Water Treatment Technology

Feasibility Support Document

for Chemical Contaminants; In

Support of EPA Six-Year

Review of National Primary

Drinking Water Regulations
 Printed on Recycled Paper

Office of Water

Office of Ground Water and Drinking Water (4607M)

EPA 815-R-03-004

www.epa.gov/safewater 

June 2003
Treatment Feasibility Review June 2003 i

EPA 815-R-03-004

Water Treatment Technology Feasibility Support Document 

for Chemical Contaminants;

In Support of EPA Six-Year Review of 

National Primary Drinking Water Regulations 

June 2003

United States Environmental Protection Agency

Office of Water

Office of Ground Water and Drinking Water

Standards and Risk Management Division

Targeting and Analysis Branch

1200 Pennsylvania Avenue, NW (4607M)

Washington, DC 20460
Treatment Feasibility Review June 2003 ii
Treatment Feasibility Review June 2003 iii

TABLE OF CONTENTS

ACRONYMS .................................................................v

I. Introduction ............................................................1

II. Treatment Reviews for MCL-type Standards for Which Health Risk Assessments Were

Completed or Anticipated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

A. Beryllium ........................................................5

B. Chromium (Total) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1. Treatment technology ........................................5

2. Additional information ........................................6

3. Potential in-place treatment modifications ........................7

4. Potential chromium treatment research ..........................8

C. Fluoride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1. Treatment technology ........................................8

2. Potential in-place treatment modifications . . . . . . . . . . . . . . . . . . . . . . . 10

3. Potential fluoride treatment research . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

D. Oxamyl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

E. Picloram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

III. Treatment Review for Chemical Contaminants Regulated by Treatment Technique (TT)

Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

A. Acrylamide and Epichlorohydrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

B. Lead and Copper Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

IV. Chemical Contaminants With MCLs Limited by Analytical Feasibility . . . . . . . . . . . . 14

A. Volatile Organic Contaminants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1. Benzene, Carbon Tetrachloride, 1, 2-dichloroethane, and

Trichloroethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2. 1,2-Dibromo-3-chloropropane (DBCP) . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Dichloromethane (Methylene Chloride) . . . . . . . . . . . . . . . . . . . . . . . . . 15

4. 1,2-Dichloropropane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5. Tetrachloroethylene ("Perc") . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

B. Other Contaminants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1. Chlordane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2. Heptachlor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3. Heptachlor Epoxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4. Hexachlorobenzene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5. Thallium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

6. Toxaphene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

7. 1,1,2-Trichloroethane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

V. Contaminant for Which BAT Is Not Clear or Is Incorrectly Specified . . . . . . . . . . . . . . 18

VI. Contaminant for Which Public Comments on EPA's Review Provided New Information 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Treatment Feasibility Review June 2003 iv

TABLE OF CONTENTS, continued...

VII. Contaminants for Which Additional Health Assessments Were Completed in 2002 or

Were Anticipated in 2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

A. 1,1-Dichloroethylene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

B. Lindane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

C. Toluene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

D. Xylenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

VIII. Summary of Potential Research Needs Related to Treatment Feasibility . . . . . . . . . . . . 22

IX. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

LIST OF TABLES

Table 1. Chemical NPDWRs Included in This Treatment Feasibility Document ............3

Table 2a. Ground Water Systems: Percentage of CWSs with Various Types of Treatment . . . . 8

Table 2b. Surface Water Systems: Percentage of CWSs with Various Types of Treatment . . . . 8
Treatment Feasibility Review June 2003 v

ACRONYMS

μg/L Micrograms per liter

BAT Best available technology

BTGA Best technology generally available

CFR Code of Federal Regulations

CWS Community water system

CWSS Community Water System Survey

EPA United States Environmental Protection Agency

FR Federal Register

GAC Granular activate carbon

GFH Granular ferric hydroxide

LCR Lead and Copper Rule

MCL Maximum contaminant level

MCLG Maximum contaminant level goal

mg/L Milligrams per liter

NPDWR National Primary Drinking Water Regulation

PAC Powdered activated carbon

POE Point-of-entry

POU Point-of-use

PQL Practical quantitation level

PTA Packed tower aeration

SDWA Safe Drinking Water Act

SnCl2 Stannous chloride

TCLP Toxicity characteristic leaching procedure

TCR Total Coliform Rule

TT Treatment technique

USEPA United States Environmental Protection Agency

VOC Volatile organic chemical
Treatment Feasibility Review June 2003 vi
Treatment Feasibility Review June 2003 1

I. Introduction

This water treatment technology feasibility support document summarizes available

treatment feasibility information in support of the United States Environmental Protection

Agency (EPA) review of National Primary Drinking Water Regulations (NPDWRs). A review

of NPDWRs is required at least once every six years under section 1412(b)(9) of the Federal

Safe Drinking Water Act (SDWA), as amended in 1996. The 1996 to 2002 Six-Year Review of

NPDWRs addresses 68 regulated chemical contaminants (i.e., most of the chemical contaminants

regulated prior to 1996), in addition to the Total Coliform Rule (TCR). This document supports

EPA's review decisions on the chemical contaminants, but it does not address the TCR review

decision, which is documented separately.

EPA sets non-enforceable maximum contaminant level goals (MCLGs), based on health

effects information and related risk analyses. EPA enforceable standards include maximum

contaminant levels (MCLs) and treatment techniques (TTs) which are dependent upon EPAdocumented treatment feasibility assessments and other considerations.

EPA developed a systematic approach or protocol for the review of these NPDWRs

(USEPA, 2003a). Several technical analyses were completed by EPA in the 1996 to 2002

review of chemical NPDWRs. In addition to water treatment technologies, the analyses

addressed human health effects of the subject contaminants, analytical methods, chemical

occurrence, and other aspects related to the regulations. These analyses were conducted

individually and are documented separately. They are referenced in this report, as appropriate.

Results of the above-cited analyses were used by EPA to make a preliminary

determination as to which NPDWRs may be appropriate for revision (i.e., the analyses identified

possible or potential candidates for revision based upon the review of new scientific data). On

April 17, 2002, EPA published its preliminary findings in the Federal Register (67 FR 19030

(USEPA, 2002a)). That was followed by a public comment period, during which EPA received

comments on its review of NPDWRs, including the review of treatment feasibility. EPA

responded to these comments in the Public Comment and Response Summary for the Six-Year

Review of National Primary Drinking Water Regulations (USEPA, 2003d), and in a subsequent

Federal Register notice.

This document contains similar material as the earlier draft report that was developed in

support of the Agency's preliminary findings (USEPA, 2002b). However, it has been augmented

with information presented and discussed in public comments on EPA's April Federal Register

notice. With this and other new information that became available since April 2002, discussions

were added in two latter sections of the document which were not included in the earlier draft

technology report. In addition, section VIII of this report incorporates a summary of potential

treatment-related research areas. The potential water treatment research areas stemmed from

EPA's review of available information, including public comments. This list will be used to

inform and guide EPA's internal research strategy and may be further discussed with external

parties, (i.e., EPA stakeholders), as appropriate. Results of appropriate treatment research,

whether initiated by the Agency or by others, would be used in support of future reviews of

NPDWRs.
Treatment Feasibility Review June 2003 2

In terms of the process EPA has followed in determining which standards require a

technology feasibility review, the Agency focused on individual NPDWRs if either of the

following conditions applied:

• A health effects technical review suggested a potential change to the MCLG; or,

• A health effects assessment was not in process (or scheduled) for the contaminant

and one of the following conditions applied: (1) the analytical feasibility

assessment suggests a potential revision to the regulated level; (2) the NPDWR is

a TT-type rule.

In addition, EPA reviewed treatment feasibility information for NPDWRs for which the

best available technology (BAT) or TT requirements were not clear or were incorrectly specified

(one such NPDWR was identified) and information that EPA received during the comment

period following publication of the April 17, 2002, Federal Register notice (67 FR 19030

(USEPA, 2002a)). Some new treatment information was supplied to EPA for the contaminant

antimony as part of the public comments on that notice. Table 1, below, lists the chemical

NPDWRs discussed in this report. This tabulation has been updated since the draft report was

released, incorporating NPDWRs for which new EPA health assessments were anticipated in

2002 or 2003.
Treatment Feasibility Review June 2003 3

Table 1. Chemical NPDWRs Included in This Treatment Feasibility Document

Contaminants Identified Under the Six-Year Health Effects Review

1 Beryllium 4 Oxamyl

2 Chromium (total) 5 Picloram

3 Fluoride

Contaminants for Which Analytical Feasibility Assessments Suggested a Potential Change

1 Benzene 8 Heptachlor epoxide

2 Carbon tetrachloride 9 Hexachlorobenzene

3 Chlordane 10 Tetrachloroethylene ("perc")

4 1,2-Dibromo-3-chloropropane (DBCP) 11 Thallium

5 1,2-Dichloroethane 12 Toxaphene

6 Dichloromethane 13 1,1,2-Trichloroethane

7 1,2-Dichloropropane 14 Trichloroethylene

Contaminants Regulated by TT Requirements

1 Acrylamide 3 Epichlorohydrin

2 Copper 4 Lead

Contaminant for Which BAT Is Not Clear or Is Incorrectly Specified

Cyanide

Contaminant for Which Public Comments Provided New Information1

Antimony2

Contaminants for Which Health Assessments Were Anticipated in 2002 or 20031

1 1,1-Dichloroethylene 3 Toluene2

2 Lindane 4 Xylenes2

1. Italicized print indicates chemicals for which new information was anticipated to be available in 2002 or 2003,

(i.e., information not discussed in the February draft report or the April Federal Register notice).

