415 ILCS 5/25d-1

For the purposes of this Title, the terms "community water system", "non-community water system", "potable", "private water system", and "semi-private water system" have the meanings ascribed to them in the Illinois Groundwater Protection Act. For the purposes of this Title, the term "soil gas" means the air existing in void spaces in the soil between the groundwater table and the ground surface.