Top 10 Worst Floods in Australian History

Australia is a land of big rivers and bigger rain when the cycle turns. Here are the top 10 worst floods in Australia, ranked by a mix of lives lost, scale of damage, record heights, area affected and lasting impact on policy and communities. Then we unpack why they happened and what you can do at home to get ready for the next big wet.

The top 10 worst floods in Australian history

1. 2022 Eastern Australia floods (NSW & QLD) — Catastrophic flooding struck South East Queensland and large parts of coastal and inland NSW, with record peaks in the Northern Rivers (including Lismore) and repeated flooding in the Hawkesbury–Nepean. It became Australia’s costliest natural disaster for insurers to date and displaced tens of thousands. Back-to-back systems, saturated catchments and complex river junctions turned a bad season into a historic one.
2. 2010–11 Queensland and Brisbane floods — A prolonged La Niña soaked much of QLD, culminating in deadly flash flooding in the Lockyer Valley and major riverine flooding in Brisbane and Ipswich. Vast areas of the state were declared disaster zones, mining and agriculture were hit hard, and the event reshaped dam operations, land-use planning and floodplain understanding across the country.
3. 1893 Brisbane River floods ("Black February") — Multiple peaks in a single month smashed records along the Brisbane River and Bremer River. Bridges were swept away, whole suburbs were inundated and the event set benchmark flood heights referenced more than a century later. For the population of the day, the scale was staggering.
4. 1955 Hunter Valley/Maitland floods — Intense rain saw the Hunter River break levees and surge through Maitland and surrounding towns. The destruction of homes and businesses led to major changes in levee design, warning systems and the way floodplains are managed in NSW. The images of rooftops above an inland sea are etched in Australian memory.
5. 1867 Hawkesbury–Nepean flood (NSW) — Among the highest recorded on that floodplain, this event set peak levels at places like Windsor that remain a planning reference. The basin’s "bathtub" geometry (narrow gorges feeding a broad floodplain) explains why even moderate rain on a saturated catchment can produce extreme depths and long-duration flooding.
6. 1974 Brisbane and South East Queensland floods — Fed by Cyclone Wanda and a very wet summer, these floods inundated Brisbane and Ipswich, damaged infrastructure and hastened the case for major flood-mitigation works. Many older suburbs saw depths not experienced since the 1890s.
7. 2019 North Queensland/Townsville floods — A stubborn monsoon trough delivered extraordinary multi-day rainfall. Controlled releases from Ross River Dam were necessary to protect the structure, yet many suburbs still flooded. The event stretched from urban Townsville to vast pastoral areas, with large stock losses and extensive recovery needs.
8. 1998 Katherine flood (NT) — Ex-Tropical Cyclone Les parked over the Top End, driving the Katherine River to a record peak. The CBD and many homes were inundated, prompting significant rebuilds, flood mapping updates and community preparedness improvements for wet-season towns.
9. 1934 Melbourne/Yarra and Maribyrnong floods — Intense rain over the Yarra catchment inundated low-lying suburbs and industrial areas. While many waterways have since been channelled or constrained, the 1934 event remains a touchstone for flood risk in Melbourne’s inner west and along the Yarra flats.
10. 1990 Nyngan (NSW) flood — The Bogan River overtopped and breached levees, forcing the near-total evacuation of Nyngan, many by helicopter. The damage relative to the town’s size and the logistical effort to recover make it one of the most significant inland floods in modern NSW history.

Any top 10 will stir debate because "worst" depends on the yardstick: casualties, insured losses, total economic cost, flood heights, duration or area. The events above consistently rank across multiple measures and left enduring lessons for policy and households.

