Floods

Tap (mains) water may be contaminated by floodwater and become unsafe to drink.

Before using tap water during or after a flood:

• check that it is safe to drink - ask your water provider or local government (shire) if there is a boil water alert.
• if you are unsure whether your tap water is safe, drink bottled water or boil water for at least one minute and cool before using.
• if water is unsafe to drink, make sure everyone in your family knows the water is unsafe to drink, including children.

'Boil water' alerts

A boil water alert is only issued for a specific area when tap water may be unsafe to drink or cook with. Follow the advice given to you to avoid getting sick.

Check the website of your local government (shire) for boil water alerts and additional information.

If a boil water alert is issued, follow the process below:

• before using tap water, run tap for a few minutes to flush out any contaminated water inside the tap, then thoroughly clean tap, handle and spout with hot water and detergent.
• boil the water for at least 1 minute, then allow it to cool. Keep children away from boiling water until the water has cooled to room temperature.
• keep cool boiled water in the fridge (if possible) in a clean container with a lid.
• wash dishes in hot soapy water or in a dishwasher
• give children bottled or cool boiled water for school.

Do not drink or cook with tap water in a boil water alert area until the alert is lifted.

Use bottled or cool boiled water for:

• drinking
• cooking
• washing raw foods (such as salads)
• making ice
• cleaning teeth
• your pet's drinking water
• washing any wounds.

When a boil water alert is lifted, follow the water provider's instructions for flushing household water pipes.

Find out more about emergency treatment of water supplies.

Rainwater tank contamination

Water in rainwater tanks may be contaminated with floodwater, debris, or bacteria.

If there is a risk your rainwater tank has been contaminated by floodwater, do not use the water for drinking or cooking.

The tank will need to be emptied, cleaned and sanitised before refilling. Seek advice on how best to do so.

Drink and cook with bottled or boiled water until the tank can be confirmed as safe.

How to know if your rainwater tank is contaminated

Assume the water in your tank is contaminated if:

• you think the tank roof was covered by floodwater
• there are dead animals on your roof, gutters, or in your tank
• the plumbing to or from the tank is damaged
• the water is cloudy, tastes or smells unusual, or has an unusual colour
• the water contains debris or mosquitoes.

You can test bacteria levels in the rainwater by contacting your local government environmental health services. Alternatively, you can test your water by contacting a NATA-accredited laboratory and ask for a 'Standard drinking water test for your drinking water supply'. 

Electrical safety

If you think your tank's pump or electrical equipment has been impacted by floodwater, you need to have it inspected and declared fit for use by a licensed electrician before reusing pumps or maintaining the tank.

Emptying, cleaning and sanitising a rainwater tank

• If you have an underground tank, do not empty the tank while the ground is still flooded as it may damage the tank walls and plumbing.
• Once the tank has been emptied, the inside of the tank should be hosed out with clean water to remove soil and debris.
• Cleaning large tanks can be a safety risk. Seek advice from a qualified professional tank cleaner to clean inside your tank.
• Following cleaning, sanitise the tank. Ask your tank supplier for the best sanitation method based on the material the tank is made of.
• Any plumbing, guttering, downpipes and roof surfaces connected to a tank that has been flooded will also need to be cleaned and sanitised.

Refilling a rainwater tank

When refilling a tank with water from a commercial water carting company, make sure that the carting company:

• only uses the tanker for drinking water
• gets water from a scheme drinking water supply
• treats the water with at least 1 milligram per litre of chlorine, in transit
• After sanitising, fill the tank with clean drinking water. If unsure about the quality of the water you should either heat the water to a rolling boil for at least 1 minute or use chemicals to disinfect
• follows the Department of Health's Guidelines for the bulk cartage of drinking water (external site).

Read Water tanks on your property for details on refilling and disinfecting rainwater tanks.

Using non-potable water

Water that may not be safe to drink may be okay for showering, bathing and personal hygiene. It is important to have clean and safe water source personal hygiene.

Tips to keep yourself healthy include:

• Keep hands clean to help prevent the spread of germs. Wash hands with soap or sanitiser, and water that has been boiled or disinfected.
• Ensure your non-drinking water source is safe for bathing and showering. Be careful not to swallow any water or get it in your eyes or up your nose. If you are unsure that your non-drinking water is safe to use for washing yourself, check with local government or the Department of Health.
• Only use drinking water to brush your teeth.
• Only use drinking water and soap to wash open wounds. Cover with a waterproof bandage and if a wound becomes red, swollen or oozes, get immediate medical care.
• Do not bathe in water that may be contaminated with sewage or toxic chemicals, or in rivers, streams, or lakes that are contaminated by floodwater, sewage, or animal waste.
• For contact lens hygiene (use and storage) follow the guidance on Acanthamoeba and contact lens use.
• For nasal irrigation hygiene, follow the guidance on Nasal irrigation - is it safe?