2. Indicates contaminants for which new health assessments had not been completed as of January 2003.

This document primarily discusses BATs specified by EPA to meet MCLs, and

technologies to meet TT-type rules. Supplemental information is provided on small systems

compliance technologies and other related treatment information. In addition, EPA has included,

as appropriate, the following: available EPA data on treatment technologies in place at

community water systems, (i.e., some baseline treatment characteristics; discussion of the

feasibility of adding treatment or modifications to existing in-place treatments; discussion of

treatment wastes as appropriate; and, general characterization of research areas that may be

pursued prior to revising an NPDWR) although, such characterization of potential research is not

meant to be exhaustive in nature, nor static. EPA is relying on available scientific and

engineering data to support this process. The end result of each contaminant-specific review

which follows is a determination of whether treatment would pose a limitation should EPA

pursue a revision to a specified standard.

This treatment review contains some recent information related to the EPA-estimated

occurrence of chemical contaminants (i.e., levels above current MCL and other threshold
Treatment Feasibility Review June 2003 4

values). These indicators of contaminant levels in drinking water may be relevant in the

assessment of feasibility of treatment or of making treatment modifications. Since EPA has not

decided to revise the MCLs for the contaminants reviewed in this document, this support

document does not contain nor assume any particular revised MCL values. The purpose of this

report is to review available information on treatment feasibility related to any potential EPA

revise/not revise decisions on the NPDWRs.

As mentioned above, this treatment technology document identifies areas of water

treatment research which may be required if EPA were to consider revisions to a standard. 

These are identified in sections II and III, in relation to chemical MCL and TT-type rules,

respectively. Section IV, related to MCL-type rules for which analytical assessment indicated

the potential for lowering a standard, does not contain research suggestions, as none have been

identified. 

The Agency is also including a discussion of potential water treatment technology in this

document to inform both the EPA drinking water program and the public. This information will

be considered within EPA's research planning process, with the longer-term aim of strengthening

regulations such that they may be more effective and implementable. Research suggestions may

also be aimed at defining new technologies that are emerging in the field, and for qualifying their

possible application to specific NPDWRs, thus providing technical information to improve one

or more aspects of treatment. The Agency continually addresses such needs, and each new

assessment of needs and resources available typically results in a modification to the research

priorities.

Ideally, research on the treatment technologies will result in specific advantages, such as

lower-cost treatments, and/or easing burdens associated with operation and maintenance. As

necessary, research may be targeted to meet the needs of certain types of water systems, (e.g.,

small water systems), or to address multiple water quality issues. Potential research areas

identified during this review are indicated at the end of each chemical discussion in sections II

and III, and summarized in section VIII of this document. 

In addition to research, other processes are in place to assist in the upgrading of treatment

technology information. Among these are the Agency's periodic review of water treatment

technologies for NPDWRs, the first of which was completed, for chemical NPDWRs, in 1998

(USEPA, 1998b). Per SDWA as amended in 1996, that review focused on small systems

compliance technologies. EPA is committed to periodic review of small systems compliance

technologies, and intends to supplement that with review of new information on emerging

technologies that may be appropriate and affordable for meeting existing standards, for both

small- and large-scale drinking water systems.

II. Treatment Reviews for MCL-type Standards for Which Health Risk

Assessments Were Completed or Anticipated

The following contaminants were identified by EPA for treatment technology review

because new health risk information was available (i.e., beryllium, oxamyl and picloram), or

because new scientific reviews were anticipated (i.e., chromium and fluoride).
1 "Credible intervals" are generated to quantify the uncertainty around each estimated probability in the Bayesian

analysis of the occurrence data. For further explanation of credible intervals and the Bayesian analysis, please see

Occurrence Estimation Methodology and Occurrence Findings Report for the Six-Year Review of Existing National

Primary Drinking Water Regulations (USEPA, 2003b).

Treatment Feasibility Review June 2003 5

A. Beryllium

Recent EPA occurrence analyses estimated beryllium occurrence in public water systems

based on a sampling of 16 States (USEPA, 2003b). Based on these analyses, EPA estimates

indicate a total of 15 water systems (credible interval of 7 to 24)1

 within these States may have a

system mean concentration exceeding the threshold of 0.004 milligrams per liter (mg/L), (i.e.,

the current MCL for beryllium). Additional occurrence estimates may be found in the abovecited 2003 EPA report.

The current BATs for beryllium removal include activated alumina, ion exchange, lime

softening, coagulation/filtration, and reverse osmosis (USEPA, 1990b; USEPA, 1990c; 57 FR

31776 at 31809, July 17, 1992 (USEPA,1992)). Compliance technologies for small systems

include these same five BATs, plus point-of-use (POU)-reverse osmosis, POU-ion exchange for

small systems (USEPA, 1998b). Removal efficiencies for the above-cited BATs range from 80

to 99 percent. Treatment technologies were discussed by EPA in its technical support

documentation on beryllium (USEPA, 1990c). If a treatment plant were to require upgrading,

additional ion exchange contact units may be added, POU treatment installed, or a modification

to precipitative processes added, as appropriate. The Agency's current assessment is that

treatment technology would not pose a limitation, should EPA pursue a revision to this standard. 

The current BATs and small system compliance technology for beryllium also apply to

other contaminants. These treatment technologies have other beneficial effects (e.g., reduction

of hardness or other common impurities) in addition to beryllium removal. If EPA were to

consider a higher MCL, the Agency does not know how many of these public water systems

currently treating to comply with the current MCL of 0.004 mg/L would be likely to discontinue

any treatment that is already in place.

B. Chromium (Total)

1. Treatment technology

Recent EPA occurrence analyses indicate chromium occurrence in public water systems

based on a sampling of 16 States (USEPA, 2003b). Based on these analyses, EPA estimates

indicate that one water system (credible interval of 0 to 3) within these States may have a system

mean concentration exceeding the threshold of 0.1 mg/L, the current MCL for total chromium. 

In addition, EPA estimates indicate a total of seven systems (credible interval of 3 to13) within

these States may exceed the threshold of 0.05 mg/L. Additional occurrence estimates may be

found in the above-cited 2003 EPA report.

In publishing the 1989 proposed and 1991 final chromium standard (54 FR 22062 at

22105, May 22, 1989 (USEPA, 1989); 56 FR 3526 at 3552, January 30, 1991 (USEPA, 1991a))

the Agency discussed BATs which include:

• Ion exchange: 80 to 96 percent efficiency;
Treatment Feasibility Review June 2003 6

• Lime softening for chromium III only: 72 to 99 percent efficiency;

• Coagulation/filtration: 90 to 99 percent efficiency; and 

• Reverse osmosis: 82 to 97 percent efficiency.

Due to the ionic properties of the two chromium species in water, chromium III and

chromium VI, there is a differentiation in BAT specification which may affect treatment

selection. Chromium III and chromium VI exist in water in cationic and anionic valence states,

respectively. Lime softening treatment is excluded as a BAT for anionic chromium VI. 

Regarding the coagulation/filtration option, the choice of coagulant will impact chromium III

and chromium VI removal. Ferric sulfate and alum are effective for removal of chromium III,

while ferrous sulfate is effective for removal of chromium VI. Regarding ion exchange, a cation

exchange resin is required for chromium III, while an anionic resin is required for chromium VI. 

Therefore, prior to use (or modification) of lime softening, ion exchange, or

coagulation/filtration treatment, a public water system should determine concentrations and

proportions of species of chromium to select proper media or chemical aid.

The 1996 SDWA Amendments require EPA to determine small system technologies for

compliance purposes, (i.e., technology designated as suitable for systems serving 25 to 10,000

persons). In 1998, EPA listed the following compliance technologies for small systems: ion

exchange, lime softening (chromium III only), coagulation/filtration, reverse osmosis, POUreverse osmosis, and POU-ion exchange (USEPA, 1998b).

Due to the high efficiencies of chromium removal by the above technologies, EPA

believes that existing BATs would be adequate in meeting a revised standard (if the standard

were lowered). Thus, the Agency's current assessment is that treatment technology would not

pose a limitation should EPA pursue a revision to the chromium standard. 

