Prepared in cooperation with Miami Conservancy District

The Effectiveness of Water-Treatment Systems 

for Arsenic Used in 11 Homes in Southwestern 

and Central Ohio, 2013

Scientific Investigations Report 2015–5156

U.S. Department of the Interior

U.S. Geological Survey
Cover. Photographs of domestic wells and arsenic treatment systems. 

Photograph credits: Mary Ann Thomas, USGS (top left); Donna Runkle, USGS (center); and 

Mike Ekberg, Miami Conservancy District (top right, bottom right, bottom left). 
The Effectiveness of Water-Treatment 

Systems for Arsenic Used in 11 Homes in 

Southwestern and Central Ohio, 2013

By Mary Ann Thomas and Mike Ekberg

Prepared in cooperation with Miami Conservancy District

Scientific Investigations Report 2015–5156

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod/.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Thomas, M.A., and Ekberg, Mike, 2016, The effectiveness of water-treatment systems for arsenic used in 11 homes 

in Southwestern and Central Ohio, 2013: U.S. Geological Survey Scientific Investigations Report 2015–5156, 26 p., 

http://dx.doi.org/10.3133/sir20155156.

ISBN 978-1-4113-4006-0 

ISSN 2328-031X (print) 

ISSN 2328-0328 (online)
iii

Acknowledgments

The authors would like to thank Thomas Sorg, U.S. Environmental Protection Agency, for providing background information, assisting with data interpretation and providing a thorough review 

of this report. The authors also thank the homeowners who participated in this study.

v

Contents

Acknowledgments........................................................................................................................................iii

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope .............................................................................................................................2

Description of Study Area ..................................................................................................................3

Sidebar—Arsenic Treatment Terms Used in this Report........................................................................4

Previous Studies ..................................................................................................................................5

U.S. Environmental Protection Agency Studies of Arsenic Removal Technology............5

Small Public-Water Systems in Ohio...............................................................................5

Domestic Wells in Ohio......................................................................................................5

Methods...........................................................................................................................................................6

Site Selection.........................................................................................................................................6

Data Collection and Analysis..............................................................................................................6

Quality Assurance.................................................................................................................................7

Quality of Raw Water ....................................................................................................................................8

Total Arsenic and Arsenic Species ...................................................................................................8

Other Water-Quality Constituents .....................................................................................................8

Types of Water-Treatment Systems Sampled.........................................................................................10

Effectiveness of The Water-Treatment Systems ....................................................................................10

Reverse Osmosis ................................................................................................................................12

Oxidation/Filtration Using Manganese-Based Media .................................................................14

Systems That Include Anion Exchange and Reverse Osmosis ..................................................16

Effects of Methods Used for Pretreatment ...................................................................................18

Factors Related To Effectiveness of Arsenic Removal..........................................................................18

Characteristics of Treatment Systems ............................................................................................18

 Raw-Water Quality ............................................................................................................................20

Summary of Results.....................................................................................................................................21

References Cited .........................................................................................................................................22

Figures

1. Map showing location of 11 study sites in southwestern and central Ohio.......................3

2. Graph showing quality of raw water from 11 domestic wells in southwestern and 

central Ohio, 2013 .........................................................................................................................9

3. Graphs showing effect of reverse-osmosis systems on concentrations of total 

arsenic, arsenite, and arsenate ...............................................................................................13

4. Graphs showing effect of oxidation/filtration systems on concentrations of 

selected constituents.................................................................................................................15

5. Graphs showing effect of systems that include anion exchange and reverse 

osmosis on concentrations of total arsenic, arsenite and arsenate .................................17
vi

6. Graphs showing arsenic removal in relation to system type and maintenance 

history for 11 sites in southwestern and central Ohio, 2013................................................19

7. Arsenic removal in relation to system type and raw-water arsenic concentrations 

for nine maintained systems in southwestern and central Ohio, 2013 with different 

ranges of raw-water arsenic concentrations........................................................................21

Tables

1. Methods used for collection and analysis of water samples from 11 domestic 

wells in southwestern and central Ohio, 2013 .........................................................................7

2. Water-quality results from 11 domestic wells in southwestern and central 

Ohio, 2013 .......................................................................................................................................8

3. Characteristics of water-treatment systems sampled in southwestern and 

central Ohio, 2013 .......................................................................................................................11

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Supplemental Information

Concentrations of chemical constituents in water are given in either milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Conversion Factors

Inch/Pound to International System of Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Volume

ounce, fluid (fl. oz) 0.02957 liter (L) 

gallon (gal) 3.785 liter (L) 

Mass

ounce, avoirdupois (oz) 28.35 gram (g) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as 

°F = (1.8 × °C) + 32.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C).
The Effectiveness of Water-Treatment Systems for Arsenic 

Used in 11 Homes in Southwestern and Central Ohio, 2013

By Mary Ann Thomas and Mike Ekberg

Abstract

In 2013, the U.S. Geological Survey and the Miami 

Conservancy District investigated the effectiveness of methods 

used to remove arsenic from drinking water at 11 homes in 

southwestern and central Ohio. The untreated (raw) groundwater had arsenic concentrations of 7.7–382 micrograms per 

liter (μg/L), and the median concentration was 30 μg/L. The 

pH was neutral to slightly alkaline, and redox conditions were 

strongly reducing, as indicated by high concentrations of iron. 

The predominant arsenic species was arsenite (As3+), which 

is difficult to treat because it exists in water as an uncharged 

compound (H3AsO3).

The water-treatment systems included (1) seven singletap reverse-osmosis systems, (2) two whole-house oxidation/

filtration systems, and (3) two systems that included wholehouse anion exchange and single-tap reverse osmosis. All but 

one system included pretreatment by a water softener, and two 

systems included preoxidation to convert arsenite (As3+) to 

arsenate (As5+) before treatment by anion exchange. 

None of the treatment systems removed all of the arsenic from the drinking water. About one-half of the systems 

decreased the arsenic concentration to less than the maximum 

contamination level of 10 μg/L. The effectiveness of the systems varied widely; the percentage of arsenic removed ranged 

from 2 to 90 percent, and the median was 65 percent. 

At some sites, the low effectiveness of arsenic removal 

may have been related to system maintenance and(or) operation issues. At two sites, homeowners acknowledged that 

the treatment systems had not been maintained for several 

years. At two other sites, the treatment systems were being 

maintained, but the water-quality data indicated that one 

of the components was not working, unbeknownst to the 

homeowner. EPA research at a small number of sites in Ohio 

indicated that operation and maintenance of some arsenictreatment systems was not always simple. 

Another factor that affected system effectiveness 

was the quality of the raw water. In general, the treatment 

systems were less effective at treating higher concentrations 

of arsenic. For five sites with raw-water arsenic concentrations of 10–30 μg/L, the systems removed 65–81 percent of 

the arsenic, and the final concentrations were less than the 

maximum contamination level. For three sites with higher 

raw-water arsenic concentrations (50–75 μg/L), the systems 

removed 22–34 percent of the arsenic; and the final concentrations were 4–5 times more than the maximum contamination 

level. Other characteristics of the raw water may have affected 

the performance of treatment systems; in general, raw water 

with the higher arsenic concentrations also had higher pH, 

higher concentrations of organic carbon and ammonia, and 

more reducing (methanogenic) redox conditions. 

For sites with raw-water arsenic concentrations of 

10–30 μg/L, two types of systems (reverse osmosis and oxidation/filtration) removed similar amounts of arsenic, but the 

quality of the treated water differed in other respects. Reverse 

osmosis caused substantial decreases in pH, alkalinity, and 

concentrations of most ions. On the other hand, oxidation/filtration using manganese-based media caused a large increase 

of manganese concentrations, from less than 50 μg/L in raw 

water to more than 700 μg/L in outflow from the oxidation/

filtration units. 

It is not known if the results of this study are widely 

applicable; the number of systems sampled was relatively 

small, and each system was sampled only once. Further study 

may be warranted to investigate whether available methods 

of arsenic removal are effective/practical for residential use in 

areas like Ohio, were groundwater with elevated arsenic concentrations is strongly reducing, and the predominant arsenic 

species is arsenite (As3+).

Introduction

Most instances of widespread arsenic contamination 

of groundwater are the result of natural sources of arsenic 

(Smedley and Kinniburgh, 2002). Arsenic is often a minor 

component of the rocks or sediments of the aquifer matrix, and 

it can be released to the groundwater under certain geochemical conditions. Long-term exposure to arsenic through drinking water is associated with multiple serious health problems. 

Arsenic is a known human carcinogen linked to cancers of 

the bladder, lungs, skin, kidney, nasal passages, liver, and 
2 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

prostate. In addition, exposure to arsenic has been determined 

to interfere with the immune system; affect cardiovascular, 

pulmonary, neurological, and hormonal processes; and may be 

an important contributor to the development of type 2 diabetes 

(U.S. Environmental Protection Agency, 2001; International 

Agency for Research on Cancer, 2004; World Health Organization, 2010). The U.S. Environmental Protection Agency 

(EPA) has determined that the concentration of arsenic with no 

known or expected health risk is 0 microgram per liter (μg/L) 

(referred to as the maximum contaminant level goal [MCLG]). 

The highest level of arsenic allowed in drinking water from 

public-water systems is 10 μg/L (referred to as the maximum contaminant level [MCL]). The MCL is higher than the 

MCLG because cost of treatment is taken into consideration 

(U.S. Environmental Protection Agency, 2009). In this report, 

arsenic concentrations greater than 10 μg/L are referred to as 

“elevated.”

Arsenic is a relatively common contaminant in Ohio 

groundwater; 17 percent of public-water systems (about one 

in six) had arsenic concentrations greater than the MCL in 

raw, untreated water (Ohio Environmental Protection Agency, 

2010b). The Ohio EPA requires that public-water systems 

monitor for arsenic, and the average annual concentration in 

finished water cannot exceed 10 μg/L. Domestic wells of Ohio 

are not routinely tested for arsenic. (MCLs are not enforceable 

for domestic wells but are often used as health guidelines.) 

About 1.8 million Ohio residents rely on domestic wells 

(Maupin and others, 2014), and most do not know the arsenic 

concentration of their water. As more people become aware 

of the potential health problems associated with arsenic in 

drinking water, they may seek guidance about water treatment 

methods. 

Removing arsenic from groundwater is complex. One 

reason is that inorganic arsenic can exist in groundwater as 

two different species; arsenate (As5+) is generally the predominant species in oxic groundwater, and arsenite (As3+) is 

generally the predominant species in reducing groundwater. 

