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Floods, cyclones and other disasters

Fact sheets


It is important that you are aware of the health risks you may come across following a flood or cyclone, particularly when you attempt to clean up your house. Some of the common health risks include: Asbestos contamination

  • Food safety and disposal
  • Bores
  • Drinking water (and rainwater)
  • Dead animal carcasses
  • General household cleanup
  • Mould (External link)
  • Injury prevention and bacterial infections
  • Mosquitoes
  • Poisons, chemicals and pesticides
  • Damaged containers and spillage
  • Snakes, pests and other wildlife
  • Recreational waters, shellfish and fishing
  • Swimming pools
  • Septic tanks
  • Sewage overflows


    1. Asbestos contamination

    Natural disasters often bring serious concerns for homeowners dealing with asbestos exposure, especially those facing clean up projects. Asbestos-containing materials pose generally no threat when in good condition, painted or sealed, and in a bonded form, but become dangerous when broken or shattered into pieces.

    Asbestos-containing materials may include:

    • Roofing, shingles and siding
    • Fencing
    • Exterior wall cladding
    • Backing material on floor tiles and vinyl flooring
    • Textured paints
    • Water or flue pipes
    • Insulation material or lagging

    Any of these materials produced before the mid 1980s may potentially contain asbestos. If in doubt, assume and manage them as if they are asbestos.

    If a home, structure or building is already damaged due to flooding or a cyclone, the site should be secured and contained. For safety reasons, a licensed asbestos contractor should be hired to remove any asbestos-containing materials from the debris. However, some homeowners may choose to do part of the clean up themselves, but this comes with great risk and is not advisable, especially if the material is in poor condition or fibrous.

    Things to avoid

    • Avoid removing asbestos materials unless absolutely necessary
    • Only remove asbestos materials that are already broken and dislodged
    • Avoid breaking asbestos materials
    • Asbestos roofs must NOT be cleaned using high pressure water cleaners or water blasters
    • Avoid walking on corrugated asbestos roofs as they may collapse from the weight
    • Do not use power tools or any abrasive materials (e.g. sanders) on asbestos materials
    • Do not put asbestos waste into bins or with items for kerbside collection

    When picking up pieces of asbestos material

    • If not already wet, wet the pieces with water
    • Systematically pick up the pieces and place them into a thick plastic bag and place this bag into another bag (double bagging). Do not over fill. Seal the bag opening with tape or a knot
    • If asbestos materials may have been covered, gently rake the surface to identify and remove them
    • Label the outer bag “Caution – Asbestos”
    • Contact your local council to find out how you can dispose of the waste safely
    • Dispose of properly as soon as practical

    Cleaning asbestos

    Asbestos-containing material surfaces that are covered with dirt or silt can be cleaned using garden hoses, or by hand. This is only appropriate for those materials which remain intact and in place. Do not use water blasters or other high pressure water or air processes on asbestos containing materials, or hard brushes, especially when cleaning asbestos roofs. Ideally you should wear an appropriate face mask and disposable overalls. These can be purchased from any reputable hardware store.

    Refer to the asbestos contamination webpage for a range of resources to help you manage asbestos contamination (including contaminated soils). The asbestos removal webpage provides additional information on how to remove and dispose of asbestos safely. 

    Decomposing food from a flooded fridge2. Food safety and disposal

    When disasters cause a power outage, it generally means the food in your fridge will start to go off. Unless cold storage is available within 2 hours of a power cut, all potentially hazardous foods stored in refrigerators or chillers need to be placed in alternative cold storage, consumed immediately or disposed of.

    When disasters cause a power outage, it generally means the food in your fridge will start to go off. Unless cold storage is available within 2 hours of a power cut, all potentially hazardous foods stored in refrigerators or chillers need to be placed in alternative cold storage, consumed immediately or disposed of.

    If the power is off for more than 4 hours throw it out!

    Food in freezers should not spoil for at least 24 hours if the door has been kept shut. The food should be eaten directly after it has defrosted, if safe to do so.

