Who is responsible for outstanding water and sewer bill?

[Laura Sullivan]

I purchased my first rental property at the end of December.  It was a foreclosure and I purchased it from the bank with cash.  At the closing I received a credit for the sanitation bill.  Now 2 months later I receive a water and sewer bill that starts back in October.  How did this happen?  I had a realtor, lawyer and a title company.  What should I do?