Arsenate (As5+) is easier to remove from water because it 

typically exists as a negatively charged compound (HAsO4

2-

or HAsO4

-

). On the other hand, As3+ exists as an uncharged 

compound (H3AsO3), and therefore is harder to remove by 

treatment processes. (In addition, As3+ is generally considered 

to be more toxic to humans than As5+.) 

In Ohio and the other parts of the Midwest, arsenic in 

groundwater is predominantly As3+, whereas As5+ is the predominant species in other regions of the United States (Sorg 

and others, 2014). There are also regional differences in other 

water-quality constituents that affect arsenic mobility (and 

effectiveness of arsenic removal) including redox conditions, 

pH, and concentrations of oxyanions. 

The effectiveness of any water treatment method depends 

on the chemical characteristics of the water being treated; 

therefore, treatment methods that are effective in other parts of 

the Country may be less effective in Ohio. Much of the available research about treating water for arsenic relates to large 

public-water systems in the western U.S. or to primitive wells 

in remote villages of southeastern Asia (for example, Ahuja 

[2008] and references therein).Very few studies have been 

done to test the effectiveness and applicability of methods for 

treating arsenic in groundwater characteristic of Ohio or other 

parts of the Midwest. In 2013, the U.S. Geological Survey 

(USGS), in cooperation with the Miami Conservancy District 

(MCD), did an investigation of arsenic-treatment systems used 

in homes of southwestern and central Ohio. Because of the 

small number of systems sampled, results of this study cannot 

be used to determine whether one type of system is better than 

another; however, results of the study provide an initial snapshot of residential arsenic treatment that can be used to guide 

the design of future studies. 

Purpose and Scope

The purpose of this report is to document the effectiveness of methods used to treat arsenic in water from 11 domestic wells in southwestern and central Ohio. The goals are to 

(1) describe the chemical characteristics of the groundwater, 

(2) describe the types of water-treatment system in use, and (3) 

document differences between raw groundwater and treated 

water with emphasis on arsenic concentrations and speciation. 

A total of 11 homes in Preble, Darke, Montgomery, 

Greene, Clark, and Licking Counties, Ohio, were selected 

for study. Unfiltered samples of raw and treated water were 

collected from each home once during 2013. Samples were 

analyzed at the USGS National Water Quality Laboratory 

(NWQL) for arsenic, arsenic species, major ions, trace elements, nutrients, and total organic carbon. Homeowners 

provided information about the type, age, and maintenance 

history of the treatment systems. Graphical methods and 

summary statistics were used to document (1) the chemical 

characteristics of the raw water, (2) the effect of the treatment 

systems on concentrations of total arsenic and arsenic species, 

and (3) factors related to the effectiveness of the treatment 

systems. 
Introduction 3

Description of Study Area

The wells sampled for this study are in Licking County 

(central Ohio), and five counties within the Great Miami River 

watershed (southwestern Ohio) (fig. 1). These are areas where 

arsenic in groundwater has been investigated or documented 

by Dumouchelle (1999), Ohio Department of Health (1999), 

Shindel and others (2000), Miami Conservancy District 

(2011), Thomas and others (2005, 2008), and Thomas (2016). 

The hydrogeology of the Great Miami River Basin has been 

summarized by Debrewer and others (2000) and the Miami 

Conservancy District (2013). The hydrogeology of Licking 

County has been described by Dove (1960), Angle (1995), and 

Siegrist and others (1997). The glacial and bedrock geology of 

both areas has been mapped by Ohio Department of Natural 

Resources as part of statewide and county coverages (Ohio 

Department of Natural Resources, n.d.). 

The geology of southwestern and central Ohio consists of 

Paleozoic sedimentary bedrock overlain by Pleistocene glacial 

deposits. In southwestern Ohio, bedrock consists of carbonates 

and shales of Ordovician-Silurian age, and glacial deposits 

are predominantly from the Miami Lobe of the Wisconsin 

glacial advance. In Licking County, bedrock is predominantly 

interbedded shales and sandstones of Devonian-Pennsylvanian 

age, and glacial deposits are from the Scioto Lobe. Despite 

these differences, many aspects of the hydrogeology are 

similar. In both areas, deep valleys were cut into bedrock by 

the preglacial Teays River system and subsequently filled with 

glacial deposits (and are referred to as “buried valleys”). In 

buried valleys, glacial deposits are 200 to more than 

600 feet (ft) thick, and in uplands between buried valleys, glacial deposits are generally 0–200 ft thick. Layers or lenses of 

sand and gravel in the glacial deposits serve as aquifers. Over 

most of the area, the sand and gravel deposits are overlain by 

relatively fine-grained material (till or clay), and the aquifers 

are confined or semiconfined. In the vicinity of modern rivers, 

sand and gravel occurs at land surface, and the glacial aquifers 

are unconfined. 

In southwestern and central Ohio, water wells tap bedrock and (or) the overlying glacial deposits. Elevated concentrations of arsenic have been detected in both types of aquifers 

but are generally higher in glacial aquifers. In southwestern 

Ohio, a survey of arsenic in 107 wells determined that 

20 percent of domestic wells in the Great Miami River Basin 

had elevated arsenic (Miami Conservancy District, 2011). In 

Licking County, a study of 168 domestic wells determined that 

12 percent had elevated arsenic concentrations (Thomas, 

2016). In both areas, elevated concentrations of arsenic were 

detected in groundwater with similar chemical characteristics: 

iron concentrations were greater than about 800 μg/L, redox 

conditions were strongly reducing, and the pH was neutral to 

slightly alkaline. In both areas, the highest arsenic concentrations were detected in methanogenic water in confined buriedvalley aquifers (Thomas and others, 2005, 2008).

Figure 1. Location of 11 study sites in southwestern and central Ohio.

D Licking arke

Lewisburg

Preble

Clark

Greene

Montgomery

D–177

PR–240

PR–241

PR–242

PR–239

MT–1285

CL–23

GR–754

LI–31

LI–36

LI–38

0

0 40

40 80 MILES

80 KILOMETERS

Base modified from U.S. Geological Survey

1:24,000-scale digital data 

N

Ohio
4 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Sidebar—Arsenic Treatment Terms 

Used in this Report

Brief explanations of the processes discussed in this 

report are provided below. The information is from U.S. 

Environmental Protection Agency (2003), Ohio Environmental Protection Agency (2010a), National Ground Water 

Association (2009), and Thomas Sorg, U.S. Environmental 

Protection Agency (written and verbal commun., 2013).

There are two general types of water-treatment systems: 

• Point-of-entry (POE) systems treat all of the water 

that enters a home—usually 250 or more gallons per 

day. The POE systems are also referred to as “wholehouse” systems. 

• Point-of-use (POU) systems treat water from a 

single faucet. They are often installed on the kitchen 

sink and treat only the water used for drinking and 

cooking—usually a few gallons per day. The POU 

systems are also referred to as “single-tap” systems. 

Four processes for removing arsenic from water are 

discussed in this report: 

• Reverse-osmosis removes arsenic by forcing water 

past a semipermeable membrane that allows water 

molecules to pass but blocks most dissolved constituents. Treated water on the other side of the membrane flows to a small pressure storage tank until 

needed. The process is more effective for removing 

As5+ than As3+. The rejected water is disposed of 

through a sewer or septic system. For every gallon of water that is treated, more than 3 gallons are 

disposed of. Reverse-osmosis systems remove most 

of the dissolved constituents in water, including 

bicarbonate, so the treated water will likely be more 

acidic that the raw water. Reverse osmosis is relatively and widely available as a single-tap system. In 

general, reverse-osmosis systems have been determined to remove 50–60 percent of As3+ and at least 

90 percent of As5+ (Thomas Sorg, U.S. Environmental Protection Agency, 2015, written commun.). 

• Anion exchange is a physical/chemical process in 

which anions are exchanged between water and 

a solid resin. The As5+ exists as an anion and can 

displace chloride from a chloride-based resin. The 

As3+ is not removed by anion resins, so pretreatment 

to convert As3+ to As5+ is required. The effectiveness 

of anion exchange is dependent on concentrations of 

sulfate and other anions that compete with As5+ for 

binding sites. The resin is regenerated by passing a 

salt solution through the resin tank, which replaces 

As5+ and other anions with chloride. The resulting 

brine solution contains the arsenic and other anions. 

If regeneration of the media is not frequent enough, 

arsenic concentration of the treated water can exceed 

that of the raw water. Because anion exchange systems remove the bicarbonate anion, the treated water 

will likely be more acidic that the raw water. Anion 

exchange is usually available as a whole-house 

system. 

• Oxidation/filtration using solid manganese (Mn)-

based media causes iron and manganese to precipitate out of the water as oxides or oxyhydroxides. 

Arsenic has a high affinity for oxyhydroxides, so 

some of the arsenic precipitates along with the iron 

(or manganese), and the particles are filtered out 

of the water. The Mn-based media can be natural 

or artificial. The solid media is regenerated by a 

backwash process that can require high pressures. 

Oxidation/filtration systems are usually available as 

whole-house systems.

• Adsorption using Fe-based media works by passing 

water through a cartridge of iron (Fe)-based adsorptive media, and the arsenic sorbs to the surface of 

the media. The removal capacity for As3+ is substantially less than for As5+, so pretreatment to convert 

As3+ to As5+ is often recommended. Other names for 

Fe-based adsorptive media include granular ferric 

oxide (GFO), and granular ferric hydroxide (GFH). 

In addition to Fe-based products, other available 

products include Fe-modified activated alumina, 

Fe-modified anion resins, and several titanium-based 

granular media. All media products have a limited 

capacity for arsenic removal. Once the capacity is 

reached, the media is thrown away and replaced 

with new media. Adsorption is usually available as 

whole-house or single-tap systems. 

One or more forms of pretreatment is recommended or 

required before the arsenic-removal step: 

• Water softeners are often used as a form of pretreatment to remove high concentrations of Fe or Mn, 

which can foul the membranes or media used for 

arsenic removal. 

