Climate change is driving an increase in daily extreme precipitation in Canada, which when combined with other landscape factors, such as urbanization, deforestation, and loss of wetlands, can result in flood events. From an environmental health perspective, flooding increases the risks of harm and disease due to physical hazards, water and food contamination, mould, and numerous other physical, biological, and chemical hazards. Extreme flood events may also result in evacuation and long-term displacement from homes and social support networks, adversely affecting health and well-being.

This topic page provides a collection of key resources on preventing extreme flooding and mitigating is risks, as well as resources to assist during the response and recovery phases. Key points of interest range from developing resilient infrastructure and public flood risk education campaigns to addressing mould, contamination, home remediation, and mental health in the recovery stages after a flood.

NCCEH Resources

• Flood zones are danger zones: Be aware of the risks (NCCEH, 2021)
  This poster quickly identifies some of the hazards existing in flood zones, both during the flood event and after the water has receded, with a QR code that links the user to further resources.
   
• Health and social impacts of long-term evacuation due to natural disasters in First Nations communities: A summary of lessons for public health (NCCPH, 2021)
  This summary document details the public health lessons gained from two case studies of Indigenous communities that experienced catastrophic events necessitating long-term displacement. The cases studies examined the experiences of the Ashcroft Indian Band during the Elephant Hill Wildfire (2017) and the Siksika Nation during the Bow River flood (2013).
   
• Impact of climate change and wild weather on mental and physical health, lost time from work and the need to prepare (INTACT Centre for Climate Adaptation, 2021)
  This webinar, from the NCCEH Environmental Health Seminar series, discusses the less quantifiable impacts of extreme flooding events and provides Canadian examples of flood mitigation activities.
   
• Mould investigation: an online course for public health professionals (NCCEH, 2020)
  This free online course provides practitioners with instruction on mould inspection, sampling, remediation, and prevention. It can be completed in 6-8 hours and learners will receive a Certificate of Completion and 7 professional development hours for CIPHI(C) holders.
   
• Finding safe water in an emergency (NCCEH, 2019)
  This video helps residents understand their likely water needs in an emergency and how to source or collect water around their homes in a safe manner. For instructions on embedding it in your website, please reach out to [email protected].
   
• Naturally occurring asbestos in an outdoor setting (Miller and Wiens, 2018)
  This field inquiry looks at assessing risk and sampling for naturally occurring asbestos, which can be deposited through flooding.
   
• Mould investigation toolkit (2015)
  This toolkit provides PHIs and EHOs with some of the tools for evaluating indoor environments for mould (and other microorganisms), providing information, conducting walkthrough investigations, and understanding laboratory and consultant reports that they may be asked to review.

• Mould remediation recommendations (2014)
  This evidence review provides PHIs and EHOs with a summary of current knowledge about mould remediation in homes and focuses on the main goals of remediation which are to reduce the risk of exposure to mould and to prevent structural damage.
   
• See our other EH Topic Pages:
  • COVID-19 Management during Public Health Emergencies
  • Mould
  • Extreme heat
  • Indigenous Disaster Response
  • Oil spills and health
  • Psychosocial impacts: Resources for mitigation, response, and recovery
  • Wildfire smoke and health

Selected External Resources

Design for flood prevention and mitigation

This section provides research on how flood risk can be minimized by adaptation at the local, regional, and watershed scales.

• Flood resilience in the face of climate change (Federation of Canadian Municipalities, 2021)
  This website, developed with the support of Infrastructure Canada, offers tools for municipalities to use when planning and implementing flood mitigation.

• Reducing urban flood risk through building- and lot-scale flood mitigation approaches: Challenges and opportunities (Sandlink and Binns, 2021)
  This peer-reviewed article looks at the various drivers of and means to prevent basement flooding in urban areas, with a focus on “private-side” strategies that can be employed by homeowners.

• Developing a research-specific emergency management programme for municipal resilience following the 2013 flood in southern Alberta(Bowerman, 2017)
  This article discusses the Calgary Emergency Management Agency’s emergency management programme for community leaders that came about in the wake of the 2013 Alberta floods. The article highlights the background and realisation of this program, offers recommendations for challenges and limitations, and considers its development going forward.

• Health co-benefits of green building design strategies and community resilience to urban flooding: a systematic review of the evidence(Houghton & Castillo-Salgado, 2017)
  This systematic review examined evidence linking green building strategies in the Leadership in Energy and Environmental Design (LEED) rating system with the potential to reduce negative health outcomes following flooding events. Green building design is found to reduce the risk of waterborne disease, flood-related morbidity and mortality, and psychological harm.

• Preventing disaster before it strikes: developing a Canadian standard for new flood-resilient residential communities (Moudrak and Feltmate, 2013)
  This report highlights the need for flood risk education in Canada, identifies priority areas of focus, and develops best practices for building new residential communities that are more resilient to flooding. Best practices were developed using criteria based on national applicability, effectiveness in reducing flood damage from severe rain events, technical feasibility for implementation, and cost-effectiveness.

