 hours to produce a gallon of water),
which is twice the RO cost and four times the SBAC
cost. Although distillation is capable of removing arsenic,
copper, lead, SOCs, radium, and uranium, it is not listed
as an SSCT in either the Federal Register or in any rule.30
Batch Treatment
One manufacturer has produced a POU approach
for treating contaminated water in a batch mode. The
motivation for developing this technology is to address
unsafe drinking water conditions caused primarily by
the presence of pathogens and arsenic in third world
countries. In particular, the goal was to overcome the
difficulty in achieving sufficient disinfection, either by
solar or chemical means, because of the presence of
turbidity. Toward this end, a combination of flocculation
and disinfection was employed. The POU consists of a
coagulant (ferrous sulfate), an alkaline agent, an oxidizing
agent (potassium permanganate), a coagulation aid
(bentonite), a flocculation aid (i.e., a polymer), and a
chlorine-based disinfectant (calcium hypochlorite). These
constituents are combined in a packet to be added to
10 liters of water. After the packet contents are mixed
with the water and floe particles have developed, a final
filtration step using any type of cotton cloth or dish towel
takes place.
Tests were conducted under laboratory and field
conditions, with varying amounts of time allowed for floe
development and contact time between the disinfectant
and the water to be treated. The laboratory results
indicated that POU treatment of test waters seeded
with microbes achieved greater than 7-log reduction
and no bacteria (less than one per liter) were detected in
the treated waters. Both poliovirus and rotavirus results
showed a greater than 4-log reduction. These results
meet the EPA requirements for water purification, which
specify that polio and rotaviruses should achieve a 4-log
reduction. Furthermore, a reduction of greater than 3
logs was achieved for Cryptosporidium oocysts, which is
consistent with the EPA performance standard for water
purification. None of the field samples treated with the
product had detectable levels of coliforms or Escherichia
coli. Pretreatment arsenic levels were reduced by greater
than 99-5 percent.31
POU/POE Product Design
Diagrams are provided showing some typical
configurations of the treatment technologies discussed
in the previous section. As discussed above, there is
a vast array of devices manufactured today, so not all
configurations or treatment combinations are shown.
Prefiltration
Many of the POU/POE treatment technologies require
prefiltration to remove coarser materials and to prevent
clogging and impairment of treatment efficiency. For
POU treatment, a prefilter made of foam or cotton can
mitigate the development of clogging in general and
inhibit bacterial growth in GAG devices. With regard
16 WIPD
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to POE treatment, a prefiltration technology developed
by one manufacturer uses a 5-part segmented device
that can remove particles down to a size of 5 um. Each
filtration segment is prevented from interacting or mixing
with other segments so that backwashing can be done
on a segment-by-segment basis and without loss of
filtration media. This technology has had application as
a prefiltration device for wastewater treatment but may
also have applicability in water treatment as a means of
protecting RO membranes.32
GAC Treatement Devices
Regardless of the type of prefiltration used, the GAC
filters will eventually need to be replaced as the adsorption
sites become filled. From that point on, contaminants
will pass through untreated. A manufacturer's prediction
for when a cartridge should be changed reflects crude
estimates because factors that are characteristic to a
specific water source, such as pollutant concentration,
are not taken into consideration. The detection of
contaminants at this breakthrough condition is usually
indicated by a reduction in water pressure, change in
taste, or the presence of sediment in the water. When
these conditions are observed, the cartridge should be
replaced. Greater acidity and lower water temperatures
tend to improve the performance of GAC filters. With
regard to operation and maintenance, tests show that
under-the-sink models generally have more carbon,
superior performance, and greater convenience than
faucet or countertop models.
An illustration of a GAC POU unit treatment train
is shown in Figure 4.
Figure 4
GAC POU Unit29
Inflow
UV Disinfection
(optional)
To Separate
Tap
Particulate
Prefilter
Note: A participate prefilter is
typically used to remove particles
and extend the life of GAC
cartridges. UV disinfection may
be needed due to GAC media's
susceptibility to heterotrophic
bacterial growth. All treatment
units would typically be placed
under the kitchen sink.
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 17
-------
RO Treatment
Figure 5 depicts an RO POU treatment unit. As
indicated in the diagram, membrane-damaging chlorine
is removed by the GAG prefilter and the GAG post-
filter removes low molecular weight organic compounds
and taste- and odor-causing compounds. When used to
comply with the SDWA requirements, the units must
have a mechanical warning device with an indicator
light that may be actuated on the basis of volume usage
registered by a water meter or due to an unacceptable
change in the TDS concentration indicated by a
conductivity meter. An optional disinfection step using a
UV light source (not shown) could be added to address
microbial colonization of the GAG filters.
Figure 5
RO POU Unit
Image was reproduced with permission from Home Water Treatment
(NRAES-48), 7995, Natural Resources, Agriculture, and Engineering Service,
Cooperative Extension, Ithaca, N.Y., http://WWW.nrdes.org
Activated Carbon
Prefilter
(optional)
RO
Membrane
Sediment
Prefilter
Feed
Water
Dispensing
Faucet
Pump
(optional)
High Pressure
Switch
Activated
Carbon
Postfilter
Storage
Tank for
Product Water
Flow Restrictor
Specialty Media
Figure 6 illustrates an SBAC POU device with specialty
media that is certified for removal of arsenic by Standard
53 of NSF/ANSI. The cartridge removes contaminants in
a way analogous to the schematic shown in Figure 4.
Ion Exchange
A typical POE unit, as depicted in Figure 7, typically has
a life expectancy of 10 years and produces treated water at
a rate of 5 to 10 gpm.
18 WIPD
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Figure 6
Specialty Media for POU Arsenic Removal
Image was reproduced with permission from Home Water Treatment
(NRAES-48), 7995, Natural Resources, Agriculture, and Engineering Service,
Cooperative Extension, Ithaca, N.Y., http:llwww.nrttes.OTV
Inflow
Adsorptive
Media Vessel
To Separate
Tap
Note: This POU device
consists of a graded density
prefilter followed by a highly
compacted solid carbon block
filter mixed with arsenic
adsorptive media,all contained
in one vessel.
