You might make a legal case for damages if the seller knew, or was capable of knowing, the home was on a floodplain. For instance, if the home, or those near it, flooded or was at risk of flooding before you bought it. Not telling you about a health and safety risk, like toxic mould caused by flooding, can make the seller liable.
High water marks on the exterior or in the basement are visible signs of previous flooding. Missing those during a showing, or hiring a professional home inspector who fails to take notice, can be grounds for the seller to counter argue the damage was “patently” obvious when you made your offer. Sellers have been excused for patent defects you could have found on your own.
Latent defects, ones hidden from sight, are a different matter. We can’t emphasize enough why hiring a competent home inspector is important. While inspectors can’t practically (without the owner’s permission) probe below the surface of drywall to see if it has been replaced, they could check for recent building permits and consult floodplain maps.
That flips the onus back to you to prove the seller deliberately hid latent defects by covering up water damage. Failing to include health or safety risks in the optional sellers property information statement (SPIS) may back up your claim. Realistically though, your case could go either way. Courts have been known to reject claims, or even split responsibility between the buyer and seller.