Due to recent interest by the State of California in setting a drinking water standard for

chromium VI (the more toxic form of chromium), that State and others have initiated treatment

studies to determine the efficacy of treatment technologies in removal of chromium VI to levels

that are lower than the federal standard for total chromium. Newer treatments of interest include

an iron-based absorptive filter medium, granular ferric hydroxide (GFH), a technology that has

been piloted for arsenic removal at California water systems, and in the United Kingdom. Also,

a treatment to reduce low levels of chromium VI to chromium III in drinking water by addition

of the chemical stannous chlorine (SnCl2) is currently under investigation at a water system in

Glendale, California. EPA will monitor treatment studies to determine acceptability for use in

removal of chromium from drinking water.

2. Additional information

Of additional interest to EPA is the likelihood that disinfection treatment, including

chlorination, plays a role in transforming, by oxidation, chromium III to chromium VI in water. 

The EPA Manual of Treatment Techniques for Meeting the Interim Primary Drinking Water

Regulations (USEPA, 1977) and the EPA Occurrence and Exposure Assessment for Chromium

in Public Drinking Water Supplies (USEPA, 1990a) discussed effects of chlorination on

chromium III in raw water (spiked) and in finished water. EPA found that time of contact, pH

and other factors influence oxidation of the species. In addition, a Health Canada criteria

summary on chromium in drinking water also indicated uncertainty with respect to whether posttreatment with chlorine, affecting conversion of residual chromium III to chromium VI, may
Treatment Feasibility Review June 2003 7

reverse as water passes through iron pipes in the distribution system (Health Canada, 1986). The

testing in Glendale, California of stannous chloride as a chromium VI mitigation treatment also

includes investigation of re-oxidation of chromium III to chromium VI under various

chlorination and ammoniation treatment disinfection scenarios. While the above information

provides a minimum baseline of information on potential transformations of chromium species,

more information may be required regarding these and other potential treatment effects.

In regard to small system technologies, EPA will review available information on newer

potential treatments as research and field studies are undertaken and publicized. EPA may also

need additional data on issues related to POU-ion exchange treatment, which the Agency

discussed in a January 2001 (arsenic) Federal Register notice (66 FR 6975 at 7034, January 22,

2001 (USEPA, 2001a)). Without additional data, the Agency cannot determine if POU-ion

exchange will be a feasible compliance option, due to operational and waste discharge concerns,

and related economic issues.

3. Potential in-place treatment modifications

EPA has previously published analyses of data collected in the 1995 Community Water

System Survey (CWSS) on treatment in place at community water systems (USEPA, 2000a as

cited in USEPA, 2001b). The data indicate that a majority of larger systems, and mainly surface

water supplied systems, are much more likely to have coagulation/filtration or lime softening

treatment in place. Some of these systems may need to modify existing treatment to allow for

more efficient removal of chromium to comply with a more stringent chromium standard. For

example, an existing lime softening plant may need to enhance the process to operate at a pH of

11 to 11.5 for optimum removal; or an existing coagulation/filtration plant may need to change

to ferric or ferrous coagulant to lower chromium levels in drinking water. The CWSS data also

indicate that small systems may need to modify or add new centralized treatment or POU

treatment to meet a standard.

The option of modifying existing treatment may be possible for a limited number of

systems, as 0.7 to 4.6 percent of small ground water systems currently have ion exchange

treatment in place. Most of these are likely to be cationic resin types (whereas anionic resins

may be required to remove excess chromium), and virtually none of the small surface water

supplies have this treatment in place. A large percentage of small (and nearly all large) surface

water supplies have either coagulation/filtration or lime softening treatment in place, whereas

only 1.5 to 8.1 percent of small ground water systems currently have coagulation/filtration or

lime softening treatment in place. However, given the occurrence information, it appears that

the majority of treatment upgrades would occur at small ground water systems, many requiring

new treatments, possibly pressurized, packaged treatment technology or other emerging

treatments mentioned above.

Tables 2a and 2b, below, contain results of the above-cited 1995 CWSS data analyses

and are provided for reference.
Treatment Feasibility Review June 2003 8

Table 2a. Ground Water Systems: Percentage of CWSs with Various Types of Treatment1

Treatment Types Service Population Category

25-100 101-500 501-1,000 1,001-3,300 3,301-10,000

Ion Exchange 0.7% 1.6% 3.8% 1.9% 4.6%

Coagulation/Filtration 1.5% 5.4% 4.2% 3.4% 8.1%

Lime/Soda Ash Softening 2.1% 3.7% 4.1% 5.2% 7.0%

1

 Treatment information from 1995 Community Water System Survey as summarized in Geometries and

Characteristics of Public Water Systems (USEPA, 2000a as cited in USEPA, 2001b).

Table 2b. Surface Water Systems: Percentage of CWSs with Various Types of Treatment1

Treatment Types Service Population Category

25-100 101-500 501-1,000 1,001-3,300 3,301-10,000

Ion Exchange 0% 0% 0% 0% 0%

Coagulation/Filtration 27.5% 52.6% 70.2% 78.5% 95.4%

Lime/Soda Ash Softening 3.9% 8.1% 20.5% 17.5% 10.8%

1

 Treatment information from 1995 Community Water System Survey as summarized in Geometries and

Characteristics of Public Water Systems (USEPA, 2000a as cited in USEPA, 2001b).

4. Potential chromium treatment research

Prior to conducting analyses in support of an NPDWR revision, should a more stringent

chromium MCL be considered, EPA would need to review literature and/or conduct new

treatment research. This may include documentation of bench, pilot, and/or full-scale studies on

GFH, other adsorption media, and membrane technologies. POU-ion exchange studies on

chromium removal may be required, including tests on efficacy of treatment and disposal of

related wastes. Studies may include optimization of centralized ion exchange treatment

efficiency and waste treatment and handling/disposal. Effects of disinfection treatments, as well

as addition of reducing agents such as SnCl2 on chromium in water may require further study

should a more stringent chromium MCL be considered. These needs would be forwarded to the

appropriate office within EPA to be considered for research.

C. Fluoride

1. Treatment technology

Recent EPA occurrence analyses indicate fluoride occurrence in public water systems

based on a sampling of 16 States (USEPA, 2003b). Based on these analyses, EPA estimates

indicate that a total of 106 water systems (credible interval of 91 to 123) within these States may

have a system mean concentration exceeding the threshold of 4 mg/L, the current MCL for

fluoride. In addition, EPA estimates indicate a total of 603 (credible interval of 566 to 640)

water systems within these States may exceed the threshold of 2 mg/L. Additional occurrence

estimates may be found in the above-cited 2003 EPA report.
Treatment Feasibility Review June 2003 9

The 1986 final fluoride regulation set "best technologies generally available" (BTGAs) as

activated alumina and reverse osmosis. BTGA was defined prior to the SDWA Amendments of

1986, based upon measures of technological efficiency and economic accessibility (i.e.,

"reasonably affordable by regional and large metropolitan public water systems"). The

following factors were considered in determination of BTGA: high removal rate; wide

applicability; compatibility with other treatments; and ability to achieve compliance for all water

in the public water system (51 FR 11396 at 11398, April 2, 1986 (USEPA, 1986)). These

requirements are comparable with current SDWA requirements for BAT determination.

In addition, the 1996 SDWA amendments require EPA to determine small system

technologies for compliance purposes, (i.e., technology designated as suitable for systems

serving 25 to 10,000 persons). In 1998, EPA listed small system compliance technologies,

including both centralized activated alumina and reverse osmosis treatment, as well as POUreverse osmosis, for removal of fluoride in drinking water (USEPA, 1998b).

The Agency does not believe that the "BTGA" or small systems compliance technologies

pose a problem. In addition, should a revision to the designation of "BATs" for this contaminant

be considered by EPA, in lieu of the originally specified "BTGA" designation, this would

represent a minor revision to the NPDWR (see 40 CFR 141.62 for MCLs for Inorganic

Contaminants; and 40 CFR 142.61, which specifies variance technologies for fluoride).

Previously published research and EPA technologies and costs documents (USEPA,

1985b) on these technologies indicate that, due to high efficiencies of removal, the above-cited

treatment technologies would not be a limiting factor in setting a lower fluoride MCL. 

Efficiencies of removal range from 85 to 95 percent, depending upon treatment system design. 

Thus, the Agency's current assessment is that treatment technology would not pose a limitation

should EPA pursue a revision to the fluoride standard.

Both activated alumina and reverse osmosis treatment remove arsenic and fluoride

among other impurities. Using activated alumina treatment, optimum removals for both

contaminants may occur in a similar range of pH 5.5 to pH 6 (USEPA, 1985b; USEPA, 2000b). 

However, because arsenic V and silica are preferentially adsorbed by activated alumina media,

effectiveness of activated alumina where arsenic and fluoride co-occur may require some

investigation. Another activated alumina treatment shortcoming, discussed further below, is the

operational difficulty of adding pH adjustment for optimizing removal efficiency (i.e., adjusting

pH prior to and after treatment). For some small systems, treatment may be limited to using

"natural" pH levels (i.e., unadjusted) thus sacrificing some removal efficiency. However, this

application for fluoride removal is not documented.

The Agency discussed technical issues related to activated alumina technology in the

above-cited fluoride final rule, including waste generation and disposal. More recent EPA

publications have also examined the operation of activated alumina technology and perceived

difficulties posed by chemical handling by small systems, (i.e., for pH adjustment and for

regeneration of the media), as well as the alternatives to regeneration of activated alumina media. 

