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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

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April 2006

How safe is my drinking water?

Test regularly and stay informed.

Natasha Kassulke and Laura Chern

Many Wisconsinites, urban and rural, are concerned about the quality of the water they drink, with good reason. Threats to a safe water supply exist everywhere, the result of our daily activities. How do you know if your water is safe to drink?


If your water is supplied by a community public water system, your water utility will mail a Consumer Confidence Report to you each fall. The report will include information on the source of the utility's drinking water, the treatment used to purify water, any contaminants that have been found in drinking water, and the potential health effects of those contaminants. Reports will also identify where additional information about the water supply can be found and how citizens can become involved in protecting water sources. Utilities must annually provide updated reports for their consumers.

Private well owners should have their wells tested periodically. Private laboratories do tests for chemical contaminants, such as volatile organic compounds or pesticides. Check the Yellow Pages under "laboratories" or "water analysis." Cost ranges from $30 to $1,000 depending on the number and type of chemicals analyzed and the test methods.

For a small fee, the State Laboratory of Hygiene will test your drinking water for several pollutants including bacteria, nitrate or fluoride. For a test kit, call the lab at (800) 442-4618 or write the State Laboratory of Hygiene, Environmental Health Division, 2601 Agriculture Dr., P.O. Box 7996, Madison, WI 53707-7996. Private labs will also do these tests.

Wells can be disinfected by displacing all the water in the well with a mixture of bleach (containing at least five percent chlorine) and water or by dropping chlorine tablets or powder down the well. Contact the DNR Bureau of Drinking Water and Groundwater, at P.O. Box 7921, Madison, WI 53707-7921 or call (608) 266-6669 for literature on private well operation.

If high nitrate is the problem, the well construction and location should be checked.

Wells can sometimes be deepened to get past contamination. Inadequate well installations may be upgraded. Wells located in pits, for example can be extended above ground and the pit filled in. These are costly options, however; it's best to have the work done properly in the beginning to avoid problems later. Your DNR private water supply specialist can give you advice on obtaining a safe drinking water supply.

If your water utility or a lab test alerts you to the presence of high levels of chemicals in your drinking water, you may be advised to drink bottled water or drill a new well. But what about low levels of contaminants? Will small quantities of benzene, a major component of gasoline, or perchloroethylene (PCE), a chemical used in dry-cleaning solvents, make your water undrinkable?

The answer is no. That's not to say, however, that the water is totally safe to drink. For instance, the Environmental Protection Agency estimates that one part per billion of PCE in drinking water could lead to one or two additional cases of cancer in a population of one million people who drink such water over a 70-year lifetime.

Drinking water contamination, even at very low levels, should not be taken lightly, nor should the risks be exaggerated. To keep the risk of contamination as low as possible, public agencies and private citizens must continue to make tough decisions on what's worth the risk and what's not.