What should I do with the unpaid water bill from the previous owner of my property?

I am the first time homebuyer and ran into this problem that has not been solved for over a year already. I purchased my property back in August 31 of 2011. Couple days after I closed and moved into my new home, I received a water bill with the reading of my usage and the outstanding amount from the previous owner. I called my Water and Sewage Company. They told me to work out with my Title Company and my Realtor. I happened to run into the previous owner and told him to come to my house and pick up his water bill. He ignored me like he didn't know what I was talking about. I emailed my realtor several times. He ignored my emails. After a year of going back and forth, the lady named "Sarah" at Title Company finally gave me an answer that "there's nothing that they could do and bill is all on me". They repeatedly lied to me that they would contact the previous owner and water company for me to work it out. They never did making any contacts. Now, I am stuck with $400 water bill that I was not even aware of until I moved into my house. I decided to make a small claim at local court. I was told that I need to know and find out where those people live in order to make a small claim. But I am lost and confused now of what to do and how to find the previous owners' address and whereabout in order to file small claim to make them pay for the unpaid water bill. Now my Water Company stated that they decided to put $400 onto my upcoming Winter Tax. What should I do?