In the case of arsenic treatment, the Agency recommended against the regeneration of activated

alumina media at both small centralized treatment and POU applications, due in part to the

difficulty of disposing of brine wastes. EPA instead assumed that spent activated alumina media

would be disposed of directly at a landfill on a "throw-away" basis and that, based upon arsenic

toxicity characteristic leaching procedure (TCLP) testing, this waste would not be deemed
Treatment Feasibility Review June 2003 10

"hazardous" (USEPA, 2000b; 66 FR 6975, January 22, 2001 (USEPA, 2001a)). However,

except where arsenic and fluoride were being co-treated, this information should not (alone) be

applied to fluoride treatment wastes because Resource Conservation and Recovery Act (RCRA)

regulations do not regulate fluoride under the toxicity characteristic hazardous waste

identification rule (40 CFR 261.24). That stated, there may be concerns regarding waste brine

(i.e., regenerate solution) that have not yet been anticipated.

As part of recent revisions to the arsenic standard, the Agency also addressed the issue of

treatment optimization (pH adjustment) for POU-activated alumina systems. For arsenic, EPA

determined that use of POU (and point-of-entry (POE))-activated alumina would be limited due

to the practical limitation of adjusting pH and then re-adjusting after treating for corrosion

control. The Agency considered the option of using activated alumina at an unadjusted "natural

pH" range of 7 to 8 as the probable application at very small systems due to the operational

capabilities that are required to properly adjust pH (USEPA, 2000b; 66 FR 6975, January 22,

2001 (USEPA, 2001a)).

While not currently a "BTGA" or "BAT", modified lime softening (30 to 70 percent

removal) may also be used where this treatment is in place to remove excess fluoride (USEPA,

1985b).

The following summarizes additional information that may relate to setting, revising,

and/or applying the above two BATs and the POU compliance option for fluoride.

2. Potential in-place treatment modifications

Cost of treatment may drive systems that have fluoride above the compliance level to the

less expensive option (i.e., activated alumina), or to newer treatments as they become available. 

Where de-fluoridation treatment is already in place, due to prior exceedance of the current

fluoride MCL, systems may opt to increase the proportion of water treated, or add more capacity

to existing treatment (or additional media vessels in series). Because centralized treatment may

be less economically feasible for very small systems, some may install POU treatment (with

reverse osmosis being the more likely choice). POU treatment may also present operational

advantages and additional treatment benefits. The BATs are known to remove fluoride and

arsenic (arsenic V is preferentially adsorbed by activated alumina media). Reverse osmosis

treatment would remove additional regulated and secondary contaminants, such as total

dissolved solids, hardness, iron, and manganese, which may co-occur with fluoride in water.

EPA's 1995 CWSS data is summarized and has been utilized in recent EPA technical

support materials (USEPA, 2000a as cited in USEPA, 2001b). These provide some

understanding of numbers and types of treatments in place at community water systems. 

However, they do not specifically include activated alumina treatment information. Therefore, it

is not possible to estimate a relationship between systems now treating with activated alumina,

and those that may need to treat further to meet a lower standard. However, in areas with high

background levels (especially if above 4 mg/L), treatment of fluoride may already be in place. 

The followup 2000 CWSS results are expected to include activated alumina treatment

information and these will be available in the 2003 time frame.

The CWSS summary tables indicate (see Tables 2a and 2b) that lime/soda ash softening

capacity exists and may provide, especially for surface water systems, a base for increased
Treatment Feasibility Review June 2003 11

fluoride removal via enhanced lime softening treatment.

3. Potential fluoride treatment research

Prior to conducting analyses in support of an NPDWR revision, if that were necessary,

EPA would review pertinent literature and/or conduct new treatment research. In 2002, EPA

initiated and drafted a literature review on fluoride treatment processes (which the Agency is

maintaining in draft status, as it may require future updating) (USEPA, 2002c). Review of the

literature, in the future, may lead to additional potential research areas. These may be further

pursued through documentation of bench, pilot, and/or full-scale studies, related to treatment

effectiveness; engineering studies on existing BATs; or other treatment processes. 

Documentation and/or study of waste treatment, handling and disposal, and POU treatment

studies may also be required should a more stringent fluoride MCL be considered. These needs

would be forwarded to the appropriate office within EPA to be considered for research.

Unrelated to the above potential fluoride treatment research, the Agency has initiated an

investigation of the kinetics and equilibria of the chemicals used in water fluoridation. This

work would contribute to the understanding of how fluoridation chemicals dissociate in finished

water. The Agency funded this project, which is underway and expected to be completed in the

2005 time frame.

D. Oxamyl

Recent EPA occurrence analyses indicate oxamyl occurrence in public water systems

based on a sampling of 16 States (USEPA, 2003b). Based on these analyses, EPA estimates

indicate zero (number and percent) water systems within these States may have a system mean

concentration exceeding the threshold of 0.2 mg/L, the current MCL for oxamyl. Additional

occurrence estimates may be found in the above-cited 2003 EPA report.

The current BAT is granular activated carbon (GAC), and removal efficiency ranges

from 85 to 95 percent depending upon design parameters (USEPA, 1990b; 55 FR 30370 at

30416, July 25, 1990 (USEPA, 1990d), 57 FR 31776 at 31809, July 17, 1992 (USEPA, 1992)). 

Compliance technologies for small systems include: GAC, powdered activated carbon (PAC),

and POU-GAC (USEPA, 1998b).

If water treatment systems were to require upgrading, additional GAC contactor(s) may

be added or PAC added, as appropriate. Given available information on treatment efficacy and

on occurrence levels, the Agency's current assessment is that treatment technology would not

pose a limitation should EPA pursue a revision to this standard.

E. Picloram

Recent EPA occurrence analyses indicate picloram occurrence in public water systems

based on a sampling of 16 States (USEPA, 2003b). Based on these analyses, EPA estimates

indicate zero (number and percent) water systems within these States may have a system mean

concentration exceeding the threshold of 0.5 mg/L, the current MCL for picloram. Additional

occurrence estimates may be found in the above-cited 2003 EPA report.

The current BAT for picloram removal is GAC treatment. Treatment technologies were

discussed by EPA in its technical support documentation (USEPA, 1990b; 55 FR 30370 at
Treatment Feasibility Review June 2003 12

30416, July 25, 1990 (USEPA, 1990d), 57 FR 31776 at 31809, July 17, 1992 (USEPA, 1992)). 

Small systems compliance technologies are GAC, PAC, and POU-GAC (USEPA, 1998b).

If treatment were to require upgrading, additional GAC contact units may be added or

POU treatment installed. Given available information on treatment efficacy and on occurrence

levels, the Agency's current assessment is that treatment technology would not pose a limitation

should EPA pursue a revision to this standard.

The current BATs and small system compliance technologies for picloram also apply to

other contaminants. These treatment technologies have other beneficial effects (e.g., reduction

of organics or other common impurities) in addition to picloram removal. If EPA were to

consider a higher MCL, the Agency does not know how many public water systems currently

treating to comply with the current MCL of 0.5 mg/L would be likely to discontinue any

treatment that is already in place.

III. Treatment Review for Chemical Contaminants Regulated by Treatment

Technique (TT) Requirements

This section contains a brief review of required treatment technologies for those

contaminants with TT-based NPDWRs, including acrylamide, epichlorohydrin, and the Lead and

Copper Rule (LCR).

As allowed under SDWA, in cases where EPA determines it is not technically or

economically feasible to establish an MCL, the Agency can instead specify a TT rule. TT rules

established treatment methods to minimize the level of a contaminant in drinking water.

A. Acrylamide and Epichlorohydrin

EPA regulations for acrylamide and epichlorohydrin, including polymer addition

practices, were discussed in Federal Register notices of 1989 and 1991 (54 FR 22062 at 22105,

May 22, 1989 (USEPA, 1989); 56 FR 3526 at 3552, January 30, 1991 (USEPA, 1991a)). EPA

has no new information that suggests it is appropriate to revise the TT requirements for

acrylamide and epichlorohydrin at this time.

B. Lead and Copper Rule

The LCR requires the mitigation of lead and copper in public drinking water supplies

through treatments, mainly through optimizing corrosion control treatment and through related

monitoring strategies (56 FR 26460, June 7, 1991 (USEPA, 1991b)).

The LCR establishes treatment-type measures to control levels of lead and copper in

public drinking water, including corrosion control treatment requirements for small, medium,

and large water systems. Treatment may be triggered following sampling and analysis of tap

water, if the value at the 90th percentile of all lead or copper samples is higher than the lead or

copper action levels of 0.015 mg/L or 1.3 mg/L, respectively.
Treatment Feasibility Review June 2003 13

Under the LCR, public water systems that are required to conduct corrosion control

studies must evaluate the effectiveness of each of the following treatments and, if appropriate,

combinations of the following treatment:

• Alkalinity and pH adjustment;

• Calcium hardness adjustment; and

• Addition of a phosphate or silicate based corrosion inhibitor. 

