I bought a house in Florida in 2017 and when I went to get the water service turned on they told me there is a water bill from 1998 and I need to pay it. Is it my responsibility even if I didn't own the house and there had been 6 other owners before me?
To get an answer tailored to your problem, you need to get a lawyer. The general answer is that the water bill goes with the property, not the person using the water. The unpaid bill can become a lien on the property, and the house can be taken and sold to satisfy the lien.
There are other factors / questions. Under Florida law (180.135), if the debt arises from a renter who incurred the debt directly with the utility, a lien cannot be placed against the property. Any lien must be perfected (filed with the courts), and the point of a title search is to find such liens – assuming that a title search was done. There is a limit to how long you can wait to collect on a debt (7 years).