Septic Tank Issues during inspection

[Daniel Pinto]

Hello

I had an offer accepted on a duplex that I got through Fannie Mae homepath. I am very interested in staying with it but during my due diligence period, I am encountering issues identifying the septic tank. I hired an experienced septic company in my area, and after meeting them at the property they spent one hour digging around and they could not find the tank at all. He told me about hiring a company that has a camera (they do not have one) and they can identify the location. He warned me it's possible that it is located under this cement patio in the yard, and then it becomes a giant construction project to inspect it and that would blow up my budget and make me back out. I called the county/city and could not get any permitting information which is concerning as it appears the previous owners did much of the work themselves and the most recent owner more than likely did no maintenance on the property which is how it fell into its current condition. 

I am thinking about asking fannie for some sort of concessions but I know that will likely be denied. Does anyone have any experience or advice on my situation? Much appreciated, Thanks!