Testing New Wells for Coliform Bacteria
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TestingNew Wellsfor Coliform Bacteria
HELPING ENSURE DRINKING WATER SAFETY
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EnsureSafety of DrinkingWater
MaintainConsumer
Confidencein
Groundwater
Why Test Well Water for Coliform Bacteria?
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Waterborne Pathogen Exposure Routes
INGESTION
FOOD
DERMAL CONTACT
AEROSOLINHALATION
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What are Coliform Bacteria?
AEROBIC AND FACULTATIVE ANAEROBIC GRAM-NEGATIVE NONSPORE-FORMING ROD-SHAPED
FERMENTS LACTOSE WITH GAS PRODUCTION WITHIN 48 HOURS @ 35 DEGREES CELSIUS
MEMBRANE FILTER ANALYSIS
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Coliform Bacteria are Indicator Organisms
Positive coliform test indicates potential presence of pathogenic (disease-causing) microbes
Testing for pathogens requires large volumes of water andcomplex lab procedures
Coliforms are found in greater numbers than pathogens
E.coli bacteria live longer than fecal coliforms
Coliform testing is easier, more economical and safer than pathogen testing.
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TOTAL COLIFORMS
FECAL COLIFORMS
E. COLI
PATHOGENIC E. COLI
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Sources of Coliform Bacteria
INTESTINESOF
WARM-BLOODEDANIMALS
SURFACEWATER
&FLOODWATER
ON-SITE SEWAGESYSTEMS &SEWERLINE
LEAKS
AGRICULTURALWASTE RUNOFF
SOIL&
VEGETATION
GROUNDWATER
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Etiologies of Waterborne Illness Outbreaks(1991 – 2002)
ACUTEGASTROINTESTINALILLNESS (AGI), UNIDENTIFIED 38%
CHEMICALPOISONING 16%
GIARDIASIS 12%
CRYPTOSPORIDIOSIS 7%
AGI – NOROVIRUS 6%
AGI – E. COLI 0157:H7 5%
SHIGELLOSIS 4%
OTHERDISEASES 6%
CAMPYLOBACTERIOSIS 3%
LEGIONELLA 3%
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Burden of Illness Pyramid
(From: Journal of Water and Health, Estimating Disease Risks Associated With Drinking Water Microbial Exposures, Vol. 4, Supplement 2, 2006)
Person is exposed to pathogen in water and becomes infected
Persons who exhibit symptoms
Persons who visit physician or health care facility
Persons who are hospitalized
Deaths
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WATERBORNEPATHOGENS
E. coli
Cryptosporidium
SymptomaticHost
ACUTE GASTROENTERITIS SYMPTOMS:
STOMACHCRAMPS
DIARRHEA
VOMITING FEVER
NAUSEA
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E. coli
Cryptosporidium
WATERBORNEPATHOGENS
AsymptomaticHost Secondary
Host
FECALTO ORAL
TRANSFEROF
PATHOGEN
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MICHIGAN GROUNDWATERIS GENERALLY FREE OF:
• COLIFORM BACTERIA• DISEASE-CAUSING MICROBES
Exceptions: Shallow carbonate bedrock (Karst)
Very shallow coarse sand & gravel
Faulty well construction
Unplugged abandonedwells
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Unsealed, Abandoned Well Causes Bacteria Problemsfor Noncommunity Public Water-Supply Well
Reported by Minnesota Dept. of Health, Minnesota Well Management News Fall 2006 / Winter 2007, Volume 26, No. 2
PERSISTENT COLIFORMS IN NCPWS (>2 YRS.)(24 YR. OLD WELL - 57 FT. DEEP - 4 IN. CASING)
REPEAT WELL DISINFECTIONS UNSUCCESSFUL
INVESTIGATION OF FACILITY HISTORY FOLLOWED BYMETAL DETECTOR SEARCH BY MDH - ABANDONED WELLWITHIN 10 FT. OF ACTIVE WELL IS SUSPECTED
EXCAVATION FINDS OLD WELL UNCAPPED 7 FT. BELOW GRADE,10 FT FROM ACTIVE WELL - UNSEALED – SAND & DEBRIS FROM 35 FT. TO BOTTOM OF 60 FT. WELL
STATIC WATER LEVEL SAME AS ACTIVE WELL – HYDRAULICCONNECTION BETWEEN WELLS
AFTER OLD WELL PROPERLY PLUGGED – CONSISTENTNEGATIVE COLIFORM BACTERIA SAMPLES
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Potential Sources of Microbial Contamination
from Well Drilling Practices
OBTAINING DRILLING WATERFROM SURFACE WATERSOURCE
USING BIODEGRADABLEDRILLING FLUID OR LOST CIRCULATION ADDITIVES
IRON BACTERIAIN SURFACEWATER
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Introducing Contaminants DuringWell Construction
FAILURE TO MAINTAINMINIMUM 10 PPMCHLORINE RESIDUALIN DRILLING WATER
TRANSFERRING CONTAMINANTS FROM GROUND SURFACE INTO WELL BOREHOLE ENCOURAGE DRILLERS
TO USE TEST STRIPS
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DOWNWARD LEAKAGE AROUND UNGROUTED CASING
UNCONFINED AQUIFER
STATIC WATER LEVEL
DOWNWARD LEAKAGE
CONTAMINANT PLUME
UNSEALED ANNULARSPACE AROUND
CASING
INFILTRATION OF SURFACE CONTAMINANTS
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UNSEALEDANNULUS BETWEENCASING &BOREHOLE
GROUTPIPE
DIRECT PATHWAY TO AQUIFERIF LEFTUNGROUTEDOR IMPROPERLYGROUTED
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Would this temporary cap keep contaminantsout of the well?
