153.76 Exemption from taxation.—As the exercise of the powers conferred by this law constitutes the performance of essential public functions and as any water system or sewer system or both constructed under the provisions of this law constitute public property used for public purposes such districts and all properties, revenues, or other assets thereof, and all bonds issued hereunder and the interest thereon, shall be exempt from all taxation by the state, or any political subdivision, agency or instrumentality thereof.