65 ILCS 5/4-5-10
The council has the power to make proper regulations for the inspection of all plants and machinery of any person exercising any right, grant, or franchise from any municipality adopting, or which is treated as having adopted, this article. The council and their authorized agents have the power to make all necessary examinations of any plant, appliances, or apparatus for the purpose of making the necessary tests to see that such person complies with the regulations of the council with reference to the quality and the character of the commodity or service furnished. The council has the power to specify, determine, and regulate the quality and character of gas and electricity furnished to the municipality and to its residents. The municipality has the power to perform all acts necessary to give effect to this section.
65 ILCS 5/4-5-10