You would need to hire a licensed home inspector and engineer to investigate the situation to make sure any flood damage has been completely repaired. This is assuming there was a flood there which I am uncertain of. With regard of future chance of flooding, there can never be a 100% guarantee so listen to your gut and do what you think is appropriate.
If you need help locating a property to purchase in Brooklyn, feel free to contact me direct. Good luck!
Mitchell S. Feldman
Associate Broker/ Director of Sales/ e-Pro Realtor
Fillmore Real Estate
Office: (718) 252-2000/ Cell: (917) 805-0783