U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2006–5183

In cooperation with the Medina County Health Department

Assessment of the Use of Selected Chemical and 

Microbiological Constituents as Indicators of 

Wastewater in Curtain Drains From Home SewageTreatment Systems in Medina County, Ohio
Assessment of the Use of Selected 

Chemical and Microbiological Constituents 

as Indicators of Wastewater in Curtain 

Drains From Home Sewage-Treatment 

Systems in Medina County, Ohio

By Denise H. Dumouchelle

In cooperation with the Medina County Health Department

Scientific Investigations Report 2006–5183

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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Suggested citation:

Dumouchelle, D.H, 2006, Assessment of the use of selected chemical and microbiological constituents as indicators 

of wastewater in curtain drains from home sewage-treatment systems in Medina County, Ohio: U.S. Geological 

Survey Scientific Investigations Report 2006−5183, 20 p.
iii

Contents 

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

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

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

Description of Home Sewage-Treatment Systems ........................................................................ 3

Selection of Constituents for Study .................................................................................................. 4

Methods of Data Collection and Analysis ................................................................................................ 4

Chemical Constituents ........................................................................................................................ 7

Microbiological Constituents............................................................................................................. 8

Occurrence of Chemical and Microbiological Constituents ................................................................. 8

Nutrients................................................................................................................................................ 8

Chloride and Bromide........................................................................................................................ 10

Chloride....................................................................................................................................... 10

Bromide ...................................................................................................................................... 11

Chloride/Bromide Ratios.......................................................................................................... 11

Coliphage............................................................................................................................................. 13

E. coli Bacteria ................................................................................................................................... 14

Utility of Study Approaches and Inferences From Available Data..................................................... 14

Summary and Conclusions........................................................................................................................ 17

Acknowledgments...................................................................................................................................... 18

References Cited......................................................................................................................................... 18

Figures

1. Map showing location of sampled home sewage-treatment systems ............................. 2

2. Schematic of leach-line septic system.................................................................................... 4

3. Construction sketches of gravel leach trench, gravelless leach trench, and 

curtain drain ................................................................................................................................. 5

4. Diagram showing design of the evaporation-transpiration-absorption (ETA) system 

used in Medina County, Ohio..................................................................................................... 6

5. Photographs showing typical sampling points at curtain drains in Medina 

County, Ohio.................................................................................................................................. 7

6. Graph showing relation of chloride concentration to chloride-bromide ratios for 

water from home sewage-treatment systems (HSTSs), HSTS curtain drain, and 

domestic-supply wells, Medina County, Ohio....................................................................... 12

7. Example of results of rep-PCR analysis showing six isolates and multiple measurements of a single isolate, demonstrating the reproducibility of results ........................... 15
iv

Tables

1. Site information for home sewage-treatment systems sampled in Medina 

County, Ohio.................................................................................................................................. 3

2. Results of analyses of samples from wells and home sewage-treament systems 

in Medina County, Ohio............................................................................................................... 9

3. Chloride/bromide ratios in samples collected from home sewage-treatment system, 

associated curtain drains, and two residential wells in Medina County, Ohio............... 11

4. Results of analyses of bacteria and coliphage in samples from wells and home 

sewage-treatment systems in Medina County, Ohio........................................................... 13

5. Sites and numbers of isolates in those operational taxonomic units (OTU) found 

from more than one source from samples in Medina County, Ohio.................................. 16

6. Summary of the utility of indicators used in this study for indicating the movement 

of partially untreated wastewater from home sewage-treatment systems to 

associated curtain drain........................................................................................................... 17

Conversion Factors

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25°C).

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

or micrograms per liter (μg/L).

Concentrations of bacteria in water are given in colonies per 100 milliliters (col/100 mL).

Concentrations of coliphage in water are given in plaques per 100 milliliters (plaques/100 mL).
Assessment of the Use of Selected Chemical and 

Microbiological Constituents as Indicators of Wastewater 

in Curtain Drains From Home Sewage-Treatment Systems 

in Medina County, Ohio

By Denise H. Dumouchelle

Abstract

Many home sewage-treatment systems (HSTS) in Ohio 

use curtain or perimeter drains to depress the level of the subsurface water in and around the systems. These drains could 

possibly intercept partially untreated wastewater and release 

potential pathogens to ground-water and surface-water bodies. The quality of water in curtain drains from two different 

HSTS designs in Medina County, Ohio, was investigated using 

several methods. Six evaporation-transpiration-absorption 

(ETA) and five leach-line (LL) systems were investigated by 

determining nutrient concentrations, chloride/bromide ratios 

(Cl/Br), Escherichia coli (E. coli) concentrations, coliphage 

genotyping, and genetic fingerprinting of E. coli. Water 

samples were collected at 11 sites and included samples from 

curtain drains, septic tanks, and residential water wells. 

Nitrate concentrations in the curtain drains ranged from 

0.03 to 3.53 mg/L (milligrams per liter), as N. Concentrations 

of chloride in 10 of the 11 curtain drains ranged from 5.5 to 

21 mg/L; the chloride concentration in the eleventh curtain 

drain was 340 mg/L. Bromide concentrations in 11 curtain 

drains ranged from 0.01 to 0.22 mg/L. Cl/Br ratios ranged 

from 86 to 2,000. F-specific coliphage were not found in any 

curtain-drain samples. Concentrations of E. coli in the curtain 

drains ranged from 1 to 760 colonies per 100 milliliters. 

The curtain-drain water-quality data were evaluated to 

determine whether HSTS-derived water was present in the 

curtain drains. Nutrient concentrations were too low to be of 

use in the determination. The Cl/Br ratios appear promising. 

Coliphage was not detected in the curtain drains, so genotyping could not be attempted. E. coli concentrations in the 

curtain drains were all less than those from the corresponding 

HSTS; only one sample exceeded the Ohio secondary-contact 

water-quality standard. The genetic fingerprinting data were 

inconclusive because multiple links between unrelated sites 

were found. 

Although the curtain-drain samples from the ETA 

systems showed somewhat more evidence of the presence of 

HSTS water than did the LL systems, most of the approaches 

were inconclusive by themselves. The best evidence of HSTS 

water, from the Cl/Br ratios, indicates that the water in 10 of 

the 11 curtain drains, at both HSTS types, was a mixture of 

dilute ground water and HSTS-derived water; the 11th drain 

also show some effects of the HSTS, although road saltaffected water may be present. Therefore, it appears that there 

is no difference between the ETA and LL systems with respect 

to the water quality in curtain drains. 

Introduction

Onsite or home sewage-treatment systems (HSTSs) are 

widely used in many areas of Ohio. The soils in Ohio are 

commonly unsuitable for traditional leach-line (LL) systems 

(Mancl and Slater, 2001), and as a result, various HSTS 

designs are used in the State. Many of these systems involve 

curtain drains, which are perforated pipes installed in trenches 

around the perimeter of the HSTS leaching area. These drains 

are typically 5 to 10 ft from and not connected to the HSTS. 

The drains are intended to depress the shallow ground water 

in and around an HSTS. However, there are concerns that 

these drains could release partially treated wastewater and 

potential pathogens to ground-water and surface-water bodies.

A conventional LL system consists of a septic tank and 

a series of perforated pipes that discharge the wastewater to 

soil for treatment. Another type of HSTS, one that requires 

less land than an LL system, is the evaporation-transpirationabsorption (ETA) system. ETA systems are being used in a 

few counties in Ohio. The ETA system consists of a moundcovered trench with trees and other plants on the mound above 

the trench. The ETA design is considered an alternative or 

experimental system in Ohio, and the performance of these 

systems in clay-rich soils is not well documented. Approximately 1,200 ETA systems, with curtain drains, have been 

installed in Medina County, Ohio. 

