Investigation of the Capability 

of Point-of-Use/Point-of-Entry 

Treatment Devices as a 

Means of Providing 

Water Security

research report on

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., P.E.

AAAS Environmental Fellow

February 2006
ii WIPD

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 (GAC) 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

GAC Treatment Devices........................................17
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices iii

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
iv WIPD

List of Figures

Figure 1 Carbon Adsorption Process.................................................. 10

Figure 2 RO Process........................................................................... 12

Figure 3 Microfiltration Process......................................................... 13

Figure 4 GAC 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
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices v

List of Tables

Table E-1 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
vi WIPD

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 Magnuson 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 Hais Office of Research and Development/National 

Homeland Security Research Center

Acknowledgments
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices vii

Mention of trade names, products, or services does not convey, and should 

not be interpreted as conveying, official EPA approval, endorsement, or 

recommendation.

Disclaimer
viii WIPD

ANSI American National Standards Institute 

AWWA American Water Works Association

AwwaRF American Water Works Association 

 Research Foundation

AX Anion Exchange 

CAM Cellulose Acetate Membrane

CX Cation Exchange

DBP Disinfection Byproduct

EPA U.S. Environmental Protection Agency

ETV Environmental Technology Verification 

 Program 

GAC granular activated carbon

gpd gallons per day

gph gallons per hour

gpm gallons per minute

HPC Heterotrophic Plate Count

HSPD Homeland Security Presidential 

 Directive

IE Ion Exchange

MCL Maximum Contaminant Level

MF Microfiltration

mJ millijoules

MGD million gallons per day

NHSRC National Homeland Security Research 

 Center 

NPDWR National Primary Drinking Water 

 Regulations

NRC National Research Council

NSF National Sanitary Foundation 

Acronyms and Abbreviations

ORD Office of Research and Development 

OW Office of Water 

POE Point-of-Entry

POU Point-of-Use

QC Quality Control 

PCB Polychlorinated Biphenyl

psi pounds per square inch

RCRA Resource Conservation and Recovery 

 Act

RO Reverse Osmosis

ROWPU Reverse Osmosis Water Purification 

 Unit

SBAC Solid Block Activated Carbon

SSCT Small System Compliance Technology 

SDWA Safe Drinking Water Act 

SOC Synthetic Organic Compound

TDS Total Dissolved Solid 

TFM Thin Film Membrane

TOC Total Organic Carbon 

TSWG Technical Support Working Group

TWPS Tactical Water Purification System

UF Ultrafiltration

UV Ultraviolet

VOC Volatile Organic Compound

WIPD Water Infrastructure Protection 

 Division

WSD Water Security Division 

WQA Water Quality Association
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices ix

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.

Executive Summary

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 (GAC), 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 

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x WIPD

Technology

Removes

Notes

Viruses Bacteria Cysts Organic 

Compounds

Solid Block 

Activated 

Carbon (SBAC)

no some yes most Limited removal capability for some 

pesticides; can remove methyl tertbutyl ether and selected disinfection 

byproducts; also removes chlorine and 

can be formulated to remove metals

Granular 

Activated 

Carbon (GAC)

no no no most Limited removal capability for atrazine, 

aldicarb, and alachor; shows promise for 

removal of biotoxins; removes chlorine; 

and is moderately effective at removing 

some metals

Reverse Osmosis 

(RO)

yes yes yes most Not effective at removing low molecular 

weight organic compounds; removes 

many metals and radionuclides

Ultraviolet (UV) 

Light

most yes yes no Requires prefiltration; used alone or in 

combination with other technologies

Microfiltration 

(MF)

no yes yes no Used as prefilters in combination with 

RO

Ultrafiltration 

(UF)

some yes yes some Cannot remove low-weight (less than 

100,000 daltons) organic compounds

Nanofiltration yes yes yes some Can be configured to remove arsenic

The final characteristic can be accomplished via 

extensive testing, using actual contaminants of concern.

Table E-1 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.

