Tenn. Code Ann. § 54-12-405

Each bond shall show expressly on its face that it is to be paid only by assessments levied and collected on the lands within the district so designated and numbered, and for the benefit of which district the bond is issued. No assessment shall be levied or collected for the payment of the bond or bonds, or the interest on the bonds, on any property, real or personal, outside the district so numbered, designated, and benefited.