Coliform bacteria are microorganisms found in the intestines of warm-blooded animals as well as in soil, on vegetation, and in surface water runoff. Finding coliform bacteria in a water supply is an indication that there is a potential for disease-producing organisms to be present also.

Coliform bacteria washed into the ground by rain or melting snow are usually filtered out as water percolates through the soil. However, poorly-constructed or unsealed wells, fractured rock outcroppings, sinkholes, and quarries may provide a path for coliform bacteria to enter groundwater.

Once in the groundwater, bacteria can easily pollute drinking water used by private well owners. Other bacteria, viruses and parasites, which can cause illness, can be in water containing coliform bacteria.

Drinking water drawn from private wells should be tested for the presence of bacteria at least once a year or any time there is a change in taste, odor, color or appearance of the well water.

Iron and sulfur bacteria may also be present in well water. Although not a health threat, these two types of bacteria can make water smell and taste bad and plug or corrode plumbing equipment. The State Laboratory of Hygiene offers a test to detect iron bacteria. Some private laboratories also test for iron or sulfur bacteria.

Although nitrate is found naturally in many types of food, high levels in drinking water pose a serious acute health threat for infants less than six months of age. Nitrate is changed to nitrite in the stomachs of small infants. The nitrite then interferes with the blood's ability to carry oxygen, and symptoms of suffocation or blue baby syndrome can occur. This problem generally does not affect older children or adults. Research is underway to ascertain if nitrate causes chronic illness.

Sources of nitrate include fertilizer infiltration in agricultural areas, animal feedlots, sewage absorption fields, municipal and industrial wastewater, urban drainage and decaying plant debris. Underground soil and bedrock structure and the direction of groundwater flow influence when and where nitrate is found. In some areas nitrate contamination may be associated with other groundwater contaminants.

A nitrate test is recommended for all wells and is essential for wells serving infants under six months of age. The State Laboratory of Hygiene as well as private laboratories certified by DNR can test water for the presence of nitrate. If the levels are over 10 mg/l (milligrams per liter or parts per million expressed as "N"), the water should not be fed to infants under six months of age, or used to prepare formula. Nitrate is not believed to be a health concern for a pregnant woman or her fetus. Adults concerned with the yet incomplete and inconclusive research results regarding chronic illness, may wish to reduce consumption of water high in nitrate.

If nitrate levels are less than 5 mg/l, retesting every few years should be adequate. If the results are between 5 and 10 mg/l, more frequent, perhaps annual testing can be considered to monitor fluctuations in nitrate concentration. Concerns about seasonal concentration fluctuations can be satisfied by quarterly testing. If additional sources or amounts of nitrate occur in the nearby area, also consider retesting for nitrate.

Other Water Tests

Radon gas is a cancer-causing agent that occurs naturally in the environment and is present to some degree in all soil and groundwater. Long-term exposure to elevated levels of radon gas will substantially increase the risk for contracting lung cancer.

The cancer risk from radon gas found in homes usually far exceeds the cancer risk associated with contaminated groundwater.

Persons concerned about reducing cancer risks should first evaluate their exposure to radon gas in their home. Before testing your water for radon gas, you should sample the air in your home. Air sampling kits are available and easy to use. If your home has a high level of radon in the air, venting and other alternatives are more economically efficient for reducing radon levels and should be considered before water testing or treatment.

For a list of EPA-certified radon testing laboratories and a recommendation on the type of test to use, call the State Radiation Protection Unit at (608)-266-1120.

Lead is a toxic metal which has been used in the construction of most household plumbing systems in Wisconsin. Excessive levels of lead can damage the brain, kidneys, nervous system, red blood cells and the reproductive system. It is a greater hazard to young children, infants and fetuses than to adults.

If you live in a home constructed before 1985 or have very soft water you are more likely to have a lead problem. The State Laboratory of Hygiene, phone number (608) 262-1293, and private laboratories certified by DNR can test water for the presence of lead. It is recommended that you use a laboratory that can detect lead in drinking water at 5 parts per billion or less.