Figure 7
Typical POE IE Installation
Image was reproduced with permission from Mr. Jeffrey
Twitchell, Vice President, Air and Water Quality Inc., http://
www. awqinc. com/softener, html
Out
To Drain
Tank-
Distributor-
Under Bed
• Resin
Brine Tank
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 19
-------
Portable Purifiers
In a pitcher-type purifier, untreated water is placed into a
pitcher that contains a sieve, GAG, and an ion exchange
resin. The water passes through the three-part filter and
is purified by carbon adsorption and ion exchange. In
other designs, water is manually pumped through units
that incorporate silver-impregnated ceramic filters to
retain and kill micoroorganisms. There are also some
hand-held pump purifiers that use GAG in combination
with ceramic filtration. However, most of the commercial
products employing these designs are not certified to be
effective against microbial contaminants.
Performance of Current POU/POE
Products
Certified POU/POE treatment devices will remove
specified inorganic chemicals, SOCs, radium, and
other radionuclides that present a health concern. Only
POE treatment devices are certified for the removal
of microbials and VOCs that pose a health concern.
The following subsections describe how commercially
available products perform with respect to arsenic,
radium, and microbial contaminants.
Arsenic
Both organic arsenic (V) [arsenate] and inorganic
(arsenite) forms of arsenic can be removed sufficiently
by distillation systems to meet NSF/ANSI Standard 62.
However, RO devices are certified under NSF/ANSI
Standard 58 only for arsenate. Any POU/POE treatment
device used to remove arsenate would not be regenerated,
and therefore, disposal would eventually be required.
Radium
About 30 companies that make about 150 POU products
using RO have been certified by NSF for radium
reduction. However, there is no current protocol in
Standard 53 for radium and no protocols in any of the
standards for other radionuclides at this time. As stated
earlier, the CX POE unit is NSF/ANSI certified for
removal of radium.11
Microbial Issues
Several studies have been performed recently to
investigate POU/POE devices for various purposes,
including homeland security. The following is a synopsis
of several studies conducted under EPAs Environmental
Technology Verification program (http://www.epa.gov/
etv) with regard to the response of commercially available
products to microbial and chemical challenges.33
Microbial challenge testing was completed33 at the
NSF facility in Ann Arbor, Michigan, in the latter part of
2004 for three POU products currently on the market.
Each manufacturer submitted ten units for testing. These
were split into two groups of five. One group received 25
days of conditioning prior to challenge testing, while the
second group was tested immediately. The two groups
were identically challenged. The challenge organisms
were the bacteriophage viruses fr, MS2, and Phi X 174
(ranging in size from 19 to 25 nm), and the bacteria
Brevundimonas diminuta and Hydrogenophaga pseudoflava
(0.1 to 0.2 um). The test units were challenged at two
different inlet pressures, 40 and 80 psi, gauge (psig). The
virus challenges were conducted at three different pH
settings (6, 7-5, and 9) to assess whether pH influences
the performance of the test units. The bacteria challenges
were conducted only at pH 7-5- The objective of the
testing was to determine whether a 6-log reduction
in viruses and a 5-log reduction in bacteria could be
achieved. All the units were challenged without sediment
or carbon filters in place to eliminate the possibility
that these filters could temporarily trap a portion of the
challenge organisms, causing a positive bias in system
performance.
All the units performed better when tested after 25
days as opposed to being tested under virgin conditions.
The best-performing unit consists of 5 stages (prefilter,
RO membrane, a virus filter, an SBAC filter, and a
micro filter), with a storage tank between the virus filter
and the SBAC filter. Another product consists of a GAG
prefilter, RO membrane, a storage tank, and a GAG final
filter. The third product consists of five stages: a sediment
filter, two SBAC filters, an RO membrane, and a final
SBAC filter. (After the water passes through the RO
membrane, it is sent to a product storage tank before the
final filtration step.)
Preliminary conclusions regarding the testing of these
units with microbial agents were:
POU devices that rely on RO can offer significant
protection against biological agents.
Variation in performance was observed among
the units of the same manufacturer and when the
units of each manufacturer were cross-compared.
Conditioning improves and/or stabilizes RO
membrane performance.
20 WIPD
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Filtration of viruses and bacteria may be more
effective at higher pressures.
Additional research and testing are needed.
Chemical Contaminants
The same three products that were microbially challenged
are currently being subjected to testing of 14 chemicals
that include heavy metals (cadmium, cesium, mercury,
and strontium), pesticides (aldicarb, carbofuran,
dicrotophos, dichlorvos, fenamiphos, mevinphos, oxamyl,
and strychnine), and other organic substances (benzene
and chloroform). The testing protocol is to first condition
each unit for 7 days with water that does not contain the
14 chemicals. Next, each unit is tested for all four metals
at once and then one organic chemical at a time at an
inlet pressure of 50 psig, using only the RO component of
the device (prefilter, post-filter, and GAG are all removed).
Next, the carbon filter of each unit is challenged for
only those chemicals that were not removed by the RO
membrane within one order of magnitude of the EPA
MCL, if one exists (if not, professional judgment was used
to determine whether carbon challenging would occur).
The challenge test period was 15 hours. Completion of
testing is anticipated by the third quarter of 2005-33
Preliminary conclusions regarding the testing of these
units with chemical agents were:
Variation in performance was observed among
the units of the same manufacturer and when the
units of each manufacturer were cross-compared.
RO membranes maintained rejection of chemicals
over an 8-hour rest period.
POU devices using RO membranes and high-
quality post-membrane carbon filters can
offer significant protection against chemical
contaminants.
More long-term testing of these units is planned,
including the testing of a membrane-impregnated GAG
device. In addition, testing of POE devices that are not
characterized as "off-the shelf" products was planned to
begin at the NSF facility in the spring of 2005 and is
expected to last three months. This shorter test period
is expected because test plans are already in place and
because of the experience of testing the POU units. The
POE systems will consist of prefiltration, RO, and carbon
filtration. They will be challenged first with microbials
and then chemicals. The POE testing may involve some
variation in that additional chemicals may be used in the
challenge.
