MADISON – Late fall’s cold temperatures and increased precipitation can increase the threat of well contamination for people who rely on private drinking water wells, but well owners can take winterization steps to assure the safety of their drinking water, state drinking water officials say.
“Most private wells provide safe drinking water, but we tend to see an increase in well contamination problems in late fall and after spring thaw,” says Mark Putra, who leads the Department of Natural Resources private water supply section. “It’s important for well-owners to take action now to make sure their drinking water is safe for the winter.”
Important steps include making sure the well has a vermin-proof cap and keeping the area around the well cap and pump clean and free from debris to prevent infestation by insects or vermin, Putra says. Getting well water tested is another important step to take to prevent these seasonally occurring problems.
Wisconsin has 800,000 to 1 million private residential wells, and a study by the U.S. Centers for Disease Control estimates that about one-quarter of them could test high for total coliform bacteria, an indicator that illness-producing viruses, bacteria and other pathogens might be present.
Insects and spiders may enter wells through loose, broken or poorly installed well caps, nest on the cap’s underside and eventually drop off and enter the well, contaminating it with bacteria. Vermin-proof caps have been required on new wells since Feb. 1, 1991, and well drillers who replace caps on older wells after that date are also required to install a vermin-proof cap. Owners of older wells should have a private well driller or pump installer inspect the cap to see whether it is vermin proof, and if it isn’t, install one, Putra says.
Late fall and early winter rains may wash more contaminants into the ground and into poorly constructed wells and unsealed wells, she says. Well owners should test their well water at least once a year, test it after flooding, and test it if they notice a change in the water’s taste, smell or appearance.
Private well water quality is not regulated by the state, so responsibility for making sure water is healthy through testing and addressing any problems rests with the well owner. Putra advises private well owners to call a certified laboratory to get a water sampling kit and arrange for testing. Tests for bacterial contamination and for nitrates are the most important.
Online lists of laboratories certified to test drinking water for bacteria and for chemical contaminants can be found on the Drinking and Groundwater page of the DNR Web site.
FOR MORE INFORMATION CONTACT: Mark Putra (608) 267-7649; Tom Riewe (608) 266-8697