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Sanitary & Preventive PracticesDuring Well Completion
KEEP WELL COMPONENTSELEVATED OFF GROUND…..USE SANITARY HANDLINGPRACTICES
CLEANDRILLING TOOLS
BETWEEN WELLS TO PREVENT
CROSS-CONTAMINATION
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COMPONENTSOF A
SAFE & RELIABLE WATER WELL
PROPERWELL
CONSTRUCTIONMATERIALS
SANITARYWELL
COMPLETIONPRACTICES
TRAINEDPROFESSIONALWATER WELL
CONTRACTORS
PROPER WATER SYSTEM
MAINTENANCE
ROUTINEMONITORING
OFWATER
QUALITY
TARGETAQUIFER HASAMPLE YIELD
&SAFE WATER
SUFFICIENTSEPARATION
FROMCONTAMINATION
SOURCES
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WELLS MOST VUNERABLE
TO MICROBIALCONTAMINATION
POOR CONSTRUCTION(UNSEALED ANNULUS
OR DUG WELL)
DEFICIENT WELL HEAD(CRACKED WELL CAP
OR OPEN VENT)
SHALLOW DEPTH(OR SHORT CASING
IN BEDROCK)
FLOODING,BURIED WELL HEAD
OR SUBMERGEDIN WELL PIT
SEWER LINE BREAK,SEWAGE OVERFLOW
OR CROSS-CONNECTION
TOO CLOSE TO SEPTIC SYSTEM,
AGRIC. RUNOFF ORABANDONED WELL
OLD WELLS WITH CORRODED
WELL CASING
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LHD Water Sampling Activities
COLLECT BACTI SAMPLES OR PROVIDE SAMPLE BOTTLES
TO WELL DRILLER OR OWNER
TRACK TEST RESULTS TOENSURE ALL NEW
WELLS ARE TESTED
WITHHOLD ISSUANCE OF WELL APPROVAL UNTIL
SAFE BACTERIOLOGICALSAMPLES ARE
ATTAINED
USE WELL PERMIT PROGRAMTO NOTIFY WELL OWNER
OF NEED TOCOLLECT SAMPLE
PROMPT FOLLOW-UP ON POSITIVE COLIFORM
RESULTS, ESPECIALLYE. COLI POSITIVES
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Why Should Well Contractors CollectBacteriological Water Samples?
• Reduce public health risk
• Enhance industry professionalism
• Validate quality of contractors’ work
• Reduce contractor liability
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Why Should Well Contractors Collect Bacteriological Water Samples?
• Improve customer confidence in groundwater
• Reduce customer anxiety over positive test results
• Gain better understanding of public health within water well industry
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Why Should Well Contractors CollectBacteriological Water Samples?
• Current practice leaves customers with sense of purchasing incomplete product
• Contractor knows when water system is complete and ready for sampling.
• Well owners are unfamiliar with sampling protocol – prone to false positives.
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Why Should Well Contractors CollectBacteriological Water Samples?
• Contractor ownership of sampling protocol• Fewer disputes over sampling location and
technique• Reduction of complaints over validity of
sample results• Encourages more sanitary
drilling practices
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WORK WITH LOCAL BUILDING CODE OFFICIAL
WATERSUPPLY
APPROVALBY LHD
BUILDINGINSPECTOR
CERTIFICATEOF
OCCUPANCY
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