    General tips:

    • Wrap spoiled food in newspaper and place in the rubbish bin. A small volume of food may be safely buried
    • Where larger quantities have to be disposed of your local shire council’s Environmental Health Officer should be contacted to organise disposal and burial. Without correct disposal, fly breeding may result and increase the risk of spread of infectious diseases
    • Some canned food may be kept but if the can is dented or damaged it should be thrown away
    • If in doubt, throw it out
    • Dishwashers - do not use a dishwasher that has been exposed to floodwater

    Refer to The power is off and so is my food (PDF 200KB) (External link) (External link)

    Vegetable gardens

    Floodwater may have contaminated your vegetable or herb garden. Some garden produce may be salvaged. Disinfecting, peeling and cooking is recommended to prevent food borne illness. 

    3. Bores

    Following flooding, the integrity of bore systems and holding tanks may be compromised by floodwater entering the system.

    Bore water should not be used for drinking purposes. However, some people use bore water for irrigation or laundry purpose. If this is the case, providing you are satisfied that the bore has not been contaminated by floodwaters, then the disinfection procedure recommended from the bore pump to the storage tanks is as follows:

    • Where the storage tank is clean, 1.5 grams of dry pool chlorine per 1000 litres is sufficient to ensure potable water
    • Where the tank has been contaminated, then 150 grams per 1000 litres for turbid water or 75 grams per 1000 litres for clear water should be left to stand in the tanks for 4 hours. The tank should then be drained (but this water is not to be drunk) and refilled adding 1.5 grams of dry pool chlorine per 1000 litres

    Refer to the bore webpage for further advice. 
     

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    4. Drinking water

    Mains scheme water

    If you are connected to the mains water it is important you find out if a ‘boil water’ alert has been issued in your area.

    If a ‘boil water’ alert has been issued, it is essential you follow this warning as it has been initiated to prevent illness. Water for consumption should be brought to a rolling boil and then be allowed to cool and placed in the refrigerator in a clean lidded container. Under no circumstances should water that has not been boiled be consumed until the alert is lifted. Alternatively bottled water may be used.

    Cooled boiled or bottled water should be used for:

    • Drinking
    • Cooking
    • Washing raw foods (such as seafood or salads)
    • Making ice
    • Cleaning teeth
    • Pet's drinking water

    Dishes should be washed in hot soapy water or in a dishwasher. Children should take bottled or cooled boiled water to school.

    Listen to your local radio station for updates. When the ‘boil water’ alert is lifted, follow the water supplier’s instructions about flushing the household water pipes.

    Rainwater

    Inundated or damaged rainwater tanks may be contaminated and/or become breeding areas for mosquitoes. Action should be taken, as soon as is safe to do so, to ensure mosquitoes are prevented from breeding in these tanks. In instances where they are not salvageable they should be drained.

    Where they are salvageable, they need to be disinfected in accordance with the Drinking water: Emergency treatment of drinking water supplies (PDF 100KB)

    Refer to the Using Rainwater After a Bushfire (PDF 100K) where rainwater tanks may have been contaminated either indirectly by ash, smoke, debris or directly by fire and fire fighting activities. 

    5. Dead animal carcasses 

    Following a natural disaster, many animals, particularly farm animals may not survive. It is important to promptly dispose of these animal carcasses to prevent fly breeding, reduce odours, and protect surviving animals from disease.

    Landholders should search their property for dead animals as soon as possible after a disaster, provided it is safe to do so. In some cases, carcasses may have commercial value, so consider sending them to a rendering plant if possible. If rendering is impractical, dispose of the dead animals on the premises. The following procedures may be used:

    • Cover a carcass with crude oil or kerosene to keep away dogs, scavenging birds and vermin. NOTE: Well fed pigs are the only animal carcasses that will burn satisfactorily. Old railway sleepers can be used as fuel. Burning of other carcasses is not recommended
    • Bury other carcasses. Use earth moving equipment if it is available
    • Choose a site where subsurface drainage will not reach water supplies
    • Bury the carcass at least 90cm -120cm (3-4 feet) deep, so predatory animals won't be able to reach them
    • If quicklime (“Builder’s Lime”) is available, cover carcasses with it before backfilling. Quicklime hastens decomposition
    • Contact your local council animal control officer for further guidelines

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    6. General household cleanup

