+Relationships Between Fecal Indicator Bacteria Prevalence in Private Water Supplies and Demographic Data in Virginia

Tamara Smith, E.I.M.S. Candidate, Virginia Tech

2012 Water and Health Conference Chapel Hill, NC31 October 2012

+Presentation Outline

Introduction-What are Private Drinking Water Systems? Research Objectives- What Do We Hope To Accomplish? Methods- How It Happens Initial Results- What Have We Done So Far? Conclusions-What Did We Learn? Future Work-What’s Next?

+Introduction

+What are Private Drinking Water Systems? Serves < 25 persons and

has < 15 connections Types:

Drilled, dug, and bored wells

Springs Cisterns

Depend on groundwater If properly maintained, these

systems can provide potable drinking water.

+Potential Problems

23 and 45 million Americans rely on private water supply systems for drinking water.

Not regulated by the Safe Drinking Water Act (SWDA) for two main reasons: Private property rights Dispersion of private water systems nationwide

Over the past 30 years, the proportion of Centers of Disease Control (CDC) annual reported outbreaks associated with private water supplies has increased.1

1. Craun et al. (2010)

+Potential Problems Cont’d

Previous studies have attempted to correlate well construction and local geology with observations of water quality. Aquifer composition(such as limestone and fractured rock) can

increase contaminant exposure. 2

Poor construction and proximity to potential sources of contamination (e.g. septic tank) can lead increased contaminant exposure.3

Although inadequate water and sanitation is often linked to poverty, there have been no studies linking private system water quality and demographic data.

2. Brunkard et al. (2011) 3. Swistock and Sharpe (2005)

+Private Drinking Water Systems in Virginia: A Particular Concern Over 1.7 million households rely on

private water systems for drinking water.4

The majority of households in 60 out of 95 counties rely on private water systems.5

In 52 counties, the number of households being served by private water supplies is increasing at a rate greater the households currently being joined to municipal systems.5

4. Gatseyer and Vaswani (2004) 5. US Census Bureau (1990)

Scientific Investigations Report (2009)

+Overall Goal and Objectives

Identify relationships between the prevalence of fecal indicator bacteria from privately supplied water systems and demographic data with the following objectives:

1) Quantification of total coliform (TC) bacteria and E. coli (EC) prevalence in water samples from private systems collected from the point-of-use;

2) Identification of possible correlations between demographic data and fecal indicator bacteria;

3) Applying a chemical source tracking technique (i.e. fluorometry) to identify possible human contamination (i.e. sewage intrusion).

+Methods

+Virginia Household Water Quality Program (VAHWQP) VAHWQP’s objective is to improve the water quality and health

of Virginians using private water supplies. A program a part of Virginia Cooperative Extension. Currently partnering with the Southeast Rural Community

Project (SERCAP).

+VAHWQP-Drinking Water Clinics

1. Kickoff Meeting

4. Interpretation Meeting

2. Sample Collection

3. Analysis

+

• 28 Counties• n=543

Counties that Participated in 2012 Drinking Water Clinics

+Sample Collection

Survey in kits contains: Homeowner perception of

water quality Homeowner-supplied

demographic data

+Sample Collection and Analysis

Household Samples (Four

Bottles)

2 Bottles (Bacterial Analysis)

100 mL- TC/EC Presence &

Quantification

250 mL- ST

2 Bottles (Other

Analysis)

pH, Conductivity, Heavy Metals,

etc.

+TC/EC Detection & Quantification

Presence- Colilert (IDEXX) defined substrate technology

Quantification-Quanti-tray/2000 (MPN)

~24h incubation ~35°C±0.5°C

+Chemical Source Tracking

Source Tracking is used to determine the source of fecal bacteria. Usually a specific marker is used that is linked to a specific source of fecal contamination.

Typically used for for surface waters, but are starting to become used for drinking water.

Fluorometry analyzes fluorescence in a sample. Optical brighteners are likely indicative of fecal contamination via septic sewage.

+Initial Results

+Primary and Secondary Maximum Contaminant Levels Maximum Contaminant Levels (MCL)

refer to the highest that is allowed in drinking water by the US EPA.

Primary MCLs are standards that are health-based. These include Total Coliforms, E. coli, and Nitrate.

Secondary MCLS are non-enforceable guidelines based on a contaminants’ cosmetic and aesthetic effects.

Although not applied to private systems can be used as a guideline

Some MCLs of Concern4

Contaminant MCLTotal Coliforms No more than 5%

positive samples in one month.

Fecal Coliforms/E. coli

Any sample tested positive from a repeat of total coliform or the reverse is true, then is in violation of MCL.