• Reducing flood damage(Government of Canada, 2013)
  This webpage offers historical background of flooding in Canada, relevant protective legislation and detailed information on non-structural measures (such as floodplain management, forecasting and warning, and emergency measures) as well as structural measures (such as dams, channel improvements, ice booms, and flood proofing)

Engaging the public in prevention and preparedness

Prevention and preparedness depend heavily on voluntarily action by community members. This section offers toolkits and resource to assist with community engagement. It also includes resources that look at other means through which the risk of natural disasters can be more evenly shared between the public and private sectors.

• Flood Ready (Government of Canada, 2020)?
  This toolkit provides resources on flood prevention and mitigation, as well as videos and infographics for quick dissemination via social media.

• Flood protection resources (INTACT Centre on Climate Adaptation, n.d.)
  This toolkit from the University of Waterloo provides detailed resources and checklists to help homeowners install and maintain key flood protections. Information on understanding insurance coverage and accessing flood protection grants is also provided.  Some resources are also available in French and Chinese.

• Engaging Canadians in flood risk management: Lessons from the international community(Centre for International Governance Innovation, 2017)
  This policy brief provides a scan of international initiatives intended to foster flood risk awareness, engage the public, and encourage changes that support flood risk management. Two key lessons for flood risk management policy are discussed and the brief provides three policy recommendations on how to better engage Canadians in flood risk management.
   
• Municipal flood risk sharing in Canada: A policy instrument analysis (Thistlethwaite and Henstra, 2017)
  This peer-reviewed article examines some of the way in which Calgary, Toronto, and other Canadian cities are sharing the responsibilities and costs of flood risk mitigation through a range of policy tools. The paper also discusses some of the key flaws in the way municipal flood risk planning is undertaken and was followed up with a survey of Canadians’ willingness to share risk in a 2018 study.

 Food safety and security during flood events

Flood events may threaten food safety through contamination of food products in homes and food businesses but may also threaten food security due to destruction of soils, farm animals, and facilities.

• Keep food safe after a disaster or emergency (US Centers for Disease Control, 2021)
  This website discusses what to do with perishable and non-perishable foods that may have been compromised during a power outage or have come into contact with flood water.

• Post-disaster food assessment and salvaging best practices (Alberta Health Services, 2020)
  This literature review examines the evidence and rationale underlying post-disaster food safety practices from Canada, the US and Australia. The review identifies those practices which are scientifically sound, and which are precautionary in nature, and flags several potential issues that require additional research.

• Managing the impact of floodwater contaminants on soil and produce in residential, community and school vegetable gardens (North Carolina State University Extension, 2020)
  This guidance document helps small producers understand the risk associated with various parts of the plant and provides advice on how to mitigate risks due to mosquitos, clean up and contaminated soil.

• Reopening your food establishment after flooding (Alberta Health Services, 2013)
  This guidance document helps operators to complete a self-inspection and address the major challenges of a flooded food premises. They also have a document for personal services establishments.

• Farm flood readiness toolkit (Upland Agricultural Consulting, 2020)
  This toolkit created on behalf of BC Ministry of Agriculture helps farmers assess their flood risk and put in place measures to limit damages, farm-related contamination, the loss of livestock, and disruption to the food system.

• Food safety for Southern US food crop producers after flooding (Alabama A&M and Auburn Universities Extension, 2019)
  This guidance document helps producers determine whether crops are safe for consumption and how to mitigate various health risks due to flooding around the farm. Information on soil testing and remediation are provided.

Health and community impacts

Floods bring the risk of both short- and long-term health impacts. During and immediately after a flood, the key risks are drowning, and physical trauma (slips, fall, electrocution), followed shortly by diarrheal illness and infected wounds. In the long term, individuals may experience psychosocial impacts due to loss, displacement from communities, and family separation. This section draws on the peer-reviewed literature to better understand these impacts and how to address them

• Environmental health effects attributed to toxic and non-infectious agents following hurricanes, cyclones, flash floods and major meteorological events (Erickson et al. 2019)
  This narrative review considers the complex issue of contamination in flood waters, outlining the wide range of infectious and non-infectious hazards and some of the work done around monitoring and assessing vulnerability to these hazards.

• Climate change, floods, and your health(Public Health Agency of Canada, 2018)
  This public health factsheet identifies the short-term dangers (such as drowning and injuries) and long-term dangers (such as disease spread through water contamination and sewage backup, food contamination, and insects, as well as carbon monoxide poisoning, and mental health effects) of flooding. The factsheet also outlines actions to take to mitigate these health risks.
   
• Health risks of flood disasters (Paterson et al. 2018)
  This short commentary provides an overview of the most common acute health impacts of flood events, including drowning, trauma, exacerbation of chronic health conditions, mental health disorders, damage to health infrastructure and increases in cutaneous, gastrointestinal, respiratory, and vector-borne diseases.

• Surface water flooding, groundwater contamination, and enteric disease in developed countries: a scoping review of connections and consequences(Andrade et al., 2018)
  This systematic review identifies and synthesizes the literature on surface flooding, groundwater contamination, and human gastroenteric outcomes. The authors discuss strategies to increase awareness about potential sources of contamination and to motivate precautionary behaviour.

