Insurer Allianz paid home insurance claims totalling more than £20m for UK flooding in 2023 alone, with the average cost of a claim costing £33,000. But beyond the immediate disruption, flooding poses a huge hidden cost for homeowners by slashing property values and complicating the property selling process. “Even if flooding of the property occurred before your ownership, you must declare it if you’re aware of it,” said Malnick. For a very high risk the sale price could be as much as 31% lower than properties not at risk. In addition, estimates by Sell House Fast suggest financial losses of £10,000 to £30,000 per property in medium-to-high-risk zones.