Mosquito breeding

After flooding, mosquitoes may breed in rainwater tanks as well as other vessels, containers, equipment or debris that may be holding water.

To prevent mosquitoes breeding in your rainwater tank, replace or repair insect screening and ensure the tank is adequately sealed to prevent further access for mosquitoes. If this cannot be achieved or if the water is contaminated, drain the tank as soon as possible.

Empty and remove or cover any other containers and equipment on your property that is holding water from rainfall or the flood.

Read Water tanks on your property for other ways to prevent mosquito breeding.

Using contaminated rainwater

If a water tank has been contaminated by floodwater, the water can be used to:

• flush toilets
• water the garden
• wash clothes (providing it will not stain clothes)
• wash cars
• fight fires.

Do not use rainwater contaminated with debris to fill swimming pools or evaporative air conditioners because the debris in the water may clog filters and pumps. Contact the air conditioner, filter or pump manufacturer for advice.

Do not use contaminated water for drinking, cooking, washing your face or cleaning skin wounds.

Bore water for drinking

Floodwater may contaminate a drinking water bore system or water storage tank.

If floodwater is suspected to enter the bore casing, the bore water is likely to be contaminated. Do not drink or use this water for cooking, washing your face or cleaning skin wounds.

If you are not sure if the bore has been inundated with floodwater, it is recommended the water is tested to confirm it is safe.

Drink and cook with bottled water.

Drinking water drawn from deep bores where flood waters have not entered the bore casing may be safe to use, though may safest to check.

Following flooding, disinfect the water from the bore pump to the storage tank by following the Emergency treatment of drinking water supplies. Seek specialist advice if required.

If your drinking water tank is supplied by a bore, the same steps to remediate the tank should be followed as those listed for rainwater tanks above.

Bore water – garden purposes 

After flooding, do not use garden bore water for drinking, cooking, washing your face or cleaning skin wounds.

You may use bore water to wash clothes or for irrigation. 

More information

• Water tanks on your property.
• Emergency treatment of drinking water supplies.
• Bore water.

Septic tank systems

Floodwaters or heavy rain may damage your septic tank, which is also known as an onsite wastewater system.

Floodwater may enter your septic tank system through the toilet, other fixtures or the overflow relief gully grate. Flooding of the septic system may wash solids out from the tank, causing blockages or system damage.

If wastewater has overflowed into the home read domestic wastewater overflows for information on how to clean-up.

Checking for damage:

• open the septic system cover/pit
• check the leaking system (including pipes)
• check for damaged/exposed pipes that need capping or sealing.

Failed septic systems are not easy to identify but signs include:

• a strong odour around the tank and surrounding area
• blocked plumbing, with wastewater overflowing on the ground
• high level of sludge close to the outlet and inlet pipes in the primary tank
• sewage flowing up through the toilet and sinks.

Damaged septic tank

Do not use any toilets, laundry, kitchen or bathroom sinks or whitegoods that are connected to the damaged septic system until:

• all parts of the septic system have been professionally inspected and repaired
• your onsite wastewater disposal system has been approved for use by the local government environmental health officer.

Some onsite wastewater treatments systems rely on equipment such as pumps, aerators and filters. This equipment may be damaged by floodwater or loss of power. To prevent further damage to your system, contact a wastewater service technical – your local government can provide you with a list of authorised personnel.

Cleaning or pumping out a flooded septic tank should be done with care as this could cause the tank to float out of the ground and damage the structure and pipes.

After a septic tank is pumped out, it should be filled with water to prevent it from floating out of the ground.

Fixing a damaged septic tank

Only trained specialists can clean, repair or pump onsite septic systems because septic tanks may contain dangerous gases and other harmful materials.

As soon as possible after flooding, when there is no visible water on the surface of the ground, arrange for a licensed septic tank operator to pump out your onsite septic system.

Contact your local government environmental health officer for a list of septic (wastewater disposal) system contractors who work in your area.

Aerated wastewater treatment system

Do not use an aerated wastewater treatment system (AWTS) that has been flooded.

Isolate the electrical connection and call a wastewater service technician immediately to fix or replace the system.

