Ala. Code § 11-50-354
As proper water and sewer facilities are essential for the health of the inhabitants of the city, and as the exercise of the powers conferred by this article to effect these purposes constitute the performance of essential governmental functions, and as these water systems and sewer systems constitute public property and are used for public purposes, the board shall not be required to pay any taxes or assessments upon any system or any part thereof, whether located within or without the corporate limits of the city. Each water system shall also be exempt from all sales and use taxes and gross receipts taxes levied by the state and any political subdivision thereof with respect to the purchase, sale, use, or consumption of property provided, nothing contained herein shall be construed to exempt each corporation from collecting and remitting the utility gross receipts tax levied in Section 40-21-80. Any revenue bonds issued under this article and their transfer and the income therefrom, including any profit made on the sale thereof, shall at all times be free from taxation within the state.
Ala. Code § 11-50-354 (1975)