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By law, when a water well is no longer used to supply water, within 30 days after nonuse, it must be sealed. The Illinois Water Well Construction Code provides detailed rules on how this is to be done. Contact your local health department for details. This law applies to small diameter residential, commercial or large municipal wells.
An abandoned water well can put your own water supply as well as neighing water wells in jeopardy of contamination. A Water well that is no longer used and not maintained can become a direct pipeline for surface water or run-off to reach the aquifer.
Abandoned water wells are also a serious threat to the health and safety of humans and animals. There are plenty of real like stories of children and livestock falling into abandoned water wells. Unfortunately, not all end on a positive note.
If you are a buyer, make any abandoned wells on the property are properly sealed to code and by a licensed water well driller. A permit is required. Get a copy of the permit. Simply filling up an unused well with sand, gravel, stones, debris or garbage is not appropriate and can add contaminants to the groundwater and can negatively affect other wells in the area.