Guidance

Flooding and health: an overview

Updated 19 December 2023

Background

The third UK Climate Change Risk Assessment (CCRA) in 2021 identified flooding as one of the most important climate change adaptation challenges facing the UK. In all future climate change scenarios, direct and indirect flood risks are projected to rise over the course of the 21st century. The health impacts of flooding are well known and understood. These include physical health effects including injury and exposure to potentially harmful environmental contaminants, a wide range of impacts on mental health such as stress or anxiety, to more severe mental health impacts which may require specialist health interventions.

This guide contains advice on what preparations should be made to reduce flood-related public and mental health risks and what should be done to protect people that are at increased risk.

This includes:

• how to raise awareness of these risks
• how to prepare and reduce exposure to risks
• how to respond in the immediate aftermath of a flood
• actions that should be taken in the longer-term recovery

Each flood event will have its own unique features and challenges and the actions described in this guide are therefore neither exhaustive nor prescriptive.

This guide does not alter any other flood risk management duties such as powers and duties described in the Flood and Water Management Act 2010.

About flooding and health

Flooding has extensive and significant impacts on health and is frequently associated with both acute and long-term effects on health and wellbeing.

Direct health effects associated with flood water and its debris include:

• drowning (for example, walking or driving through flood water)
• physical trauma (for example, concealed or displaced objects, electrocution, fire)
• skin and gut infections from exposure to contaminated flood water

Longer-term health effects that may occur as a consequence of flooding include:

• mental health impacts
• carbon monoxide poisoning due to inappropriate use of generators
• respiratory disease from mould and damp
• rodent-borne disease

Floodwaters can contain contaminants that cause infections or irritation, that may remain even after the water has receded. These can build up in the surrounding environment such as in soil and waterways and be harmful to humans, pets, and livestock. Moreover, floods can damage the sewage system when groundwater, rivers and coastal waterbodies overflow, resulting in sewage, human and animal waste entering flood waters, and can be a health risk to affected populations if not cleaned up properly.

Flood events can significantly impact all aspects of a community due to deaths, harms to health, damage of homes, businesses and personal belongings, loss or power or water supplies to homes, and reduced access to essential public services. There may be the possibility of infectious disease outbreaks occurring after flooding, although there is relatively little evidence of such outbreaks occurring in the UK to date.

The clean-up process after a flood can also be stressful, and exposure to contaminated flood water can make residents feel sick due to the pollution or sewage found in floodwater. Often, only the immediate traumatic deaths from flooding are recorded. It is not always easy to identify the longer-term health effects associated with flooding, such as those caused by displacement, destruction of homes, delayed recovery, power outages, water shortages and disruption of access to health services. In England, most of the health burden associated with flooding is due to the impacts of flooding on mental health and wellbeing.

Over the course of the 21st century, rising average rainfall and changing rainfall patterns alongside rising sea levels will contribute to a predicted rise in the frequency and severity of flood events. Flood risk is predicted to increase in the future across all major flood risk categories: fluvial (river), ground water, surface water and coastal flooding. While the greatest damages are likely to remain to be caused by river flooding, the greatest increase in relative risk is projected to be coastal-related, which is expected to be more than double compared to current levels. This is important given that coastal flooding is associated with greater risk to life and livelihoods.

Unless there is adequate long-term planning to support adaptation and resilience to flooding, these predictions could lead to an increase in flood-related physical and mental health impacts.

A tiered response to flooding

The response to a flood can be illustrated as a phased approach where the first 2 response activities encompass the actions needed for the majority of the population. This is followed by more focused and targeted care for those at higher risk.

The tiers for flood response are as follows:

Tier 1 – immediate response:

• address immediate physical needs
• communicate key public health messages

Tier 2 – short-term recovery:

• deliver evidence-based psychosocial support such as psychological first aid involving appropriately trained responders
• offer short-term one-to-one support where needed – develop an active monitoring support system either face to face or by phone
• involve voluntary and community sector organisations
• continue to offer practical measures to support flood recovery

Tier 3 – short-medium term:

• provide active monitoring and seek to identify and support individuals with more acute psychological support needs
• recognise the specific needs of children through an active screening programme for those exposed, and provide mental health support as appropriate

Tier 4 – long-term recovery:

• individuals with severe or long-lasting symptoms should be advised on how to access psychological support and, or referrals should be made to specialist clinical teams ensuring support is given as soon as possible
• mental health and social care specialists should continue to offer advice to responder organisations

Who is at risk

Some groups are at greater risk of health effects due to flooding than others. This may be due to specific vulnerabilities (for example due to age), but multiple risk factors may also coincide.

For example, a household with children living in rented accommodation may be especially vulnerable to flood-related distress and other mental health impacts. It should also not be assumed that having a risk factor or factors automatically implies vulnerability – a person with a risk factor may also have resilience if they are prepared and have the appropriate support.