Table E-1 Most Promising Technologies
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices xi

Treatment Technology Cost

RO POU without UV disinfection $400 – 700

RO POU with UV disinfection $600 – 900

RO/GAC - faucet mount $50

RO/GAC - under the sink $300

RO POE $5,000 – 20,000

UV POE $1,000

Specialty media POU - arsenic removal $300 – 650

Cation exchange (CX) POE $3,300

GAC POU without UV - faucet mount $10 – 30

GAC POU without UV - under the sink $500

GAC POU with UV - under the sink $750

GAC POE with UV $3,000

Rented RO POU without UV $20 per month

Treatment Technology Amortized Cost

RO POU $200 – 400

Rented RO POU $200 – 300

Specialty media POU $150 – 250

Pitcher filters $75

GAC - under the sink $100 – 150

CX POE $600 – 650

Rented GAC POU without UV $250 – 300

Rented GAC POU with UV $350 – 400

Table E-2 Comparative POU/POE Treatment 

 Costs — Reactive Scenario

Table E-3 Comparative POU/POE Treatment Costs at 

 Households — Proactive Scenario
xii WIPD

Average 

flow (in 

gallons per 

day)

RO GAC/UV MF/UV RO/UV/GAC

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 GAC 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.

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Table E-4 Comparative POE Treatment Costs at 

 Large Facilities/Institutions 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices xiii

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 postcontamination 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.

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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 highrisk 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 

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xiv WIPD

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.

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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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 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 1

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 

OW’s 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 security.4

 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 

Introduction
2 WIPD

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
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 3

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.

Study Objectives
4 WIPD
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 5

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 flowthrough 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 (μm) pore space 

plus an activated agent to remove lead; the latter uses a 

sieve filter, granular activated carbon (GAC), 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 

•

•

•

Literature Review on the 

State of the Art 1
6 WIPD

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 

GAC 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. 

•

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•

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 (TOC), 

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-μm 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 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 7

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 62.11 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 
8 WIPD

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 entry.12

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 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 9

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 GAC 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.

•

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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
10 WIPD

Contaminated

Water

Purified

Water

Activated

Carbon Filter

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 (μm), which 

would be effective at removing asbestos fibers, protozoan 

cysts (e.g., Cryptosporidia, Giardia), and some bacteria 

(e.g., Escherichia coli, Bacillus anthracis). SBAC filters are 

less prone than GAC 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.nraes.org
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 11

Granular Activated Carbon (GAC) Filters

GAC 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)1/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 smallsystem 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 μm, 

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 
12 WIPD

Feed Water

Under Pressure

Water Stream

to Storage Tank

Rejected Contaminants

(Concentrate)

Waste Stream

to Drain

Semipermeable

Membrane

Water Flow Treated Water

(Diluted)

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 geometry.20 

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 posttreatment GAC 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.

 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.nraes.org
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 13

Untreated

Water

Filtered

Water

Suspended solids

accumlate on the

filter material.

Filter housing

Filtered water contains

particles too small to be

trapped by the filter.

 Figure 3 Microfiltration Process

Microfine Filters

Microfiltration (MF) membranes have pore sizes that 

typically range from about 0.1 to 0.2 μm. These filters 

are capable of removing bacteria and cysts and typically 

can retain particles down to 0.1 μm in size. For example, 

Cryptosporidium oocysts range from 4 to 7 μm 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 flatsheet, 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 μm 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 GAC 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.

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.nraes.org
14 WIPD

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 μm 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 (AlOOH). These fibers 

are 2 nanometers (nm) in diameter, tens to hundreds 

of nm long, and are distributed over a microglass 

fiber (0.6 μm) 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 manufacturer 23, 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 AlOOH, 

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/etv). 

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 GAC 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), UVC (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 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 15

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 DBPs 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-μm 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 DBPs will result. However, if the bromide 

ion is present in the source water, its reaction with ozone 

can form brominated DBPs. 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 POE treatment train involving other 

technologies such as GAC 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 POE 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 
16 WIPD

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 anthracis are also killed. These devices typically 

produce 1 gallon of water per 3 kilowatt-hours of 

electricity.29 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 floc 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 floc 

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 GAC devices. With regard 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 17

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 μm. 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.

Inflow

Particulate

Prefilter

GAC

Cartridge

UV Disinfection

(optional)

To Separate

Tap

Note: A particulate 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.