Public water systems are also required to monitor for lead and copper, and the following

water quality parameters, before and after evaluating the above treatments: pH, alkalinity,

calcium, conductivity, orthophosphate or silicate (where added), and water temperature. Water

systems must identify constraints that limit or prohibit the use of a particular corrosion control

treatment(s), and evaluate effect(s) of corrosion control chemicals on other water quality

treatment processes. On the basis of the above, a public water system recommends the treatment

option best suited for its system, and the State review agency considers the public water system

information, and then designates optimal treatment for that system.

EPA has no information that suggests it is appropriate to revise the current TT

requirements for lead and copper. However, EPA received public comments on the Agency's

preliminary decisions, published in the April 17, 2002, Federal Register, which indicate that

there is an interest in examining treatment and other aspects of the LCR (67 FR 19030 (USEPA,

2002a)). The Agency recognizes that there are challenging aspects to this rule, and that more

research would be useful to obtain additional information that could be utilized to address some

of the issues associated with implementation of the LCR.

Because no new data are available to make a revise/not revise determination, EPA has

decided to place lead in the "data gaps" category, indicating that research may need to be

completed prior to making further determinations. Copper has been placed in another category,

because an EPA copper health effects assessment is underway and must be completed before

EPA can determine if a revision to the NPDWR is warranted. Nonetheless, some of the potential

research that is indicated below could affect the control of both copper and lead.

EPA believes that research on treatment aspects of the LCR, (i.e., on effective corrosion

control measures), and on other pertinent issues affecting implementation, may be appropriate. 

The following list represents the Agency's current understanding of general needs that may be

filled by research to better inform future reviews of the NPDWR:

• Investigation of effects related to compliance with the LCR and the requirements

related to disinfectants and disinfection byproducts.

• Investigation of corrosion control chemicals, including optimization and use of

chemicals, constraints related to distribution system materials, possible secondary

effects, and alternative approaches to current corrosion control strategies.

• Other needs including: investigation of optimization of corrosion control at

systems with high alkalinity and/or hardness in source water; monitoring (e.g.,

targeted monitoring to represent copper levels); and small systems LCR treatment

compliance issues, that may be of considerable interest. 
Treatment Feasibility Review June 2003 14

The above represents a current synopsis of the most critical research areas related to the

LCR. It is not intended to be all-inclusive nor a static listing of subject areas. The February

2002 draft version of this report included a longer listing. The above combines some of the

issues and adds others. EPA believes that the above-listed items would take variable periods of

time to complete, and would most likely be done in steps. In addition, they may be handled by

more than one party, depending on interests and relative priorities, available funding, and other

critical factors. Determining the most effective use of resources and the exact nature of research

would require additional study/discussion.

EPA includes priority research within its multi-year planning process, and in its

comprehensive drinking water research strategy. These help EPA prioritize and plan future

research and help the Agency track current efforts. The Agency reviews plans periodically and

changes them as necessary. In addition, EPA expects to further explore LCR-related research

needs within the Agency, and with interested stakeholders, to inform future Agency decisions.

IV. Chemical Contaminants With MCLs Limited by Analytical Feasibility 

This section includes a brief treatment technology assessment of chemicals currently

regulated at MCL values that were based on analytical feasibility. More recent EPA assessments

of analytical feasibility indicate the potential for lower practical quantitative levels (PQLs) for

these contaminants (USEPA, 2003c).

For all contaminants discussed in this section, the Agency's current assessment is that

treatment technology would not pose a limitation should EPA pursue a revision to any of the

referenced standards. Chemical occurrence is not referenced for these contaminants, since the

known occurrence levels for these (USEPA, 2003b) would not pose an obstacle to specification

of treatments. Likewise, MCL values for these contaminants are not referenced.

A. Volatile Organic Contaminants

1. Benzene, Carbon Tetrachloride, 1, 2-dichloroethane, and Trichloroethylene

Since the results of the analytical methods feasibility review indicate that it may be

possible to recalculate the PQL for benzene; carbon tetrachloride; 1, 2-dichloroethane; and

trichloroethylene, EPA has reviewed treatment feasibility for these contaminants to determine if

it is likely to become an issue if EPA were to revise any of their MCLs. The BATs for each of

these contaminants are packed tower aeration (PTA) and GAC (56 FR 3526 at 3552, January 30,

1991 (USEPA, 1991a)). Small system compliance technologies for each include: PTA, diffused

aeration, multi-stage bubble aerators, tray aeration, shallow tray aeration, and GAC (USEPA,

1998b).

The Agency discussed treatment for volatile organic chemicals (VOCs) in the 1985

proposed VOC regulation (50 FR 46902 at 46909, November 13, 1985 (USEPA, 1985a)). Under

optimum conditions, up to 99.9 percent removal of VOCs may be achieved by aeration

technology, and the Agency considers 99 percent reduction to be achievable under all anticipated

conditions. In addition, in the above-cited proposed rule, EPA discussed GAC treatment for

VOCs, and considers 99 percent removal to be achievable under all anticipated conditions. 

Thus, treatment is not known to be a limiting concern for any of the current MCLs for these four

contaminants: benzene; carbon tetrachloride; 1, 2-dichloroethane; and trichloroethylene. Based
Treatment Feasibility Review June 2003 15

on this information, EPA's current assessment is that treatment technology would not pose a

limitation, should the Agency consider revising any of their current MCLs.

2. 1,2-Dibromo-3-chloropropane (DBCP)

Since the results of the analytical methods feasibility review indicate that it may be

possible to recalculate the PQL for DBCP, EPA has reviewed treatment feasibility to determine

if it is likely to become an issue if EPA were to revise the MCL. BATs include aeration and

GAC (54 FR 22062 at 22105, May 22, 1989 (USEPA,1989); 56 FR 3526 at 3552, January 30,

1991 (USEPA, 1991a)), and compliance technologies for small systems include GAC, PAC, and

POU-GAC (USEPA, 1998b). Treatment is not known to be a limiting concern for the current

MCL.

Since the Henry's coefficient for this contaminant is relatively low (i.e., 7 atmospheres

DBCP, which is considered "less strippable" than other contaminants), GAC may in some cases

be the preferred treatment. Based on this information, EPA's current assessment is that treatment

technology would not pose a limitation should the Agency consider revising the current MCL.

3. Dichloromethane (Methylene Chloride)

Since the results of the analytical methods feasibility review indicate that it may be

possible to recalculate the PQL for dichloromethane, EPA has reviewed treatment feasibility to

determine if it is likely to become an issue if EPA were to revise the MCL. As a VOC, the BAT

for dichloromethane is PTA (57 FR 31776 at 31809, July 17, 1992 (USEPA, 1992)). Small

system compliance technologies include: PTA, diffused aeration, multi-stage bubble aerators,

tray aeration, shallow tray aeration, and GAC (USEPA, 1998b). Treatment is not known to be a

limiting concern for the current MCL.

The Agency discussed treatment for VOCs in the 1985 proposed VOC regulation (50 FR

46902 at 46909, November 13, 1985 (USEPA, 1985a)). Under optimum conditions, up to 99.9

percent removal of VOCs may be achieved by aeration technology, and the Agency considers 99

percent reduction to be achievable under all anticipated conditions. Based on this information,

EPA's current assessment is that treatment technology would not pose a limitation, should the

Agency consider revising the current MCL.

4. 1,2-Dichloropropane

Since the results of the analytical methods feasibility review indicate that it may be

possible to recalculate the PQL for 1,2-dichloropropane, EPA has reviewed treatment feasibility

to determine if it is likely to become an issue if EPA were to revise the MCL. BATs for 1,2-

dichloropropane includes both PTA and GAC (54 FR 22062 at 22105, May 22, 1989 (USEPA,

1989); 56 FR 3526 at 3552, January 30, 1991 (USEPA, 1991a)). Small system compliance

technologies include: PTA, diffused aeration, multi-stage bubble aerators, tray aeration, shallow

tray aeration, and GAC (USEPA, 1998b). Treatment is not known to be a limiting concern for

the current MCL.

Among volatile contaminants, this contaminant exhibits "average strippability" (54 FR

22062 at 22105, May 22, 1989 (USEPA, 1989)). The Agency discussed treatment for VOCs in

the 1985 proposed VOC regulation (50 FR 46902 at 46909, November 13, 1985 (USEPA,

1985a)). Under optimum conditions, up to 99.9 percent removal of VOCs may be achieved by
Treatment Feasibility Review June 2003 16

aeration technology, and the Agency considers 99 percent reduction to be achievable under all

anticipated conditions. Based on this information, EPA's current assessment is that treatment

technology would not pose a limitation, should the Agency consider revising the current MCL.

5. Tetrachloroethylene ("Perc")

Since the results of the analytical methods feasibility review indicate that it may be

possible to recalculate the PQL for tetrachloroethylene, EPA has reviewed treatment feasibility

to determine if it is likely to become an issue if EPA were to revise the MCL. BATs for

tetrachloroethylene include PTA and GAC (56 FR 3526 at 3552, January 30, 1991 (USEPA,

1991a)), and small systems compliance technologies include: PTA, diffused aeration, multistage bubble aerators, tray aeration, shallow tray aeration, and GAC (USEPA, 1998b). 

