Any sanitary district created hereunder, after being authorized by an affirmative vote of the legal voters of the district at an election to be held as is hereinafter provided, may acquire, purchase or construct a drainage system, and thereafter operate, improve and extend the same, and pay the cost of such purchase, construction, improvement or extension by the issuance and sale of revenue bonds of the district, payable solely from the revenue to be derived from the operation of the drainage system.
70 ILCS 2805/26a