Hello again. Thanks for your patience.
It sounds like you may have a viable case against the seller and the seller's agent (assuming they used an agent). The argument is that they misrepresented their right to use the neighbor's Well, that you reasonably relied on the misrepresentation, and that the misrepresentation induced you into buying the property, which you would not have done had you known that you had no rights to the neighbor's Well. Here is clear Tennessee legal authority supporting this legal position:
In Goodale v. Langenberg, 243 S.W.3d 575 (Tenn. Ct. App. 2007), appeal denied, (Nov. 19, 2007), the court stated that if a real estate agent and the sellers fraudulently misrepresent the condition of a home to purchasers, the purchasers are entitled to rescission of the purchase agreement if an award of money damages alone cannot make the purchasers whole. Further, the court stated that punitive damages may be awarded in an action for equitable rescission and incidental damages when fraud is the basis for rescission. See also Davis v. McGuigan, 325 S.W.3d 149 (Tenn. 2010).
My suggestion is that you retain a local attorney to write a demand letter to the seller and the agent. The letter should demand the full cost of installing a Well, and threaten a lawsuit if the demand is ignored. If you are required to sue, then you can seek punitive damages as well as compensatory damages.
Does that answer your question? Please let me know if you need clarification, as I am happy to continue helping you until you are satisfied.