(a) Any waterworks board which borrows money under the authority of this division may evidence the loan by revenue bonds in such form and of such tenor and maturities as may be agreed upon between the lender and the board. Any such bonds so issued may thereafter from time to time be refunded by the issuance by sale or exchange of refunding bonds at such times and in such form and of such tenor and maturities as may be agreed on by the board and the holders of the bonds so refunded if such refunding is by exchange and as may be determined by the board if such refunding is by sale of refunding bonds. Such waterworks board may restrict the source of payment of such bonds and the security given therefor to whatever extent the board of directors thereof shall deem advisable, but no such bonds shall purport to be effective to impose on the board or its funds or property any liability in excess of or inconsistent with the liability authorized to be incurred or assumed by this division. Such borrowing may be evidenced by sale of such bonds either at private or public sale in such manner and from time to time as may be determined by the board of directors of such waterworks board to be most advantageous, and the board may pay all expenses, premiums, and commissions which its board of directors may deem necessary and advantageous in connection with any such financing. All such bonds shall be regarded as negotiable instruments. All such bonds and all instruments executed as security therefor shall be exempt from all taxation under the laws of the State of Alabama. No city or town in which a waterworks board was organized to operate shall in any event be liable for any money so borrowed or any debt created by such waterworks board, nor shall the same be construed to be an indebtedness of or against such city or town. When any waterworks board shall have borrowed money as aforesaid, it shall charge, collect, and account for sufficient revenues from the operation of the plant and system to repay the money borrowed with interest thereon as the same shall mature and to pay all operating and maintenance expenses of such plant and system, and each year any income of the board in excess of operating and maintenance expenses and the amount required to be applied on any money so borrowed and the interest thereon shall be held or disbursed as may be provided in the proceedings pursuant to which such loan shall have been procured.
(b) When the cost of construction or purchase or other acquisition and all indebtedness otherwise incurred against such gas plant and system shall have been fully paid, then such gas plant and system, together with all rights-of-way, pipelines, improvements and appurtenances thereto and all other property pertaining to such gas plant and system, whether tangible or intangible, including franchises, shall thereupon become the property of the city or town in which the board was organized to operate, and all rights of said corporation in and to the same shall thereupon immediately vest in such city or town.