Mobile Treatment Technologies
Most of the mobile treatment units described below have
not been purposefully demonstrated to remove chemical,
biological, or radiological contaminants of water security
concern. However, they have demonstrated success for
purifying water under natural emergency conditions and
for use in military applications. For example, the Federal
Emergency Management Agency can deploy mobile
units called Reverse Osmosis Water Purification Units
(ROWPUs) to provide potable water at a rate of about
300 to 480 gallons per hour (gph). The Department
of Defense (DoD) has ROWPUs that can produce
potable water at an average rate of 600 gph. (The actual
rate of potable water production is dependent on the
temperature and salinity of the feed water.) These units
include a 3,000-gallon capacity tanker to haul non-
potable feed water, a generator, and a pump to overcome
elevation changes. While the 600-gph ROWPU units
are the ones most commonly used in DoD's inventory,
there are also some other ROWPUs that produce 3,000
gph and still larger ROWPUs that have a maximum
capacity of 150,000 gph. A review of national programs
for mobile treatment units is among the objectives of
a current EPA and Army Corps of Engineers study
regarding alternative water supplies for consideration by
utilities in an emergency34
Next Generation ROWPU-Type Units
The next generation DoD ROWPUs are called Tactical
Water Purification Systems (TWPS). TWPS also produce
600 gph and are still being field-tested. The Office of
Naval Research's (ONR's) Expeditionary Unit Water
Purification (EUWP) system has already manufactured
a mobile treatment unit based on ultrafiltration and RO
technology and is developing an improved version that is
expected to have a higher production rate and can be used
to treat seawater and brackish water.34
Technical Support Working Group (TSWG)
Project
A mobile POE treatment device has been developed as a
Technical Support Working Group (TSWG, httpillwww.
tswg.gov) project by an engineering firm (http://www.
RAScoEngineers.coni), which is also the vendor. This
project has progressed from concept to bench-scale to
prototype and is now ready for deployment. The unit uses
commercial off-the-shelf technology and has a treatment
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 21
-------
train that consists of carbon filtration, RO using multi-
element modular vertical membranes, ozonation, carbon
polishing, and chlorination. It has a control system that
monitors forTDS, oxidation-reduction potential, pH,
and chlorine, and the control system has the ability
to interface with other supervisory control and data
acquisition systems. These units are also scalable in terms
of the physical size of the unit and finished water output
and can be readily configured for either built-in, skid-
mounted, or trailer-portable applications. It was also
reported as scalable from about 20 gpm to 2 mgd and can
be leased from the manufacturer.28
The manufacturer claims that this technology
is capable of removing very high concentrations of
diverse chemical and biological agents as well as levels of
certain types of dissolved radionuclides and suspended
radioactive particulates. This unit successfully met a very
rigorous TSWG test protocol and has reportedly been
tested with actual contaminants of concern that include
military grade weapons agents (e.g., VX), industrial (e.g.,
cyanide) and agricultural chemicals, hallucinogenic drugs,
and viruses. While there are data reports showing how
water quality monitor fluctuations served as indicators
of contamination, EPA has not yet reviewed these data.
Disposal of wastewater that may be contaminated was
recognized as an issue. One means of addressing this
potential issue is to have a holding tank to which the
contaminated wastewater can be conveyed until it is
confirmed that the contamination event has ended.
22 WIPD
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Potential Water Security Role of
POU/POE Devices
If the public is asked not to drink or use the water, a
water utility should consider provisions for an alternate
drinking water supply. A discussion of issues surrounding
the provision of alternative water supplies, either through
direct or indirect means, is provided in EPA's Response
Protocol Toolbox, downloadable at http://wunv.epa,
gov/safewater/watersecurity/pubs and summarized in
Magnuson, et al.35 In terms of providing water directly
to consumers, options for consideration include bottled
water, packaged treatment plants (i.e., POE treatment),
and POU/POE treatment devices.
The following section specifically discusses topics
that include administrative planning and optimal design
associated with POU/POE usage in water security
applications. It then describes the potential roles of these
devices in both a proactive mode, i.e., being placed before
a contamination incident, and in a reactive mode, i.e.,
in response to a contamination incident. In the latter,
their use could occur during an incident and also during
remediation and recovery. The costs associated with the
use of these devices in both modes are presented, along
with considerations surrounding POU/POE devices
after a water contamination incident. Finally, benefits
and limitations of these devices from a water security
perspective are summarized.
It is not the purpose of this section to exhaustively
compare and contrast all means of providing alternative
water supplies; however, it is worth mentioning that
although bottled water can play a role in response to
an incident, POE treatment is a more comprehensive
response action. Unlike bottled water, it can continually
meet other water-related needs over time such as cooking
and bathing. Also, POE treatment would enable the
continued operation of hot water heating systems and the
potential use of water pumps to operate standby electrical
generators. Furthermore, while bottled water is regulated
by the U.S. Food and Drug Administration, which
has established allowable levels for its microbiological
(e.g., allowable coliform levels), chemical (more than 70
substances), radiological (e.g., radium-226 and radium-
228 radioactivity), and physical (e.g., turbidity and color)
quality,36 this product is seldom tested for parasites such
as Cryptosporidium?7
Administrative Planning for
Possible POU/POE Usage
To maximize the effectiveness of POU/POE usage during
a water security response, there are several administrative
challenges and issues. Some of these are listed below,
although others may exist, depending on the situation.
Identifying manufacturers and types of devices, as
well as their locations and delivery time
Evaluating the ability of manufacturers to ramp
up production of devices if needed
Factoring in user plumbing configurations and
climate conditions
Determining unit costs for delivery and
installation
Catagorizing devices with respect to effectiveness
against a given contaminant or class of
contaminants
Indicating the performance capability with regard
to utility water characteristics, where feasible
Defining the skill level needed to install and
maintain devices if implemented
Determining installation time (typically, about
1 hour for POU units and 3 to 24 hours for POE
units)
Comparing time requirements for POU/POE
implementation with respect to other strategies
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 23
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Optimal Design Features of
POU/POE Devices for Water
Security Applications
Because the type of contaminant threat can be so
variable and unpredictable, a combination of treatment
technologies would be most successful. There are
limitations against some types of contaminants when
using RO, GAG, UV light, or distillation alone. However,
combining RO with GAG, for example, can offer a more
effective approach. In some cases, if the contaminant
or contaminant group (e.g., VOC or biological) is well
identified, a single technology might be sufficient. Some
desirable characteristics for these units identified by
AwwaRF include:
having greater than 99 percent removal efficiency
for chemicals and greater than 3-log reduction for
microbial agents
remaining sound mechanically and maintaining
a consistent performance level over time, despite
variations in intake water characteristics
exhibiting a high level of quality assurance/quality
control by the manufacturer to ensure confidence
by many users
signaling either by sounding an alarm or by
shutting down when the unit no longer can
achieve desirable removal efficiencies (e.g., if GAG
breakthrough has occurred)
being easy to install and maintain to encourage
continued use
having the ability to obtain performance
certification
being readily available and relatively inexpensive
demonstrating an acceptable level of performance
under real-agent exposure conditions10
The final characteristic can be accomplished via
extensive testing using actual contaminants of concern.