 Figure 4 GAC POU Unit29
18 WIPD

RO Treatment

Figure 5 depicts an RO POU treatment unit. As 

indicated in the diagram, membrane-damaging chlorine 

is removed by the GAC prefilter and the GAC postfilter 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 GAC filters.

Feed

Water

Sediment

Prefilter

Activated Carbon

Prefilter

(optional)

Pump

(optional)

RO

Membrane

Flow Restrictor

Drain

Waste

Flow

Activated

Carbon

Postfilter

Storage

Tank for

Product Water

High Pressure

Switch

Dispensing

Faucet

 Figure 5 RO POU Unit

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.nraes.org

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.
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 19

In Out

To Drain

Tank

Resin

Under Bed

Distributor

Brine Tank

Head

Inflow

Adsorptive

Media Vessel To Separate

Tap

Note: This POU device

consists of a graded density

prefilter followed by a highly

compacted soild carbon block

filter mixed with arsenic

adsorptive media, all contained

in one vessel.

 Figure 6 Specialty Media for POU Arsenic Removal

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.nraes.org

 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
20 WIPD

Portable Purifiers

In a pitcher-type purifier, untreated water is placed into a 

pitcher that contains a sieve, GAC, 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 GAC 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 EPA’s 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 μm). 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 

microfilter), with a storage tank between the virus filter 

and the SBAC filter. Another product consists of a GAC 

prefilter, RO membrane, a storage tank, and a GAC 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.

•

•

•
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 21

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 GAC 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 highquality 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 GAC 

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 nonpotable 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 emergency.34

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, http://www.

tswg.gov) project by an engineering firm (http://www.

RAScoEngineers.com), 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 
22 WIPD

train that consists of carbon filtration, RO using multielement modular vertical membranes, ozonation, carbon 

polishing, and chlorination. It has a control system that 

monitors for TDS, 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, skidmounted, 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. 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 23

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://www.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 radium228 radioactivity), and physical (e.g., turbidity and color) 

quality,36 this product is seldom tested for parasites such 

as Cryptosporidium.

37

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

•

•

•

•

•

•

•

•

•

Potential Water Security Role of 

POU/POE Devices 2
24 WIPD

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, GAC, UV light, or distillation alone. However, 

combining RO with GAC, 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 GAC 

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, GAC) 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 subpar 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 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 25

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/safewater/watersecurity/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 

The SDWA (42 USC 300i) 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.”

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 300i and Section 300j; http://

ehso.com/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 
26 WIPD

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 the TSWG 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 μm 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; http://www.epa.gov/

safewater/pws/pn/pnrule.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 EPA’s 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. 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 27

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 GAC POU devices. Specific microbial 

contaminants undergoing extraction tests include 

Escherichia 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 filtertype 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-bycase 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 
28 WIPD

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 GAC 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 radium226 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 GAC 

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 
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 29

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 PostService 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, and 29 

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 a peak 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, 14, 16, and 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

GAC POU end-of-faucet (no UV capability): $10 

to $30

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•

•

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•

•

•

•
30 WIPD

GAC POU under-the-sink units (no UV 

capability): $500 

GAC POU under-the-sink units (with UV 

capability): $750

GAC POE (with UV capability): $3,000

The cost of renting an RO POU unit (with no UV 

capability)is $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-thesink 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, pilottesting, 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 

GAC 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 GAC units (under-the-sink)

$600 to $650 for CX POE units

$250 to $300 for rented GAC POU units 

without UV

$350 to $400 for rented GAC 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

•

•

•

•

•

•

•

•

•
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 31

Average 

flow, gpd

RO GAC/UV MF/UV RO/UV/GAC

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

 Table 1 Comparative POE Treatment Costs at 

 Large Facilities/Institutions10

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-μm 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 GAC 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 

•

•

•

•
32 WIPD

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 postcontamination 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.

•

•

•

•

•

•

•

•
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 33

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 highrisk 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 

•

•

•

•

Conclusions and 

Recommendations 3

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 

•

•

•

•
34 WIPD

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.

•
 Capability of Point-Of-Use/Point-Of-Entry Treatment Devices 35

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36 WIPD

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United States

Environmental Protection

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