Public health officials are urging Iowans to be wary of using private wells that may have been inundated with flood water. About 75% of the water Iowans drink comes from underground sources. Some cities, such as Cedar Rapids, use wells rather than a lake or river as a drinking water source, but many Iowans get their drinking water from a private well.

Iowa Department of Public Health director Tom Newton says: "If you know or suspect your private water well has been compromised by flood water you must stop using that well immediately. Contaminated well water should not be used for drinking, laundry or bathing."

Once the flood waters have receded, Newton says Iowans who have a contaminated well should call a professional contract who will "shock chlorinate" the well to flush the contaminants out. In the meantime, Newton suggests using bottled water or hauling water from a nearby municipal system. If that’s not possible, boiling the contaminated well water is a last resort.

"Bring it to a rolling boil for exactly one minute," Newton says. "You don’t want to boil it any longer. If you do boil it longer, there’s a chance if chemicals got into your water well that you could concentrate those chemicals, so keep that rolling boil to just a minute." Twenty percent of Iowans get their drinking water for surface supplies, like rivers and lakes.