    General tips before you start:

    • Use protective clothing: rubber boots, waterproof gloves. Use a facemask or goggles to protect your eyes if you are scrubbing, hosing or pressure-washing
    • Cover any open cuts, scratches, grazes/wounds with waterproof dressings
    • Be careful with any electrical or gas equipment or lines. Do not switch on electrical or gas equipment until it has been checked by a licensed electrician or gas fitter
    • Keep children and pets away from the flooded building until it has been cleaned and made safe.
    • Remember to wash your hands thoroughly after each clean-up session and always before eating or handling food
    • Take your time, do not overdo it when cleaning up. You will be under enough stress and strain from the flooding, your health is critical. Take frequent breaks. Stay warm when it is cold and be careful not to overheat when it is hot
    • Do not wait until you are thirsty to drink and ensure you drink plenty of fluids
    • As you clean up, take photographs or make a list as you go for your insurance claim
    • Refer to the “Recovering After the Flood Clean up Information to Householders (PDF 100KB)”. 

    7. Mould

     

    Cleaning up mould:

    If you intend to clean up mouldy areas it is recommended that you wear:

    • a shower cap
    • goggles and
    • ‘P1’ or ‘P2’ particulate face respirator to prevent breathing in mould spores.

    Steps to minimise mould after a flood

    Mould removal efforts should focus on:

    • Removing all sources of pooled water or excessive moisture from the home
    • Removing all wet or flood damaged materials or items, including wallpaper, plasterboard, carpet, rugs, bedding, mattresses, furniture, stuffed toys, clothing, and other wet or damaged materials that cannot be adequately dried or cleaned
    • Removing all porous (i.e. soft or absorbent) materials with mould growth
    • Temporarily storing damaged or discarded items outside the home (in a safe, clean, dry place such as a shed or garage) until your insurance claim is processed
    • Cleaning and disinfecting all affected surfaces inside the house, including floors, walls, the kitchen, bathroom and laundry
    • Allowing the house to dry throughout by airing or active drying (e.g. fans or dehumidifiers)

    Drying out the house after a flood

    When returning to your home after a flood, open doors and windows to let the house air out for as long as possible.

    Once reliable, safe power is restored use fans and dehumidifiers to dry out the house.

    Air conditioning or central heating should not be used unless they are undamaged and uncontaminated by the floodwaters. If you suspect contamination with mould or floodwaters, do not use until these systems have been cleaned and checked by a qualified person.

    Refer to the mould webpage for further details. 

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    8. Injury prevention and bacterial infections

    Dirty water, mud and silt that floods and cyclones may bring into our home, backyards, streets, parks and local playgrounds can contain a range of bacteria and viruses that can make you or your family sick. Such illnesses may include diarrhoea and gastroenteritis, or skin and soft tissue infections.

    Floodwaters also make surfaces, such as footpaths, roads and floors very slippery and falls are not unusual in flood clean-ups. Cyclonic winds can lift a range of materials and debris such as fences, roofs, electricity wires and even cars into potentially hazardous areas. It is important that you take proper precautions to prevent illness and injury during and following a disaster including:

    • Always wearing protective clothing when cleaning such as boots, gloves and a face mask
    • Not exposing broken skin or cuts to dirty water, mud or silt
    • Not using petrol or diesel-powered equipment, such as generators or pumps, in enclosed spaces
    • Being alert to snakes, spiders and rats that may have taken refuge in your home
    • Making sure your immunisations – especially tetanus – are up-to-date
    • Always washing your hands and any part of your body that has been exposed to dirty water, mud or silt, especially before eating or preparing food
    • Wearing a mask when working with heavy mould
    • Never touching electric wires, even if you think they are not ‘live’

    If you do become ill or injure yourself, you need to seek medical attention, particularly if any cut becomes painful and red and if you develop a fever. 

    Potential mosquito breeding after a flood9. Mosquitoes

    Stagnant water left behind by floods and rain also provides an excellent breeding ground for mosquitoes, increasing the risk of the mosquito-borne diseases such as Ross River Virus (RRV) disease and Barmah Forest Virus (BFV) disease. In the North, there is also the potential for the rare, but potentially fatal Murray Valley Encephalitis (MVE).