Why these floods were so destructive

Floods are simple in concept (too much water, too fast) and complex in reality. The standouts here share a few ingredients:

• Climate drivers lined up: La Niña phases shift the odds towards wetter conditions in eastern and northern Australia. Add a monsoon burst, an East Coast Low or a slow-moving tropical cyclone and extreme rain becomes more likely.
• Saturated catchments: A big wet after weeks of prior rain means the ground can’t soak up much, so most of the water runs off into creeks and rivers.
• Floodplain geometry: Basins like the Hawkesbury–Nepean have narrow "choke points" that back water up over broad plains, producing high, long-lasting floods.
• Urban growth: More roofs and roads speed runoff into drains and rivers. When towns expand onto floodplains, more assets are exposed.
• Compounding and repeat peaks: Some years deliver multiple systems and peaks only days apart (1893, 2022), exhausting defenses and communities.

How floods hit homes and hot water systems

Beyond the headlines, floods are about damp plasterboard, silt in meters, and appliances full of dirty water. Hot water systems are especially vulnerable because they often sit outdoors or under houses.

• Before a flood watch: Know your cut-offs. Label the main power switch, gas isolation valve and water stopcock. If you’re in a flood-prone area, consider elevating the water heater on a sturdy plinth above known flood levels and securing LPG cylinders with chains.
• When flooding is likely: Move portable appliances and chemicals high and dry. Turn off non-essential circuits. If advised to evacuate and it’s safe, shut off gas and electricity at the mains.
• After waters recede: Do not energise an electric or heat-pump unit, or relight a gas water heater, until a licensed electrician and plumber have checked it. Sediment in burners, controls and valves is a safety risk. Many submerged storage tanks, instantaneous gas units and heat pumps need replacement rather than repair.
• Disinfection and flushing: If floodwater entered pipework, taps may spit silt and air. Flush lines until clear. For rainwater-fed hot water, disinfect the tank and have the tempering valve checked. See our guide to emergency hot water shut-off for safe isolation steps.
• Insurance and records: Photograph waterlines on walls and appliances before cleanup. Keep serial numbers and invoices; insurers and disaster relief services will ask.

What we’ve learned (and what’s changing)

Every major flood reshapes how Australia manages water and builds on floodplains:

• Better warnings: The Bureau of Meteorology and state agencies have expanded gauges, models and flood-watch services. Community education now focuses on consequences (depths, road cuts, isolation) not just peak times.
• Mitigation, not elimination: Dams, levees and detention basins reduce peaks but can’t eliminate risk. Many towns now mix structural measures with planning controls and voluntary house-raising or buybacks in the highest-risk zones.
• Planning rules: Minimum floor levels, flood overlays and building standards better reflect local hazards. Post-2011 and post-2022 reviews tightened requirements in several councils.
• Household resilience: More owners elevate switchboards, hot water units and air-con condensers; choose flood-tolerant finishes downstairs; fit backflow devices; and keep an evacuation and documents plan.

Prepare your place for the next big wet

You can’t steer the rain, but you can cut your risk and downtime:

• Know your risk: Check council flood maps, historic peaks in your street and where water will likely come from (river, overland flow, storm surge).
• Sort the services: Raise sockets, the switchboard (where possible) and the hot water unit above likely flood levels. Seal wall penetrations and fit non-return valves to low-level drains.
• Maintain the property: Keep gutters, yard drains and street gutters clear. Regrade garden beds that steer water toward the house.
• Emergency ready: Store critical spares up high: extension leads, torches, a basic tool kit, plastic sheeting, pipe caps and a wrench for gas bottles. Keep important documents in a dry grab-bag.
• Insurance and photos: Review your policy’s flood definition and sums insured. Take yearly photos of each room and key appliances (including the data plate on your water heater) to speed claims.
• After a near-miss: If water lapped the slab or entered subfloors, get a post-event electrical and plumbing check. Damp connections and valves can fail weeks later.

Floods are part of Australia’s climate story. Knowing which ones were the worst helps explain today’s maps, rules and warnings — and reminds us to prepare. A few practical changes at home, especially around power, gas and hot water, can turn a disaster into a tough week rather than a lost season.