• Preoxidation refers to a process that converts As3+ to 

As5+ before treatment by other methods. Preoxidation is required before anion exchange if arsenic is 

present as As3+. In addition, preoxidation is recommended for reverse osmosis, oxidation/filtration, 

and Fe-based adsorption. Oxygen is not effective 

at oxidizing As3+. Methods used for preoxidation 

include chlorination, ozone, and oxidation using Mnbased media. 
Introduction 5

Previous Studies

In 2009–10, the Miami Conservancy District sampled 

107 domestic wells in southwestern Ohio to document arsenic 

concentrations in groundwater of the Great Miami River 

watershed (Miami Conservancy District, 2011). As part of that 

study, pairs of raw and treated water samples were analyzed 

for nine wells with treatment systems consisting of water 

softeners and single-tap reverse-osmosis units. Four of the 

nine systems decreased the arsenic concentrations to less than 

2 μg/L; however, for two of the nine systems, the arsenic 

concentrations of treated water were greater than the MCL of 

10 μg/L. These systems were resampled after being serviced 

by a professional technician or the homeowner, and one of 

the systems still produced water that did not meet the MCL. 

The overall conclusions of the study were that (1) private well 

owners must be aware that all arsenic might not be removed 

by water-treatment systems, and (2) the water-treatment systems must be maintained. 

Arsenic treatment methods have been evaluated for 

domestic wells in other states, but it is difficult to translate 

these results to Ohio, where the water quality and arsenic 

speciation may be different. Walker and others (2008) evaluated single-tap, reverse-osmosis systems in 59 households in 

rural Nevada. The conclusion was that two factors affected 

the results—the arsenic concentration in the raw water and the 

arsenic speciation. Reverse osmosis worked well in the 85 percent of wells in which As5+ was the predominant species; however, removal efficiency was reduced for the 15 percent of the 

wells that had As3+ as predominant species. Another conclusion was that specific conductance (SC) measurements, which 

are used by technicians to determine whether reverse-osmosis 

systems are operating, were not sufficient to determine effectiveness of arsenic removal. Investigations of the performance 

of arsenic treatment using Fe-based adsorptive media were 

done in New Jersey (Spayd, 2007, 2009) and North Carolina 

(Pratson and others, 2009).The treatment systems were judged 

to be effective at decreasing arsenic concentrations to less than 

the MCL.

U.S. Environmental Protection Agency Studies of 

Arsenic Removal Technology

After the MCL was lowered from 50 to10 μg/L in 2001, 

the EPA instituted a research program to evaluate arsenic 

removal technologies for use in small public-water systems 

(U.S. Environmental Protection Agency, 2010). Arsenic 

removal technology demonstration studies and pilot-scale 

studies were completed at sites across the United States, four 

of which were in Ohio. 

Small Public-Water Systems in Ohio

One of the EPA arsenic removal technology demonstration sites was a mobile home park in Clark County, Ohio 

(McCall and others, 2007). The average arsenic concentration 

of the raw water was 21.5 μg/L, and the predominant species 

was As3+. The arsenic treatment system included chlorination, 

oxidation/filtration using Mn-based media, and adsorption 

using Fe-based media. The treatment system decreased arsenic 

concentrations to less than the MCL. Skill was required to 

operate the system, and several revisions were necessary to 

maintain acceptable levels of free and total chlorine in the 

treated water (McCall and others, 2007).

Another arsenic removal technology demonstration site 

was a preschool in Licking County, Ohio (Chen and others, 

2011). Average arsenic concentration in the raw water was 

15.2 μg/L, and the predominant species was As3+. The arsenic 

treatment system included a water softener, chlorination, and 

adsorption using Fe-based media. During almost 4 years of 

operation, the system reduced arsenic concentrations to an 

average of 1.3 μg/L; however, significantly elevated concentrations of disinfection byproducts (DBP) were detected in the 

treated water. The investigators hypothesized that the Fe-based 

adsorptive media could promote the formation of DBP if the 

influent water contained chlorine and total organic carbon 

(Chen and others, 2011). 

A pilot-scale arsenic removal technology study was done 

at a high school in Licking County, Ohio (U.S. Environmental 

Protection Agency, 2011). The average arsenic concentration 

of the raw water was 69 μg/L, which was almost all As3+. The 

arsenic treatment system included potassium permanganate 

oxidation, oxidation/filtration using Mn-based media, and 

chlorination. The system removed 93 percent of the arsenic 

during the first 6 months of operation; however, elevated Mn 

concentrations were detected in the treated water, and investigators concluded that it had likely leached from the Mn-based 

media used for oxidation/filtration. Multiple attempts were 

made to try to maintain low concentrations of Mn and arsenic 

in the treated water (U.S. Environmental Protection Agency, 

2011). 

In addition, raw water from the Licking County High 

School was used as part of a lab-based investigation of the 

effectiveness of four types of adsorptive media: granular 

ferric hydroxide (GFH), Fe oxide-based media, hybrid ionexchange media, and modified activated alumina. Results of 

the study indicated that GFH outperformed the other media 

(Benn, 2006). A comparison of results between the lab-based 

and pilot-scale studies indicated that the life of the adsorptive 

media was lower in pilot-scale studies than in the lab-based 

studies (Westerhoff and others, 2008). 

Domestic Wells in Ohio

In 1998, elevated concentrations of arsenic were detected 

in domestic wells in the vicinity of a waste site near Lewisburg, Ohio (fig. 1). (Further investigation indicated that the 

source of the arsenic was natural and not related to the waste 

site [Ohio Department of Health, 1999].) As part of remedial 

actions, EPA contractors installed arsenic treatment systems 

in 28 homes (Wang and others, n.d.). The systems included a 
6 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

sediment filter, water softener, preoxidation using Mn-based 

media, anion exchange, and single-tap reverse osmosis. From 

1998–2001, the systems were periodically monitored, and 

results indicated that arsenic concentrations were less than 

the MCL, which was 50 μg/L at that time. In 2004, some of 

the sites were revisited as part of EPA-sponsored studies. The 

home with the highest arsenic concentration was included as 

one of the EPA arsenic removal technology demonstration 

sites (Wang and others, n.d.). The raw water had an average 

arsenic concentration of 453 μg/L, which was mostly As3+. 

The treatment system was initially successful at decreasing 

the arsenic concentration to less than the MCL, but the results 

could not be sustained. The EPA and its contractors revised 

the treatment system three times between 2004 and 2011. The 

final system included aeration to remove methane, preoxidation by chlorination, carbon filtration, water softening, 

anion exchange, and a single-tap reverse osmosis. This site 

is included in the current study along with three others in the 

Lewisburg area that had arsenic treatment systems installed by 

the EPA in 1998. 

Methods

Site Selection

The criteria for selecting study sites were that (1) a 

domestic well produces water with an arsenic concentration 

greater than the MCL of 10 μg/L, and (2) a water-treatment 

system for reducing arsenic concentrations is in use. To identify potential sites, letters were sent to homeowners who had 

participated in earlier arsenic investigations by the USGS and 

MCD (Thomas and others, 2005; Miami Conservancy District, 

2011). In addition, letters were sent to personnel at the Ohio 

Department of Health and local health departments in six 

counties to request help in identifying potential participants. 

A total of 31 letters were sent out, and, of those, 4 positive 

responses were received. To increase the number of study 

participants, letters were sent to homeowners in Preble and 

Darke Counties, the area where the EPA and its contractors 

had installed arsenic treatment systems in homes as part of 

remedial actions near a waste site (Ohio Department of Health, 

1999). To further increase the number of study participants, 

the study area was expanded to include Licking County in central Ohio. During 2012, 168 domestic wells in Licking County 

were tested for arsenic (Thomas, 2016), and, of those, 3 were 

identified as meeting the selection criteria. 

The final dataset includes three homes in Licking County 

and eight homes in southwestern Ohio. For 6 of the 11 sites, 

the water-treatment system was installed specifically to treat 

arsenic. For the other five sites, the system was not installed 

for the purpose of treating arsenic, but is one of the types of 

systems recommended for arsenic treatment. 

Data Collection and Analysis

Water-treatment systems in 11 homes were sampled once 

in 2013. Six homes were sampled during a week in April, and 

the other five homes were sampled during a week in June. 

The methods used for collection and analysis of water-quality 

samples are summarized in table 1. A minimum of two water 

samples were collected at each home: a raw sample (untreated 

groundwater from the well), and a final sample (fully treated 

water from the kitchen faucet). In addition, at most homes 

it was possible to collect at least one “intermediate” sample 

along the treatment train (for example, after the water softener 

and before the reverse-osmosis system). The total number of 

environmental samples collected was 36. 

None of the samples was filtered at the time of collection; therefore, all laboratory results represent total concentrations. The final samples were not filtered because the goal 

was to document the quality of the water being consumed by 

homeowners. The raw and intermediate samples also were not 

filtered because the goal was to identify water-quality changes 

attributed only to the effects of the home-treatment systems. 

Samples of raw water were collected following documented procedures for well purging, field measurements, 

sample withdrawal, collection and preservation, and quality 

assurance (U.S. Geological Survey, 2012). Measurements of 

specific conductance, pH, temperature, and acid-neutralizing 

capacity (ANC) were made in the field at the time of sample 

collection. Samples were analyzed for major ions, trace elements, nutrients, total organic carbon, and arsenic speciation at 

the USGS NWQL in Denver, Colorado. 

Final and intermediate samples were collected using 

similar methods as raw samples, except that bottles were filled 

directly from a faucet inside the home. Before filling sample 

bottles, the plumbing lines were flushed for several minutes 

to remove standing water. Field measurements of specific 

conductance, pH, temperature, and ANC were made using the 

subsample method (readings were taken from a multiparameter sonde immersed in a measurement vessel). 

While water samples were being collected by a twoperson team, a third person briefly interviewed homeowners 

about their water-treatment systems. The questions were primarily related to when and how each component of the treatment system was purchased and installed and whether the system was being actively maintained by either the homeowner or 

a professional. Information was not collected about type and 

frequency of system maintenance or the amount of water used 

in each home. Information about well construction and aquifer 

characteristics were not available for every well. Only 4 of 

the 11 wells had well logs on file at the Ohio Department of 

Natural Resources. Homeowners reported approximate depths 

of three of the wells that did not have well logs. 
Methods 7

Quality Assurance

Quality-control (QC) samples were collected following 

USGS procedures (U.S. Geological Survey, var. dated) and 

analyzed at the NWQL. Before the start of each week of sampling, an equipment blank was collected to assess bias related 

to the sampling equipment or decontamination procedures. 

During each week of sampling, two additional QC samples 

were collected: a replicate (to assess variability because of 

field or laboratory practices), and a field blank (to assess bias 

because of field or laboratory practices or conditions). For 

each equipment and field blank, a source-solution blank (a 

sample of the contaminant-free water used for the equipment 

and field blanks) was also analyzed. Over the 2-week sampling 

period, a total of two equipment blanks, two replicates, two 

field blanks, and four source-solution blanks were collected. 

