Clean, safe drinking water is one of the most important elements of good health. Testing well water on an annual basis is one of the easiest things a private well owner can do to take care of their health and the health of their loved ones. It’s estimated that 20-25% of Wisconsin wells have bacterial contamination, so Marathon County Health Department advises all private well owners to have their well water tested for coliform bacteria. If there are infants under six months of age or women of childbearing age drinking the water, it should also be tested for nitrate. How do I test my private well drinking water? How often do I need to test? To test your private well water, obtain a water sample bottles, instructions, and a lab submission form from the Marathon County Health Department. Most Wisconsin wells provide safe water. However, bacterial and chemical contaminants can pollute ground water in a variety of ways. Common tests include coliform bacteria, nitrates, and fluoride. Every private well should be tested routinely and whenever there are changes in taste or clarity. Contact Marathon County Health Department to find more information by calling (715) 261-1900.