House was listed as having sewer and now we have found out that it has septic. Agent claims seller had no knowledge of septic. What is my recourse?

You might have a claim for fraudulent representation. If the listing misrepresented the facts of the charachteristics of the property then you can seek recourse. You will need an attorney, and an estimate of the cost of removing the septic and connecting to the sewer. However, it would be important for your attorney to look at the contract of sale and any and all promotional documents/representations made to you prior to or on or about the time of the sale. I suggest that you get an estimate first and try to resolve this with the brokers both listing and selling, if unsuccessful go to an attorney. Communicate in writing and keep copies. Good luck.   Walter Jennings, Esq.