In Michigan, about 95% of all rural residents and a smaller but significant percentage of non-rural residents rely on their own private wells for their drinking water. Unlike municipal water sources, no regulations exist requiring the regular testing of private water wells. Consequently, the responsibility for monitoring water quality and identifying potential health risks to family members falls upon the homeowner.

If you do rely on a private water well for your drinking water, it is recommended that it be tested regularly. The nature of aquifers makes them particularly vulnerable to contamination from a variety of land-uses including industry, manufacturing and agriculture. While you may follow some basic practices to prevent contamination such as (1) maintaining your septic system, (2) properly disposing household hazardous wastes, (3) judiciously applying fertilizers and pesticides and (4) reducing your use of household hazardous wastes, there is no guarantee that your neighbor or anyone else who can contaminate the same aquifer is doing likewise.

It is important to note that contaminated water does not necessarily taste, smell or look any different from safe drinking water. For example, you cannot taste or smell inorganic arsenic, nitrates, coliform bacteria and organic compounds such as PCB's and PBB's in your drinking water. The only way to detect these substances and others like them is by testing your well water.

What should I test for and how often?

As a homeowner, you can have your water tested for a wide range of substances, however, these tests can be very expensive, and in most cases, are not necessary. It is important to identify which substances you should test for if it cannot be detected using the more common water test kits. To safeguard against the most common and serious health concerns, environmental health professionals suggest that at a minimum you test your water well for coliform bacteria, nitrates and pH annually.

Because nitrates enter groundwater through the same pathways as other contaminants, the detection of nitrates in your drinking water may indicate the presence of pesticides and other substances in your aquifer. If nitrates are detected, further tests are recommended to identify the contaminants that might be present. A specific chemical analysis detects one of a few specific chemicals. To determine which chemicals to test for, consult your local environmental health sanitarian or your county extension agent and consider present and past land-uses on and around your water supply area. Even if you find that your drinking water is safe, testing your water annually is a good way to establish a water quality record.

What do the test results mean?

Test results are given in terms of concentration (milligrams per liter). For contaminants that pose a health risk, the Environmental Protection Agency (EPA) has set Maximum Contaminant Levels (MCL). Prolonged exposure to substances exceeding their MCL may cause adverse health effects. The EPA has also set Secondary Maximum Contaminant Levels (SMCL) for substances that do not pose a health risk but that can affect the smell, taste, turbidity and color of your water. Your local health department can help you in interpreting the results of your water test. Below is a brief explanation of what the test results mean for the tests described above.

Bacteriological analysis: Counts of one or higher suggest that your well water is contaminated with either human or animal wastes and follow-up with your local sanitarian is warranted.

If you and your sanitarian decide that further testing is necessary, a number of private consultants and laboratories can assist you in testing for specific substances.

What if a problem is detected?

If your water tests indicate the presence of a contaminant above the EPA's MCL or SMCL, you should first talk to your environmental health sanitarian who can help you determine the seriousness of the problem, suggest possible follow-up tests, and help you in choosing the most appropriate remedy. Depending upon the results of further testing, you could have four choices: (1) repair your well to better protect your water supply; (2) disinfect your water supply; (3) install a water treatment system; or (4) find a new water supply.

Repairing your well could be a remedy for problems with animal or human wastes, agricultural chemicals and other substances. The presence of bacteria, nitrates or other organic compounds in your well could mean that contaminants are entering your water supply via a space between the well casing and bore hole or an improperly sealed well cap.

Disinfecting the water supply usually is done if coliform is detected in your water well. It involves introducing a shock treatment of chlorine to your water well. Before employing this method, however, first contact your sanitarian for more information.

Home water treatment. There are a number of home water quality treatment methods available and the choice will depend upon your specific problem. Listed below are five of the most commonly used methods, the substances that they remove and problems associated with each.

Finding a new water supply could mean hooking into a community water system or drilling a new and deeper well. However, if these are not feasible, then another option is to purchase bottled water for your drinking water. If none of these options are feasible and the contaminants in your well water pose a serious health risk, then you should consult your local health department for assistance in identifying other alternatives.