The U.S. Geological Survey (USGS), in cooperation with 

the Medina County Health Department (MCHD), sampled 

Introduction   
   Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

water from curtain drains from ETA systems and LL systems to obtain a better understanding of whether wastewater 

migrates from either HSTS design to the curtain drains. The 

objectives of the study were to evaluate several approaches to 

test for the presence of HSTS-derived water in curtain drains, 

to compare the approaches, and to describe the results with 

respect to two types of HSTS. This study builds on a series 

of previous USGS studies (Dumouchelle and Stoeckel, 2005; 

Jagucki and Darner, 2001; multiple references in Stoeckel, 

2005) involving water quality or microbiological data as lines 

of evidence in identifying sources of contamination.

Purpose and Scope

This report presents data and results from the study 

described previously. The study area was Medina County, in 

northeastern Ohio (fig. 1). Water samples were collected at 

11 HSTS sites in late June 2004. The samples were collected 

from curtain drains, septic tanks, and two residential water 

wells. Samples were analyzed for nutrients, chloride, bromide, 

coliphage, and Escherichia coli (E. coli) bacteria. Six ETA and 

five LL systems were investigated. 

82o 1”

81o 8”

41o 0”

41o 2”

0 10

0

20 MILES

20 KILOMETERS

MEDINA COUNTY

County location

OHIO

Geauga County

EXPLANATION

MD-16

MD-17 MD-18

MD-15

MD-20

MD-19

MD-21

MD-23

MD-22

MD-24

MD-25

MD-17

MD-16 Evaporation-transpiration-

 absorption system

Leach-line system

U.S. 42

Interstate 71

Interstate 76

Interstate 271

Figure 1. Location of sampled home sewage-treatment systems.
Description of Home Sewage-Treatment 

Systems

Medina County has an estimated (2004) population of 

more than 165,000 people (Ohio Department of Development, 

2005). About 31 percent of households in the county (more 

than 18,000) use HSTSs. Most of the soils in the county have 

some limitations with respect to the use of an HSTS, such as 

poor drainage, poor permeability, and high water tables (near 

land surface). The soils surrounding the HSTSs investigated 

in this study have all been rated as having severe limitations 

for an HSTS for one or more of these reasons (Hayhurst and 

others, 1977). Eleven HSTSs of two designs (LL or ETA) were 

investigated (fig. 1, table 1). Both designs incorporated curtain 

drains intended to depress shallow ground water. Curtain 

drains are not connected to the HSTS, and usually drain by 

gravity to a low area or ditch.

The five LL systems examined for this study consisted 

of either a septic tank or an aeration unit (table 1), followed 

by a diverter box that routed wastewater flow to one of two 

leaching-tile fields (fig. 2). The tile fields consisted of either 

a perforated pipe within a gravel-filled trench or a similar 

pipe, wrapped in a geotextile, within a gravelless trench (fig. 

3A, B). Curtain drains are constructed in a similar manner as 

the leach lines (fig. 3C). For all LL systems in this study, the 

curtain drain surrounded the leach field on all four sides and 

discharged through a single outlet pipe (fig. 2). The approximate average distance between the outermost leach tile and the 

curtain-drain tile ranged from 7.5 ft to 11.8 ft (table 1).

Six ETA systems were examined in this study. The ETA 

design consists of an aeration unit that discharges to a single 

leach line that is placed at the top of a gravel-lined trench (fig. 

4). A mound of topsoil is placed above the trench, the sides 

of the mound are compacted soil or clay, and evergreen trees 

and thick grass are planted within the topsoil along the top 

of the mound. For the ETA systems in this study, the curtain 

drains were installed along the longitudinal sides of the mound 

and around at least one end of the mound. The approximate 

average distance between the mound and the curtain-drain tile 

ranged from 7 ft to 9.5 ft (table 1).

Introduction   

Table 1. Site information for home sewage-treatment systems sampled in Medina County, Ohio.

[LL, leach-line system; ETA, evaporation-transpiration-absorption system] 

Site 

name

System type 

and year of 

installation

Soil series

(Hayhurst and 

others, 1977)

Approximate distance from system 

to curtain drain, 

in feet

Curtain-drain sample location

Approximate minimum distance from 

road to drain, in feet

MD-15 ETA 2003 Mahoning Silt Loam 8.5 Flow in gravel, pool 351

MD-16 ETA 1998 Mahoning Silt Loam 8 From pipe 306

MD-17 LL 2003 Mahoning Silt Loam 8 From pipe 300

MD-18 ETA 2002 Mahoning/Ellsworth 7.5 Pool below pipe 129

MD-19 ETA 2003 Rittman Silt Loam 8.5/9.5 From pipe 225

MD-20 LL 2000 Ellsworth Silt Loam 11.8 From pool at end 237

MD-21a LL 1993 Rittman Silt Loam 11.6 From pipe 94

MD-22 LL 2003 Wadsworth/Rittman 7.7 Pool below pipe 312

MD-23b ETA 2002 Fitchville/Glenford 7.2 From pipe at lift pump 33

MD-24 ETA 2004 Ellsworth Silt Loam 7 From pipe 168

MD-25a,b LL 1998 Canfield/Ravenna 7.5 From pipe 276

a

 These systems used a septic tank rather than an aerator unit.

b

 Residential wells sampled at these locations.
   Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

Selection of Constituents for Study

Samples of water collected from the curtain drains and 

the HSTSs were analyzed for a selected suite of chemical and 

microbiological constituents. The presence, or absence, of 

these constituents in the samples provided multiple lines of 

evidence as to the source of the water; that is, whether or not 

it was derived from the HSTSs. The chemical constituents of 

interest in this study were nutrients, chloride, and bromide; the 

microbiological constituents of interest were coliphage and 

E. coli bacteria.

Nutrients are ions or organic compounds that contain 

nitrogen or phosphorus. Nitrogen concentrations are of concern with respect to human-health issues; for drinking water, 

the Maximum Contaminant Level (MCL) established for 

nitrite is 1 mg/L (as N), and that for nitrate is 10 mg/L (as N) 

(U.S. Environmental Protection Agency, 2004). Nitrogen fertilizers and sewage are common sources of nitrogen contamination in waters. Nitrate, the main form of nitrogen in ground 

water, is very mobile. Nitrogen from HSTSs generally enters 

the soil as organic nitrogen, nitrate, or ammonia. In the soil, 

above the water table, oxidation converts the various nitrogen forms to nitrate, and bacterial systems or redox reactions 

convert the nitrate to nitrogen and nitrous oxide. Nitrogen and 

nitrous oxide can be lost to the atmosphere and, if dissolved, 

are not harmful in drinking water (Freeze and Cherry, 1979, 

p. 413−415). 

The ratio of chloride to bromide (Cl/Br) concentrations 

has been used to identify or confirm sources of ground-water 

contamination (Davis and others, 1998; Eberts and others, 

1990; Jagucki and Darner, 2001; Thomas, 2000). These constituents can be useful because they are both soluble in water 

and conservative; that is, they are not prone to adsorption to 

sediment or redox alterations (Hem, 1989; Davis and others, 

1998).