Nitrate 10 mg/L

4. US EPA (2011)

+Objective 1: Overall Prevalence of Fecal Indicator Bacteria Positive Samples2012 Drinking Water Clinics (n=543)Counties Participating

28

Percent Positive for TC

38%

Average TC Concentration

~118 MPN/ 100 mL

Percent Positive for EC

6%

Average EC Concentration

~11 MPN/ 100 mL

Nitrate Below MCL

Average Nitrate Concentration

0.80 mg/L

Although these bacteria prevalences seem high, it coincides with previous studies in private water supplies5,6,7,8,9,10,11

5. Sandhu et al. (1979) 6. Lamka et al. (1980) 7. Sworobuk et al.( 1987) 8. Bauder et al. (1991) 9. Kross et al. (1993) 10. Gosselin et al. (1997) 11. Borchardt et al. (2003)

+Objective 1: Cumulative Distribution for Total Coliform Concentrations

Non-zero samples around 61st percentile.

13 samples above detection limit

0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 10

500

1000

1500

2000

2500

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10500

1000150020002500

Percentile

TC M

PN/ 1

00 m

L

+Objective 1: Cumulative Distribution for E. coli Concentrations

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10500

1000150020002500

Percentile

EC M

PN/ 1

00 m

L

Non-zero samples around 94th percentile.

1 sample above detection limit

0.9 0.92 0.94 0.96 0.98 10

500

1000

1500

2000

2500

+Objective 2. Total Coliform Presence by Income Level

<$10K $11K-$24K $25K-$40K $41K-$64K >$65K0%10%20%30%40%50%60%70%80%90%

100% n=476

Income Level

Perc

ent

Posi

tive

for

Each

Cat

egor

y

n=15 n=252

n=88

n=86

n=35

+Objective 2. E. coli Presence by Income Level

<$10K $11K-$24K $25K-$40K $41K-$64K >$65K0%10%20%30%40%50%60%70%80%90%

100% n=476

Income Level

Perc

ent

Posi

tive

for

Each

Cat

egor

y

n=15 n=252n=88

n=86n=35

+

0%20%40%60%80%

100% n=516

Education Level

Perc

ent

Posi

tive

for

Each

Cat

egor

y

Objective 2. Total Coliform Presence by Education Level

n=7n=81

n=17

n=146

n=149

n=116

+Objective 2. E. coli Presence by Education Level

0%20%40%60%80%

100% n=516

Education Level

Perc

ent

Posi

tive

for

Each

Cat

egor

y

n=7n=81n=17 n=146n=149

n=116

+Objective 2. Correlations Between Bacteria Prevalence and Demographics Chi-squared Test were used to

determine differences in categorical distributions between TC/EC Presence and Income

Level TC/EC Presence and

Education LevelAlpha= 0.05

For TC Presence P-valueIncome Level 0.0025Education Level 0.0516

For EC Presence P-valueIncome Level 0.0119Education Level 0.0730

+Objective 3. Application of Chemical Source Tracking Technique 11/543 were tested positive for optical brighteners 45.5% positive for TC; 36.4% positive for EC Average TC concentration: 503.1 MPN/100 mL Average EC concentration: 249.6 MPN/100 mL 27% of systems have some type of treatment (i.e. chlorination, filtering, etc.) 18.2% of systems 100 ft or less to septic system drain field County Location: 27.3% Lancaster, 27.3% Northumberland, 18.2% Tazewell, 18.2%

Charlotte 72.7% households <$65K; 18.2% >$65k

+Conclusions

There is presence of total coliform and E. coli bacteria in private drinking water supplies.

TC and EC presence are statistically different between income levels, but not necessarily for education levels.

Fluorometry positive samples have some similarities in location and income level, but not all tested positive for E. coli contamination.

+Future Work

Continuing analysis of 2012 Drinking Water Clinic Data Analysis of E. coli-positive samples for Bacteroides human marker

(BacHum) via qPCR Further explore relationships between fluorometry positive samples Statistical correlations between E. coli incidence and self-reported

illness

+Acknowledgements Dr. Leigh-Anne Krometis All the members of my research committee: Dr. Brian Benham, Dr. Charles

Hagedorn III, and Susan Marmagas VAHWQP & The Krometis Research Group Sponsor: USDA-NIFA Rural Health Education Program Competitive

Grant No. 2011-46100-31115

+

Questions & Discussion

tams44@vt.edu

+Types of Sources

Source Number of Samples PercentDrilled Well 400 74%Dug/Bored Well 79 15%Unknown Wells 44 8%Spring 12 2%Other 7 1%