In our experience, this is fairly common.  In short, what can be done about this depends on the terms of the contract agreed with the seller and the extent to which the information that they provided to you was misleading and caused you to enter into the contract by reason of your reliance on it.  If a seller has expressly stated “no”, the property has never flooded and it transpires that it has (and evidence of this would be important to locate), then there could be a claim against the seller.