Microbiological constituents of interest in this study 

were coliphage and E. coli. Coliphage are viruses that infect 

bacteria, including E. coli. Coliphage are an indicator of fecal 

contamination and are sometimes used as a surrogate for the 

subsurface transport of fecal-origin human viruses. Samples 

from HSTSs were analyzed for both somatic and F-specific 

coliphage. Genotyping analysis of coliphage, to determine 

human as opposed to nonhuman sources, can be done only on 

F-specific RNA-based coliphage, so these were of most interest for detection of the transport of any partially treated wastewater between an HSTS and curtain drains. E. coli is itself a 

longstanding indicator of fecal contamination, although E. coli

detection alone does not address the source of the contamination. However, repetitive DNA element polymerase chain reaction (rep-PCR) has been used to indicate the source of E. coli

(Dombeck and others, 2000; Carson and others, 2003). 

Methods of Data Collection and 

Analysis

Sites were selected by the MCHD to represent a combination of ETA and LL HSTSs throughout the county. Water 

samples were collected by the USGS at 11 properties. Samples 

were collected from curtain-drain outfalls and within the 

HSTSs; samples also were collected from the faucets in two 

homes supplied with water from their own wells. The wells 

were completed in sandstone, with open intervals from 62 to 

100 ft (below ground) and 35 to 78 ft.

Most of the curtain-drain outfalls (fig. 5) were partly 

buried and (or) produced minimal flows; so, in some cases, 

the area beneath the outfall pipe was dug out to create a pool 

for sample collection. When possible, samples were collected 

from the outfall by placing a collection bottle underneath the 

pipe or by using a peristaltic pump and sterile tubing from 

within the pipe. Other curtain-drain samples were collected 

from a pool near the outfall discharge with a peristaltic pump 

and sterile tubing (table 1). Samples from the HSTSs were collected post aerator (when present), either from within the tank 

or from the diverter box using a peristaltic pump and sterile, 

weighted tubing. In addition, one known sample from surface 

scat (dog) was collected for E. coli analysis using methods 

described in Dumouchelle and Stoeckel (2005)

 Replicate samples and one field blank were collected for 

quality control. These samples were analyzed to identify any 

variability in analytical results that might be associated with 

sample-collection or laboratory methods. 

Inactive

leach line

Diverter

box

Curtain drain

 Tank

Not to scale

to discharge point

Active

leach line

Figure 2. Schematic of leach-line septic system.
Backfill

Gravel

Perforated pipe

2 inches minimum

4 inches minimum

A. Gravel leach trench.

Preapplied

filter

fabric

Backfill

Holes

8 or 10 inches

6 inches minimum

18 - 24 inches

0 - 2 inches

B. Gravelless leach trench.

18 - 36 inches

Perforated

pipe

Gravel

C. Curtain drain.

10 inches minimum

Trench width

Backfill

Figure 3. Construction sketches: A, Gravel leach trench. B, Gravelless leach trench. C, Curtain drain.

Methods of Data Collection and Analysis   
   Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

8 feet 3 feet 8 feet

2 feet

18 - 24 inches

Topsoil

Lift station 

Pump line 

Aerobic treatment unit 

Placement of tree 

Curtain drain 

Curtain drain 

Trench 

perimeter

Leach line 

To curtain 

drain lift 

station or 

discharge point 

Compacted spoil subsoil

from trench

Excavated earth 

backfill

Curtain drain 

Curtain drain trench 

Gravel

Leach tubing Curtain drain 

Cross section 

Schematic

Gravel

not to scale

Figure 4. Diagram showing design of the evaporation-transpiration-absorption (ETA) system used in Medina County, Ohio
Chemical Constituents

Water samples from the 11 curtain drains, 2 HSTSs, and 

2 wells were analyzed for nutrients, chloride, and bromide. 

Samples were transferred from a common collection bottle 

to the analysis bottles by use of a peristaltic pump with an 

inline filter on the tubing. Sampling tubing was cleaned with 

nonphosphate detergent and deionized water, followed by 

sterilization in an autoclave. The samples were shipped to the 

USGS National Water-Quality Laboratory (NWQL) in Denver, 

Colo. The nutrient samples were analyzed for concentrations 

of ammonia, nitrite, nitrite plus nitrate, and orthophosphate 

(Fishman, 1993); the reporting limits, respectively, for these 

constituents were 0.04, 0.008, 0.06, and 0.018 mg/L. Nitrate 

concentrations were calculated by subtracting the concentration of nitrite from the concentration of nitrate plus nitrite. 

Nitrate and nitrite concentrations are reported as nitrogen (as 

N). Chloride analysis was done by ion-exchange chromatography (Fishman and Friedman, 1989) and at a reporting limit 

of 1 mg/L. The bromide analysis was done by fluorescein 

colorimetry (Fishman and Friedman, 1989); the reporting limit 

for this method was 0.02 mg/L. 

Figure 5. Photographs showing typical sampling points at curtain drains in Medina County, Ohio.

MD-15 MD-23

MD-24

Methods of Data Collection and Analysis   
 Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

Two replicate samples were collected for analysis of 

nutrients, chloride, and bromide. Analytical results of the 

replicate samples were compared qualitatively with those of 

the field samples. The analytical results of the two sample 

sets were comparable (less than 5 percent difference) except 

those for one ammonia and one nitrite sample. The replicate 

ammonia analysis had a concentration of 0.057 mg/L as compared to less than 0.04 mg/L. The replicate nitrite analysis 

had a concentration of less than 0.008 mg/L as compared to 

an estimated concentration of 0.005 mg/L. A blank sample for 

analysis of nutrients, chloride, and bromide was collected by 

pumping blank water from the supply bottle into the sample 

bottle; no analytes were detected in the blank sample.

Microbiological Constituents

Water samples for microbiological analyses were collected with the same tubing used for chemical-constituents 

sampling. The tubing was cleaned with nonphosphate detergent and deionized water, followed by sterilization in an 

autoclave. Samples were analyzed for F-specific and somatic 

coliphage and E. coli. Selected E. coli isolates were subjected 

to rep-PCR analysis. These analyses were done in the USGS 

Ohio Water Microbiology Lab (OWML). Standard operating procedures, quality assurance, and quality control were 

followed and are detailed in Francy and others (2004) and 

Dumouchelle and Stoeckel (2005).

Water samples for analyses of F-specific and somatic 

coliphage were collected from the curtain drains and HSTSs 

at all 11 sites. The water from the HSTS was analyzed first, 

and the curtain-drain sample was analyzed only if F-specific 

coliphage was found in the HSTS sample. Samples were analyzed for coliphage by use of a quantitative, single-agar-layer 

method (U.S. Environmental Protection Agency, 2001). The 

intent was to genotype the coliphage if it was found in both the 

curtain drains and the HSTS. Coliphage genotyping methods 

are described in Hsu and others (1995) and Beekwilder and 

others (1996). Genotyping of F-specific coliphage can be used 

to help distinguish between human and nonhuman sources 

(Noble and others, 2003). Coliphage were not detected in any 

samples from curtain drains; therefore, no genotyping was 

done.

Water samples were plated to measure E. coli concentrations from the 11 curtain drains, 11 HSTSs, and 2 wells. Plating was done within 24 hours of sampling by use of the membrane filtration method with mTEC agar (U.S. Environmental 

Protection Agency, 2000). Nonstandard collection methods 

were required to obtain water samples from the HSTSs for 

E. coli analysis; these methods are described in Dumouchelle 

and Stoeckel (2005).

