A method for monetising the mental health costs of flooding

Recent research from Public Health England (PHE) shows that people that experience flooding in their homes can suffer from mental health illnesses, including depression, anxiety and post-traumatic stress disorder. This has an economic impact, including costs to the health service and lost days at work.

This project developed a method for evaluating the impact of flooding on mental health and assessing these economic impacts. Prior to this study, the economic case for flood defence schemes and strategies focused on the physical damage of flooding on properties or businesses. This new approach will allow the benefits of avoiding negative impacts on mental health to be considered in the main economic business case when selecting preferred options and applying for flood risk investment.

Mental health impacts increase with the severity of a flood. The costs of flooding were found to increase with the depth of floodwater inside the home. Costs increase from an average of £1,878per adult per flood event with internal depths up to 30cm, to £4,136 where the depth is more than 1m deep. This methodology is informing guidance for economic flood appraisals, specifically for projects or strategies seeking flood defence grant-in-aid funding.