In February and March 2022, the Northern Rivers region of NSW experienced what became one of the most devastating flood events in Australian history. Floodwaters in Lismore rose more than two metres above the previous record. Residents were stranded on rooftops. More than 10,800 homes were damaged. Landslides cut communities off for weeks. Emergency services were overwhelmed and warning systems proved inadequate.
Years later, many people in the region are still struggling — with housing, with finances, with their health. Some of that struggle is visible. Much of it is not.
This post is about what flooding actually does to health, beyond the immediate emergency — and why the home environment sits at the centre of so much of the long-term damage.
The Immediate Threats
The acute risks of flooding are well understood. Drowning, injury, contaminated water and disrupted access to healthcare and medications are the most immediate concerns. Floodwater carries sewage, agricultural chemicals, heavy metals, pesticides, biotoxins and waterborne pathogens directly into buildings — and after the water recedes, toxic contaminants remain in dried sediments on floors, walls and surfaces, becoming airborne again through everyday activity like walking and cleaning.
This means the health risk does not end when the water does.
Mould: The Hidden Health Crisis After a Flood
The most significant and most overlooked long-term health consequence of flooding is mould. Buildings that are not dried out within 24 to 48 hours of water ingress will develop mould — and in a major flood event, comprehensive drying within that window is almost impossible for most households.
Following Hurricane Katrina in 2005, indoor mould spore counts in flooded homes ranged from 6,142 to 735,123 spores per cubic metre. Cases of mould-induced asthma among children in Louisiana increased dramatically in the aftermath. The same pattern emerges after every major flood event.
Research has shown that mould exposure activates the innate immune system, triggering neural immune responses with concomitant cognitive and emotional dysfunction. People who spend time in mould-affected buildings report respiratory problems, chronic fatigue, muscle and joint pain, anxiety and cognitive impairment. In some studies, neurologists could not distinguish between the neurological profiles of people with prolonged mould exposure and those with mild to moderate traumatic brain injury.
For those already dealing with illness — or those who developed Toxicant Induced Loss of Tolerance following the flood exposure — returning to a home that has not been properly remediated is not recovery. It is continued exposure.
Respiratory Health
A Yale School of Public Health study found that flooding exposure was associated with increased mortality from cardiovascular disease, respiratory disease and mental disorders — well beyond the immediate disaster period. The US Centres for Disease Control has identified that damp indoor environments are correlated with upper respiratory tract symptoms, cough and wheeze in otherwise healthy people, and with worsening asthma. For children in flood-affected homes, lower respiratory tract symptoms are the most common post-flood health outcome.
Flooding also creates conditions for mosquito-borne infections including Ross River virus, and for bacterial infections such as leptospirosis, which spreads through contaminated soil and water.
Mental Health: The Longest Tail
Research from the University of Sydney following the 2017 Northern Rivers floods found that people displaced from their homes for more than six months had double the probability of reporting continuing distress, post-traumatic stress disorder, anxiety and depression compared to those who were briefly displaced.
The 2022 floods compounded that existing burden. The Northern Rivers had already experienced major flooding in 2017, bushfires in 2019 and 2020, and the COVID pandemic before the 2022 event. Research shows that repeated disasters have a compounding effect on mental health, producing worse outcomes than a single event alone.
Insurance disputes, financial stress, ongoing housing insecurity and the slow pace of government support are all documented stressors that extend the mental health impact well beyond the disaster itself. In some Northern Rivers communities, only 18% of people accessing flood recovery services have permanent housing — years after the event.
Why the Home Environment Is Central
The health consequences of flooding are not evenly distributed. They cluster in people who remain in or return to flood-damaged homes that have not been properly assessed and remediated. Hidden mould in wall cavities, subfloors and ceiling spaces continues to drive immune activation, respiratory symptoms, cognitive impairment and chemical sensitivity long after the visible damage has been repaired.
Visible remediation — new gyprock, fresh paint, repaired floors — does not address what is inside the walls. For people who are not recovering as expected, the home environment is a critical variable that is almost never systematically assessed or included in insurance claims.
The Compounding Reality
It would be dishonest not to acknowledge how difficult proper remediation is. Flood restoration is expensive, technically complex and often contested by insurers. The Northern Rivers was already experiencing a housing affordability crisis before 2022 — with rental vacancy rates among the lowest in the state and purchase prices that had surged through the pandemic years. The floods destroyed or damaged thousands of homes in a market where there was nowhere else to go. For many families, the choice has not been between a fully remediated home and a healthy one. It has been between a damaged home and homelessness.
Rising construction costs and building inflation since 2022 have made the problem worse. Remediation that would have cost a certain amount in 2021 costs significantly more today, and many households — particularly renters and uninsured or underinsured owners — are carrying the burden of that gap. The health consequences described in this post are not simply the result of inadequate individual action. They are also the result of structural failures in disaster response, insurance, housing and public health support.
This is the long tail of flood recovery — the silent, ongoing health crisis that follows a severe and region-wide water event, and that our public health systems are not yet adequately equipped to see, measure or address.