    Common symptoms of RRV and BFV diseases include joint pain and inflammation, as well as tiredness and muscle aches. MVE symptoms include fever, drowsiness, headache, stiff neck, nausea and dizziness, leading to fits and coma.

    Mosquito breeding may occur over vast areas after flooding. However, you can make a difference by preventing mosquitoes breeding around your home. Empty or discard any containers that can hold water, such as pot plant drip trays, buckets, bottles, cans and tyres. Ensure that open drains and roof gutters are kept clean and use mosquito-proof mesh to cover rainwater tank inlets and overflows.

    To protect yourself from mosquito bites wear loose, light-coloured clothing, use insect repellent and stay indoors behind screens when mosquitoes are around. You should also consider repairing defective insect screens around the house and using insect spray to kill mosquitoes in the home.

    The most effective mosquito repellents contain 20-50 per cent DEET or picaridin.

    Refer to the Mosquito webpage for further information, including information on Mosquitoes and Cyclones. 

    10. Poisons, chemicals and pesticides

    The floods may have buried, moved or damaged goods including gas cylinders and containers of corrosives, oils, pesticides, pool chemicals, and industrial chemicals.

    Extreme care must be taken when handling any spills or containers of suspected poisons, chemicals or pesticide, especially if the containers are damaged. Areas where these are found should be isolated until safe management has been arranged.

    To safely handle and dispose of such dangerous goods, the following should be considered:

    • Monitor atmospheres in enclosed spaces using a suitable air monitoring device (e.g. gas detector) where plant and equipment exhaust is generated. Ensure exhaust gases are ventilated to prevent the build up of contaminant exhaust gases such as carbon monoxide. Reduce this risk by operating generators and other fuel-powered equipment outdoors wherever possible. For example, pumps used for removing water from a basement should be placed in external well ventilated areas
    • Try to identify chemicals and their hazards using labels and markings. If water has removed the label, seek expert advice and chemical identification from a waste management consultant
    • Wear personal protective equipment such as chemical resistant gloves, protective eyewear, enclosed footwear and long sleeved shirts and trousers to minimise exposure to skin. Note: If there is a chemical odour present, wear a respirator with the correct chemically rated filter and ensure that when handling drums, you work upwind. General protective equipment can be purchased from any good hardware store
    • Separate chemicals from general waste
    • Separate chemicals based on the condition of the container (damaged or undamaged) and on whether they might chemically react with each other. For example, oils and dry pool chlorine may cause a fire if brought together
    • Contact your local council for advice regarding the disposal of dangerous goods and chemicals.
    • Take precautions to protect the area from further damage during the clean up, such as preventing mobile plant (e.g. earth-moving equipment) coming into contact with containers, particularly gas cylinders
    • Chemical processing and handling equipment that has been flood affected should be checked prior to operation, ensuring electrical installations are checked by a qualified electrician.
    • For gas supply systems, e.g. town gas or fixed tank installations, contact your supplier regarding the safe return to operation
    • Ensure the appropriate decontamination of clothing and equipment after handling or coming in contact with chemicals. Wash down clothing with water and launder separately

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    Chemical drums displaced due to a flood11. Damaged containers and spillage

    If there is damage to containers resulting in a leak or spill:

    • Contact the local Fire Services branch and any other relevant Authority for expert assistance for advice, removal or repair
    • Cordon off the area
    • Do not wash spillage down drains
    • Take action to prevent spread of spilled material by using sand, earth or other
    • commercial spill-containing products, when safe to do so
    • Minimise the potential for presence of an ignition point or flame in case the chemical is flammable 

    12. Snakes, rodents and other wildlife

    Dealing with snakes

    Like residents, snakes can become displaced during a flood. As a result, they may seek shelter and food inside houses, storage sheds and other buildings. Damaged structures and debris are more accessible to snakes.

    When outdoors:

    • Wear sturdy work boots and gloves, and long trousers to protect your legs
    • Watch where you place your hands and feet when removing or cleaning up debris
    • If you see a snake, step back from it slowly and allow it to proceed on its way. Do not touch it
    • Remove debris from around your home as soon as practically possible as it can attract rodents, lizards and insects on which snakes feed
    • Be aware of snakes that may be swimming in the water trying to get to higher ground. Be aware that snakes will swim towards a boat and attempt to gain entry. They should be warded off with an oar or other long stake.

