Since this home is not currently for sale, I would recommend bringing your concerns directly to the home owner. They may already be aware and may have already remediated the situation when they purchased.
Dave, If you are looking for a home and through a flood determination that you are in any other zone other than "x" you need flood insurance. Right now in Bucks County their are redoing a lot of the mapping so a property that is close to a plain may not have needed flood insurance but it does this year. Two more things. One, even if your not in a flood plain but have a house with a basement it's a good idea to consider flood insurance and becuase your not in a plain it's so cheap but your covered in case you ever get any water in there especially if it's finished. The second is that if you do have a house in a flood plain you can get an elevation survey done. This can reduce the cost of the insurance possibly but thousands a dollars a year. You have to hire a survey company to preform the survey and then provide the information to your insurance carrier. If you are above the body of water, river or otherwise grade wise then chances are this will help you get the premium reduced. Lastly if your in a known floodplain as far as I know, your required to carry flood insurance. Hope that helps...... more