POU/POE Treatment in a
Proactive Role
For proactive scenarios, the POU/POE treatment
devices could be used by consumers voluntarily with
the expectation that the devices can provide a protective
barrier if contaminants enter the distribution system. A
caveat for the installation of POU/POE treatment devices
in a proactive manner is that without knowing what the
contaminant is, it is virtually impossible to anticipate
what specific type of device (e.g., RO, GAG) should be
used and what level of effectiveness can be expected.
One type of proactive scenario discussed in the
AwwaRF study involved the installation of POU and/or
POE treatment devices at highly vulnerable or potentially
targeted locations (e.g., hospitals, schools, sports stadia,
military bases, government buildings, airports) and/or at
facilities that would be involved with immediate response
actions (e.g., police and fire stations). For this type of
scenario, POE treatment using a treatment train approach
would be more cost effective than POU treatment
because of the large volume of water being treated and
the large number of taps that would need to be protected.
Since the volume of water needing treatment could be
thousands to tens of thousands of gallons per day, the size
and extent of the treatment train for potentially targeted
facilities could be comparable to that of a small- scale or
packaged water treatment plant.10 Additionally, more
than one POE unit may be employed in a high-asset
building where there are multiple tenants (e.g., one that
is used for national communications/command/control
and intelligence) and where there is public access, so that
the entire building is provided protection at the point
of entry. The redundant unit could provide additional
protection in a particularly sensitive area of the building
(e.g., a building with a regional command post for
emergency response operations) and could provide an
additional layer of protection against the introduction of
contaminants of concern from within the building's water
distribution system.
For cases in which a gap exists between current sub-
par security conditions and an acceptable level of security,
POU/POE treatment could be provided by the utilities
for their users as an interim measure. Similarly, the central
treatment plant may have a tenuous record of meeting
the drinking water needs of its users under nonthreat
conditions. In a related scenario, the public water supplier
may decide that users should be provided with POU and/
or POE treatment devices because of high vulnerability
concerns that surpass the expectation of the utility's
ability to address a contamination incident at the central
treatment plant. In another scenario, there is a warning of
an imminent risk and subsequently these devices are used
to provide protection in anticipation of the impending
incident. In this case, POU treatment devices would
have to be distributed in sufficient quantities, encompass
24 WIPD
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a sufficient area, and contain the most appropriate
treatment capabilities that are commensurate with the
threat.
POU/POE Treatment
in Response to a
Contamination Incident
(Reactive Mode)
There are several conventional actions that water utilities
could take in response to suspected or confirmed
drinking water contamination. These actions include
system flushing, hyperchlorination, temporary use of
bottled water, a boil advisory, and a "do not use" order.
A comprehensive set of response actions can be found
in EPA's Response Protocol Toolbox, downloadable at
http://www. epa.gov/safewa.ter/wa.tersecurity/pubs and
summarized in Magnuson, et al.35 The specific response
actions should be implemented according to the needs
of the situation at hand. In one case study, a distribution
system serving about 30,000 people was compromised
by a chemical that resulted in turbidity, taste, and odor
problems. The public health department set strict
remediation levels, and it took nine months for these to
be achieved. During that time, water was brought in by
trucks or distributed as bottled water, and bulk water
was made available at certain locations for sanitary use.
While ingestion was prohibited, showering and bathing
could occur because there were no dermal or inhalation
concerns. The utility remedied the problem by system
flushing using heated water, and the discharge was
allowed to go to storm sewers.10
Each of these conventional response actions
has limitations. For example, while utilities can be
experienced in flushing their systems for maintenance
purposes, this approach has limited utility if contaminants
have been introduced because a flushing pressure may
not be forceful enough to reach those sections of the
distribution system that have been impacted. It also
may be necessary to continue the flushing action for
months. For some contaminants, it may be necessary
to physically scrape or even replace affected piping.
Although hyperchlorination at an appropriate pH would
be effective against some microbial contaminants and
could render other potential contaminants less toxic
(e.g., converting cyanide to cyanate), other contaminants
would not be affected, and chlorination byproducts, albeit
short-term, would result. In addition, the taste and odor
of the water would not be as pleasing to the consumer.
While a "do not use" order could allow continued water
usage for sanitation and firefighting purposes, it would
be necessary to bring in bulk or bottled water to meet
drinking, bathing, cleaning, and cooking needs for the
impacted community.10
General Considerations
In order to properly instruct the public on what type
of POU or POE device to employ, ideally the likely
contaminant would be identified. Other factors affecting
the decision to use these units in an emergency would be
the availability of the devices; complications associated
with initiating the purchase of the units, which may
involve procurement obstacles; the logistics of getting
them to the public being impacted; and the identification
of which segments of the public should be outfitted first.
With regard to procurement complications, the SDWA
(provision 42 USC Section 3001 and Section 300J; http://
ehso. cam/ehso.php?URL=http %3A %2F%2Fwww. epa.
gov/region5/defs/html/sdwa.htm) does give the EPA
Administrator and other public health officials emergency
powers to respond to situations of "imminent and
substantial endangerment to health." For example, one
type of response could include the expedited purchase
and distribution of treatment equipment such as POU
or POE devices.10 Concurrent with these decisions
would be operation and maintenance considerations, the
anticipated level of performance of the devices, and an
overall management of their use during the emergency.
Once implemented, continued use of POU/POE
treatment may be appropriate until the situation has been
abated either through successful decontamination of the
The SDWA (42 USC 3001) states that "notwithstanding any other provision of this subchapter, the Administrator, upon receipt of
information that a contaminant which is present or is likely to enter a public water system ... or that there is a threatened or potential terrorist
attack (or other intentional act designed to disrupt the provision of safe drinking water or to impact adversely the safety of drinking water supplied
to communities and individuals), which may present an imminent or substantial endangerment to the health of persons, and that appropriate State
or local authorities have not acted ... the Administrator may take action that is deemed necessary to protect the health of such persons."
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 25
-------
water supply or through a connection to an alternative
drinking water source. POU treatment devices can also
serve as a polishing step when decontamination is in its
final stages but is not yet totally complete.