    When indoors:

    If you find a snake in your house do not panic:

    • Seek advice from someone who knows how to safely remove the snake. Contact the Department of Environment and Conservation for names of the nearest licensed snake catcher.

    If bitten by a snake refer to the St John Ambulance website for the most up to date first aid treatment.

    Spiders

    If bitten by a red back spider:

    • Wash the affected area well and soothe the pain with ice packs or clean iced water
    • Applying pressure is not recommended for red back spider bites and often worsens the pain
    • Seek immediate medical help

    For other spider bites:

    • Wash the area with soap and water
    • Apply a cold pack if the bite is painful
    • For most spider bites, no other first aid is necessary
    • Contact your doctor if symptoms develop or persist
    • If possible – and safe - the spider should be caught for positive identification

    Discourage rodents

    • Rodents carry disease and are a nuisance
    • Remove food sources and items that can provide shelter for rodents
    • Wash dishes and cooking utensils immediately after use
    • Dispose of garbage and debris as soon as practically possible
    • Lay rodent baits or traps

    Flies

    • Carry disease and are a nuisance
    • If food and garbage builds up, this becomes a breeding ground for flies
    • Clean up food wastes as soon as practically possible

    Refer to the pests and insects webpage for further information 

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    13. Recreational waters, eating shellfish and fishing

    Flood river contaminated with polluted waterRecreational waters (lakes, rivers, estuaries, coastal waters)

    Never swim in floodwaters. Not only is the water likely to be contaminated with sewage and chemicals, there are also unpredictable currents and submerged hazards that are very dangerous.

    Sewage and chemical contamination may continue for some time (weeks) and will affect the quality of the water. If you swim and submerse your head under water you may become ill with severe gastroenteritis, or contract an ear, nose or throat infection.

    If you have an open wound or infection and go swimming in polluted water, your infection may become more infected. Reduce your risk and do not swim if you have an open wound or infection.

    As a standard precaution, the Department of Health recommends that you do not swim for at least:

    • 1 day after heavy rainfall (>10mm) in coastal waters
    • 3 days after heavy rainfall (>10mm) in river/estuarine systems

    If you are uncertain about the quality of water, contact the local council.

    Refer to the environmental waters webpage for further information.

    Shellfish (oysters, mussels, clams, pipis, scallops, cockles, and razorclams)

    Do not eat shellfish from flood affected waters.

    Shellfish feed by filtering food from the water. They can sometimes accumulate harmful substances in their flesh, such as bacteria, viruses, metals, and algal toxins that may be present in the water. These microorganisms and toxins can make people sick if they eat the contaminated flesh.

    Symptoms of food poisoning may range from diarrhoea and/or vomiting to severe respiratory and neurological problems, and occasionally even death.

    Following a flood, it is almost certain that harmful microorganisms and toxins will be present in waterways (including rivers, lakes, estuaries and the ocean) due to run-off from the land.

    Refer to the Wild shellfish collection brochure (PDF 50KB).

    Fishing

    Fish caught during flood periods should be rinsed prior to scaling and filleting. Fish should be cooked thoroughly and people should avoid cross contamination between raw and cooked fish.

    Flooded swimming pool14. Swimming pools 

    Whatever the disaster, unless domestic and commercial swimming pools are kept chlorinated, then the water quality will deteriorate causing them to be a source of odours, possible mosquito breeding and a risk to people who may use them.

    Inundated pools should be drained and cleaned after checking with an expert that the pool will not ‘lift’ out of the ground when drained. ‘Lifting’ is particularly a problem in inundated ground.

    Where a pool has been inundated with floodwater, the pool water will be heavily contaminated and the integrity of the pool structure may be compromised. The filters may need replacing. If the pool cannot be drained, it is recommended that the pool be super-chlorinated to a concentration of 10 mg/L of free chlorine for one hour.

    Refer to the Swimming pools inundated by flood waters (PDF 172KB) brochure.