E. coli isolates, individual colonies isolated from the 

agar plate, were characterized by rep-PCR genomic analysis by a protocol similar to that reported by Rademaker and 

de Bruijn (1997), modified and standardized by Bacterial 

Barcodes (2004). Dumouchelle and Stoeckel (2005) describe 

these methods and related quality assurance/quality control 

procedures in detail. The rep-PCR method measures an index 

of genetic similarity but does not give information on species, 

so operational taxonomic units (OTU) were defined to assign 

genetically similar isolates to groups; isolates in an OTU had 

at least 96 percent genetic similarity by the procedures used. 

At least 10 percent of each OTU were tested to confirm that 

the OTU belonged to the species E. coli. Because of the clonal 

nature of E. coli populations (Whittam, 1989) and the diversity 

of E. coli reported in literature studies (Caugant and others, 

1981; Johnson and others, 2004; Kariuki and others, 1999; 

McLellan, 2004; and Yang and others, 2004), all E. coli isolates belonging to the same OTU were assumed to have come 

from the same source.

Three replicate samples were collected for E. coli analysis; because of the wide range of variability in concentrations 

in microbiological analyses, quality-assurance analysis is 

frequently done with log10 transformed data (D.S. Francy, 

U.S. Geological Survey, oral commun., 2005). Two of the 

replicate analyses had less than 1 percent difference in E. coli

counts between the (log-transformed) standard and replicate 

samples. The difference in the third (log-transformed) replicate analysis was only 10 percent, which is not considered 

significant (particularly because the replicate sample count 

of 16 col/100 mL was below the ideal range). One replicate 

sample for coliphage was analyzed. The standard sample 

had a count of 6,000 plaques/100 mL, and the replicate had 

a count of 8,000 plaques/100 mL, yielding a log-transformed 

difference of 18 percent. Given the difficulty in counting such 

a large number of plaques, the large percent difference is not 

unexpected.

Occurrence of Chemical and 

Microbiological Constituents

To determine whether HSTS-derived water was present in 

the curtain drains, data from several indicators were evaluated 

to provide multiple lines of evidence: the occurrence and concentrations of nutrient, chloride and bromide ratios, and 

E. coli; Cl/Br ratios; genotyping of coliphage; and genetic 

fingerprinting of E. coli. Differences in the composition of 

water in the drains at ETA and LL systems were evaluated 

qualitatively.

Nutrients

In the curtain drains, ammonia concentrations ranged 

from 0.03 to 2.17 mg/L; concentrations in the HSTS were 

1.20 and 25.7 mg/L; concentrations in both wells were less 

than 0.04 mg/L (table 2). Concentrations of orthophosphate 

were generally less than 0.02 mg/L; the highest concentrations 

were in the HSTS at 4.37 and 4.39 mg/L. In the curtain drains, 

nitrite concentrations ranged from 0.005 to 0.011 mg/L; 
Table 2. Results of analyses of samples from wells and home sewage-treatment systems in Medina County, Ohio.

[HSTS, home sewage-treatment system; CD, curtain drain; WE, residential water well; μS/cm, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; <, less than; --, no data; E, estimated value] 

Site name Date Sample 

source

pH

(standard 

units)

Specific 

conductance

(μS/cm)

Ammonia

(mg/L as N)

Nitrite 

+ nitrate

(mg/L as N)

Nitrite

(mg/L as N)

Nitrate,

calculated 

(mg/L

as N)

Orthophosphate

(mg/L as P)

Chloride,

dissolved

(mg/L)

Bromide,

dissovled

(mg/L)

Evaporation-transpiration-absorption systems (ETA)

MD-15 6-21-2004 CD 7.3 801 E .03 3.54 < 0.008 3.53 < 0.02 15 0.05MD-16 6-21-2004 CD 8.0 632 <.04 1.34 < .008 1.33 < .02 21 .10MD-18 6-22-2004 HSTS -- -- 25.7 .99 .635 .36 4.39 35 .03

CD 7.7 703 <.04 .66 .011 .65 < .02 13 .04

MD-19 6-22-2004 HSTS -- -- 1.20 4.24 3.77 .47 4.37 41 .08

CD 6.9 863 <.04 .06 E .006 E .05 < .02 13 .06a

MD-23 6-23-2004 CD 6.7 1880 E .03 2.25 .009 2.24 .20 340 .17

WE -- -- <.04 1.67 < .008 1.66 < .02 45 .03

MD-24 6-24-2004 CD 6.5 651 2.17 < .06 E .005 E < .06 < .02 19 .22

Leach-line systems (LL)

MD-17 6-21-2004 CD -- 350 <0.04 1.37 < 0.008 1.36 < 0.02 5.5 E .01MD-20 6-22-2004 CD 7.4 582 .06 .46 E .006 E .45 < .02 8.3 .03MD-21 6-22-2004 CD -- 428 .20 E .04 < .008 E .03 .04 14 .06MD-22 6-23-2004 CD -- 642 .14 .50 .010 .49 < .02 11 .04MD-25 6-24-2004 CD 7.0 480 <.04 1.50 < .008 1.49 < .02 11 .04

WE -- -- <.04 .67 < .008 .66 < .02 48 .05

a Concentration is from a replicate sample because the regular sample was not analyzed for bromide.

Occurrence of Chemical and Microbiological Constituents   
10 Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

concentrations in the HSTS were 0.635 and 3.77 mg/L; concentrations in the wells were less than 0.008 mg/L. Calculated 

nitrate concentrations in the curtain drains ranged from 0.03 

to 3.53 mg/L; concentrations in the HSTS were 0.36 and 0.47 

mg/L, and concentrations in the wells were 0.66 and 1.66 

mg/L.

Baker and others (1989) analyzed 16,166 samples of 

water from private wells throughout Ohio. They considered 

nitrate concentrations1 of 0.3 mg/L (as N) or less as representative of background concentrations, concentrations of 3.1 to 

10 mg/L (as N) as possibly indicating effects of human activity, and concentrations greater than 10 mg/L (as N) as being 

most likely due to human activity. In the spring of 1987 and 

spring 1988, water samples from 182 private wells in Medina 

County were analyzed; 75 percent (136 wells) had nitrate 

concentrations less than 0.3 mg/L; 7 percent (13 wells) had 

concentrations between 3.0 and 10 mg/L; 2 percent (4 wells) 

had concentrations greater than 10 mg/L (Baker and others, 

1989).

The highest concentration of nitrate detected in this study, 

3.53 mg/L in a sample from the curtain drain at MD-15 (table 

2), was well below the MCL of 10 mg/L. Nitrate concentrations from curtain drains at the 6 ETA systems ranged from 

less than 0.05 to 3.53 mg/L, with a median concentration of 

0.99 mg/L. Nitrate concentrations from curtain drains at 5 LL 

systems ranged from 0.03 to 1.49 mg/L, with a median concentration of 0.49 mg/L. 

In a similar study by the Ohio Department of Health 

(ODH), 28 samples were collected from 21 curtain drains (all 

LL systems) in 2 counties (J. Caudill, Ohio Department of 

Health, written commun., 2005). The ODH-reported nitrite 

plus nitrate concentrations ranged from less than 1 to 3.64 

mg/L, with a median of 0.43 mg/L. In comparison, the nitrite 

plus nitrate concentrations in curtain-drain samples from the 

Medina County LL systems ranged from 0.04 to 1.5 mg/L, 

with a median of 0.5 mg/L; concentrations in curtain-drain 

samples from the Medina County ETA systems ranged from 

less than 0.06 to 3.54 mg/L, with a median of 1.0 mg/L. 

