Staying healthy after a flood

Be careful around contaminated water

Sewage and other hazards can contaminate water and debris.

If you are concerned about the quality of your drinking water, contact your water supplier, local council or local public health unit on 1300 066 055.

Avoid swimming in rivers, lagoons and estuaries for at least 3 days after heavy rain.

Infrastructure and utilities after floods

Infrastructure that supplies clean drinking water, sewage, power and gas can be damaged by floods. Check with your power, gas or water supplier about what to do after an emergency.

If you think your septic tank vessel or pipe junctions have been damaged, get them inspected.

If a water bore you use for domestic purposes has been affected by floodwater:

• use an alternative source (e.g., bottled or rainwater), or
• bring the water to a rolling boil before use.

Blue-green algae

Blue-green algae (cyanobacteria) can form in stagnant water, such as floodwater. Blooms of algae can range from dark green to brown, and can turn surrounding water green.  

Water affected by blue-green algae is not suitable for drinking.  

Some species of blue-green algae can also produce toxins which can harm you when inhaled or when it touches your skin. Symptoms can include: 

• skin irritation

• respiratory effects 

• vomiting  

• diarrhoea  

• fever

• headaches.  

Pets can also be poisoned by blue-green algae. Do not let your animals swim in algae-affected areas. Likewise, livestock owners should continuously check water supplies to ensure it’s safe. 

If you or any animals come into contact with affected water, wash thoroughly with clean water, and monitor for symptoms. 

Boil water alerts following floods or storms

If a boil water alert has been issued in your area, it means water from the tap is not safe to drink.

Find out more about what to do if a boil water alert is in place.

NSW Health publishes local drinking water quality and incidents.

When a boil water alert is in place, all water for eating and drinking should be brought to a rolling boil and then allowed to cool, including water for:

• brushing teeth
• washing raw food
• making ice
• your pets to drink.

If possible, use bottled water.

You can also disinfect water with unscented household bleach (containing 4% – 5% available chlorine):

• add 2 drops of bleach to 1 litre of water, or 4 drops of bleach if water is cloudy
• mix well
• allow to stand for 30 minutes before using.  

After a boil water alert is lifted, make sure you follow your water supplier's advice on how to flush your water pipes.

Practise good hygiene in flooded areas

Make sure you practice good hygiene during and after a flood.

Always wear a nose and mouth guard or dust mask when collecting and removing rotting material including vegetation or spoiled food.

Use personal protective equipment, including gloves, covered shoes or boots and full-length clothing to cover your arms and legs.

Wash your hands with soap and water (bottled, boiled or disinfected) after:

• handling items that are potentially contaminated with floodwater or sewage
• going to the toilet
• before handling or eating food.

Avoid coughing or sneezing on others. Use only clean eating utensils, toothbrushes, towels or handkerchiefs and avoid sharing these items.

If using disinfectants or other cleaners, follow safety advice on labels and do not touch your face (especially your eyes).

All wounds other than clean, minor cuts are at risk of tetanus. Seek medical advice for dirty wounds or wounds where the skin has been penetrated. First aid treatment should always include cleaning the wound and using an antiseptic.

After heavy rain or flooding you may find mould in your home or workplace.  Read more about mould and your health on the NSW Health mould fact sheet.

Be careful of what you eat

Throw out any food that has been in direct contact with floodwater or has an unusual smell, colour or texture. Eating unsafe food can cause serious illness. Food is considered spoiled if it has been in:

• direct contact with floodwater

• a fridge that has been left above 5°C for more than 4 hours
• containers with screw caps, snap-lids, soft drink bottles, twist caps, flip-top lids or home-canned foods.

If a freezer door is kept shut, frozen food will not spoil for 24 hours. Never refreeze food that has defrosted.

For more information about cleaning up after a flood, visit Clean-up assistance and advice.

Mosquitoes can cause serious illness

Mosquitoes can transmit serious illnesses that spread to humans through mosquito bites. Mosquito-borne ilnesses that are found in NSW include Murray Valley encephalitis, Ross River virus, Barmah Forest virus, Kunjin virus, and Japanese encephalitis. 

Mosquito numbers can rapidly increase in the water left behind by flooding. If you live or work in a flood-affected area, you are at higher risk of catching a mosquito-borne illness. 

Most mosquito-borne illnesses in NSW are not vaccine preventable, so it is important to take protective measures to avoid bites:

Spray up
Apply mosquito repellent evenly to all areas of exposed skin. The most effective repellents contain picaridin, DEET or oil of lemon eucalyptus. Read the instructions to find out how often you should reapply repellent. Always apply sunscreen first and then apply repellent. 

Cover up
Cover up while outside and wear loose, long-sleeved, light-coloured clothing and covered footwear and socks, particularly at dawn and dusk when mosquitoes are most active.

Screen up
Close doors and windows when indoors, or install fly screens on windows and doors, vents and other entrances to keep mosquitoes out of your home.

Clean up
Mosquitoes need stagnant water to breed and lay their eggs. Remove items around your home that might collect water such as children’s toys, buckets, empty pots or old tyres. Think about improving drainage around your home to ensure water doesn’t pool and become stagnant.

More information on preventing bites and mosquito-borne diseases is available at NSW Health.

Encephalitis symptoms 

Most people infected with the Japanese encephalitis virus or the Murray Valley virus do not get any symptoms. In rare cases, symptoms can appear 5 to 15 days after being bitten by mosquitoes. 

If you develop these symptoms, immediately contact a doctor or Healthdirect on 1800 022 222: 

• fever 

• headache 

• vomiting 

• nausea 

• loss of appetite 

• diarrhoea 

• muscle aches 

• neck stiffness 

• sensitivity to bright lights 

• drowsiness and confusion. 

In a life-threatening situation, call Triple Zero (000) or visit your nearest emergency department.