I recently moved into a house in South Carolina. Upon trying to get my water turned on they informed me I was going to have to pay $1500 in "unpaid fees" in order to get it turned back on. I have a lease, I don't understand why I'm being held accountable for these fees. Can they really deny me water and force me to pay this?
Water charges are the responsibility of the person who has the contract with the water utility.
However, if they are unpaid, they become a lien over the property irrespective of who owns it. In fact, they usually have the right to seize the property and sell it to recover their money. They can also, as you found out, refuse to provide water until they get paid.
Unfortunately, your uncle needs to pay them and try to recover the money by suing the former tenant - I hope he still has their security deposit!