Although the concentrations in curtain-drain samples from 

the Medina County ETA systems have a slightly larger range 

and higher median value than those in samples from the LL 

systems, the concentrations from the curtain drains at both 

systems were, with one exception, below the range that Baker 

and others (1989) thought indicative of possible anthropogenic 

effects.

Phosphorus, a component of sewage, is an essential 

nutrient for plant growth; phosphorus enrichment, however, 

can lead to algal blooms and eutrophication of water bodies. 

In water samples, orthophosphate is the most stable form of 

phosphorus. Phosphorus tends to precipitate out of solution, 

so dissolved phosphorus added to soils from an HSTS may not 

remain available for long periods (Hem, 1989). No standards 

1

 Nitrite plus nitrate concentrations were referred to as “nitrate” in their 

study.

have been established for phosphorus in the Ohio Water Quality Standards; however, large-volume point-source discharges 

in the Lake Erie basin have a permit limit of 1.0 mg/L in the 

final effluent (Ohio Environmental Protection Agency, 2003a). 

Orthophosphate concentrations above the detection limit were 

found only in the HSTS samples at MD-18 and MD-19 (table 

2). There were no meaningful differences between ETA and 

LL systems with respect to orthophosphate concentrations in 

curtain drains.

Chloride and Bromide

Concentrations of chloride in 10 of the 11 curtain drains 

sampled ranged from 5.5 to 21 mg/L; the chloride concentration in the 11th curtain drain was 340 mg/L (table 2). Chloride 

concentrations in the samples from the HSTS were 35 and 41 

mg/L and from the water wells, 45 and 48 mg/L. It should be 

noted that the homes at which the HSTS water samples were 

collected for the analyses of chloride and bromide used citysupplied water with an average chloride concentration of 20 

parts per million (parts per million are roughly equivalent to 

milligrams per liter). 

 The bromide concentration in one curtain drain sample, 

MD-19, was not determined; fortunately, a replicate sample 

was collected at that site, so the results of the replicate analysis 

is reported. Bromide concentrations in the 11 curtain drains 

ranged from 0.01 to 0.22 mg/L. Bromide concentrations in the 

HSTSs were 0.03 and 0.08 mg/L; concentrations in the wells 

were 0.03 and 0.05 mg/L. Bromide analyses were not available for the city water supply.

Chloride

Chloride concentrations in sewage are frequently elevated 

relative to natural waters but the degree to which HSTS effluent affected the chloride concentrations in curtain drains in this 

study cannot be definitively determined. On the basis of data 

on chloride concentrations in septic effluent, road salt runoff, 

and background concentrations in ground water, however, it 

may be possible to identify some HSTS effects on the quality of water in the drains. Panno and others (2006) reported 

chloride concentrations in 29 samples from septic systems 

ranged 21 to 5,620 mg/L; with a median concentration of 91 

mg/L. The two samples collected from the septic tanks in this 

study had chloride concentrations of 35 and 41 mg/L (table 2), 

within the range reported by Panno and others (2006).

Elevated chloride concentrations also could result from 

road salt contamination. Panno and others (2006) reported 

chloride concentrations in 13 wells affected by road salt 

ranged from 44 to 416 mg/L, which was similar to the range 

of chloride concentrations, 40 to 116 mg/L, they reported in 3 

wells affected by septic contamination. The highest chloride 

concentration detected in Medina County, 340 mg/L, was in 

the sample from the curtain drain at MD-23. The HSTS is 
close to the road at MD-23, with the curtain drain as close as 

33 ft from the road (table 1). In addition, a water softener was 

known to be in use at the site. The relatively high chloride 

concentration could be the result of road salt or HSTS-derived 

water or a combination of both.

The curtain drains are not within material that would be 

considered an aquifer but rather in clay-rich, glacially derived 

soils. Background or reference chloride concentrations used 

for comparison should reflect such conditions. Dumouchelle 

and Stoeckel (2005) noted that reported chloride concentrations in glacial sediments in Ohio and southeastern Michigan ranged from 1.0 to 544 mg/L, with the median values 

for datasets ranging from 4 to 79 mg/L. Given these ranges, 

Dumouchelle and Stoeckel (2005) used a chloride concentration of 200 mg/L as a conservative indicator that water 

sampled from piezometers a few feet from HSTS leach lines 

was likely affected by HSTS effluent.

Although the range in and median concentrations of 

chloride in samples from the ETA system curtain drains (13 to 

340 mg/L; 17 mg/L) were larger than those for the LL systems 

(5.5 to 14 mg/L; 11 mg/L), the concentrations in all but one 

of the samples were less than 22 mg/L (table 2). In the study 

by the ODH mentioned earlier (J. Caudill, Ohio Department 

of Health, written commun., 2005), chloride concentrations 

ranged from less than 5 mg/L to 2,380 mg/L, with a median of 

14 mg/L. Considering the data from both studies, no difference could be determined between ETA and LL systems with 

respect to chloride concentrations. 

Bromide 

Bromide concentrations are naturally low; concentrations 

in rainwater and snow range from about 0.005 to 0.15 mg/L 

(Hem, 1989) and typically are about 0.02 mg/L in streams 

(Drever, 1988). The ranges of reported bromide concentrations 

for various sources of water overlap, making it difficult to use 

bromide itself as an indicator of the source of water. Bromide 

values can be useful in ratio with chloride values, however, 

because small changes in bromide concentrations can give rise 

to large variations in the Cl/Br ratio.

The bromide concentrations in the ETA curtain-drain 

samples ranged from 0.04 to 0.22 mg/L, with a median of 

0.08 mg/L. The concentrations in samples from the LL curtain 

drains ranged from 0.01 to 0.06 mg/L, with a median of 

0.04 mg/L. Although the data are few and the concentrations 

low, samples from the ETA curtain drains seem to the have 

higher bromide concentrations. 

Chloride/Bromide Ratios

The ratio of chloride to bromide concentrations has 

been used in several studies as an indicator of the presence 

of sewage. Several ranges for Cl/Br ratios in sewage have 

been reported: 275–531(Behl and others, 1987, cited in 

Thomas, 2000), 410–873 (Vengosh and Pankratov, 1998, cited 

in Thomas, 2000), 300–600 (Davis and others, 1998), and 

64–5,404 (Panno and others, 2006). These ranges were used 

to define the “sewage box” in figure 6 indicating the range 

of ratios in sewage. The ranges of chloride concentrations in 

sewage were discussed previously. The Cl/Br ratios in the two 

samples from septic tanks in Medina County, 520 and 1,200 

(table 3), fall within the sewage box in figure 6.

The “road-salt” box (fig. 6) was defined by data from 

samples from ground water wells contaminated with road salt 

(Panno and others, 2006) rather than from samples of a pure 

solution. This road-salt box is also consistent with multiyear 

data from four road-salt/ground-water study sites in northcentral and northeast Ohio (Jones and Sroka, 1997). Davis and 

others (1998) noted that the water affected by halite dissolution (road salt) generally has Cl/Br ratios in the range of 1,000 

to 10,000.

The two wells in Medina County, at sites MD-23 and 

MD-25, were sampled in this study to provide background 

water-quality data; however, the data from these wells were 

Table 3. Chloride/bromide ratios in samples collected from 

home-sewage treatment systems, associated curtain drains, 

and two residential wells in Medina County, Ohio.

