A press release issued this morning warned of potential contamination of private supply wells after heavy rainfall caused an overflow of wastewater at four locations within the city's collection system.

An estimated 100,000 gallons of domestic wastewater was discharged at each location within the past two days, the release said. Affected drainage systems include Prairie Creek, Floyd Branch, Nantucket Branch and Duck Creek.

Only residents living within a half-mile of the discharge points and using personal wells should take protective action, the press release said. People using potable water provided by the city's water mains are not at risk for contamination.

Those affected should only use water that has been distilled or cooked at a rolling boil for at least one minute for all personal uses, including drinking, cooking, bathing and tooth brushing. Prior to resuming normal use, the release suggested residents using private wells have their water tested and disinfected. Those who purchase water from a public water supply can contact their distributor to determine if water is safe for personal use, the release said.

Members of the public should avoid contact with waste material, soil or water in the areas potentially affected by the spills.

A 24-hour response line has been set up for residents with questions regarding this matter. The phone number for that line is 972-744-4111.