    For further information on maintaing swimming pools refer to the aquatic facility webpage.

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    15. Septic tanks 

    Flood waters may affect your septic tank system (also known as an onsite wastewater system).

    How will I know if my septic tank system has been affected?

    Septic tank systems typically comprise a concrete, plastic or fibreglass tank which collects the wastewater from toilets, the bathroom, kitchen and laundry in the home.

    Most septic tanks should not be structurally damaged by flooding as they are below ground. However, flood water may enter your septic tank system through the toilet, other fixtures or the overflow relief gully grate. Flooding of the septic system may wash out solids from the tank causing blockages or system damage.

    Collapsed septic tank following a floodSafety issues that need to be checked:

    • beware of open covers/pits
    • ruptured/leaking systems (including pipes)
    • damaged/exposed pipes that may need capping/sealing off.

    Failed systems are not easy to identify, however some simple indicators may include:

    • a pungent odour around the tank and land application area
    • blocked fixtures, with wastewater overflowing from the relief point
    • high sludge levels within the primary tank
    • sewage flowing up through the toilet and sinks

    Some onsite wastewater treatment systems may rely on mechanical and electrical equipment, such as pumps, aerators and filters. This equipment may be damaged by flood or loss of power. To prevent injury or further damage to your system contact your service agent.

    What can happen to the Onsite Waste Water Disposal System during a flood?

    Flooding of the chambers in the septic tank or primary/secondary treatment tanks can lift the floating crust of fats, grease and other materials that naturally form on top of the waste water. Once lifted, the crust can block either the inlet or outlet pipes of the tank and possibly cause solids to transfer from the septic tank to the leach drain or disposal system. In addition, septic tanks, leach drains, pump pits and irrigation pipework can fill with silt and debris which will either reduce the capacity, or effectiveness of the treatment system.

    What should I do if my onsite waste water disposal system has been under flood water?

    Do not use any toilets, laundry, kitchen, bathroom or clean-up equipment connected to the onsite waste water disposal system until:

    • all parts of the waste water treatment and disposal system have been professionally inspected and repaired
    • your onsite waste water disposal system has been approved for use by the Local Authority Environmental Health Officer. (Contact your Local Authority Environmental Health Officer for more information.)

    How can my onsite waste water disposal system be repaired?

    Only trained specialists are suitably equipped to clean or repair onsite waste disposal systems because tanks may contain dangerous gases and other harmful materials. Contact your Local Authority Environmental Health Officer for a list of waste water disposal system contractors who work in your area

    • Onsite waste water disposal systems should be pumped out by a licensed septic tank operator as soon as possible after the flood. However, before this can be done, it is important to ensure that the water level in the ground surrounding the tanks is as low as possible. It is possible for empty tanks to float out of the ground causing damage to underground pipework

    Aerated Wastewater Treatment System (AWTS)

    The AWTS should not be used if it has been inundated with floodwater. Isolate the electrical connection and call the service technician immediately.

    Refer to the Restarting Onsite Waste Water Disposal Systems (PDF 150KB) brochure for further information.

    Additional information on wastewater systems is available on the wastewater management webpage

    16. Sewage overflows

    In all situations where a sewage overflow (also referred to as wastewater overflow) clean up procedure is needed for your property, persons involved in the cleanup procedure should wear personal protective clothing such as rubber boots, rubber gloves and washable or disposable coveralls.

    Unprotected persons should be evacuated from the affected area until the area has been thoroughly cleaned and disinfected.

    Other safety precautions to be followed include:

    • Assume anything touched by wastewater is contaminated
    • Wash your hands and affected areas of the body thoroughly with clean warm water and soap, especially before eating or smoking
    • Immediately wash and disinfect any wounds that come into contact with wastewater
    • Change out of dirty clothes and wash clothes separately
    • Clean and dry dirty footwear
    • Contact your doctor immediately if you experience any illness

    Refer to the Domestic wastewater overflows brochure (PDF 106KB) 

    Fact sheets

    Useful links

    Warnings

    Advice for you and your family

    For further information contact the Environmental Health Directorate on ehinfo@health.wa.gov.au or (08) 9388 4999 

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