Since some POU treatment devices can be easily
installed, they offer a relatively rapid response alternative
that would provide at least some protection during
an emergency, even if the contaminant has not yet
been identified and continues to impact the system
intermittently. For example, there are faucet-mounted
RO/GAC units that are certified to meet ANSI/NSF
Standard 58 and can be installed by a homeowner in
minutes. For an emergency affecting a small area of
the distribution system, a utility could have a sufficient
number of these units on hand for distribution, subject
to the limitations below. This type of device can be
effective against metals, salts, cysts, etc. and can provide
about eight gallons of water per day. Therefore, water
beyond what is needed for daily drinking can be treated
and stored to meet longer-term needs. The limitations
of this strategy would be the costs to maintain this
inventory and possible lack of consumer confidence in
the unit's performance ability, since the type of unit in
the inventory may not be effective against the actual
contaminant used.
Mobile treatment units could be employed in
response to a contamination incident or if service
has been interrupted, as they have been in past flood
emergencies. However, their effectiveness would be
uncertain since they have not been tested against
potential contaminants of concern, with the exception
of theTSWG mobile product (see page 21). Also, the
implementation of ROWPUs for a security-related
application may be problematic since many of the units
are now deployed in Afghanistan and Iraq, these units are
aging, and there could be a logistical challenge as many of
the remaining units are not located near large population
centers. Some of the availability constraints may be met
by the private sector, although the uncertainty regarding
removal of contaminants of concern would remain. For
example, one manufacturer can provide trailer-mounted
units that treat the water by means of demineralization,
softening, filtration, RO, and chemical decontamination.
According to this manufacturer, a temporary service can
be established within 36 to 72 hours, with flow rates of
500 gpm for raw water and 200 gpm for seawater. Other
companies also meet similar treatment needs: desalination
units that treat at a rate of 1,300 to 500,000 gpd and
ultrafiltration units that can remove 0.1 um particles.
One company claims it can provide emergency water by
ultrafiltration at 1.67 MGD.34
Specific Scenarios for Reactive
POU/POE Implementation
In one scenario, a contaminant has been intentionally
introduced into the distribution system such that it
continues to leach slowly over time. Examples would
include substances with high octanol/water coefficients
that could be difficult to dissolve away from the
inside surfaces of distribution piping and microbial
contaminants that could colonize these surfaces.
Response actions would first involve investigation and
precautionary measures and then likely flushing and
hyperchlorination. Depending on the level of concern,
a boil advisory or a do-not-use order may be issued, in
accordance with the SDWA's Public Notification Rule (40
CFR Parts 9, 141, 142, and 143; httpillwwui.epa.govl
safewaterlpwslpnlpnrule.pdf) , which requires water
utilities to inform the public when NPDWRs have been
violated or when there is a risk to public health. Once
contamination is confirmed, the utility could elect to
bring in bottled water or a mobile treatment unit or begin
to evaluate the implementation of POU/POE treatment
as a supplementary step.
In another scenario, the central treatment system has
been contaminated and there is no available dependable
bottled water source or the contamination has migrated
beyond the point where conventional treatment means
can be effective. For this case, POU/POE treatment offers
a means of protection until the central treatment system
is brought back on line.
Finally, there could be a decision on the part of a
homeowner to use POU/POE treatment at a location
within the distribution system during the final stages of
cleanup, even though the water is deemed safe to drink.
Similarly, after the cleanup has been completed, the
homeowner may continue to use POU/POE treatment
because he or she is not convinced that the water is
safe to drink. While the use in these scenarios would
not be mandatory from a utility's or EPAs perspective,
POU/POE implementation could be driven more
by perception of what is safe to drink than by what is
deemed safe to drink based on post-incident evaluations
of the drinking water supply.
26 WIPD
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Monitoring and Forensics Roles
As technologies capable of detecting specific
contaminants or contaminant groups continue to develop
and become more sophisticated, incorporating this
feature into POU treatment devices used by consumers at
various locations throughout the distribution system may
provide a means for improving the ability to minimize
the effects of a distribution system incident. Another
potential role for these devices involves examining them
from a forensics perspective after an incident to determine
the cause of the contamination. A current AwwaRF study
is testing various extraction techniques and methods that
would simultaneously elute bacterial, viral, and parasitic
agents from GAG POU devices. Specific microbial
contaminants undergoing extraction tests include
Escherkhia coli, Bacillus subtilis, bacteriophage PP7, and
the MS-2 virus. The results of this study are expected by
December 2005-7
Practical Considerations for
Widespread POU/POE Use
The available inventory of POU and POE treatment
devices will be one factor in considering widespread
use, either proactively or reactively The current supply
of POE units is insufficient to protect all potentially
vulnerable assets and facilities. Another factor is the
need for a backup energy supply to enable continued
operation of the unit during an emergency. A third factor
is the need for skilled personnel to operate and maintain
these units. A final factor has to do with potential
liability concerns for a water utility if the units fail due to
problems beyond the utility's control.
With regard to response time, the need to mobilize
a large number of units and trained personnel during an
emergency can make the widespread implementation of
a POU or POE installation program impractical when
potential impacts from contamination are imminent,
except in very small communities or if only a small
portion of the distribution system has been affected.
The reasons for the time delays include limited product
inventories, limited skilled installers, complex logistics,
and limited production capacity. For example, it can take
between one and two weeks to protect a community of
1,000 homes with properly installed under-the-faucet
type devices; in communities of 10,000 homes it may
take substantially more time. Assuming inventory and
logistics are not constraining factors, the time delays can
be shortened by supplying residents with pitcher filter-
type devices if it is determined that such devices will be
effective against the contaminant (s) of concern. While
skid-mounted POE devices could arrive at a vulnerable
facility or residence within a matter of hours, the same
issues regarding inventory, installation, production
capacity, and logistics limit response actions at a
multitude of facilities or residences.
There are some other factors that could affect
widespread use. If the EPA were to advise the use of
POU treatment as a response action, there also could
be liability assumed by the Agency. This liability would
have to be weighed against the percentage of those likely
protected by the order to use the devices. On a case-by-
case basis, the Agency would have to decide whether
the potential liability risk was worth taking. In addition
to liability concerns, there are quality control (QC)
concerns. Because the performance among devices from
the same manufacturer may vary, this uncertainty may
affect a decision to distribute a large number of units
from the same manufacturer in response to a biological
contaminant where there could be little margin for error.
Depending on what is known about the contamination
incident, such QC concerns may factor into determining
whether a certain type of POU device should even be
employed as a response action.