Treatment is not known to be a limiting concern for the current MCL.

The high level of volatility of tetrachloroethylene is reflected in this chemical's Henry's

Law Coefficient of 214.0 atmospheres. Design of air stripping equipment was discussed in the

proposal for this NPDWR. Several factors which affect engineering design include: air-to-water

ratio; packed material height; available area for mass transfer; water and air temperature; and

physical chemistry of the contaminant (54 FR 22062 at 22105, May 22, 1989 (USEPA, 1989)). 

Tetrachloroethylene, while volatile, is also highly amenable to GAC adsorption treatment. 

Carbon use rates for this contaminant are relatively low.

The Agency discussed treatment for VOCs in the 1985 proposed VOC regulation (50 FR

46902 at 46909, November 30, 1985 (USEPA, 1985a)). Under optimum conditions, up to 99.9

percent removal of VOCs may be achieved by aeration technology, and the Agency considers 99

percent reduction to be achievable under all anticipated conditions. Based on this information,

EPA's current assessment is that treatment technology would not pose a limitation, should the

Agency consider revising the current MCL.

B. Other Contaminants

1. Chlordane

The BAT for chlordane is GAC (56 FR 3526 at 3552, January 30, 1991 (USEPA,

1991a)). Treatment is not known to be a limiting concern for the current MCL. However, since

the results of the analytical methods feasibility review indicate that it may be possible to

recalculate the PQL for chlordane, EPA has reviewed treatment feasibility. Chlordane is a

moderately adsorbed pesticide (54 FR 22062 at 22105, May 22, 1989 (USEPA, 1989); 56 FR

3526 at 3552, January 30, 1991 (USEPA, 1991a)). Therefore, EPA's current assessment is that

treatment technology is not anticipated to pose a limitation, should the Agency consider revising

the current MCL.

2. Heptachlor

The BAT for heptachlor is GAC (56 FR 3526 at 3552, January 30, 1991 (USEPA,

1991a)), and small systems compliance technologies include: GAC, POU-GAC, and PAC

(USEPA, 1998b). Since the results of the analytical methods feasibility review indicate that it

may be possible to recalculate the PQL for heptachlor, EPA has reviewed treatment feasibility to

determine if it is likely to become an issue if EPA were to revise the MCL. Treatment is not

known to be a limiting concern for the current MCL.
Treatment Feasibility Review June 2003 17

Heptachlor is a moderately adsorbed organic contaminant (54 FR 22062 at 22105, May

22, 1989 (USEPA, 1989); 56 FR 3526 at 3552, January 30, 1991 (USEPA, 1991a)). EPA's

preliminary assessment is that treatment technology is not anticipated to pose a limitation should

the Agency consider revising the current MCL.

3. Heptachlor Epoxide

The BAT for heptachlor epoxide is GAC (56 FR 3526 at 3552, January 30, 1991

(USEPA, 1991a)), and compliance technologies for small systems include GAC, PAC, and POUGAC (USEPA, 1998b). Since the results of the analytical methods feasibility review indicate

that it may be possible to recalculate the PQL for heptachlor epoxide, EPA has reviewed

treatment feasibility to determine if it is likely to become an issue if EPA were to revise the

MCL. Treatment is not known to be a limiting concern for the current MCL.

Heptachlor epoxide is a strongly adsorbed organic contaminant, generally attributed to a

low carbon usage rate (54 FR 22062 at 22105, May 22, 1989 (USEPA, 1989); 56 FR 3526 at

3552, January 30, 1991 (USEPA, 1991a)). Based on this information, EPA's current assessment

is that treatment technology is not anticipated to pose a limitation should the Agency consider

revising the current MCL.

4. Hexachlorobenzene

The BAT for hexachlorobenzene is GAC (57 FR 31776 at 31809, July 17, 1992 (USEPA,

1992)), and compliance technologies for small systems include GAC, PAC, and POU-GAC

(USEPA, 1998b). Since the results of the analytical methods feasibility review indicate that it

may be possible to recalculate the PQL for hexachlorobenzene, EPA has reviewed treatment

feasibility to determine if it is likely to become an issue if EPA were to revise the MCL. 

Treatment is not known to be a limiting concern for the current MCL.

Since hexachlorobenzene is a moderately adsorbed contaminant, EPA's current

assessment is that treatment technology is not anticipated to pose a limitation should the Agency

consider revising the current MCL.

5. Thallium

BATs for thallium include activated alumina and ion exchange (57 FR 31776 at 31809,

July 17, 1992 (USEPA, 1992)). EPA also listed small systems compliance technologies for this

contaminant as activated alumina, ion exchange, POU-ion exchange (USEPA, 1998b). Since the

results of the analytical methods feasibility review indicate that it may be possible to recalculate

the PQL for thallium, EPA has reviewed treatment feasibility to determine if it is likely to

become an issue if EPA were to revise the MCL. Treatment is not known to be a limiting

concern for the current MCL.

According to technical information provided previously by EPA for thallium, competing

ions in water may affect treatment run lengths (USEPA, 1998b). Assuming reasonable

engineering practices, high removals of this contaminant are feasible. Removals may be

expected to be greater than 90 percent using cation exchange systems, and greater than 95

percent using activated alumina treatment (55 FR 30370 at 30416, July 25, 1990 (USEPA,

1990d)). Based on this information, EPA's current assessment is that treatment technology is not

anticipated to pose a limitation should the Agency consider revising the current MCL.
Treatment Feasibility Review June 2003 18

6. Toxaphene

The BAT for toxaphene is GAC (56 FR 3526 at 3552, January 30, 1991 (USEPA,

1991a)), and small systems compliance technologies include: GAC, POU-GAC, and PAC

(USEPA, 1998b). Since the results of the analytical methods feasibility review indicate that it

may be possible to recalculate the PQL for toxaphene, EPA has reviewed treatment feasibility to

determine if it is likely to become an issue if EPA were to revise the MCL. Treatment is not

known to be a limiting concern for the current MCL.

According to technical information provided with the final NPDWR for toxaphene, this

compound is among those that are moderately to well-adsorbed, exhibiting a relatively low

carbon usage rate (54 FR 22062 at 22105, May 22, 1989 (USEPA, 1989); 56 FR 3526 at 3552,

January 30, 1991 (USEPA, 1991a)). Assuming reasonable engineering practices, high removals

of this contaminant are feasible. Based on the above information, EPA's current assessment is

that treatment technology is not anticipated to pose a limitation should the Agency consider

revising the current MCL.

7. 1,1,2-Trichloroethane

BATs for 1,1,2-trichloroethane includes both PTA and GAC (57 FR 31776 at 31809, July

17, 1992 (USEPA, 1992)). Small systems compliance technologies for this contaminant include: 

PTA; diffused aeration; multi-stage bubble aerators; tray aeration; shallow tray aeration; and

GAC (USEPA, 1998b). Since the results of the analytical methods feasibility review indicate

that it may be possible to recalculate the PQL for 1,1,2-trichloroethane, EPA has reviewed

treatment feasibility to determine if it is likely to become an issue if EPA were to revise the

MCL. Treatment is not known to be a limiting concern for the current MCL.

According to technical information provided by EPA within the final NPDWR for 1,1,2-

trichloroethane, this compound is among those moderately adsorbed chemicals, exhibiting a

moderate carbon usage rate (57 FR 31776 at 31809, July 17, 1992 (USEPA, 1992)). 1,1,2-

Trichloroethane may be among the less volatile organic chemicals (55 FR 30370 at 30416, July

25, 1990 (USEPA, 1990d)). Assuming reasonable engineering practices, treatment for removal

of this contaminant is feasible. Based on this information, EPA's current assessment is that

treatment technology is not anticipated to pose a limitation should the Agency consider revising

the current MCL.

V. Contaminant for Which BAT Is Not Clear or Is Incorrectly Specified

BATs for cyanide include ion exchange, reverse osmosis, and "chlorine" treatment (57

FR 31776 at 31809, July 17, 1992 (USEPA, 1992)). CFR §141.62 and §142.62 contain

erroneous BAT designations for cyanide. These will need to be revised to read "alkaline

chlorination" in place of "chlorine" as a BAT for cyanide. EPA will publish a Federal Register

notice to make the appropriate corrections to the cyanide regulation.

EPA discussed chlorination in the proposed and final regulations for cyanide (55 FR

30370 at 30416, July 25, 1990 (USEPA, 1990d); 57 FR 31776 at 31809, July 17, 1992 (USEPA,

1992)). The Agency discussed the effectiveness of oxidation of cyanide at high pH in the related
Treatment Feasibility Review June 2003 19

technology support document (USEPA, 1990c). Thus, the Agency had technically described the

correct treatment (i.e., the use of chlorination at elevated pH conditions) but had an error in the

published listings of BATs.