[HSTS, home sewage-treatment system; CD, curtain drain; WE, residential 

water well] 

Site name Sample 

source

Chloride/bromide 

ratio

Evaporation-transpiration-absorption systems (ETA)

MD-15 CD 300

MD-16 CD 210

MD-18 HSTS 1,200

CD 330

MD-19 HSTS 520

CD 220a

MD-23 CD 2,000

WE 1,500

MD-24 CD 86

Leach-line systems (LL)

MD-17 CD 550

MD-20 CD 280

MD-21 CD 230

MD-22 CD 280

MD-25 CD 280

WE 960

a

 Chloride/bromide ratio from analyses of replicate sample. 

Occurrence of Chemical and Microbiological Constituents 11
12 Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

not used in this analysis because the Cl/Br ratios indicate that 

the wells may be affected by halite dissolution (fig. 6). The 

possible impact of halite dissolution is also supported from 

work by Eberts and others (1990), who used bromide-tochloride ratios to compare ground water and brine in nearby 

Geauga County (fig. 1); the ratios in the samples from the two 

wells in Medina County are within the ranges identified as a 

mixture of ground water and local halite-solution brines (fig. 

25 in Eberts and others, 1990). Therefore, other data were 

used to define the “dilute ground-water” box on figure 6; the 

box was based on samples from 7 of 12 wells completed in 

glacial deposits in Geauga County; data from the other wells 

were not used because of indications of ground water mixing 

with halite solution and/or anthropogenic affects (Eberts and 

others, 1990; Jagucki and Darner, 2001). 

The data points for 10 of the curtain drains in this study 

fall between the boxes for dilute ground water and domestic 

sewage (fig. 6), possibly indicating a mixing of these waters 

in the drains. The data point for the 11th site, MD-23, plots 

within both the sewage and the road-salt boxes. The sample 

from the drain at MD-23 has an unusually high concentration 

of chloride that may reflect the use of a water softener at the 

site and/or its proximity to the road and road salt. Chloride 

concentrations were much lower at sites MD-21 and MD-22 

where softeners also were in use, but these sites are farther 

from the road (table 1). This may indicate that road-salt effects 

have a greater impact at site MD-23 than the use of a water 

softener. 

For the majority of the sites, the Cl/Br ratios in samples 

from the drains are less than 1,000, which is generally the 

lower end of the range of ratios reported for road-salt-affected 

waters. The Cl/Br ratios in the samples from the 10 drains 

plotting between the dilute ground water and sewage boxes in 

figure 6 range from 86 to 550. Jagucki and Darner (2001) note 

that the theoretical upper limit of the Cl/Br ratio for natural 

water is 400; they considered ratios in the 110–400 range as 

indicating possible effects of anthropogenic sources and that 

those in the 400–10,000 range as indicating probable effects 

of anthropogenic sources. Using the ranges from Jagucki and 

Darner (2001), the Cl/Br ratios from samples from the curtain 

0.1 1 10 100 1,000 10,000

10

100

1,000

10,000

domestic sewage

15-CD

16-CD

17-CD

18-CD

19-CD

20-CD

21-CD 22-CD

23-CD

24-CD

25-CD

25-WE

23-WE

18-TK

19-TK

dilute

groundwater

Cl/Br = 400

CHLORIDE/BROMIDE RATIO

CHLORIDE CONCENTRATION, IN MILLIGRAMS PER LITER

24-CD ETA CURTAIN DRAIN

17-CD LL CURTAIN DRAIN

23-WE DOMESTIC WELL

18-TK HSTS TANK

ROAD-SALT-AFFECTED

WATER (Panno and Others, 2006)

Figure 6. Relation of chloride concentration to chloride-bromide ratios for water from home sewage-treatment 

systems (HSTSs), HSTS curtain drains, and domestic-supply wells, Medina County, Ohio.
drains (table 3, fig. 6) at sites MD-15, MD-16, MD-18, MD19, MD-20, MD-21, MD-22 and MD-25, indicate possible

anthropogenic sources, whereas the samples from sites MD-17 

and MD-23 indicate probable anthropogenic sources. Cl/Br 

ratios indicating possible or probable anthropogenic sources 

in curtain-drain samples were virtually the same for both ETA 

and LL systems. There was no meaningful difference between 

ETA and LL systems with respect to Cl/Br ratios.

Coliphage

Somatic coliphage was detected in seven HSTSs, but 

F-specific coliphage was detected in only two HSTSs, MD-16 

and MD-22 (table 4). Somatic coliphage was detected in one 

of the two curtain-drain samples tested. No F-specific coliphage was detected in either of the two curtain-drain samples 

tested.

Occurrence of Chemical and Microbiological Constituents 13

Table 4. Results of analyses of bacteria and coliphage in samples from wells and home sewage-treatment 

system sites in Medina County, Ohio. 

[CD, curtain drain; HSTS, home sewage-treatment system; WE, residential water well; col/100 mL, colonies per 100 milliliters; plaq/100 

mL, plaques per 100 milliliters; <, less than; --, no data; E, estimated]

Site name Sample source Date E. coli

(col/100 mL)

Somatic 

coliphage 

(plaq/100 mL)

F-specific 

coliphage 

(plaq/100 mL)

Evaporation-transpiration-absorption systems (ETA)

MD-15 CD 6-21-2004 110 -- --

HSTS 160,000 < 1 < 1

MD-16 CD 6-21-2004 300 -- < 1

HSTS 96,000 < 1 69,000 

MD-18 CD 6-22-2004 760 -- --

HSTS 830 1,600 < 1

MD-19 CD 6-22-2004 47 -- --

HSTS 12,000 < 1 < 1 

MD-23 CD 6-23-2004 61 -- --

HSTS 16,000 67 < 1 

WE <1 -- --

MD-24 CD 6-24-2004 22 6,000 --

HSTS 250 27 < 1 

Leach-line systems (LL)

MD-17 CD 6-21-2004 14 -- --

HSTS 29,000 < 1 < 1 

MD-20 CD 6-22-2004 30 -- --

HSTS 350 70 < 1 

MD-21 CD 6-22-2004 230 -- --

HSTS 620 17 < 1 

MD-22 CD 6-23-2004 60 < 1 < 1

HSTS 720 200 28

MD-25 CD 6-24-2004 E 1 -- --

HSTS 11,000 453 < 1 

WE <1 -- --
14 Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

On the basis of findings in a USGS study in Oregon 

in which F-specific coliphage was detected in 19 out of 51 

samples (S.R. Hinkle, U.S. Geological Survey, oral commun., 

2004), it was expected that sufficient coliphage would be 

detected in this study for genotyping analysis. However, only 2 

of the 11 sites had detectable levels of F-specific coliphage in 

the HSTS, and none was detected in the curtain drains at these 

sites; therefore, no genotyping analyses were possible.

E. coli Bacteria

Concentrations of E. coli in the HSTSs ranged from 250 

to 160,000 col/100 mL, with a median of 11,000 col/100 mL 

(table 4). Concentrations of E. coli in the curtain drains ranged 

from 1 to 760 col/100 mL, with a median of 60 col/100 mL. 

At all sites, the concentrations of E. coli in the curtain drains 

were less than those in the HSTS. With respect to median 

concentrations, there was an order of magnitude reduction 

between the HSTS and curtain drains at LL systems (720 to 30 

col/100 mL) and three orders of magnitude reduction at ETA 

systems (14,000 to 80 col/100 mL). No E. coli were detected 

in the well-water samples.

Of the 11 samples from curtain drains, only 2 had 

concentrations of E. coli exceeding the single-sample bathing-water standard of 235 col/100 mL (Ohio Environmental 

Protection Agency, 2003b). Only one site had a concentration 

exceeding the more relevant standard of 576 col/100 mL for 

secondary contact such as wading, which could occur if, for 

example, children were to play at or near the curtain-drain 

outfalls (fig. 5).

