Okla. Stat. tit. 68, § 2903

All property, both real and personal, of any rural water or sewer district, as defined in the "Rural Water and Sewer Districts Act" contained in Chapter 266, Oklahoma Session Laws 1963, as amended (Chapter 18, Title 82, O.S. Supp. 1969), and created and organized for the purposes therein described, but which districts are incorporated as nonprofit corporations under the provisions of Chapter 13, Oklahoma Session Laws 1968 (Chapter 19, Title 18, O.S. Supp. 1969), shall be exempt from all ad valorem taxation. The motor vehicles or other vehicles of any such district shall be registered and licensed each year for a license fee of One Dollar ($1.00), and said districts shall be exempt from sales and use taxes.