In addition, since this standard was promulgated, EPA distributed a "Public Water

System Warning" (USEPA, 1994) through its regional offices. This warning included

information on the use of chlorination (non-alkaline) and the potential for formation of harmful

cyanogen chloride, due to reaction of chlorine with cyanide in water under those conditions. 

This warning also states, "EPA will change the regulations specifying BAT for removing

cyanide from chlorination to alkaline chlorination."

Alkaline chlorination, through use of excess chlorine at pH values greater than 8.5,

oxidizes cyanide to harmless bicarbonate and nitrogen gas. The higher the pH, the faster this

reaction proceeds. The "Public Water System Warning" explains this process in detail and

outlines treatment practice, including contact times, required chlorine concentrations, and

compensation for temperature effects.

VI. Contaminant for Which Public Comments on EPA's Review Provided

New Information 

The MCL for antimony is 6 micrograms per liter (μg/L). EPA discussed BATs for

antimony (i.e., coagulation/filtration and reverse osmosis) in the proposed and final regulations

for this contaminant (55 FR 30370 at 30416, July 25, 1990 (USEPA, 1990d); 57 FR 31776 at

31809, July 17, 1992 (USEPA, 1992)). Small systems compliance technologies for antimony

include reverse osmosis and coagulation/filtration, and POU-reverse osmosis (USEPA, 1998b).

Prior to promulgating this regulation, EPA conducted laboratory tests to determine

treatment removal efficiencies on source water that had been spiked with antimony to a

relatively high level, approximately 100 μg/L.

Following publication of the April 17, 2002, Federal Register notice with the preliminary

Six-Year Review findings (67 FR 19030 (USEPA, 2002a)), the Agency received several

comments from parties in Utah which indicated a difficulty in implementing the antimony

standard. A few small systems have levels of antimony in their source water at or above the

MCL value of 6 μg/L (i.e., at levels between 6 and 19 μg/L).

Some of these systems have been investigating treatment options for the removal of

antimony from their source water. Commenters submitted supporting data documenting the

results of their testing and cost analyses. According to commenters, on-site testing indicated that

the designated BATs (i.e., reverse osmosis and coagulation/filtration) and most of the other

tested treatments were ineffective and/or prohibitively expensive due to: raw water quality

concerns; water conservation needs; current costs for water production; and other concerns, such

as waste water management. In addition, commenters indicated that coagulation/filtration

assisted by microfiltration was unsuccessful in the removal of antimony to the MCL. These

commenters noted other concerns that included: the handling of treatment chemicals, safety, and

pretreatment of water. Commenters also pointed to the marked difference between the ambient

water levels, at their systems, and the value at which EPA had tested the BATs.
Treatment Feasibility Review June 2003 20

Commenters also indicated that one technology that they tested, GFH, was very

promising for antimony removal, in regard to its efficiency and operational parameters. Relative

cost evaluations were also conducted. Cost analyses for the Salt Lake County Service Area No.

3 site in Snowbird, Utah, indicated that GFH may be the lowest-cost treatment option, at a total

annualized (capital and operations and maintenance included) cost of $1.80/kgal, compared to

approximately $3.90/kgal for reverse osmosis treatment. In addition to the cost issue,

commenters said that reverse osmosis presented waste disposal problems and was not an

acceptable option due to the volume of wasted water.

EPA believes that, should a decision be made to revise this standard (i.e., to a lower

level), or if the Agency determined that the occurrence of this contaminant is more widespread

than currently believed, there may be a need for further research on antimony treatment removal

technologies. Results of research may be useful for expanding the technology information base

for this NPDWR. (Note that EPA is prohibited from making revisions to an MCL based on

feasibility unless such changes maintain or provide for greater health protection.) The scope and

priority of research for antimony treatment has yet to be determined by EPA. The level of

priority will be better understood when the Agency has completed an assessment of the antimony

health risk information.

VII. Contaminants for Which Additional Health Assessments Were

Completed in 2002 or Were Anticipated in 2003

This section includes a brief treatment technology assessment of regulated chemicals for

which health assessments were recently completed or were possibly going to be completed prior

to, or soon after the close of the 1996 - 2002 Six-Year Review. These contaminants include, 1,1-

dichloroethylene, lindane, toluene, and xylene.

A. 1,1-Dichloroethylene

The current MCL for 1,1-dichloroethylene is 0.007 mg/L. BATs and small system

compliance technologies for 1,1-dichloroethylene include aeration and GAC (56 FR 3526 at

3552, January 30, 1991 (USEPA, 1991a); USEPA, 1998b). These treatment technologies also

apply to other contaminants and have other beneficial effects (e.g., removal or reduction of other

organics and other common impurities), in addition to removal of 1,1-dichloroethylene from

water. Therefore, if EPA were to raise the MCLG/MCL, the Agency believes that few, if any,

public water systems currently treating to comply with the current MCL would be likely to

discontinue any such treatment that is already in place (USEPA, 2002d).

B. Lindane

The current MCL for this contaminant is 0.0002 mg/L. BAT and small system

compliance technology for lindane is GAC (57 FR 31776 at 31809, July 17, 1992 (USEPA,

1992); USEPA, 1998b). This treatment technology also applies to removal or reduction of other

contaminants and has other beneficial effects (e.g., removal or reduction of other organics and

other common impurities), in addition to removal of lindane in water. Therefore, if EPA were to

raise the MCLG/MCL, the Agency believes that few, if any, public water systems currently

treating to comply with the current MCL would be likely to discontinue any such treatment that

is already in place (USEPA, 2002d).
Treatment Feasibility Review June 2003 21

C. Toluene

The current MCL for toluene is 1 mg/L. The current BATs and small system compliance

technologies for toluene include several forms of aeration and GAC (57 FR 31776 at 31809, July

17, 1992 (USEPA, 1992); USEPA, 1998b).

Field studies performed in three States using PTA demonstrated a removal efficiency of

greater than 96 percent for toluene, with initial concentrations of up to 0.6 mg/L (Ram et al.,

1990 as cited in USEPA, 1998b). Performance studies employing diffused aeration, which is

another air stripping technology used to treat toluene, have demonstrated 50 to 90 percent

removal efficiencies. The study noted higher removals for VOCs that had higher Henry's Law

coefficients (USEPA, 1985b as cited in USEPA, 1998a).

GAC may also be an effective treatment option for toluene, although based on cost

estimates (54 FR 22062 at 22105, May 22, 1989 (USEPA, 1989)), it may be more than twice as

expensive as PTA for large systems on a dollar per household per year basis. If off-gas control

of PTA is necessary, costs between PTA and GAC are more competitive, but PTA is still likely

to be more cost-effective for system sizes up to 1 to 10 million gallons per day (Adams and

Clark, 1991). Specific cost information for GAC and PTA control of toluene is available

(Adams et al., 1989; Adams and Clark, 1991). Based on this information, EPA does not

anticipate that treatment would pose a limitation should the Agency consider revising the current

standard(s) for toluene.

D. Xylenes

The current MCL for total xylenes is 10 mg/L. The current BATs and small system

compliance technologies for xylenes include several forms of aeration and GAC (57 FR 31776 at

31809, July 17, 1992 (USEPA, 1992); USEPA, 1998b).

Field studies performed in three States using PTA demonstrated a removal efficiency of

greater than 96 percent for toluene, with initial concentrations of up to 0.6 mg/L (Ram et al.,

1990 as cited in USEPA, 1998b). Although no specific efficiency of removal by PTA was

available, xylenes have larger Henry's Law coefficients (0.22 to 0.32 atmosphere-m3

/mole), as

compared to a coefficient of 0.0066 for toluene, and so would likely be removed at least as

effectively as toluene by PTA or other air stripping technologies (HSDB, 2002; 54 FR 22062 at

22105, May 22, 1989 (USEPA, 1989); USEPA, 2002b).

Performance studies employing diffused aeration, which is another air stripping

technology like PTA, to treat xylenes have demonstrated 50 to 90 percent removal efficiencies. 

The study noted higher removals for VOCs that had higher Henry's Law coefficients (USEPA,

1985b as cited in USEPA, 1998a).

GAC may also be an effective treatment option for xylenes, although based on cost

estimates (54 FR 22062 at 22105, May 22, 1989 (USEPA, 1989)) it may be more than twice as

expensive as PTA for large systems on a cost per household basis. If off-gas control of PTA is

necessary, costs between PTA and GAC are more competitive, but PTA is still likely to be more

cost-effective for system sizes up to 1 to 10 million gallons per day (Adams and Clark, 1991). 

Specific cost information for GAC and PTA control of xylenes is available (Adams et al., 1989;

Adams and Clark, 1991). Based on this information, EPA does not anticipate that treatment

would pose a limitation, should the Agency consider revising the current standard for xylenes.
Treatment Feasibility Review June 2003 22

VIII. Summary of Potential Research Needs Related to Treatment Feasibility

This report contains a number of suggestions for potential research that may be pursued

by EPA or by others. It incorporates information discussed in the February 2002 draft of this

report and material submitted by reviewers and commenters.