Potential Implementation of
POE Treatment in a Reactive
Decontamination Role
The portability and capability for modification and
adaptation make mobile POE treatment technologies
applicable for collecting and rendering safe many types
of chemically, biologically, or radiologically contaminated
"wash-off' or "hose-down" water. Such contaminated
water is typically created when clean, safe water is
employed to remove external contaminants from affected
citizens, emergency responders, equipment, vehicles, and/
or buildings, facilities, and infrastructure. In instances
when only contaminated water is available, these portable
units could produce safe and clean "wash-off' and
"hose-down" water, as well as volumes of safe emergency
drinking water for affected citizens and emergency
responders. This practice would reduce the volume of
contaminated water requiring additional, specialized
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 27
-------
treatment. Use of these mobile units, therefore,
could reduce both the volume and the transportation
and disposal costs associated with the disposal of
decontamination water containing contaminants
of concern. Because of post-treatment contaminant
leaching concerns, use of these devices in association
with decontamination efforts could still necessitate
eventual disposal of components or the entire system
once the POE device nears removal capacity or when the
contamination event has ended.10'13
Post-Incident Considerations
for POU/POE Treatment
Devices
Disposal Considerations and
Residuals Management
Disposal costs for POU/POE devices under normal
operating conditions (e.g., neither proactive nor reactive
terrorist-related use scenarios) are typically negligible
because of the small size and volume involved. They
represent a small contribution to the overall waste stream
as media and resins are usually taken for disposal along
with household garbage or may be taken off-site by
vendors for regeneration (as in the case of GAG filters).
The Action Plan3 recognizes the need for an
evaluation of the ultimate disposal of POU/POE
treatment devices that have become contaminated
with chemical, biological, or radiological material. The
waste material would include media, resins, distillation
residuals, and the solid surfaces of the devices that
come in contact with the incoming drinking water
stream. Although residuals generated in residences are
exempt from federal regulations such as the Resource
Conservation and Recovery Act (RCRA), state and
local regulations could determine that the residuals are
hazardous. (For example in California, media that now
contain arsenic removed during treatment may fail a
Waste Extraction Test.) For POU/POE devices installed
in commercial or business operations, the waste products
would be exempt from RCRA if the mass generated did
not exceed 100 kilograms per month. In the case of liquid
wastes generated by POU and POE treatment devices
that incorporate RO or IE in the overall treatment train,
disposal may be allowed at publicly owned treatment
works (POTWs) upon approval by plant operators, via
an on-site septic system subject to a permit requirement
from a state or local agency, or via an injection well,
provided the wastes do not exceed 60 pCi/L of radium-
226 and radium-228 and 300 pCi/L of uranium. Some
states may have additional restrictions for disposal of
radioactive wastes.13
However, because of the toxicity and uncertainty
about fate and transport associated with many
contaminants of concern, state and local authorities
might not allow disposal of solid wastes in a sanitary
landfill or liquid wastes to be discharged to a POTW, nor
is it likely that impacted media would be regenerated or
recycled. Therefore, an operating assumption regarding
disposal costs is that the devices would have to be taken to
a hazardous waste disposal facility or secure landfill.
The cost components would consist of a disposal fee
(i.e., based on the weight of the POU/POE units) and
the cost of transportation (i.e., based on the distance to
the disposal site). A second operating assumption has
to do with the transportation cost, which will depend
on the proximity of the disposal site. For estimation
purposes, assume that the average disposal cost, including
transportation, at a hazardous waste disposal facility is
$500 per ton (i.e., $0.25 per pound) and that POU
devices range from 10 to 20 pounds, while POE units
range from 100 pounds at a residence to 1,000 pounds
at a potentially targeted facility to 10,000 pounds for a
military base. Given these assumptions, the unit cost for
disposal as hazardous waste for POU treatment devices
will vary from $2.50 to $5-00. (Also, given the relatively
small size of these devices and the concern that residues
may leach out after a terrorist incident has ended,
decontamination is not likely to be considered an option.)
POE unit disposal costs will vary from $25 to $250 in
most cases and $2,500 for those from large facilities.38 If
the device is contaminated with a radioactive material, the
disposal cost could increase by a factor of 10 or more.39
Liquid wastes are generated by POU and POE
treatment devices that use RO, IE, and possibly GAG
as well if there is a backwashing feature. In these cases, it
is unlikely that conventional disposal options would be
considered during an intentional contamination incident.
There could also be additional costs associated with
impacts to indoor plumbing and the sewerage conveyance
system by wastewater containing contaminants of
concern (see next section). If a POE product has the
ability to detect a potential contamination incident,
theoretically it could divert this wastewater to a holding
28 WIPD
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tank. It is assumed that this diverted waste would be
considered hazardous, with a disposal cost ranging from
$5 to $10 per gallon.38 Again, if the liquid waste is
radioactive, the disposal cost could increase by a factor of
10 or more.39
Decontamination Study of Post-
Service Connections
There is a current project that has some relevance to the
feasibility of decontaminating a POU or POE treatment
device as an alternative to disposal. The National
Institute for Standards and Testing is conducting a
decontamination study regarding post-service connections
that include small pipes within a building or residence
and appliances such as hot water heaters, water softeners,
water filters (e.g., POU and POE treatment devices),
dishwashers, clothes washers, and ice makers. The project
goals are to determine contaminant accumulation rates in
various appliances and develop a predictive model, and to
develop decontamination methods for various potential
contaminants that will help facilitate the restoration of a
water supply system.40
Costs of POU/POE Devices
Reactive Scenario
For comparison purposes, the installation costs shown
below apply to implementation of these devices in
response to a water security incident and typically do not
include those costs associated with training installers or
any overall project management. While additional costs
(e.g., those associated with monitoring) could be incurred
as these devices are being used during an emergency, the
costs below assume a brief period of use and then removal
and disposal. 10'16'and29
The following are basic assumptions leading to the
cost estimates (in 2005 dollars):
EPA and the AWWA have estimated a per capita
consumption rate of water from POU treatment
devices of 1.3 gpd, with apeak of 0.5 to 1 gpm.
Given an average per capita use of water per
average household, POE units would treat about
165 gpd, as well as meeting peak demands of 5 to
10 gpm.
Discount rates for a large number of units may
apply (potential volume discounts, which are
not reflected below, can achieve cost reductions
of about 30 to 50 percent); however, the bulk
discount rate may be offset by costs associated
with increased demand during an emergency.
Because of the uncertain cost adjustment
associated with a potential markup during an
emergency, the costs shown below do not include
such a markup and are intended only to provide
a basis of comparison for their implementation in
response to a contamination event.
