By Brian K. Murhpy
Wilson County News

Although it appears July’s flood affected only a small number of water wells in Wilson County, residents might want to test their wells anyway.

Experts suggest wells used for drinking water should be tested every six months to a year, even under normal conditions.

Cliff Lowe, a hydrogeologist with the Evergreen Underground Water Conservation District, said only wells that were actually under water would show any signs of contamination from the July flood.

But any such contamination could take years to reach other water wells because water moves so slowly through the Carrizo Aquifer.

"So many people think it’s just a running river down there … and that’s just way off base," Lowe said last week. "It takes water a long time to migrate through this aquifer."

Lowe said studies using carbon-dating technology have shown that water moves through the heavy sand of the Carrizo Aquifer at a rate of about 100 feet per year.

But residents should not assume a well that didn’t go under water this year automatically is free from contamination.

After all, unsafe water can spread a number of waterborne diseases, including typhoid, cholera, and dysentery, according to the Texas Natural Resource Conservation Commission.

Even less serious diseases can be unpleasant to contract, as they can cause stomach cramps or diarrhea.

There are a number of laboratories in and around San Antonio that can test water samples.

In Wilson County, water samples can be tested at Petroleum Specialist Lab on U.S. 181, north of Floresville.

There also is at least one lab in or near the following towns: Seguin, New Braunfels, and Victoria.

Residents can check with their local public health office for instructions and supplies to collect water samples and a list of nearby labs.

Collecting a sample is fairly easy, according to the following TNRCC guidelines:

oUse a sample container provided by an approved lab.

oUse an outside faucet that does not leak (avoid rubber hoses, fire hydrants, dirty areas, and areas behind bushes).

oDisinfect the faucet before collecting the sample. This can be accomplished by pouring a solution of household bleach (one tablespoon in a quart of water) over the threads of the faucet.

oBe careful to not contaminate the sample, which can be done by touching the inside of the container or rinsing it out.

oBe sure to close the sample container tightly as leaking samples cannot be accepted for analysis.

oComplete the necessary paperwork and deliver or mail the water sample to an approved lab. A sample must arrive at the lab within 30 hours after it was collected.

oOnce the water sample is tested, the results will be sent by mail.

The most important part of the test results, according to TNRCC, will be the indication of "coliform organisms found" or "coliform organisms not found."

Coliforms are microorganisms that do not cause disease but are found in the lower intestinal tract of human beings and other warm-blooded animals.

These organisms have been chosen to indicate the relative safety of drinking water because of their ease of determination and their similarity to pathogens, according to the "Water Well Guide" published by the Guadalupe-Blanco River Authority.

A "not found" report indicates the coliforms are absent, which means the water is considered bacteriologically safe to drink at the time of sampling.

A positive, or "coliform found," report indicates the organisms are present and the water may be unsafe. If repeated testing reveals the presence of the organisms, the well may need to be disinfected.

If, however, the report indicates the presence of fecal coliform or E. coli (Escherichia coli), do not touch the water and do not use it for drinking, bathing, cooking, preparing food, making ice, or cleaning.

A well contaminated with E. coli must be disinfected and retested until tests indicate these contaminants are no longer present.

For detailed, step-by-step instructions on well disinfection, contact the Wilson County Health and Public Safety Office at 830-393-7346.

Or, order the "Private Well Disinfection & Water Sampling" pamphlet by phoning the TNRCC at 512-239-0028.

The "Private Well Disinfection & Water Sampling" pamphlet also is available as a downloadable "PDF" file at the TNRCC Web site www.tnrcc.state.tx.us/index.html.

Then click on the following links in this order:

o"After the Flood: Is Your Water Safe to Drink?"

o"Advice for disinfecting your own well."

o"Private Well Disinfection & Water Sampling,"

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P.O. Box 115, Floresville, Texas 78114
830-216-4519, fax 830-393-3219