Neighbor rescinds water share agreement

[Nat C.]

I decided to sell my duplex in Las Vegas which I bought in 2013. When I purchased it I was told I shared a water and sewer line with the neighboring property. The long running agreement was that the neighbor paid the trash and the owner of the property I was buying paid water/sewer. My realtor just informed me he spoke to the neighbor and the neighbor says he is rescinding the offer for the next owner. He said he wants to buy the property and offered an outrageously low price. We are now screwed as we would have to disclose to any potential buyer that a new owner would have to put in their owner water and sewer lines. I'm told the cost would be around 20K.