Equipment blanks and field blanks were analyzed for 

trace elements and major ions, and one of the field blanks 

was also analyzed for total organic carbon. The data were not 

tabulated herein because all constituents were not detected or 

detected at a concentration that was less than the laboratory 

reporting level. The only exception was boron, which was 

detected in one of the equipment blanks at a concentration 

greater than the laboratory reporting level; however, a similar 

concentration of boron was also detected in the associated 

source-solution blank, so the detection is not considered to be 

a problem.

Replicate samples were analyzed for arsenic speciation, 

and one of the replicates was also analyzed for nutrients. 

Arsenic speciation results for one sample showed a relatively 

high amount of variability: compared to the environmental 

sample, the replicate sample was 19 percent lower in terms of 

As3+ and 20 percent higher in terms of As5+. In addition, arsenic speciation results for environmental samples were a cause 

for concern because the sum of As3+ and As5+ concentrations 

did not equal the total arsenic concentration for most sites. It 

is not known whether this variability was the result of field 

or lab activities; however, these issues were considered to be 

acceptable for this study because the speciation data are used 

in a semiquantitative way to identify the predominant species 

of arsenic in each water sample. 

USGS personnel collected a total of 

36 samples of raw and treated water from 

11 homes. Ten additional samples were 

collected for quality assurance. Photograph 

by Ralph Haefner, USGS. 

Table 1. Methods used for collection and analysis of water samples from 11 domestic wells in southwestern and central Ohio, 2013.

[NWQL, National Water Quality Laboratory; WG, groundwater; HHXX, time designation used to identify position of sample in treatment train; USGS, U.S. 

Geological Survey; SC, specific conductance; ANC, acid-neutralizing capacity; DO, dissolved oxygen; WT, treated water]

Sample type Sample type 

identifier Sample collection methods Field measurements Constituents analyzed at NWQL 

Raw 

(groundwater from wellhead)

Medium=WG 

Time= HH00

Standard USGS methods for 

groundwater (U.S. Geological Survey, variously dated)

pH, SC, DO, temperature, turbidity, and 

ANC

Trace elements, arsenic 

speciation, major ions, 

nutrients, and total 

organic carbon (Fishman, 1993; Brenton and 

Arnette, 1993; Garbarino and others, 2012).

Intermediate 

(partially treated water 

collected along treatment 

train)

Medium=WT 

Time= HH51, 

HH52, HH53, 

HH54

Collected samples from 

taps inside home. Field 

measurements were made 

using subsample method 

(U.S. Geological Survey, 

variously dated)

pH and SC 

Final 

(fully treated water from 

kitchen faucet)

Medium=WT 

Time= HH59

pH, SC, and ANC
8 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Quality of Raw Water

The effectiveness of a water-treatment method depends 

on the chemistry of the water being treated. This section of the 

report presents water-quality characteristics of raw water with 

emphasis on arsenic concentrations, arsenic speciation, and 

concentrations of constituents that affect the performance of 

arsenic-treatment methods. Raw and treated water-quality data 

are presented in table 2 (see page 26, or the Excel file can be 

accessed at http://dx.doi.org/10.3133/sir20155156).

Total Arsenic and Arsenic Species

Samples of untreated (raw) groundwater were collected 

from the wellheads at 11 homes. Total arsenic concentrations 

ranged from 7.7 to 382 μg/L, and the median concentration 

was about 30 μg/L. A total of 10 samples had arsenic concentrations greater than the MCL of 10 μg/L (fig. 2). 

Raw water samples were analyzed for concentrations of 

four arsenic species: two inorganic species (As5+ and As3+) 

and two organic species (dimethylarsinate and monomethylarsonate). The organic species were not detected at concentrations above the lab reporting limits (0.6 μg/L and 3.2 μg/L, 

respectively).

Arsenite (As3+) was the predominant species in 10 of 11 

raw water samples (fig. 2). For these 10 samples, the fraction 

of As3+ was 70–92 percent. These results are consistent with 

the limited amount of arsenic speciation data available for 

Ohio groundwater (Sorg and others, 2014; Thomas and others, 

2008). As3+ exists as an uncharged compound (H3AsO3), and 

therefore is harder to remove by treatment processes. On the 

other hand, arsenate (As5+) is easier to remove from water 

because it typically exists as negatively-charged compound 

(HAsO4

2- or HAsO4-

).

One sample (D–177) was unusual in that the arsenic was 

predominantly (99 percent) As5+. The Fe concentration of the 

water was unusually high (15,800 μg/L). In addition, concentrations of orthophosphate, zinc, nickel, lead, vanadium, 

aluminum, cadmium, and cobalt that were much higher than 

the other 10 samples. It is not known why this sample was 

so different from the others. It is possible that groundwater 

at this site is unique with respect to the arsenic source and/

or mechanism of mobilization. (No well log was found for 

this site, so details about the aquifer characteristics and well 

construction are not available.) Another possible explanation 

is that the samples were not adequately preserved at the time 

of sampling. Sampling protocols require that ethylenediaminetetraacetic acid (EDTA) be added to the samples in the field 

to preserve the concentration of species (Garbarino and others, 

2012), and it is possible that the amount of EDTA was not sufficient to prevent As3+ from oxidizing to As5+ between sample 

collection and analysis. The fact that the arsenic speciation 

samples were unfiltered may have affected the analytical 

results. 

Other Water-Quality Constituents

The EPA recommends that key water-quality constituents should be known before selection of an arsenic treatment 

system: arsenic, arsenic speciation, chloride, fluoride, Fe, Mn, 

nitrate, nitrite, phosphate, pH, silica, sulfate, total dissolved 

solids, and total organic carbon (U.S. Environmental Protection Agency, 2003). Concentrations of these constituents are 

presented in figure 2. (Ammonium is shown instead of nitrate 

and nitrite, which were not detected. Specific conductance 

(SC) is shown instead of total dissolved solids. Orthophosphate is shown instead of phosphate). 

The pH of the raw water was neutral or slightly alkaline 

(7.1–8.1). Iron concentrations were was 853–15,800 μg/L, and 

the median was 2,270 μg/L. All Fe concentrations were above 

the EPA Secondary MCL (SMCL) of 300 μg/L. Redox conditions were estimated based on concentrations of dissolved 

oxygen, nitrate, manganese, iron and sulfate (McMahon and 

Chapelle, 2008). The seven samples with the lowest arsenic 

concentrations (7.7–51 μg/L) were estimated to be Fe-reducing or sulfate-reducing. The four samples with the highest 

arsenic concentrations (67.5–382 μg/L) were estimated to be 

methanogenic (methane producing), which is the most reduced 

state. The methanogenic samples had unusually high concentrations of total organic carbon (7.3–11.3 μg/L) and ammonia 

(4.28–22.9 μg/L). 

Also shown are Fe:Arsenic ratios, a measure used 

as an indicator of whether Fe-removal methods are applicable for arsenic removal (U.S. Environmental Protection 

Agency, 2005). Three of the four methanogenic samples had 

Fe:Arsenic ratios less than 20, which indicates that oxidation/filtration using Mn-based media may not be effective for 

removing arsenic. 
Quality of Raw Water 9

Figure 2. Quality of raw water from 11 domestic wells in southwestern and central Ohio, 2013 [As3+, arsenite; 

As5+, arsenate; %, percent; mg/L, milligram per liter; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees 

Celsius; Fe, iron, As, arsenic].

Site name MT–

1285

CL–

23

PR–

239

GR–

754

LI–

36

Li–

38

Li–

31

D–

177

PR–

241

PR–

240

PR–

242

Arsenic, in μg/L 7.7 10.3 18.0 19.4 29.8 29.8 51.0 67.5 74.9 177 382

As3+, as percent of As3++As5+ 71% 82% 70% 70% 80% 80% 92% 1% 90% 91% 87%

pH, in standard units 7.2 7.2 7.1 7.1 7.0 7.0 7.7 7.1 8.1 7.8 7.3

Iron, in μg/L 1,360 2,590 2,270 1,790 2,450 2,320 1,690 15,800 853 1,660 4,850

Manganese, in μg/L 43.2 35.4 24.4 13 23.3 36.7 89.1 74.7 6 3.1 19.1

Sulfate, in mg/L 51.6 51.2 17.1 5.85 73.7 160 4.1 <0.09 <0.09 <0.09 <0.09

Ammonia, in mg/L 0.645 0.165 0.492 0.409 0.427 0.3 0.205 17.5 4.28 4.82 22.9

Total organic carbon, in mg/L 0.05 <0.05 0.06 0.06 1.8 1.9 1.4 11.2 7.3 7.9 11.3

Orthophosphate, in mg/L 0.006 0.008 0.008 0.02 0.006 0.007 0.012 0.296 0.009 0.03 0.097

Silica, in mg/L 15.7 16.9 19.3 17.6 19 20.1 12.1 20.5 7.29 9.16 24.2

Fluoride, in mg/L 1.6 0.32 1.24 0.36 0.834 0.58 0.153 0.68 0.66 0.64 0.28

Chloride, in mg/L 4.5 46.8 9.82 18.6 4.51 1.93 1.78 10.8 8.79 15 18.1

Specific conductance, in μS/cm 805 810 805 752 783 896 390 955 546 745 988

Redox condition1 Fe-reducing or sulfate-reducing Methanogenic

Fe:As >20 <20 Arsenic concentration, in micrograms per liter (μg/L) 

0

10

20

30

40

50

60

70

80

90

100

177 μg/L 382 μg/L

1 Estimated using method of McMahon and Chapelle (2008). 

Maximum 

contaminant 

level
10 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Types of Water-Treatment Systems 

Sampled

Three general types of water-treatment systems were 

sampled for this study. (See “Sidebar—Arsenic Treatment 

Terms Used in This Report” for a description of the treatment 

processes.) 

• Single-tap reverse-osmosis systems were in use at 

seven sites. Two of the seven systems had not been 

maintained for more than 6 years at the time of sampling. 

• Whole-house oxidation/filtration systems using Mnbased media were in use at two sites. Both systems 

included water softeners, and one system included 

chlorination.

• Systems that included whole-house anion exchange 

and single-tap reverse osmosis were in use at two sites. 

Both systems included water softeners and preoxidation (chlorination at one site and oxidation using Mnbased media at the second site). At one of the sites, the 

single-tap reverse-osmosis unit included a cartridge of 

Fe-based adsorptive media. 

Additional details about each system are included in table 3. 