Fourteen types of pesticides (insecticides and herbicides) have been found in Wisconsin water supplies. Atrazine, a popular herbicide used widely to control weeds in corn, is by far the most frequently detected pesticide. Atrazine is considered a possible cancer causing substance by the U.S. Environmental Protection Agency. Many pesticides are suspected of causing cancer.

In areas where corn has been planted, any wells contaminated with pesticides almost always contain some level of atrazine thus making the test for atrazine the best indicator of pesticide contamination. The occasions where other pesticides are present, but atrazine is not, are limited to those areas where atrazine has not been regularly used.

An atrazine test is readily available and inexpensive. Have your well tested for atrazine at least once if you live in an area of atrazine use and especially if your well has elevated nitrate levels or the soils are non-clay.

If atrazine has not been used in the area of your well and other pesticides have been used or spilled, you may wish to test for the other types of pesticides used in your area. The State Laboratory of Hygiene offers an inexpensive test for atrazine; call 1-800-442-4618 for more information. Private laboratories certified by DNR will also test drinking water for the presence of atrazine and other pesticides.

Radium is a naturally-occurring radioactive metal which is usually found at low levels in soil, rock, water and plants. Radium levels can sometimes exceed the drinking water standard in eastern and west-central Wisconsin where wells obtain water from sandstone formations and in a few areas of north-central Wisconsin where wells are constructed in granite.

There is no immediate health risk from drinking water contaminated with levels of radium found in Wisconsin groundwater, but use of water with high radium over a lifetime can increase the risk for contracting bone cancer. It is suggested that you contact your local DNR drinking water specialist for guidance before having your water tested for radium.

Volatile organic chemicals (VOC) are widely used as cleaning and liquefying agents in fuels, paints, degreasers, solvents, polishes, cosmetics, and cleaning solutions. If spilled or dumped on the ground these substances can seep into underground drinking water supplies. A common source of VOC in groundwater is leaking underground fuel tanks.

In high doses, VOC can harm the kidneys, liver and central nervous system. Many VOCs also cause cancer and reproductive system problems. Wells near underground gas tanks and old landfills are most likely to be contaminated with these substances.

Private laboratories certified by DNR can test drinking water for the presence of VOC. Get your water tested for VOC if you are aware of a spill or leak in your area, or if you notice a solvent or fuel taste or odor.

Often taste and odor problems are caused by tannins, sulfur, sulfide bacteria, iron or iron bacteria. Tests by private laboratories can be done to evaluate these non-health related water quality problems. However, a change in taste, odor, color or appearance could be indicative of a more serious contamination problem and the need for additional testing.

Laboratories

The DNR maintains a list of laboratories certified to test drinking water for bacteria and . You can also look in the yellow pages of the phone book in larger cities under "Laboratories-Testing" or "Chemists-Analytical." Look for laboratories that indicate "Water Analysis". Ask the laboratory if they are certified by the DNR or DHSS for the type of test you are requesting. Certification helps to ensure that the test results will be accurate.

You can obtain a list of certified labs from the DNR or the Central Wisconsin Groundwater Center in Stevens Point, phone number (715) 346-4270.

Follow all instructions for sample collection to ensure reliable test results. The laboratory will inform you whether your drinking water meets the health standard for any test you have done.

Links to more testing information on specific contaminants

For more information select from the following topics or contact your County Extension, Sanitary, Zoning or Health Department offices; or a licensed well drillers or pump installers:

• Atrazine Testing
• Bacteriological Contamination of Drinking Water
• Iron Bacteria Problems in Wells
• Lead in Drinking Water
• Nitrate in Drinking Water
• Pesticides in Drinking Water
• Radium in Drinking Water
• Sulfur Bacteria Problems in Wells
• Volatile Organic Chemicals in Drinking Water

For more information on radon gas, contact the or the State Radiation Protection Unit at 608-266-1120. You may also wish to request one of the following EPA brochures from the State Radiation Protection Radon Program:

• A Citizen's Guide to Radon
• Radon Reduction Methods
• Reducing Your Exposure to Radon

For more information, contact: Margie Damgaard, IS Professional, Public Water Section

The Official Internet site for the Wisconsin Department of Natural Resources