• Linking water infrastructure, public health, and sea level rise: Integrated assessment of flood resilience in coastal cities (Allen et al. 2018)
  This study describes a project that integrated public health, planning, and water utility managers into tabletop exercises carried out by emergency managers, leading to a much more thorough understanding of the hazards involved in specific emergency situations.

• Wellbeing in the aftermath of floods(Walker-Springett, 2017)
  This study analyzed several processes that explain wellbeing for those experiencing flooding. Key pathways to wellbeing outcomes included perceptions of lack of agency, dislocation from the home, and disrupted futures. There were offsetting positive impacts to these negative effects via community networks and interactions.
   
• Flooding and mental health: A systematic review(Fernandez et al., 2015)
  This systematic review mapped and assessed scientific evidence on mental health impacts of floods caused by extensive periods of heavy rain in river catchments. Four broad areas of findings were identified: 1) main mental health disorders, post-traumatic stress disorder, depression, and anxiety; 2) factors associated with mental health among those affected by floods; 3) the narratives associated with flooding and long-term stressors; and 4) management actions.
   
• No calm after the storm: A systematic review of human health following flood and storm disasters(Saulnier et al., 2017)
  This systematic review analyzed morbidity and mortality linked to floods or storm disasters with attention to how the burden of disease varies during different phases after floods and storms. The review included 113 studies and found that poisonings, wounds, gastrointestinal infections, and skin or soft tissue infections all increased after storms and that gastrointestinal infections were more frequent after floods. The majority of health changes occurred within four weeks of floods or storms.
   
• Health effects of flooding in Canada: a 2015 review and description of gaps in research(Burton et al., 2016)
  This review summarized the epidemiological evidence of flood-related health effects and the Canadian susceptibility to these effects. Recommendations are also offered for addressing the health-related effects of flooding.

Re-occupying flood-affected communities

These resources address some of the immediate physical and chemical hazards encountered when re-entering flood affected areas, such as mould, carcasses, gas leaks, live electrical connections, structural instability and contamination from hazardous materials like fuel and household and agricultural chemicals. These hazards may be encountered in homes, but also businesses and public spaces like parks and playgrounds.

• Flood zones are danger zones (BCCDC, 2021)
  This website summarizes the primary physical, chemical, and microbiological risks for members of the public who are trying to re-enter a home in a flood zone. The resources provided within this document are specific to British Columbia.

• Post-disaster building assessment training (BC Housing, 2021)
  This toolkit offers online resources and training to rapidly capacitate practitioners, enabling them to perform first-pass structural assessments on buildings impacted by flooding or other natural disasters.

• Reopening outdoor public spaces after flooding (US Centers for Disease Control and Prevention, 2021)
  This website provides suggestions for public health officials who must assess public parks and playgrounds and determine what action should be taken before reopening to the public.

• Re-entering your flooded home (US Centers for Disease Control and Prevention, 2020)
  This website helps homeowners identify the major hazard encountered during clean up. Additional checklists for structural safety and for inspecting household utilities are provided by the American Red Cross.

• The impact of flood and post-flood cleaning on airborne microbiological and particle contamination in residential houses (He et al., 2014)
  This study analyzed results from a comprehensive, multi-parameter indoor and outdoor measurement campaign to assess the effects of flooding on air quality and the role of prompt cleaning activities in reducing airborne exposure risks.
   
• Cleaning the house after a flood (Alberta Health Services, 2013)
  This detailed guidance document provides advice on how to safely clean and prepare homes for re-entry. The guide focuses on personal protective equipment, food safety, floors, walls, ceilings, electrical equipment, lights, fixtures, wiring, appliances, furnaces, water heaters, plumbing, and what to discard and what to save. AHS has also provided these helpful checklists to help prioritize and address specific areas of the house to allow safe re-habitation.

Water safety during flood events

Flood waters are highly contaminated and can compromise drinking water and wastewater utilities of all sizes. However, smaller systems, including private water wells and small community water systems, will be at greatest risk due to lack of knowledge on how to respond to floods.

• Use safe water after a natural disaster or emergency (US CDC, 2021)
  This website explains the ways in which drinking water may become contaminated and provides advice on how to find safe water sources and what they can be used for.

• Be Well Aware - Ensure your well water is safe during and after emergencies (Government of Canada, 2019)
  This guidance document explains the risks that flood pose to wells. Detailed information on how to shock chlorinate a well can be found here.

• Be Well Aware - Test your well water (Government of Canada, 2019)
  This guidance document provides information on chemical and microbiological well water testing. Detailed information on well testing in eight languages can be found here.

• Flood resilience: A basic guide for water and wastewater utilities (US Environmental Protection Agency, 2015) 
  This guidance document helps small and medium utilities, which are more numerous and less resourced than large utilities, to address their flood-related vulnerabilities.

• Sewage systems and flooding: Safety, sanitation, and clean-up (Government of British Columbia, n.d.)
  This guidance document describes how to assess whether a septic system has been compromised by flood and steps to restore it to service.

 This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.