Recreational waters

After a flood, recreational waters including lakes, rivers, estuaries and beaches are likely to be contaminated with sewage and chemicals.

Recreational waters may also have dangerous, unpredictable currents, fast-flowing water, underwater hazards, and floating objects, such as trees.

Never swim in or attempt to drive through floodwaters.

Depending on the extent of the flooding, you may need to avoid swimming until the local government says it is safe to do so.

Read more tips for healthy swimming.

Fishing

Do not eat fish from floodwaters or flood impacted rivers where there is known or potential contamination by wastewater, animal waste and other contaminants such as agricultural or industrial chemicals.

Fish caught in areas that are downstream from the flooded areas should be rinsed with clean water before being scaled and fileted.

Cook fish thoroughly. Avoid cross-contamination between raw and cooked fish.

Shellfish

Shellfish includes oysters, mussels, clams, pipis, scallops, cockles, and razor clams.

After a flood, shellfish in waterways including rivers, lakes, estuaries and the ocean are likely to be contaminated with harmful microorganisms and toxins due to wastewater runoff.

Do not eat shellfish from flood-affected waters as they can make you sick.

Swimming pools that have been contaminated with floodwater can be:

• a source of odour and bacteria
• a breeding place for mosquitoes
• a health risk to people who use them.

If the pool can be emptied

Dirty swimming pools should be emptied as soon as possible after flooding.

Ask a trained pool technician or building consultant to assess whether it is safe to empty the pool, especially in areas with a high water table, to avoid cracking and collapsing of the pool.

When emptying a pool, the water needs to be disposed of by a method approved by your local government. The water must not be discharged:

• into the sewer without approval from the service provider.
• into an onsite wastewater system without approval from the local government.
• to a location where it will cause overflows in already flooded/overloaded drainage systems.

If it is safe to empty the pool, all water and residue should be removed.

You may need to ask a trained pool technician to help empty and restart a pool.

Once emptied:

• Flush the plumbing pipes leading to the pool filters and replace filters.
• Clean and sanitise the pool floor using 10 parts per million (ppm) chlorine solution.
• Clean pool walls with a 10 per cent bicarbonate solution. Bicarbonate is also used to raise the pH level of the water.
• Once cleaned and sanitised, the pool can be refilled using clean tap water.

If the pool cannot be emptied

Where a pool cannot be emptied, ask a trained pool technician to inspect the pool and determine the best way to treat the water.

Depending on the amount and type of flooding, the water may need to be treated over several days. This will allow the sand and sludge to fall to the pool floor, ready to be vacuumed.

After all the sand and sludge has been removed from the pool, you can start super-chlorination.

The pool and filters should be super-chlorinated to 20mg/l (ppm) for up to 13 hours.

Depending on the amount of contamination and the volume of the pool, the chemical treatment process and chlorination of the pool may take up to one week to complete.

Once the pool water is visibly clean, the pool motor and filter(s) can be used to operate at the required chemical levels (chlorine, pH, bromine, cyanuric acid level).

Four complete cycles of the pool water (circulated through the treatment system) are required to achieve 98 per cent filtration of pool water. A trained pool technician will be able to determine a complete filtration cycle.

Sampling swimming pool water

If the above measures are followed, the water should be safe to swim in. You may verify the microbiological water quality of your pool using an independent water sampling service by a trained pool technician. The samples should be tested by a National Association of Testing Authorities (NATA) accredited water laboratory.

Read more about maintaining water quality in swimming pools and spas.

• Broken building materials that contain asbestos present a hazard and need to be cleaned up and removed.
• In most cases the risk of exposure to asbestos fibres will be extremely low because they will be wet, bonded within cement and unlikely to become airborne.
• When returning to your property, protect yourself and do not breakup or disturb asbestos-containing building products.
• If in doubt, treat suspicious materials as asbestos.
• If you handle suspect material, wear personal protective clothing.
• Never use power tools, including pressure cleaners/washers on asbestos-containing materials.
• A licensed asbestos removalist should remove asbestos-containing materials from your property.

Flooding may damage asbestos containing materials on your property. For example, pieces of asbestos sheeting from fences, walls and eaves may break off.

The asbestos in these broken sheets will still be 'bonded'. That is, the fibres will be held together in the cement matrix and unlikely to be released and become airborne. Therefore, they present a very low risk for asbestos exposure unless you disturb or break the materials further.

Emergency management agencies will usually organise for a licensed asbestos removalist to clean up large-scale asbestos damage so you don't have to handle it.

Removing small amounts of asbestos

Use a licensed asbestos removalist to remove asbestos from materials that have been badly damaged, present in large amounts or easily breaks down when you touch it.