Effectiveness of The Water-Treatment 

Systems

One measure of the effectiveness of arsenic treatment 

systems is whether the arsenic concentration of the final water 

sample is less than the MCL of 10 μg/L. Arsenic concentrations in the final samples ranged from 3.6 to 173 μg/L, and 

the median value was 9 μg/L. About one-half of the systems 

decreased the arsenic concentration to less than the MCL. 

A second measure of effectiveness is the percent decrease 

in arsenic concentrations between the raw and final samples 

computed as ([Asraw-Asfinal)/Asraw] *100). The percentage of 

arsenic removed by the 11 treatment systems ranged from 2 to 

90 percent, and the median was 65 percent. 

About 1.8 million Ohio residents use domestic wells as a source of drinking water. 

Photograph by Mary Ann Thomas, USGS.
Effectiveness of The Water-Treatment Systems 11

Table 3. Characteristics of water-treatment systems sampled in southwestern and central Ohio, 2013.

[Numbers indicate position in treatment train. Bold text denotes component used for arsenic removal. All components are point of entry (whole house) unless 

denoted as point of use (single tap). POU, point of use; <, less than; EPA, U.S. Environmental Protection Agency; Mn, manganese; Fe, iron]

Site 

name Components in treatment system

History

Age of 

system Purchase and installation Maintenance

MT–1285 1. Water softener

2. Reverse osmosis—POU

Unknown Installed by previous homeowner No maintenance in at 

least 6 years.

PR–239 1. Water softener

2. Reverse osmosis—POU

5 years Homeowner’s son Homeowner’s son.

LI–36 1. Water softener 

2. Reverse osmosis—POU

<1 year Equipment purchased at home maintenance store and 

installed by homeowner

None; system was 

new at the time of 

sampling. 

LI–31 1. Sediment filter

2. Water softener

3. Reverse osmosis—POU

<1 year Equipment supplied and installed by water-treatment 

professional.

None; system was 

new at the time of 

sampling.

D–177 1. Sediment filter

2. Water softener

3. Reverse osmosis—POU1

15 years System similar to PR–241 originally installed by the EPA 

in 1999; homeowners later disconnected two components (anion exchange and oxidation using Mn-based 

media) because of cost/maintenance reasons

Professional.

PR–240 1. Sediment filter

2. Water softener

3. Reverse osmosis—POU

15 years System similar to PR–241 originally installed by the EPA 

in 1999; homeowners later disconnected two components (anion exchange and oxidation using Mn-based 

media) because of cost/maintenance reasons

No maintenance in at 

least 6 years.

CL–23 1. Reverse osmosis—POU 25 years Professional Professional.

Oxidation/filtration using Mn-based media

LI–38 1. Sediment filter

2. Oxidation/filtration using Mnbased media

3. Water softener

10 years Equipment supplied and installed by a professional. Professional.

GR–754 1. Sediment filter

2. Chlorination

3. Oxidation/filtration using Mnbased media

4. Carbon filter

5. Water softener

<1 year Equipment purchased online and installed by homeowner Homeowner.

Anion exchange and reverse osmosis

PR–241 1. Sediment filter

2. Water softener

3. Oxidation using Mn-based media1

4. Anion exchange

5. Reverse osmosis—POU

15 years Installed by the EPA in 1999. Professional.

PR–242 1. Aeration (to remove methane gas)

2. Chlorination

3. Carbon filter

4. Anion exchange

5. Water softener

6. POU unit with four cartridges:

 (a) Sediment filter—POU

 (b) Carbon filter—POU

 (c) Reverse osmosis—POU

 (d) Adsorption using Fe-based me 

dia (Fe-modified anion-exchange 

resin)—POU

<4 years Installed by the EPA in 1999; system revised three times 

between 2004 and 2011. Fe-based adsorption cartridge 

added to POU reverse-osmosis system by homeowner 

in 2012

Homeowner.

1

Results of water-quality analysis indicate that this component was not functioning correctly.
12 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Reverse Osmosis

At seven sites, reverse-osmosis units were installed 

beneath kitchen sinks to treat the water used for drinking and 

cooking. At six of the sites, water softeners served as pretreatment to remove elevated concentrations of Fe and Mn that can 

foul reverse-osmosis membranes. Sediment filters preceded 

the water softeners at two sites. Five of the reverse-osmosis 

systems were being maintained at time of sampling, and two 

systems had not been maintained. 

Results for the five maintained systems are shown in 

figure 3A. For four of the systems, arsenic concentrations in 

the final samples were less than 10 μg/L. The percent decrease 

in arsenic concentrations ranged from 22 to 81 percent. For the 

two systems that were not maintained, the decrease in arsenic 

concentration was 2–26 percent (fig. 3B). At most of the sites, 

As5+ was the predominant species in the final samples (figs. 3A

and 3B). 

Substantial decreases in pH, ANC, and most concentrations of cations and anions were observed in final samples 

from the reverse-osmosis systems (table 2). Values of SC in 

the raw and final samples were compared as a general indicator of whether the reverse-osmosis systems were operating 

correctly. Six of the systems showed SC decreases of 89 to 

98 percent; however, for one system (at site D–177), the SC of 

the final sample was slightly higher than the raw water, which 

suggests that the reverse-osmosis system was not working at 

the time of sampling even though the homeowners described 

the systems as being maintained. 

Reverse osmosis is typically part of a single-tap system used to treat just the water used for drinking and 

cooking. Photograph by Mike Ekberg, Miami Conservancy District.
Effectiveness of The Water-Treatment Systems 13 Figure 3. Effect of reverse-osmosis systems on concentrations of total arsenic, arsenite, and arsenate. 

A, Systems that had been maintained. 

B, Systems that had not 

been maintained.

0

40302010

Soft RO 

soft

RO 

soft

RO

soft

Soft

LI–36

81 percent decrease in total arsenic 

Raw

PR– 239

70 percent decrease in total arsenic

0

8070605040302010

Soft RO1

Soft

CL– 23

65 percent decrease in total arsenic

D–177

34 percent decrease in total arsenic

LI–31

22 percent decrease in total arsenic 

Raw Raw

Raw Raw

Concentration, in micrograms per liter RO

A

Maximum 

contaminant 

level

Maximum 

contaminant 

level

As3+

As3+

As3+

As3+

As3+

As5+

As5+

As5+

As5+ As5+

Total arsenic

Total arsenic

Total arsenic

Total arsenic

Total arsenic

0

80604020

100120140160180200

RO

Soft

Soft

86420

10

Raw Soft

Concentration, in micrograms per liter

Total arsenic As 3+ (arsenite)

As 5+ (arsenate)

Type of treatment

Untreated ground

water

After water softener 

After sediment filter

After reverse osmosis (single tap) 

RawSoftSedRO

MT –1285

26 percent decrease in total arsenic

PR– 240

2 percent decrease in total arsenic 

Raw

EXPLANATION

r et li r ep s ma gr o icr mni , noi at rt necnoc ic nes Ar

ni , noi at rt necnoc ic nes Ar

r et li r ep s ma gr o icr m

ROSoft

B

As3+

As3+

As5+

As5+

Total arsenic

Total arsenic

1Analysis of water-quality data indicated 

that this component was not working.
14 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Oxidation/Filtration Using Manganese-Based 

Media

At two sites, the water-treatment systems included oxidation/filtration using solid Mn-based media (fig. 4A). At site 

Li–38, the system consisted of a sediment filter, oxidation/

filtration using Mn-based media (Birm), and water softening. 

This system decreased the arsenic concentration by 69 percent 

from 29.8 to 9.3 μg/L. At site GR–754, the system included 

chlorination, oxidation/filtration using Mn-based media 

(Greensand Plus), carbon filtration, and water softening. This 

system decreased the arsenic concentration by 70 percent from 

19.4 to 5.8 μg/L. 

At both sites, concentrations of Mn increased greatly 

after treatment by the oxidation/filtration component of the 

system (fig. 4B). Concentrations of Mn of 13.0 and 36.7 μg/L 

in raw water increased to 726 and 997 μg/L, respectively, 

after oxidation/filtration using Mn-based media. At Li–38, the 

elevated Mn was removed by the water softener before being 

consumed by the homeowners. At GR–754, the final sample 

collected from the kitchen tap had a Mn concentration of 

712 μg/L, which is well above the EPA lifetime health advisory of 300 μg/L and the secondary MCL (based on esthetic 

criteria such as staining) of 50 μg/L (U.S. Environmental 

Protection Agency, 2009). It is not known why this high concentration of Mn was not removed by the water softener. The 

supplier of the water-treatment system advised the homeowner 

that the problem could be fixed by increasing the amount of 

chlorine used in the preoxidation step. An increase in Mn concentration of treated water was also observed in the EPA pilotscale study at the Licking County High School (discussed in 

“Previous Studies”). At this site, the system required multiple 

revisions to try to maintain low concentrations of arsenic 

and Mn in the treated water (U.S. Environmental Protection 

Agency, 2011).

Oxidation/filtration is typically part of a whole-house treatment system installed in the basement of 

a home. Photograph by Mike Ekberg, Miami Conservancy District. 
Effectiveness of The Water-Treatment Systems 15

Figure 4. Effect of oxidation/filtration systems on concentrations of selected constituents. A Total 

arsenic, arsenite and arsenate. B, Manganese.

0

10

20

30

40

As3+

As3+

As5+ As5+

Raw Soft

Ox/fil-Mn2

Sed

LI–38

69 percent decrease in total arsenic 

Chlor

1Greensand Plus 

2Birm

GR–754

70 percent decrease in total arsenic 

Raw

Total arsenic

Arsenic concentration, 

in micrograms per liter 

Total arsenic

Chlor Carb

Ox/fil-Mn1

Chlor

Ox/fil-Mn1

Chlor

Soft

Carb

Ox/fil-Mn1

Chlor

Manganese concentration, 

in micrograms per liter

Manganese

0

300

600

900

1,200

Manganese

GR–754 LI–38

B

A 

Manganese

1

Ox/fil-Mn2

Sed

Raw Soft

Ox/fil-Mn2

Sed

Chlor Carb Raw

Ox/fil-Mn1

Chlor

Ox/fil-Mn1

Chlor

Soft

Carb

Ox/fil-Mn1

Chlor

Ox/fil-Mn2

Sed

Health 

advisory 

level

Maximum 

contaminant 

level

Concentration, in micrograms 

 per liter

Total arsenic 

As 3+ (arsenite)

As 5+ (arsenate)

Type of treatment

Untreated groundwater

After chlorination

Carb After carbon filter

After water softener 

 After sediment filter

 After oxidation/filtration using 

 manganese-based media

Raw

Soft

Sed

Ox/fil-Mn

EXPLANATION
16 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Systems That Include Anion Exchange and 

Reverse Osmosis

At two sites, the treatment systems included whole-house 

anion exchange and single-tap reverse osmosis (fig. 5). At 

site PR–241, the treatment system included a sediment filter, 

a water softener, preoxidation using Mn-based media (Filox), 

anion exchange, and single-tap reverse osmosis. The system 

decreased the arsenic concentration by 23 percent from 74.9 

to 57.5 μg/L. The reason for the relatively low effectiveness 

of this system could not be determined because samples were 

not collected after each treatment step. Personnel from EPA 

resampled the system in November, 2013, and concluded that 

the component for preoxidation using Mn-based media was 

not working (Thomas Sorg, U.S. Environmental Protection 

Agency, 2015, written commun.). Anion exchange only 

removes As5+, so without preoxidation of As3+ to As5+, anion 

exchange was not effective. 