Concentrations of E. coli in the drains from the six ETA 

systems ranged from an estimated 22 to 760 col/100 mL, with 

a median concentration of 86 col/100 mL. Concentrations in 

the drains from the five LL systems ranged from an estimated 

1 to 230 col/100 mL, with a median concentration of 30 

col/100 mL. Although it appears that the E. coli concentrations 

at LL systems were generally lower than at ETA systems, the 

small number of samples makes it impossible to evaluate relative concentrations with certainty. For example, if the curtaindrain sample from MD-18 (highest E. coli concentration) had 

not been collected, the range and median of the remaining five 

ETA curtain-drain samples would have been 22 to 300 col/100 

mL and 61 col/100 mL—comparable to the LL systems. 

Although there is no reason to discount the MD-18 sample, the 

differences between the two systems would have to be considerable to be significant given so few samples.

Presumptive E. coli from the sites were isolated from 

the agar plates, saved by freezing, and later characterized by 

rep-PCR analysis. The rep-PCR process produces a graphical display of the genetic makeup of an isolate, similar to a 

barcode. The similarity of any two isolates can be determined 

by comparing their genetic patterns. (See Dumouchelle and 

Stoeckel, 2005, for more detail.) A representation of 14 

rep-PCR patterns is shown on figure 7. Each banding pattern 

represents a portion of the genetic makeup of one isolate. 

On figure 7, differences in isolates A and B cannot be distinguished within the precision of the method; the same is 

true for isolates C through E. Therefore, isolates A and B are 

considered the same, as are isolates C through E. Similar isolates are assigned to a sequentially numbered group called an 

OTU (operational taxonomic unit). In some cases, professional 

judgment is required to decide whether isolates belong to an 

OTU. For example, isolates A–B and C–E (fig. 7) appear to be 

different on the basis of the intensity of a single band, and are 

thus considered genetically distinct and assigned to separate 

OTUs. It is more clear, however, that isolate F is different from 

isolates A–E.

On the basis of rep-PCR results, 97 OTUs were identified in this study. Many OTUs contained isolates from only 

a single sample source, such as an HSTS. Nineteen OTUs 

contained isolates from more than one sample source (table 5). 

In a previous study, detection of the same OTU in the HSTS 

and adjacent curtain drain was considered evidence of transport of partially treated wastewater from the HSTS to the drain 

(Dumouchelle and Stoeckel, 2005). In that previous study, no 

OTUs were detected at multiple sites; however, in this study, 

10 OTUs contained isolates from two unrelated sites and 3 

OTUs (14, 27, and 55) contained isolates from three unrelated 

sites (table 5). Five OTUs from three sites had shared isolates 

from the curtain-drain and tank samples at a single site—OTU 

1 at MD-23, OTU 37 at MD-16, and OTUs 21, 76, and 80 at 

MD-24 (table 5)—but these three sites also shared isolates 

with unrelated sites. Although the detection of a given OTU 

in an HSTS and curtain drain remains evidence of wastewater 

migration, the multiple occurrences of the same OTU at unrelated HSTSs indicates that the method cannot be considered 

positive proof of origin from a single household.

Utility of Study Approaches and 

Inferences From Available Data

One of the objectives of this study was to evaluate several 

indicators to test for the presence of HSTS-derived water in 

curtain drains. Two water-quality indicators were used—nutrient, concentrations and Cl/Br ratios—and three microbiological indicators were used—E. coli concentrations, coliphage 

genotyping, and genetic fingerprinting of E. coli. 

The results of the tests of various indicators evaluated in 

this study are summarized in table 6. Of these, only the Cl/Br 

ratios provided evidence of the presence of HSTS-derived 

water in curtain drains. The nutrient data were not particularly 

useful because no orthophosphate was detected in any curtain 

drains, and only one site had a nitrate concentration that could 

indicate partially treated HSTS water in the curtain drain. 

The nitrate concentration in water from the curtain drain at 

MD-15, however, was 3.5 mg/L, at the low end of the range 

of 3 to 10 mg/L that indicates possible anthropogenic effects. 

The Cl/Br ratios were useful in indicating the movement of 

HSTS-derived water to the drains. When a mixing plot (fig. 6) 
The bars labeled A–F are individual isol ates. The banding patterns on the bars 

represent a portion of genetic information for the isolate. The bars labeled R

are repeated measurements of a control strain (E. coli ATCC 25922). The

percent similarity of these control measurements is indicated by the lines to the

left of the bars—the controls are greater than 97 percent similar. The dashed

line indicates the precision of the analytical method as determined by the

repeated measurements (R).

The measurement precision (dashed line) and professional judgment are used

to assign the isolates A-F to an arbitrary operational taxonomic unit (OTU).

Based on the similarity of the banding patterns, isolates A and B are assigned 

to OTU 1, isolates C, D and E are assigned to OTU 2, and isolate F is assigned 

to OTU 3. 

75 80 85 90 95 100

Percent similarity

Isolate

A

B

C

D

E

F

R

R

R

R

R

R

R

R

OTU

1

2

3

Figure 7. Example of results of rep-PCR analysis showing six isolates and multiple measurements of a single isolate, demonstrating the 

reproducibility of results. 

Utility of Study Approaches and Inferences From Available Data 15
16 Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

was generated from the ratios and chloride concentrations, the 

curtain-drain samples from 10 of the 11 sites reflected some 

mixing of dilute ground water and HSTS-derived water; data 

for the 11th site plotted within the range of sewage- and roadsalt-affected water.

In a previous study, coliphage was detected in 37 percent of samples; thus, it was hoped that a similar detection 

frequency would provide sufficient opportunity to detect 

coliphage in a curtain drain. Coliphage was detected only 

in two HSTSs (18 percent of samples), however, decreasing the chance of detecting it in a drain. Thus, the F-specific 

coliphage genotyping was not considered useful for indicating HSTS-derived waster in curtain drains. Although E. coli

were detected in 10 of the 11 curtain drains, detection alone 

cannot identify the source of the bacteria. Previous studies had 

indicated that genetic analysis methods such as rep-PCR might 

be useful for linking the source of E. coli in a curtain drain 

sample to the HSTS; however, the multiple links between 

unrelated sites seen in this study shows that this approach cannot provide definitive answers in this setting. 

Previous studies had indicated that each of the 

approaches used in this study could be useful in determining 

in the presence of HSTS-derived water in curtain drains; however, this study encountered difficulties in applying most of 

these approaches. Hence, caution is necessary when using any 

of these methods individually. Although the use of Cl/Br ratios 

appears promising, the use of multiple approaches to provide 

several lines of evidence in determining the effects of HSTS 

on curtain-drain water quality is warranted. Additional studies 

investigating other water-quality based indicators of HSTSaffected water, such as the presence of wastewater compounds, 

surfactants, or optical brighteners, and/or other microbiological constituents, may be useful as well.

Another objective of this study was to describe the results 

of the various approaches with respect to ETA and LL systems. The small sample size of this reconnaissance assessment 

Table 5. Sites and numbers of isolates in those operational taxonomic units (OTU) found from more than one 

source from samples in Medina County, Ohio.