From a treatment train perspective, assume the
RO units are comparable to the one shown in
Figure 5- However, because of potential dermal,
inhalation, and nonprotected tap concerns, the
maximum benefit would be realized by using this
combination at the point of entry.
Installation costs for POU/POE units can vary
depending on whether extensive carpentry
or electrical work by licensed professionals is
necessary. In general, it is assumed that POU
units will be installed at one tap per household
and POE units will be installed inside of the
house or facility being serviced. Installation
generally adds from $50 to $150 to the purchase
cost (units with UV are twice as expensive to
install); the installation time for an RO/carbon
tap-mounted unit is minimal and the technology
can treat 10 gpd. The installation time for an
RO/carbon under-the-sink device is 1 to 2 hours.
This technology can treat 10 to 40 gpd. The
installation time for a UV POE device is 1 to 2
hours and this technology can treat about 8 gpm.
For the costs shown below, a 10 percent general
contingency factor is included.
Purchase and installation costs for various home
POU and POE devices:10'H 16> "*29
RO POU units (no UV capability): $400 to $750
RO POU units (with UV capability): $600 to
$950
RO/GAC units (faucet-mount): $50
RO/GAC units (under-the-sink): $300
RO POE: $5,000 and $20,000
UV POE: $1,000
Specialty media for arsenic removal POU units
(NSF certified units are more costly): $300 to
$650
CX POE: $3,300
GAG POU end-of-faucet (no UV capability): $10
to $30
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 29
-------
GAG POU under-the-sink units (no UV
capability): $500
GAG POU under-the-sink units (with UV
capability): $750
GAG POE (with UV capability): $3,000
The cost of renting an RO POU unit (with no UV
capability^ $20 per month. This includes installation,
operation and maintenance, and contingency costs.
Mobile treatment unit cost:34
In emergency situations, there are commercial mobile
treatment units available that incorporate technologies
similar to the ROWPUs. An approximate cost to provide
adequate treatment at a rate of 500 gpm using primarily
an RO system would be about $10,000 for setup and an
additional $1,500 to $3,000 for each day of operation.
Proactive Scenario
The costs for maintenance and replacement of parts
apply to a proactive use of these devices. For example,
maintenance/part replacement costs likely will occur after
one year for RO faucet-mounted units and UV POE
devices and after two to four years for RO under-the-
sink units. An additional 25 percent in installation costs
should be added to the costs shown above if the units are
deployed proactively to account for permitting, pilot-
testing, and legal and engineering costs.16'29 Additional
proactive scenario costs are as follows:
Maintenance:
The annual operating and maintenance costs for
RO POU units, including labor and replacement
parts, can range from $150 to $250 per year,
depending on whether UV is included and
whether there would be volume discounts.
The annual operating and maintenance costs for
specialty media POU units, including labor and
replacement parts, can range from $100 to $150
per year as the replacement cycle can be from 12
to 24 months.
The annual operating and maintenance costs for
CX POE units consists primarily of biannual salt
delivery for regeneration and radium monitoring.
The estimated cost is about $200 per year.
The annual operating and maintenance costs for
GAG POU units, including labor and replacement
parts, can range from $200 to $300 per year,
depending on whether UV is included, whether the
cartridges are replaced annually or biannually, and
whether volume discounts would apply.
Monitoring and laboratory analysis:
If the units are being used solely by homeowners
as a proactive step because of homeland security related
concerns, no monitoring or analysis is necessary. However,
if the units also are being used to meet federal requirements,
the utility must test the POU/POE units annually to ensure
compliance with the NPDWR. After the first year, one third
of all units would be sampled each year.
Total amortized costs at 7 percent for a 10-year life
expectancy (proactive, household use only):
$200 to $400 for RO POU units
$200 to $300 for rented RO POU units
$150 to $250 for specialty media POU units
$75 for pitcher filters
$100 to $150 for GAG units (under-the-sink)
$600 to $650 for CX POE units
$250 to $300 for rented GAG POU units
without UV
$350 to $400 for rented GAG POU units with UV
Large Facilities and Institutions:
Refer to Table 1 for a comparison of approximate
capital and annual operating and maintenance (O&M)
costs for different POE treatment technologies. While
MF/UF and RO/UV/GAC offer the greatest protection
against the largest variety of potential contaminants, all
four treatment systems have limitations against certain
contaminants. Therefore, costs must be weighed against the
desired level of protection.10
30 WIPD
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Comparative POE Treatment Costs at
Large Facilities/Institutions10
50,000
$350,000/$40,000
$250,000/$20,000
$600,000/$40,000
$550,000/$40,000
100,000
$500,000/$50,000
$350,000/$25,000
$750,000/$50,000
$800,000/$50,000
250,000
$900,000/$85,000
$600,000/$40,000
$1,200,000/$80,000
$1,400,000/$75,000
500,000
$1,500,000/$125,000
$1,000,000/$60,000
$2,000,000/$100,000
$2,000,000/$100,000
Benefits and Limitations
Associated With the
Implementation of POU/
POE Treatment for Water
Security
POU/POE treatment devices can contribute to increased
water security, subject to the circumstances of the water
security concern and the limitations described below.
The type of contaminant a terrorist might use cannot
be known ahead of time, but the use of POU/POE
treatment can serve in a protective role. When one of
these technologies is being used for other reasons (e.g.,
aesthetics or to address a specific problem with the
finished water), there could be an added, serendipitous
security benefit if the device happens to be effective
against the contaminant that was introduced into the
distribution system. In addition, consumers may feel that
by using these units, they have taken an action to increase
their security against an intentional act. This sense of
empowerment can also be a motivating force for using
these devices in the first place.
In addition to the water security benefits described
in "Benefits/Applicability of POU/POE Treatment,"
POU/POE treatment may have some collateral beneficial
effects not necessarily related to protecting against
intentional contamination of the distribution system.
In one example, a microbial filter POU was used solely
in the intensive care unit of a hospital to protect burn
patients from opportunistic pathogens. In a more detailed
evaluation, studies in Canada involving RO devices10
and Milwaukee involving sub-um filters and/or RO
devices37 indicated that there was a reduced incidence
of gastrointestinal disease for homes that had POU
treatment compared with those that did not. However,
another study in the Davenport, Iowa, area did not show
a significant benefit.41 The lack of benefit in the Iowa
study may be attributed to the fact that the subjects did
drink water away from home and may have been exposed
to pathogens in food, water, and other sources; therefore,
it is possible that any true benefit from the active POU
device was too small to be detected, especially if the
municipal treatment plant was already providing safe
drinking water.
