65 ILCS 5/11-151-4

If a municipality annexes all of the territory of a public water district, the municipality shall take over all the properties and assets of the district, assume all debts, liabilities and obligations of the district and perform all functions and services of the district. The district shall be abolished and the rights and duties imposed on the municipality of this Section shall commence 90 days after the effective date of the annexation or at such earlier date as the corporate authorities of the municipality, by ordinance, provide.