[ OTU, operational taxonomic unit; HSTS, home sewage-treatment system]

OTU Sample source Number of 

isolates OTU Sample source Number of isolates

1 MD-23 curtain drain 6 30 MD-16 curtain drain 2

MD-23 HSTS 8 MD-17 HSTS 1

7 MD-20 curtain drain 1 32 MD-18 dog scat 4

MD-24 HSTS 1 MD-18 HSTS 1

11 MD-23 curtain drain 1 34 MD-18 HSTS 1

MD-24 curtain drain 2 MD-24 curtain drain 1

12 MD-16 curtain drain 1 37 MD-16 curtain drain 2

MD-18 curtain drain 1 MD-16 HSTS 2

14 MD-18 surface scat (dog) 1 50 MD-20 curtain drain 1

MD-21 curtain drain 1 MD-21 curtain drain 3

MD-24 curtain drain 3

55 MD-19 curtain drain 1

21 MD-24 curtain drain 1 MD-20 curtain drain 3

MD-24 HSTS 4 MD-21 curtain drain 1

22 MD-16 curtain drain 1 75 MD-17 curtain drain 1

MD-19 HSTS 7 MD-24 curtain drain 1

24 MD-16 HSTS 1 76 MD-24 curtain drain 2

MD-24 curtain drain 1 MD-24 HSTS 2

25 MD-19 curtain drain 2 80 MD-24 curtain drain 2

MD-22 HSTS 9 MD-24 HSTS 1

27 MD-15 curtain drain 2

MD-17 curtain drain 3

MD-24 curtain drain 2
precludes rigorous statistical comparisons; therefore, only 

simple comparisons between the two systems could be made. 

Although the nitrate concentrations in curtain-drain samples 

from the ETA systems had a slightly larger range and median 

value than did samples from the LL systems, the values for 

both systems were, with one exception, below the range that 

can be considered indicative of possible anthropogenic effects; 

therefore, the differences were not particularly meaningful. 

There were no differences between the two systems with 

respect to the chloride-bromide ratios, nor were there differences with respect to chloride concentrations. The curtaindrain samples from the ETA systems had somewhat higher 

bromide concentrations, but the reason for this was unclear. 

E. coli bacteria were found in the curtain-drain samples from 

both systems, with ETA systems having higher concentrations, 

though the difference between both systems is not statistically significant. Although only ETA sites showed a link 

between the HSTS and curtain-drain samples on the basis of 

the rep-PCR analysis, the numerous links between unrelated 

sites in this study means that such links were ambiguous. 

Therefore, although the curtain-drain samples from the ETA 

systems appear to show slightly more evidence of the presence 

of HSTS-derived water than do samples from the LL systems 

(table 6), the best evidence is from the Cl/Br ratios, and both 

ETA and LL systems reflect the presence of HSTS-derived 

water. Therefore, with the data from this reconnaissance study, 

it is not possible to state definitively whether there are any differences between the ETA and LL systems with respect to the 

water quality in curtain drains.

Summary and Conclusions

A variety of home sewage-treatment system (HSTS) 

designs are used in Ohio. Many of these systems use curtain 

or perimeter drains to depress the level of the subsurface water 

in and around the HSTS. There are concerns that these drains 

could release untreated wastewater and potential pathogens to 

Table 6. Summary of the utility of indicators used in this study for indicating the movement of partially 

untreated wastewater from home sewage-treatment systems to associated curtain drain.

[>, greater than; mg/L, milligrams per liter; HSTS, home sewage-treatment systems; rep-PCR, repetitive DNA element polymerase 

chain reaction; x, indicates evidence of untreated wastewater movement; --, no evidence of untreated wastewater movement]

Site 

number

Nitrate concentration a

> 3 mg/L 

Chloride / bromide ratio a E. coli

detected

in curtain 

draind

Indication of a link

between the HSTS and 

curtain drain

by way of rep-PCR

x-y

plotb 110 – 400c > 400 c

Evaporation-transpiration-absorption systems (ETA)

MD-15 x x x -- x --

MD-16 -- x x -- x x

MD-18 -- x x -- x --

MD-19 -- x x -- x --

MD-23 -- x -- x x x

MD-24 -- -- -- x xe

Leach-line systems (LL)

MD-17 -- x -- x x --

MD-20 -- x x -- x --

MD-21 -- x x -- x --

MD-22 -- x x -- x --

MD-25 -- x x -- --f --

a

See text for explanation of why the Cl/Br ratio and these concentrations are used as indicators.

b

Based on chloride/bromide plot in figure 6.

c

Range of 110–400 indicates possible anthropogenic effects; values of ratio greater than 400 indicates probable effects.

d

The presence of E. coli indicates fecal contamination but does not indicate the source of contamination.

e

Indication of a link between the curtain drain and HSTS by more than one operational taxonomic unit (OTU).

f

Estimated concentration of 1 colony per 100 milliliters.

Summary and Conclusions 17
18  Indicators of Wastewater in Curtain Drains From Home Sewage-Treatement Systems, Medina County, Ohio

ground-water and surface-water bodies. The quality of water 

from two different HSTS designs in Medina County, Ohio, 

was investigated in this reconnaissance study, in cooperation with the Medina County Health Department. Several 

approaches were evaluated in this study for testing for the 

presence of HSTS-derived water in the curtain drains. Water 

samples were collected at 11 sites from curtain drains, septic 

tanks and residential water wells (at 2 of the 11 sites) and 

analyzed for nutrients, chloride, bromide, coliphage, and 

E. coli bacteria. In addition, genetic fingerprinting (rep-PCR) 

was used to determine whether bacteria in the curtain drains 

could be linked to the HSTS. Six evaporation-transpiration-absorption (ETA) and five leach-line (LL) systems were 

investigated.

Nitrate concentrations in the curtain drains ranged from 

an estimated 0.03 to 3.53 mg/L. Concentrations of chloride 

in 10 of the 11 curtain drains ranged from 5.5 to 21 mg/L; the 

chloride concentration in the 11th curtain drain was 340 mg/L. 

Bromide concentrations in the curtain drains ranged from an 

estimated 0.01 to 0.22 mg/L. Chloride-bromide (Cl/Br) ratios 

ranged from 86 to 2,000. No F-specific coliphage was found in 

any curtain-drain samples. Concentrations of E. coli in all of 

the curtain drains ranged from an estimated 1 to 760 col/100 

mL; the Ohio secondary-contact water-quality standard of 576 

col/100 mL was exceeded in only one sample.

Nutrient concentrations, Cl/Br ratios, genotyping of 

coliphage, E. coli concentrations, and genetic fingerprinting 

of bacteria were evaluated for their usefulness in determining whether partially treated wastewater was present in the 

curtain drains. Nutrient concentrations were too low to be 

useful indicators. The chloride-bromide ratios were useful and 

reflected a mixture of ground water and HSTS-derived water 

in 10 of the 11 the sampled drains; the water in the 11th drain 

may be affected by road-salt contamination. Coliphage was 

not detected in the curtain drains, so genotyping could not be 

attempted. 

Although it appeared from multiple lines of evidence 

that the curtain-drain samples from the ETA systems showed 

slightly more evidence of the presence of HSTS water than did 

the LL systems, the most promising evidence is from the Cl/Br 

ratios, which indicate that both ETA and LL systems were 

affected by the presence of HSTS-derived water. Therefore, 

with the data from this reconnaissance study, it is not possible 

to state definitively whether there are any differences between 

the ETA and LL systems with respect to the water quality in 

curtain drains.

Acknowledgments

The author thanks the numerous property owners who 

allowed access to their HSTS and yards.

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Denise H. Dumouchelle—Assessment of the Use of Selected Chemical and Microbiological Constituents as Indicators of Wastewater in Curtain Drains From 

Home Sewage-Treatment Systems in Medina County, Ohio—Scientific Investigations Report 2006–5183 

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