This section summarizes the potential research areas identified within the report. This is

meant to be informative to the public. It does not, however, presume a relative ranking among

them, and it is not to be considered a "static" listing, as it will be subject to further discussion

and change. Please note that EPA and stakeholder priorities on the drinking water regulatory

agenda will likely evolve; current budgets may not reflect future conditions; and, other factors

will likely impact the nature of this listing over time.

EPA is using this list as the starting point in terms of identifying research and planning

for research over long periods of time, including as information for the Agency's Comprehensive

Drinking Water Research Strategy and for other internal Agency planning tools.

Below is a listing of areas identified during the course of the Six-Year Review as

potential areas of treatment-related research. This list does not include potential research areas

related to other technical areas, such as NPDWR contaminant occurrence, analytical methods,

sampling requirements, or other matters which may be discussed in other EPA support

documents.

• Investigation of treatment and water quality effects related to compliance with the

LCR and requirements under the disinfectants and disinfection byproducts

NPDWRs.

• Investigation of corrosion control chemicals, including optimization and use of

chemicals; constraints related to distribution system materials; secondary effects;

and, alternative approaches.

• Investigation of optimization of corrosion control at systems with high alkalinity

and/or hardness in source water; monitoring such as targeted monitoring to

represent copper levels; and small systems LCR issues.

• Efficacy of treatment technologies in removal of specific contaminants, such as

antimony, chromium, and/or fluoride in drinking water. Specific needs may

include investigation of operational factors, waste disposal issues, treatment

effectiveness, source water quality effects, co-treatment effects, interferences

from other contaminants, secondary effects related to other NPDWRs, and POU

and POE applications.

• Oxidation and/or reduction effects on chromium species in water (EPA research

is underway).

The following is not a treatment-related research area; it has been identified by EPA as a

chemistry research need which may be of interest in relation to the common practice of drinking

water fluoridation:

• The kinetics and equilibria of chemical silicofluorides used in water fluoridation

treatment (EPA research is underway).
Treatment Feasibility Review June 2003 23

IX. References

Adams, J.Q., and R.M. Clark. 1991. Evaluating the Costs of Packed-Tower Aeration and GAC

for Controlling Selected Organics. Journal of the American Water Works Association. v. 83, n.

1, p. 132-140.

Adams, J.Q., R.M. Clark, and R.J. Miltner. 1989. Controlling Organics With GAC: A Cost and

Performance Analysis. Journal of the American Water Works Association. v. 81, n. 4, p. 49-57.

Hazardous Substances Data Bank (HSDB). 2002. Search for Toluene. Available on the Internet

through TOXNET, sponsored by the National Institute of Health's National Library of Medicine.

http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB, accessed September 12, 2002.

Health Canada. 1986. Federal-Provincial Subcommittee on Drinking Water. Guidelines for

Canadian Drinking Water Quality - Supporting Document (Chromium). Updated September

1986. Accessed on Internet October 15, 2001:

http://www.hc-sc.gc.ca/ehp/ehd/catalogue/bch_pubs/dwgsup_doc/dwgsup_doc.htm

Ram, N.M., R.F. Christman, and K.P. Cantor. 1990. Significance and Treatment of Volatile

Organic Compounds in Water Supplies. Lewis Publishers. p. 363-391. (As cited in USEPA,

1998b)

United States Environmental Protection Agency (USEPA). 1977. Manual of Treatment

Techniques for Meeting the Interim Primary Drinking Water Regulations. EPA Report 600/8-

77-005. Cincinnati, OH. May 1977.

USEPA. 1985a. National Primary Drinking Water Regulations – Volatile Organic Chemicals;

Proposed Rulemaking. Federal Register. Vol. 50, No. 219. p. 46902, November 13, 1985.

USEPA. 1985b. Technologies and Costs for the Removal of Volatile Organic Chemicals from

Potable Water Supplies.

USEPA. 1986. National Primary Drinking Water Regulations; Volatile Synthetic Organic

Chemicals; Final Rule and Proposed Rule. Federal Register. Vol. 51, No. 63. p. 11396, April

2, 1986.

USEPA. 1989. National Primary and Secondary Drinking Water Regulations; Proposed Rule. 

Federal Register. Vol. 54, No. 97. p. 22062, May 22, 1989.

USEPA. 1990a. Occurrence and Exposure Assessment for Chromium in Public Drinking Water

Supplies. July 24, 1990.

USEPA. 1990b. Technologies and Costs for the Removal of Phase V Synthetic Organic

Chemicals from Potable Water Supplies. Office of Drinking Water. September 1990.

USEPA. 1990c. Technologies and Costs for the Removal of Phase V Inorganic Contaminants

from Potable Water Sources. Revised Draft. January 1990.
Treatment Feasibility Review June 2003 24

USEPA. 1990d. National Primary and Secondary Drinking Water Regulations – Synthetic

Organic Chemicals and Inorganic Chemicals; Proposed Rule. Federal Register. Vol. 55, No.

143. p. 30370, July 25, 1990.

USEPA. 1991a. National Primary Drinking Water Regulations – Synthetic Organic Chemicals

and Inorganic Chemicals; Monitoring for Unregulated Contaminants; National Primary Drinking

Water Regulations Implementation; National Secondary Drinking Water Regulations; Final

Rule. Federal Register. Vol. 56, No. 30. p. 3526, January 30, 1991. 

USEPA. 1991b. Maximum Contaminant Level Goals and National Primary Drinking Water

Regulations for Lead and Copper; Final Rule. Federal Register. Vol. 56, No. 110. p. 26460,

June 7, 1991.

USEPA. 1992. National Primary Drinking Water Regulations; Synthetic Organic Chemicals

and Inorganic Chemicals; Final Rule. Federal Register. Vol. 57, No. 138. p. 31776, July 17,

1992.

USEPA. 1994. Public Water System Warning: Cyanide. Memo from William R. Diamond,

Acting Director of Drinking Water Standards Division. Office of Ground Water and Drinking

Water. March 7, 1994.

USEPA. 1998a. Cost Evaluation of Small System Compliance Options-Point-of-Use and Pointof-Entry Treatment Units. Draft. Standards and Risk Management Division, Office of Ground

Water and Drinking Water. Washington, DC. June 1998.

USEPA. 1998b. Small System Compliance Technology List for the Non-Microbial

Contaminants Regulated Before 1996. EPA Report 815-R-98-002. Office of Water. September

1998.

USEPA. 2000a. Geometries and Characteristics of Public Water Systems. Final Report. EPA

Report 815-R-00-024. Office of Ground Water and Drinking Water. December 2000. (As cited

in USEPA, 2001b)

USEPA. 2000b. Arsenic Technologies and Costs for the Removal of Arsenic from Drinking

Water. EPA Report 815-R-00-028. December 2000.

USEPA. 2001a. National Primary Drinking Water Regulations; Arsenic and Clarifications to

Compliance and New Source Contaminants Monitoring; Final Rule. Federal Register. Vol. 66,

No. 14. p. 6975, January 22, 2001.

USEPA. 2001b. Water Industry Drinking Water Baseline Handbook. Third Edition (Draft). 

May 2001.

USEPA. 2002a. National Primary Drinking Water Regulations; Announcement of the Results

of EPA's Review of Existing Drinking Water Standards and Request for Public Comment;

Proposed Rule. Federal Register. Vol. 67, No. 74. p. 19030, April 17, 2002.
Treatment Feasibility Review June 2003 25

USEPA. 2002b. Water Treatment Technology Feasibility Support Document for Chemical

Contaminants; In Support of EPA Six-Year Review of National Primary Drinking Water

Regulations. Office of Water. EPA Report 815-D-02-001. Draft. February 2002.

USEPA. 2002c. Draft Report; Review of Literature on Removal of Fluoride From Drinking

Water. Office of Water. November 2002. 

USEPA. 2002d. An Evaluation of Available Economic Information in Support of the Six-Year

Review of Existing NPDWRs. Memo from Marc Parrotta, Targeting and Analysis Branch, Office

of Ground Water and Drinking Water. March 18, 2002.

USEPA. 2003a. Protocol for Review of Existing National Primary Drinking Water Regulations. 

EPA Report 815-R-03-002. Final. June 2003.

USEPA. 2003b. Occurrence Estimation Methodology and Occurrence Findings Report for SixYear Review of National Primary Drinking Water Regulations. EPA Report 815-R-03-006. 

Final. June 2003.

USEPA. 2003c. Analytical Feasibility Support Document for the Six-Year Review of Existing

National Primary Drinking Water Regulations. EPA Report 815-R-03-003. Final. March 2003.

USEPA. 2003d. Public Comment and Response Summary for the Six-Year Review of National

Primary Drinking Water Regulations. EPA Report 815-R-03-001. Final. June 2003.
Treatment Feasibility Review June 2003 26

EPA_815-R-03-004

Water_Treatment_Technology_Feasibility_Support_Document_for_Chemical_Contaminants;

In_Support_of_EPA_Six-Year_Review_of_National_Primary_Drinking_Water_Regulations