Meanwhile, people without a risk factor may yet experience health impacts. For these and other reasons, following sections in this guide cover advice for individuals and households, but also on ways of supporting community-wide resilience building.

The following groups may be at increased risk of impacts on health and wellbeing following a flood event and should be identified by flood preparedness and response organisations.

Older people

Older people have been found to be less likely to respond to flood warnings, and this is likely due to factors associated with ageing rather than age per se.

Older people who are more reluctant or less physically able to leave their homes, or who have mobility issues that make it more difficult to use property level flood gates, are less likely to respond to a flood warning. They may be less likely to receive a flood warning if not registered to receive them and/or if they do not have home internet or a mobile phone.

People with pre-existing mental health conditions

People with underlying mental health conditions may be more vulnerable to the psychological impacts of flooding. Personal factors that may increase risk and which should be considered include a history of clinically important symptoms of post-traumatic stress disorder (PTSD), family history of mental health problems, an absence of social networks, stressful life events, substance misuse, bereavement or a dissociative response during the event.

People with chronic illness or with physical, sensory or cognitive impairments

People with chronic conditions have been identified to experience floods as a factor that worsens or accelerates the deterioration of their health. Flooding may also disrupt access to care or essential medicines and services, especially if internet connections and transport routes are disrupted. In particular, it has been found people who are obese and have a body mass index (BMI) of over 40 may find it more challenging to evacuate.

Children

Studies of effects of flooding on children have found an association with increased mental and behavioural problems, potentially mediated by disruption of schooling and home life.

People in socioeconomically disadvantaged groups

Although flooding affects all income groups, in many rural towns and villages, and smaller urban cities and towns, the most socially vulnerable are, on average, exposed to greater flood risk. This difference in relative risk is compounded by differences in income and insurance take-up, which on average, are lower in more socially vulnerable communities.

This inequality is projected to widen as the frequency and severity of flood events increase in some areas.

People with language and culture-based vulnerabilities

People who face a language barrier are less likely to receive flood alerts and warnings and, therefore, to be adequately prepared for a flood event.

People sleeping rough and experiencing homelessness

Those who are homeless may be less aware of flood risk and less able to access services designed to support residents following a flood.

University students

University students often live away from home during term, and may be less familiar with the local and regional area. They may not be signed up to local flood alerts.

Transient communities and people with no connection to a place or services

People who are not long-term residents of the affected area (for example tourists, migrant workers) may not be aware of flood risk in the area and therefore are harder to reach than known residents.

People experiencing temporary vulnerabilities

People who have an illness, injury, have recently been discharged from hospital, are pregnant or have recently had a baby, may face barriers to preparing for or responding to a flood.

People receiving complex healthcare interventions at home

People who are receiving interventions at home such as receiving oxygen, dialysis or palliative care may face barriers to evacuation.

People living in rental accommodation

People living in rental accommodation may lack insurance coverage, among other potential vulnerabilities.

Suggested next steps for public agencies and local authorities

This guide on the public health effects of flooding is a good-practice document. The suggested flood response activities are sourced from real-time flood case studies and literature reviews, to provide evidence-informed support to vulnerable and affected populations. The guide is to support local authorities, resilience forums, volunteer groups and relevant agencies in their considerations, actions and activities, when planning for flooding events. This document contains information that can be adapted and incorporated as appropriate to local situations.

This guide presents good practice suggestions. The main messages can be summarised into the following points.

First, local authorities and agencies play an important role in helping to prepare vulnerable communities in advance of flooding and to build community resilience. This can be through identifying households and areas with higher vulnerability to the impacts of flooding to offer targeted and tailored interventions and communications. Activities that support social cohesion at a local level are known to mitigate some of the public and mental health consequences caused by flooding where social action supports long-term preparedness, making appropriate arrangements to support people who have been flooded more than once as they can experience cumulative effects.

Second, public agencies and authorities should review this guide across the local health and social care systems to ensure that the response activities reach those that need to take appropriate actions, both in preparation and in response to flooding. The pyramid for flood response illustrates the phases of the response actions required during and following a flood. Local areas need to adapt these to their particular situations and ensure that the cascades are working appropriately.

Local authority commissioners, together with local resilience forums, should seek assurance that organisations and main stakeholders are taking appropriate actions for flood alerts or warnings, and to be mindful of recovery gaps (refers to the period after emergency response).

The suggestions identified in this guide are based on the best evidence and practice available. It is for local areas to amend and adapt this information and to involve local groups and organisations to help develop plans that can be actioned when needed.

Preparing for flooding

How to prepare for flooding

Responding to flooding

How to respond to flooding

Recovering from flooding

How to recover from flooding