or 40-plus years, Christopher Wenke drank water that flowed from the well he drilled into the basement floor of his Village of Comstock home in Kalamazoo County. It ran clear and cold, like the refreshing springwater he remembered tasting as a teenager after long, summer hikes into the country.

"We drove a 20-foot pipe down through the basement. The soil down below was nice and gravelly. The water was always tasty and cold. We thought we had good water," recalled Wenke, 83, whose family owns two lawn and garden nurseries.

Like 43 per cent of all Michigan residents, his drinking water came from groundwater -- that essential, life-giving liquid which is held in pores and fractures found in the sand, gravel and rock that lie beneath the earth's surface.

In all those years, he arranged for the water to be tested once or twice. But two years ago, some samples from his outside taps revealed that pollutants from a nearby factory had leached into the groundwater supply.

For the six weeks it took to hook his home up to a water supply provided by the City of Kalamazoo, Wenke drank, cooked, washed and brushed his teeth with bottled water.

In general, Michigan's groundwater supply is good and plentiful. But what happened to Wenke has happened to thousands of Michigan residents over the years. In Kalamazoo County alone, there are more than 300 sites where contamination exists, half of them from leaking gasoline or fuel storage tanks.

Homeowners must be vigilant about potential risks to their water well supplies and have them regularly tested.

The need to protect our groundwater supplies spurred the W.K. Kellogg Foundation to fund the Groundwater Education in Michigan (GEM) Program, designed to educate us on how to protect our drinking water by protecting our groundwater.

Appearances can be deceiving. People are often concerned about contaminants that make drinking water look, taste or smell bad. Some easily noticed contaminants actually pose no health risks. But some of the most hazardous chemical or disease-causing organisms that can occur in drinking water can't be seen or tasted.

The state and federal governments share responsibility for ensuring that the public water supply is free of contaminants. Public water utilities are required to notify their customers immediately if regular testing reveals that a federal standard has been violated.

But homeowners who rely on private wells for their drinking water ultimately bear the responsibility for ensuring that their water is clean and safe. According to the 1990 Census, more than 1.1 million households in Michigan have private wells that provide their drinking water.

If testing indicates that a problem exists with a private well, first contact your local health department to determine the seriousness of the problem. Local health officials may provide any follow-up testing necessary. Depending on the contaminant, the remedy may involve disinfecting the water source, having a new well drilled, repairing the system, hooking into a community water system or installing a water treatment device.

Protecting the groundwater for your well isn't always that easy because your neighbors activities may affect your water. Still there are some basic practices that can help prevent contamination:

• Properly maintain your septic system. It should be pumped every three to five years.
• Use native plants for landscaping. They're usually drought and pest resistant.
• Fertilize at the proper time and rate. Hand weed or apply herbicides only when necessary.
• Use non-toxic alternatives whenever possible.
• Properly dispose of hazardous wastes at local collection sites. Contact your county or city for more information.
• Never dump oil or gasoline on the ground. Find out who recycles these products in your community.
• To see if your well is properly located, check with your county health department.
• Keep good records of when the well was installed, any repairs that have been made, results of pump tests, and water quality tests.
• If you replace your well, it's vital that a well driller properly seals your old well. Improperly abandoned wells provide a direct conduit for pollutants to reach the groundwater supply.
• Contact your local Groundwater Education in Michigan Regional Center.
• Contact your local MSU Extension office for Home*A*Syst and Farm*A*Syst fact sheets and work sheets.