Benefits/Applicability of POU/POE
Treatment
Based on the discussion of POU/POE devices in this
document, the benefits/applicability of POU/POE
treatment can be summarized as follows:
For certain contaminants, POU/POE treatment
devices can serve a proactive role and perhaps be
protective of human health.
In an emergency situation, POU devices can
reduce human exposure associated with chronic/
subchronic effects caused by contaminants,
even though these devices would not offer total
protection from acute contaminants and all
exposure pathways, particularly those other than
ingestion.
POE devices using RO plus GAG plus UV
represents a promising technology combination
for a large number, albeit not all, contaminants of
concern.
POE devices may be desirable as a means of
protecting vulnerable or potential target facilities
both proactively and also by reacting to a water
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 31
-------
contamination emergency involving these
facilities.
POU devices could serve as an interim measure
until a water treatment system has been
decontaminated or an alternative supply has been
put into service.
POU devices could serve as a polishing step
during the final stages of water treatment system
decontamination.
For long-term distribution system leaching
scenarios involving a contaminant that can cause
chronic toxicological and/or aesthetic effects,
POU/POE devices may be appropriate.
POU devices placed by utilities at critical points
in the distribution system might play monitoring
and forensics roles to either detect a contaminant
or confirm a contaminant after the fact.
Limitations of POU/POE Treatment
The limitations of POU/POE can be summarized as
follows:
POU is not recommended in a post-
contamination mode for infectious agents as
these devices may slowly leach trapped, absorbed,
or adsorbed contaminants over time. This effect
is of particular concern for immunosuppressed
individuals and other sensitive subpopulations.
Nonpathogenic bacteria tend to accumulate in
carbon POU devices and can adversely affect
children and other susceptible individuals,
especially when these devices are not well
maintained.
If POU rather than POE is used, the potential
risk exists of using an untreated tap especially for
an interval of time when a contaminant has been
introduced but has not yet been detected.
During a contamination incident, users of POU
devices must be informed that only the faucet in
their homes that is fitted with the POU device is
to be used.
Many POU/POE treatment devices are not
effective against all possible contaminants.
Choosing the appropriate device must be done
carefully and would be assisted by accurate
knowledge of the contaminant identity.
There is limited historical information available
on the performance of POU/POE treatment
devices using chemical or biological agents or their
simulants or surrogates.
Except in small communities, widespread
distribution of POU or POE devices that require
minimal to several hours of installation time in a
post-contamination mode may be too slow.
POE treatment trains can be expensive ($5,000
to $20,000); POU devices generally cost $500 to
$1,000 per unit, as discussed above.
Widespread installation as a response action
would likely not be done until flushing,
hyperchlorination, and the use of bottled water
were deemed impractical or inadequate.
Bottled water may offer a higher confidence
alternative to consumers during an emergency
incident but would not address other uses for
water.
Additional technicians and installers may be
needed for possible widespread installation
scenarios.
32 WIPD
-------
and
POU/POE treatment devices can provide some water
security benefits, especially if selectively deployed. For
example, POE treatment devices could be employed at
certain high-risk or sensitive facilities such as hospitals,
military bases, police stations, and fire stations. While
widespread proactive use of POU treatment devices
is not recommended, they could have a water security
application under circumstances where a limited
population has been affected, the type of contamination
is well understood, and the POU treatment technology
has demonstrated effectiveness against that type of
contamination. Prefiltration, RO, carbon adsorption,
and UV disinfection represent the most promising
combination of technologies that will likely be effective
against the vast majority of potential contaminants,
especially during an acute incident.
The following short-term considerations should be
taken into account when weighing the risks and benefits
for the particular situation:
Consider the installation of POE devices that use
SBAC, RO, and UV for all facilities that would be
of critical value during an attack (e.g., hospitals,
fire departments, police stations) and all high-
risk targets (e.g., government buildings, military
bases).
Continue the testing of POU/POE treatment
devices against actual contaminants of concern.
This testing will help inform the Agency and the
public regarding which devices are effective in
either a proactive or reactive manner.
Compile and periodically update an informational
database, reflecting the test results on the
efficacy of each type of device against various
contaminants. This information would provide
guidance regarding the use of devices with the
highest likelihood of success.
Compile and periodically update an inventory
database of manufacturers and distributors of
various POU and POE treatment devices to
include production capacity, number of devices
and replacement cartridges in stock, delivery
time estimates, and, where available, testing and
certification status for contaminants or classes of
contaminants of concern.
Include a distribution plan as part of local
emergency response preparation for POU
treatment devices to provide short-term protection
in the event an incident occurs in the community.
This distribution plan would be dependent upon
the informational database developed as part of
the previous recommendation.
The following strategies should be considered
but require further analysis to determine whether
implementation of the strategy is to be recommended:
Investigate whether POU devices may have some
value being readily attachable to a faucet and
being available for engagement by the homeowner
once a warning has been issued about a potential
or confirmed emergency. To prevent use of the
device in non-emergency situations that would
raise maintenance costs and concerns, there could
be a carefully considered lockout feature.
Consider the potential benefits of a proactive and
random distribution of POU treatment devices
from a post-contamination forensics perspective.
If technology permits, there is the potential
for these devices to provide sensing points for
collection and transmission of water quality data
in the distribution system, that could be part of a
more extensive contamination warning system.
Research the development of a consumer kit that
could provide a bridge response action during an
emergency. This kit would contain such items
as different modular units employing various
treatment technologies. For example, there would
be a prefiltration module, an SBAC module, an
RO module, and possibly a UV module as well.
The kit would also include adaptors so that the
modules could be properly attached to a faucet.
The parts of the kit would not be used until the
responsible authority specified what module
or combination of modules should be used in
Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 33
-------
the short-term. Consumer use of the modules
on a routine basis could be a drawback to this
recommendation.
Consider the implications of decontamination
and disposal of treatment devices once they have
served their purpose. Issues to consider include
routine versus incident-specific use, the type
of contaminant captured or retained, and the
most effective methods for decontamination and
disposal of the device and its contents.
34 WIPD
-------
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Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 37
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&EPA
United States
Environmental Protection
Agency
Office of Research and Development
National Homeland Security Research Center
Cincinnati, OH 45268
Official Business
Penalty for Private Use
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