At site PR–242, the treatment system included aeration 

to remove methane gas, preoxidation by chlorination, carbon 

filtration, water softening, anion exchange, and a single-tap 

unit that included cartridges for reverse osmosis and adsorptive using Fe-based media (Fe-modified anion exchange resin). 

The arsenic concentration of the raw water was 382 μg/L. 

After treatment, the concentration decreased by 90 percent, 

to 38.4 μg/L. Anion exchange removed most of the As5+, and 

caused a decrease in the arsenic concentration from 326 to 

86.8 μg/L. After the single-tap unit with cartridges for reverse 

osmosis and Fe-based adsorption, the arsenic concentration 

was decreased by 56 percent from 86.8 to 38.4 μg/L. 

Some arsenic treatment systems can be relatively complex. Pre-oxidation is needed to convert As3+ to As5+

prior to removal by anion exchange. Photograph by Mike Ekberg, Miami Conservancy District. 
Effectiveness of The Water-Treatment Systems 17

Figure 5. Effect of systems that include anion exchange and reverse osmosis on concentrations of 

total arsenic, arsenite and arsenate.

PR– 242

90 percent decrease in total arsenic

PR– 241

23 percent decrease in total arsenic

Total arsenic

As3+

Raw Air

Chlor

RO and Adsorp

Soft

AE

Carbon

Chlor

Air

Soft

AE

Carbon

Chlor

Air

0

20

40

60

80

100

Concentration, in micrograms per liter 

0

100

200

300

400

Total arsenic

As 3+

As 5+

As5+

Soft

Sed

AE

Ox-Mn1

Soft

Sed

RO

AE

Ox-Mn1

Soft

Sed

Raw

1

Analysis of water-quality data indicated this 

component was not working. 

Chlor

Concentration, in micrograms 

 per liter

Total arsenic 

As 3+ (arsenite)

As 5+ (arsenate)

Type of treatment

Untreated groundwater

After chlorination

Air After aeration to remove methane

Carb After carbon filter

After water softener 

After sediment filter

After oxidation using manganese-

 based media (Filox)

Raw

Soft

Sed

Ox-Mn1

AE After anion exchange

RO After reverse osmosis (single tap)

 After adsorption using iron-based 

 media (single tap)

Adsorb

EXPLANATION
18 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Effects of Methods Used for Pretreatment 

Water softening.—Water softeners, which employ cation 

exchange, are used as a form of pretreatment to remove high 

concentrations of Fe and Mn that can foul media or membranes in arsenic removal units. The effect of water softeners 

alone was investigated using data from six of the maintained 

systems. Results indicate that a small (2–34 percent) decrease 

in total arsenic concentrations happened after softening. There 

is some indication that softening increased the proportion of 

As3+ in the water, but the differences are small relative to the 

variability of the arsenic speciation data. 

Chlorination.—Two water-treatment systems included 

chlorination. Results indicate that chlorination oxidized some 

but not all of the As3+ in the raw water. At site GR–754, the 

percentage of As3+ decreased from 70 percent in raw water to 

49 percent in chlorinated water. At site PR–242, the percentage of As3+ decreased from 87 percent in raw water to 40 

percent in chlorinated water. 

Chlorination of water with high concentrations of organic 

carbon can create DBP, but these compounds were not analyzed. The four samples with the highest raw arsenic concentrations had very high concentrations of total organic carbon, 

so formation of DBPs is a possible concern. 

Oxidation using Mn-based media.—At one site, oxidation using Mn-based media (Filox) was used to oxidize As3+

to As5+ before anion exchange. The preoxidation component 

was effective when it was first installed in 1998, but it was not 

working in 2013 at the time of this study. The same oxidation/

filtration media was used successfully at public-water systems; 

however, the backwash process used to regenerate the media 

requires water pressures of 23–30 gallons per minute (gal/

min), which may not be feasible at most homes (Wang and 

others, n.d.).

Factors Related To Effectiveness of 

Arsenic Removal

Based on the data from this study, it is not possible to 

determine which type of arsenic treatment system is most 

effective because the number of sites sampled is small relative 

to the variation among the sites in terms of (1) methods of 

treatment and pretreatment, (2) age and maintenance history of 

the systems; and (3) arsenic concentrations and other chemical characteristics of the raw water. Despite the wide range of 

variability, the data show some broad relations between effectiveness of arsenic removal, characteristics of the treatment 

systems, and the quality of the raw water. 

Characteristics of Treatment Systems

Arsenic concentrations in raw and final water samples 

were compared to two characteristics of the treatment systems—the system type and maintenance history (fig. 6). There 

is no clear relation between the system type and the effectiveness of arsenic removal; for example, the percentage of 

arsenic removed by five reverse-osmosis systems ranged from 

22 to 81 percent. On the other hand, there is a general relation between system maintenance and effectiveness of arsenic 

removal. It is not surprising that the nine systems that received 

maintenance were generally more effective (22–90 percent 

decrease in arsenic) than the two systems that had not been 

maintained in several years (2–26 percent decrease). 

In addition, for two of the systems that received maintenance (D–177 and PR-241), analysis of water-quality data 

indicates that a component of the treatment system was 

not working, unbeknownst to the homeowner (discussed 

in “Reverse Osmosis” and “Anion Exchange and Reverse 

Osmosis” sections). These systems also had low effectiveness 

(23–34 percent removal). But maintenance is not the only factor related to system effectiveness; one of the lowest arsenic 

removal percentages (22 percent) was from a relatively new 

system (about six months old) installed by a water-treatment 

professional. 
Factors Related To Effectiveness of Arsenic Removal 19 Figure 6. Arsenic removal in relation to system type and maintenance history for 11 sites in southwestern and central Ohio, 2013. 

Site name CL– 23 PR–239 LI–36 LI–31 D–177 GR–754 LI–38 PR–241 PR–242 MT–1285 PR–240

Arsenicconcentration, in μg/L

Raw sample 10.3 18.0 29.8 51.0 67.5 19.4 29.8 74.9 382 7.7 177

Final sample 3.6 5.4 5.7 39.9 44.8 5.8 9.3 57.5 38.4 5.7 173

Decrease,

in percent (%)

65% 70% 81% 22% 34% 70% 69% 23% 90% 26% 2%

Systemcomponents

Sed

RO

Soft

RO

Soft

RO

Sed

Soft

RO

SedSoftRO1

SedChlor

Carb

Ox/fil -Mn

Soft

SedOx/fil -Mn

Soft

SedSoftOx-Mn1

AERO

AirChlorCarb

AESoftROAdsorp

SoftRO

SedSoft

RO

0

8070605040302010

No maintenance Systems received maintenance

, noitatrnecnoccin serA

)L/gμ(ret lireps amrgorcimni

Final

Raw

Reverse osmosis

Oxidation/filtrationusing Mn-based media

Anion exchange and

reverse osmosis

Reverseosmosis

1Analysis of water-quality data indicated this component was not working.
20 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Raw-Water Quality

For the nine sites that received maintenance, system 

effectiveness was compared to the arsenic concentration of 

the raw water. At sites with raw-water arsenic concentrations of 10–30 μg/L (fig. 7A), the treatment systems removed 

65–81 percent of the arsenic, and the final arsenic concentrations were less than the MCL of 10 μg/L. Similar results were 

observed from two different types of systems—single-tap 

reverse osmosis and whole-house oxidation/filtration using 

Mn-based media. 

On the other hand, for the three sites with raw-water arsenic concentrations of 50–75 μg/L (fig. 7B), the effectiveness 

of the treatment systems was lower; the systems removed 

22–34 percent of the arsenic in the raw water, and arsenic 

concentrations in the final samples were greater than the MCL 

(fig. 7). 

Other chemical characteristics of the raw water may 

contribute to differences in treatment effectiveness that are 

shown in 7A and B. In general, the five samples with lower 

arsenic concentrations (10–30 μg/L) also had relatively lower 

pH (7.0–7.2), lower concentrations of organic carbon (less 

than 0.05–1.9 milligrams per liter [mg/L]) and ammonia 

(0.165–0.492 mg/L), and the redox conditions were classified as Fe- or sulfate-reducing. In contrast, the three samples 

with higher arsenic concentrations (50–75 μg/L) had higher 

or more varied pH (7.1–8.1), and concentrations of organic 

carbon (1.4–11.2 mg/L), and ammonia (0.205–17.5 mg/L), and 

the redox condition of two of the three samples was classified 

as methanogenic. One or more of these factors can influence 

the performance of the arsenic treatment processes (U.S. Environmental Protection Agency, 2003). 

One site did not fit the general trend of decreased effectiveness at higher raw-water arsenic concentrations (fig. 7C). 

At site PR–242, the raw-water arsenic concentration was very 

high (382 μg/L), and the effectiveness of the treatment system 

was also high (90 percent). Despite this, the arsenic concentration of the final sample (38.4 μg/L) was still substantially 

greater than the MCL. Site PR–242 was atypical in several 

ways. One is that the treatment system was designed, installed, 

monitored, and maintained as part of an EPA research program. Between 2004 and 2011, the system was revised three 

times, and, as a result, the resources devoted to this treatment 

system were unusually high. As an indication of this, one of 

the conclusions of the final report was that drilling a new well 

to an aquifer with lower arsenic concentrations was a low-cost 

option that warrants consideration (Wang and others, n.d.). 

