Disaster Resources - University of Illinois Extension

Disinfect And Test Flooded Wells

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If you are a private well owner, and a natural disaster has occurred on or near your property, there are some things you should know about your drinking water supply.

Once a flood or tornado (with flashflooding) has occurred it is worth checking your well for bacterial infiltration. During a flood of major proportions, bacteria has most likely infiltrated the well. At this point if you are planning to use your well for drinking and cooking purposes, steps toward disinfecting the well should begin. Shock chlorination is the preferred method for eliminating bacterial contamination in wells.

To disinfect a well contaminated with coliform bacteria (bacteria from the intestines of animals or humans), you'll need to chlorinate using a chemical disinfectant such as chlorine tablets or liquid chlorine in required proportions. For drill wells, you'll have to disassemble the top of the casing. For bored or dug wells, open the cover and then add the disinfectant. To kill the pathogens(disease causing organisms) in well water requires a chlorine concentration of at least 100 parts per million(ppm). The chlorine solution must remain in the well for a 24-hour period, preferably over night, before it is pumped out.

In addition to disinfecting the well,you should also disinfect the plumbing system in the home and other buildings on your property which rely on the well water. To do this, turn on all water faucets after the chlorine is added to the well. When a chlorine odor is detected in the taps, turn off the faucets. Do not use the water lines for several hours (again preferably over night). After allowing the water to stay in the pipes over night, you can open the faucets and let the water run until the chlorine smell is no longer present.

Disinfecting the well, however, does not guarantee that the water is free from contamination. After treating the well, take water samples from the well and submit them for testing by a state-certified laboratory. Most labs charge a fee for this service.

Once you have completed shock chlorination, you can use the well water for washing and uses other than drinking. Use the water for about a week and then have the water tested for pathogens, such as Total Coliformsand Fecal Coliforms. If the tests show no contamination, the water can be used for drinking.

The Illinois Department of Public Health has a laboratory equipped to test for bacteria. They may ask some questions about your well, including it's age, location on the property and how recently you have had it tested before the natural disaster.

You may get quicker test results from a private laboratory. The following is a list of commercial laboratories certified by the Illinois Department of Public Health for microbiological analysis of drinking water as of May 1993. These labs are listed for informational purposes only; this is not an endorsement.

ANALYTICAL LABORATORIES, INC.
28662 W. Northwest Highway
Barrington, IL 60010
708/304-8700

ArRo LABORATORIES, INC.
P.O Box 686Joliet, IL 60434
815/727-5436

CRAWFORD, MURPHY & TILLY
2750 W. Washington St.
Springfield, IL 62702
217/787-8050

DAILY ANALYTICAL LABS.
1621 W. Candletree Drive
Peoria, IL 61614
309/692-5252

DAILY LABORATORIES
5120 Big Hollow Road
Peoria, IL 61615
309/691-4513

ENV. SCIENCE & ENG.
8901 N. Industrial Rd.
Peoria, IL 61615
309/692-4422

ENVIRO-TEST/PERRY LABS.
319 Ogden Ave.
Downers Grove, IL 60515
708/963-4672

KEY LABORATORY SERV
2277 Hubbard St.
Decatur, IL 62526
217/875-2691

MCHENRY ANAL. WATER LAB.
4318H Crystal Lake Rd.
McHenry, IL 60050
815/344-4044

NET MIDWEST, INC.
850 West Bartlett Rd.
Bartlett, IL 60130
708/420-6128

SILLIKER OF ILLINOIS, INC.
1304 Halstead St.
Chicago Heights, IL 60411
708/756-3210

TEKLAB, INC.
6 Meadow Hgts. Prof. Park
Collinsville, IL 62234
618/344-1004

TEST, INC.
330 5th St., P.O. Box 483
Peru, IL 61354
815/224-1650

WESTON/GULF COAST LABS.
2417 Bond St.
University Park, IL 60466
708/534-5200

Issued by Mel Bromberg, University of Illinois Extension Specialist, Water Quality/Health Issues.

February 1995.

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