About 20 million Americans get their water from private wells.
There are about 390,000 private wells in the state, according to the department.
As further evidence, drinking water for one nursing home on the south side came from a private well.
Homes using private wells and public systems can be affected.
There are more than 20,000 private wells in the towns.
Approximately 6,300 people get their drinking water from public and private wells within three miles of the Site.
The town's water supply originally came through public and private wells.
About 1 million people are not served by water companies at all and depend on their own private wells.
Water from a private well that has been flooded may be contaminated.
If a problem with water from a private well is suspected, the local health department should be notified.