A second reason that site PR–242 is atypical is that the 

raw-water arsenic concentration was very high compared to 

other wells sampled in southwestern and central Ohio (Miami 

Conservancy District, 2011; Thomas and others, 2005, 2008; 

Shindel and others, 2000; Dumouchelle, 1999). The nexthighest arsenic concentration reported for Ohio is 225 μg/L, 

which was detected in a domestic well in southeastern Ohio 

(Petty, 2000). Sampling for arsenic has been relatively limited, 

so higher concentrations may exist in areas that have not been 

sampled; however, available data indicate that arsenic concentrations similar to 382 μg/L may be uncommon in Ohio 

groundwater. 

Results of arsenic studies in southwestern and central 

Ohio indicate that most (80 percent) of the elevated arsenic 

concentrations detected in domestic wells range from 10 to 

30 μg/L, and redox conditions are Fe- or sulfate-reducing 

(Shindel and others, 2000; Thomas and others, 2005; Thomas, 

2016). In other words, 80 percent of samples may be somewhat similar to the five samples in figure 7A in terms of rawwater quality. Groundwater with higher arsenic concentrations 

(about 40–70 μg/L) and methanogenic redox conditions were 

less common but should be expected especially in the vicinity 

of buried valleys (Thomas and others, 2005; Thomas, 2016). 

Results of the current study suggest that, for these types of 

groundwater, it may be difficult to reduce arsenic concentrations to less than the MCL using water-treatment methods 

available to homeowners; however, additional study may be 

needed to confirm or disprove this idea. 

Domestic wells in Ohio are not routinely tested 

for arsenic. Photograph by Mike Ekberg, Miami 

Conservancy District. 
Summary of Results 21

Summary of Results

In 2013, the U.S. Geological Survey and the Miami 

Conservancy District investigated the effectiveness of arsenictreatment methods used at 11 homes in southwestern and 

central Ohio. Unfiltered samples of raw and treated water 

were collected from each home and analyzed for arsenic, 

arsenic species, major ions, trace elements, nutrients, and total 

organic carbon. Information about the type, age, and maintenance history of the treatment systems was provided by the 

homeowners. 

The untreated (raw) groundwater had arsenic concentrations of 7.7–382 micrograms per liter (μg/L), and the median 

concentration was about 30 μg/L. The raw water was neutral 

to slightly alkaline (pH of 7.0–8.1) and strongly reducing, as 

indicated by high concentrations of iron. Arsenite (As3+) was 

the predominant species in 10 of the 11 raw water samples.

The treatment systems included (1) seven single-tap 

reverse-osmosis systems, (2) two whole-house oxidation/filtration systems using manganese (Mn)-based media, and (3) two 

systems that included whole-house anion exchange and singletap reverse osmosis. All but one system included pretreatment 

by a water softener, and two systems included preoxidation to 

convert arsenite (As3+) to arsenate (As5+) before treatment by 

anion exchange. 

None of the treatment systems removed all of the arsenic 

in the raw water. About one-half of the systems decreased 

the arsenic concentrations to less than the maximum contaminant level of 10 μg/L. The amount of arsenic removed by the 

11 systems varied greatly, from 2 to 90 percent. 

It was not possible to determine if one type of system 

was more effective than another because the sample size was 

small relative to the variation among the systems with respect 

to system configuration, pretreatment methods, maintenance 

history, and raw-water quality. However, the data indicate that 

arsenic removal is broadly related to two general factors—system maintenance and raw-water quality. 

At some sites, the low effectiveness of arsenic removal 

may have been related to system maintenance and (or) operation issues. At two sites, homeowners acknowledged that the 

treatment systems had not been maintained for several years. 

At two other sites, the treatment systems were being maintained, but analysis of the water-quality data indicated that 

one of the components was not working, unbeknownst to the 

homeowner. EPA research at a small number of sites in Ohio 

indicated that operation and maintenance of some arsenictreatment systems was not always simple. 

Figure 7. Arsenic removal in relation to system type and raw-water arsenic 

concentrations for nine maintained systems in southwestern and central Ohio, 

2013 with different ranges of raw-water arsenic concentrations. A, 10–30 μg/L. 

B, 50–75 μg/L. C, 382 μg/L.

Type of treatment system

EXPLANATION

CL-23 PR-239 LI-36 GR-754 LI-38

0

20

40

60

80

100

Arsenic decrease, in percent

Arsenic concentration in raw water, in micrograms per liter (μg/L)

C. 382 μg/L 

LI-31 PR-242 1

D-177 1

PR-241

1

Analysis of water-quality data indicated that one component of the system was not working.

A. 10–30 μg/L B. 50–75 μg/L

Reverse osmosis, single-tap system 

Oxidation/filtration using manganese-based media, whole-house system

Anion exchange and reverse osmosis, whole-house and single-tap systems 
22

Another factor related to system effectiveness was the 

quality of the raw water. Among the maintained systems, treatment methods were less effective at removing higher concentrations of arsenic. For sites with raw-water concentrations of 

10–30 μg/L, the systems decreased arsenic concentrations by 

65–81 percent, and arsenic concentrations in the treated water 

were less than the MCL of 10 μg/L. For sites with higher 

raw-water arsenic concentrations (50–75 μg/L), the arsenic 

decrease was 23–34 percent, and concentrations in the treated 

water were 4–5 times higher than the MCL. Other characteristics of the raw water may have affected the performance of 

treatment systems; in general, raw water with the higher arsenic concentrations also had higher pH, higher concentrations 

of organic carbon and ammonia, and more reducing (methanogenic) redox conditions. 

One system clearly did not fit the general trend of 

decreased effectiveness at higher raw-water arsenic concentrations. At site PR–242, concentration of arsenic in the raw 

water was very high (382 μg/L), and the treatment system 

decreased it by 90 percent. Despite this large decrease, the 

arsenic concentration of the final water (38.4 μg/L) was 

substantially greater than the MCL. The treatment system 

at this site was unusual because it was installed, monitored 

and revised over 7 years as part of the U.S. Environmental 

Protection Agency research program. The site was also atypical because the raw-water arsenic concentration was much 

greater than other concentrations measured in domestic wells 

of southwestern and central Ohio. 

For sites with raw-water arsenic concentrations of 

10–30 μg/L, two types of systems (single-tap reverse osmosis 

and whole-house oxidation/filtration) produced similar results 

in terms of arsenic removal, but the quality of the treated water 

differed in other respects. Reverse osmosis caused substantial 

decreases in pH, alkalinity, and most ions in the treated water. 

On the other hand, oxidation/filtration using Mn-based media 

caused a large increase of Mn concentrations, from less than 

50 μg/L in raw water to more than 700 μg/L in outflow from 

the oxidation/filtration units. 

One of the limitations of this study is that the number of 

sites is small relative to the variation among sites in terms the 

system type, age and maintenance of the system, water use, 

and the chemical composition of the raw water. However, the 

results of this study indicate that additional investigation may 

be warranted to determine which methods of arsenic removal 

are effective/practical for residential use in areas like Ohio, 

where groundwater with elevated arsenic concentrations is 

strongly reducing, and the predominant arsenic species is 

arsenite (As3+).

References Cited

Ahuja, Satinder, ed., 2008, Arsenic contamination of groundwater—Mechanism, analysis, and remediation: Hoboken, 

N.J., John Wiley & Sons, Inc., 387 p. [Also available at 

http://dx.doi.org/10.1002/9780470371046.]

Angle, M.P., 1995, Ground water pollution potential of Licking County, Ohio: Ohio Department of Natural Resources, 

Division of Water, Water Resources Section, Ground Water 

Pollution Potential Report No. 31, 165 p.

Benn, T.M., 2006, Analysis of adsorptive media to remove 

arsenic and co-occurring oxyanions from groundwater: 

Phoenix, Arizona State University, M.S. Thesis, 184 p. 

Brenton, R.W., and Arnett, T.L., 1993, Methods of analysis by 

the U.S. Geological Survey National Water Quality Laboratory—Determination of dissolved organic carbon by UVpromoted persulfate oxidation and infrared spectrometry: 

U.S. Geological Survey Open-File Report 92–480, 12 p. 

[Also available at http://pubs.usgs.gov/of/1992/0480/report.

pdf.]

Chen, A.S.C., Lipps, J.P., Stowe, R.J., Yates, B.J., Lal, Vivek, 

and Wang, Lili, 2011, Arsenic removal from drinking 

water by adsorptive media—U.S. EPA Demonstration 

Project at LEADS Head Start building in Buckeye Lake, 

OH—Final performance evaluation report: Cincinnati, 

U.S. Environmental Protection Agency, Office of Research 

and Development, National Risk Management Research 

Laboratory, EPA/600/R–11/002, 99 p., accessed April 

2015 at http://nepis.epa.gov/Exe/ZyPDF.cgi/P1009PT2.

PDF?Dockey=P1009PT2.PDF.

Debrewer, L.M., Rowe, G.L., Reuter, D.C., Moore, R.C., 

Hambrook, J.A., and Baker, N.T., 2000, Environmental 

setting and effects on water quality in the Great and Little 

Miami River Basins, Ohio and Indiana: U.S. Geological 

Survey Water-Resources Investigations Report 99–4201, 

98 p. [Also available at http://pubs.er.usgs.gov/publication/

wri994201.]

Dove, G.D., 1960, Water resources of Licking County, Ohio: 

Ohio Division of Water Bulletin 36, 96 p.

Dumouchelle, D.H., 1999, Selected ground-water-quality data 

of the Lockport Dolomite in Darke, Miami, Montgomery, 

and Preble Counties, Ohio: U.S. Geological Survey Open 

File Report 98–655, 13 p. [Also available at http://pubs.

er.usgs.gov/publication/ofr98655.]

Fishman, M.J., ed., 1993, Methods of analysis by the U.S. 

Geological Survey National Water-Quality Laboratory—

Determination of inorganic and organic constituents in 

water and fluvial sediments: U.S. Geological Survey OpenFile Report 93–125, 217 p. [Also available at http://pubs.

er.usgs.gov/publication/ofr93125.]
23

Garbarino, J.R., Lewis, M.J., and Bednar, A.J., 2012, Arsenic 

speciation (ver. 2.1): U.S. Geological Survey Techniques 

of Water-Resources Investigations, book 9, chap. A5, 

sec. 5.6.4.A. 

International Agency for Research on Cancer (IARC), 2004, 

Summaries and evaluations—Arsenic in drinking-water 

(Group 1): Lyon, International Agency for Research on 

Cancer, IARC Monographs on the Evaluation of Carcinogenic Risk to Humans, v. 84, p. 39, accessed July 30, 2015, 

at http://www.inchem.org/documents/iarc/vol84/84-01-arsenic.html.

Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., 

Barber, N.L., and Linsey, K.S., 2014, Estimated use of 

water in the United States in 2010: U.S. Geological Survey 

Circular 1405, 56 p., accessed April 2015 at http://dx.doi.

org/10.3133/cir1405.

McCall, S.E., Chen, A.S.C., and Wang, Lili, 2007, Arsenic 

removal from drinking water by adsorptive media—U.S. 

EPA demonstration project at Chateau Estates mobile home 

park in Springfield, OH—Final performance evaluation 

report: Cincinnati, U.S. Environmental Protection Agency, 

Office of Research and Development, National Risk Management Research Laboratory, EPA/600/R–07/072, 

84 p. [Also available at http://nepis.epa.gov/Exe/ZyPDF.cgi/

P100AE02.PDF?Dockey=P100AE02.PDF.]

McMahon, P.B., and Chapelle, F.H., 2008, Redox processes 

and water quality of selected principal aquifer systems: 

Groundwater, v. 46, no. 2, p. 259–271. [Also available at 

http://dx.doi.org/10.1111/j.1745-6584.2007.00385.x.]

Miami Conservancy District, 2011, Study of arsenic levels in 

private wells in the Great Miami River Watershed: Dayton, Ohio, Miami Conservancy District Report 2011–06, 

accessed April 2015 at http://www.miamiconservancy.org/

water/documents/ArsenicLevelsintheGMRWatershedstudy110324final.pdf.

Miami Conservancy District, 2013, Water resources report for 

the Great Miami River Watershed: Dayton, Ohio, Miami 

Conservancy District Report 2013–24, 79 p., accessed April 

2015 at http://newserver.miamiconservancy.org/water/documents/FINAL2013WaterResourcesReport_000.pdf.

National Ground Water Association, 2009, Reducing problematic concentrations of arsenic in residential well systems: 

National Ground Water Association Press, Catalog No. 

BSP04, 13 p., accessed April 2015 at http://www.ngwa.org/

Professional-Resources/bsp/Pages/default.aspx.

Ohio Department of Natural Resources, 2015, Statewide 

aquifer mapping program: Ohio Department of Natural 

Resources, Division of Soil and Water, accessed April 2015 

at http://soilandwater.ohiodnr.gov/maps/statewide-aquifermaps.

Ohio Department of Health, 1999, Health consultation no. 

4—Lewisburg drum sites Lewisburg, Preble County, Ohio: 

CERCLIS No. OH0001954791, prepared for the Agency for 

Toxic Substances and Disease Registry. 

Ohio Environmental Protection Agency, 2010a, Guidelines 

for arsenic removal treatment for small public drinking 

water systems: Columbus, Ohio Environmental Protection 

Agency, Division of Drinking and Ground Waters. [Also 

available at http://www.epa.ohio.gov/portals/28/documents/

engineering/ArsenicManual.pdf.]

Ohio Environmental Protection Agency, 2010b, An overview 

of ground water quality in Ohio: Ohio Environmental 

Protection Agency 2010 Integrated Report, sec. N, 29 p. 

[Also available at http://www.epa.state.oh.us/Portals/35/

tmdl/2010IntReport/Section_N.pdf.]

Odell, Lee, and Perry, Sam, 2013, Arsenic removal—Lessons 

learned since 2002: Water Online, 12 p. 

Petty, R.J., 2000, Investigation of arsenic in private water systems in Jackson, Vinton, and Perry Counties, Ohio [abs.]: 

Midwest Ground Water Conference, 45th, Columbus, Ohio, 

October 17–19, 2000, p. 64. 

Pratson, Elizabeth, Vengosh, Avner, Dwyer, Gary, Pratson, 

Lincoln, and Klein, Emily, 2009, The effectiveness of 

arsenic remediation from groundwater in a private home: 

Ground Water Monitoring & Remediation, v. 30, no. 1, 

p. 87–93. [Also available at http://dx.doi.org/10.1111/

j.1745-6592.2009.01269.x.] 

Shindel, H.L., Mangus, J.P., and Frum, S.R., 2000, Water 

resources data, Ohio, water year 1999—Volume 2. St. Lawrence River Basin and Statewide project data: Columbus, 

U.S. Geological Survey Water-Data Report OH–99–2.

Siegrist, Howard, Ricker, K.T., and Brown, L.C., 1997, Water 

resources of Licking County: Ohio State University Extension Fact Sheet, AEX–480.45–97, 5 p. [Also available at 

http://ohioline.osu.edu/aex-fact/0480_45.html.]

Smedley, P.L., and Kinniburgh, D.G., 2002, A review of 

the source, behavior and distribution of arsenic in natural 

waters: Applied Geochemistry, v. 17, no. 5, p. 517–568. 

[Also available at http://dx.doi.org/10.1016/S0883-

2927(02)00018-5.]

Sorg, T.J., Chen, A.S.C., Wang, Lili, 2014, Arsenic species in 

drinking water wells in the USA with high arsenic concentrations: Water Research, v. 48, p. 156–169. [Also available 

at http://dx.doi.org/10.1016/j.watres.2013.09.016.]

Spayd, S.E., 2007, Arsenic water treatment for residential 

wells in New Jersey: New Jersey Geological Survey Information Circular, 2 p. [Also available at http://www.nj.gov/

dep/pwta/Arsenic_Treatment.pdf.]
24 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Spayd, S.E., 2009, Efficacy of arsenic exposure reduction via 

drinking water treatment systems: New Brunswick, N.J., 

Rutgers, The State University of New Jersey, Ph.D. dissertation, 204 p. [Also available at https://rucore.libraries.

rutgers.edu/rutgers-lib/28465/.]

Thomas, M.A., Diehl, S.F., Pletsch, B.A., Schumann, T.L., 

Pavey, R.R., and Swinford, E.M., 2008, Relation between 

solid-phase and dissolved arsenic in the ground-water 

system underlying northern Preble County, Ohio: U.S. 

Geological Survey Scientific Investigations Report 2008–

5205, 56 p., accessed April 2015 at http://pubs.usgs.gov/

sir/2008/5205/.

Thomas, M.A., Schumann, T.L., and Pletsch, B.A., 2005, 

Arsenic in ground water in selected parts of Southwestern 

Ohio, 2002–03: U.S. Geological Survey Scientific Investigations Report 2005–5138, 30 p., accessed April 2015 at 

http://pubs.usgs.gov/sir/2005/5138/.

Thomas, M.A., 2016, Arsenic in groundwater of Licking 

County, Ohio, 2012—Occurrence and relation to hydrogeology: U.S. Geological Survey Scientific Investigations Report 2015–5148, 38 p., http://dx.doi.org/10.3133/

sir20155148.

U.S. Environmental Protection Agency, 2001, Fact sheet—

Drinking water standard for arsenic: U.S. Environmental 

Protection Agency, EPA 815–F–00–015, accessed February 

26, 2015, at http://water.epa.gov/lawsregs/rulesregs/sdwa/

arsenic/regulations_factsheet.cfm.

U.S. Environmental Protection Agency, 2003, Arsenic treatment technology evaluation handbook for small systems: 

U.S. Environmental Protection Agency, Office of Water, 

EPA 816–R–03–014, 126 p. [Also available at http://water.

epa.gov/drink/info/arsenic/upload/2005_11_21_arsenic_

handbook_arsenic_treatment-tech.pdf.]

U.S. Environmental Protection Agency, 2005, Treatment 

technologies for arsenic removal: Cincinnati, U.S. Environmental Protection Agency, National Risk Management 

Research Laboratory, EPA/600/S–05/006, 11 p. [Also 

available at http://nepis.epa.gov/Exe/ZyPDF.cgi/20017IDW.

PDF?Dockey=20017IDW.PDF.]

U.S. Environmental Protection Agency, 2009, National 

primary drinking water regulations: U.S. Environmental 

Protection Agency, EPA 816–F–09–004, accessed February 

26, 2015, at http://www.epa.gov/safewater/consumer/pdf/

mcl.pdf.

U.S. Environmental Protection Agency, 2011, Letter Report—

Arsenic removal by full-scale greensand system at Licking 

Valley High School: U.S. Environmental Protection Agency, 

Contract No. EP–C–05–057, Task Order No. 0004, 45 p. 

U.S. Environmental Protection Agency, 2010, Evaluation 

of arsenic removal technology—Arsenic demonstration 

program: National Risk Management Research Laboratory: 

EPA/600/F-10/011, 2 p. 

U.S. Geological Survey, variously dated, The national field 

manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chaps. A1–A9, accessed April 2013 at http://

water.usgs.gov/owq/FieldManual/.

Walker, Mark, Seiler, R.L. and Meinert, Michael, 2008, 

Effectiveness of household reverse-osmosis systems in a 

western U.S. region with high arsenic in groundwater: 

Science of The Total Environment, v. 389, no. 2–3, 

p. 245–252. [Also available at http://dx.doi.org/10.1016/j.

scitotenv.2007.08.061.]

Wang, Lili, Chen, A.S.C., and Stowe, Ryan, [n.d.], Project 

summary—Arsenic removal from private wells by residential treatment systems—U.S. EPA demonstration project at 

Lewisburg, Ohio: U.S. Environmental Protection Agency, 

9 p. 

Welch, A.H., Westjohn, D.B., Helsel, D.R., and Wanty, R.B., 

2000, Arsenic in ground water of the United States—Occurrence and geochemistry: Ground Water, v. 38, no. 4, 

p. 589–604. [Also available at http://water.usgs.gov/nawqa/

trace/pubs/gw_v38n4/.]

Westerhoff, P.K., Benn, T.M., Chen, A.S.C., Wang, Lili, 

and Cumming, L.J., 2008, Assessing arsenic removal by 

metal (hydr)oxide adsorptive media using rapid small 

scale column tests: Cincinnati, Ohio, U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 

EPA/600/R–08/051, 50 p.

World Health Organization (WHO), 2010, Exposure to 

arsenic—A major public health concern: accessed July 2015 

at http://www.who.int/ipcs/features/arsenic.pdf?ua=1.
Table 2
26 The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013

Table 2. Water-quality results from 11 domestic wells in southwestern and central Ohio, 2013.

Table 2 is an Excel file that can be accessed at http://dx.doi.org/10.3133/sir20155156.
Publishing support provided by the U.S. Geological Survey

Science Publishing Network,

Madison and Rolla Publishing Service Centers

Printed on recycled paper

Thomas and Ekberg—The Effectiveness of Water-Treatment Systems for Arsenic Used in 11 Homes in Southwestern and Central Ohio, 2013—Scientific Investigations Report 2015–5156

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20155156