Tenn. Code Ann. § 7-35-303

When such municipalities do not adjoin but lie in such proximity to one another as to make such contract to their mutual advantage, then either of the municipalities may, from the public funds of either of the municipalities, build such lines of main sewer or water pipes over the intermediate territory, using any streets, roads, or public ways for the sewers or water pipes that may be necessary, so as to enable the pipes and systems of the two (2) or more municipalities to be joined together and consolidated into one.