If you want to remove small amounts of asbestos cement sheets and pieces on your property, follow the advice below:

Leave it

• ONLY handle small amounts of damaged or broken bonded (non-friable/intact) asbestos materials.
• Prevent anyone accessing areas with damaged asbestos containing materials.
• Do not break or crush asbestos material when moving it.
• Never use power tools on asbestos containing materials.

Gear-up

Wear personal protective clothing, including:

• P1, P2 (Australian Standards Approved) or N95 disposable respirator
• Disposable overalls or old clothes that can be disposed of after use
• Disposable gloves
• Disposable shoe covers or closed/waterproof, laceless shoes that can be cleaned like gumboots.

Wet it

Bag or wrap it

• Carefully pick up and place asbestos materials in heavy-duty (200 µm thick) plastic bags orplastic wrap (available from hardware stores)
• Bags - Do not fill the bag more than halfway. Seal the bag by tightly twisting the bag opening, fold over and secure with strong duct tape.
• Place the bag containing asbestos inside another heavy-duty bag, so it is double-bagged and taped.
• Wrap - Wrap only the amount of asbestos that is about the size of a single fence sheet so it isn’t heavy for a single person to lift. Double wrap and seal with strong duct tape.

Tag it

• Label bagged or wrapped waste with 'DANGER ASBESTOS WASTE'.

Clean up

• Wet wipe any reusable equipment and dispose of wipes with the asbestos waste.
• Remove all disposal personal protective equipment and clothing and wrap/bag it as asbestos waste. Remove your respiratory protection last.

Dispose it

• Dispose of bagged and wrapped asbestos as required by your local government or emergency response agency.
• Never place asbestos containing materials in general rubbish. 

The following video outlines safe clean-up procedures after a storm. Video courtesy of the Queensland Government.

Flooding and extreme rainfall can increase the risk of mould and dampness in homes and buildings. Mould and dampness must be managed to prevent health problems.

Mould and dampness can cause unpleasant odours and damage building materials, contents and structures, resulting in expensive maintenance and management costs.

Read mould and dampness or download Managing mould and dampness and related public health risks.

Floodwaters may bury, move or damage dangerous goods including:

• gas cylinders
• containers of corrosive substances
• oils and fuel
• pesticides
• pool chemicals
• industrial chemicals.

Take extreme care when handling spills or containers of suspected poisons, chemicals or pesticides, especially if the containers are damaged.

Contact emergency services if you find damaged gas cylinders.

Wear the protective clothing and respiratory protection that is recommended on the product label or material safety data sheet.

Always follow the manufacturer's recommendations when handling chemicals.

If the label is damaged, you can search for the manufacture's material safety data sheet online or seek advice from Poisons Information on 13 11 26.

Protective clothing that might be needed includes:

• heavy duty gloves
• protective eye wear
• respiratory protection
• enclosed footwear
• long sleeves and pants.

Work up-wind from any chemical spills, in an area with good ventilation.

Remove soils or other materials affected by chemical spills. Treat the soil or other material as chemical waste.

Floodwater can damage utilities and result in services being cut.

Damaged electricity networks can leave you without power.

If you see a downed power line, stay at least 8 metres clear and report the hazard in metropolitan Perth to Western Power by calling 13 13 51 and in regional WA, call Horizon Power on 13 23 51.

Tap (mains) water may not work due to damaged pipes, or power outages that prevent water being pumped.

Mains gas supplies may be damaged or turned off.

Mobile phone towers may be damaged or not supplied with the power needed to operate (these towers only have limited back up battery power).

You may not have access to internet services.

Local government services may be affected.

Food

Throw out any food that has come into contact with floodwater.

If the power goes out but the fridge has not been flooded:

• refrigerated food can be used for up to four hours - after this it should be thrown out.
• frozen foods last for up to 24 hours.

Disposing of spoiled food

Throw out spoiled food from the fridge and freezer. If in doubt, throw it out.

Dispose of food properly to prevent flies breeding and the risk of infectious diseases spreading:

• Wrap spoiled food in newspaper and place in the rubbish bin
• A small amount of food may be buried.

Where larger amounts of food need to be disposed of, such as from restaurants or cafes, contact the environmental health officer at your local government (external site).

Read more about guidelines on Food safety and storage, particularly during a power cut.

Wash dishes that have been exposed to floodwater in hot soapy water or a dishwasher.

Make sure the dishwasher is safe to use. If it has been contaminated by floodwater, thoroughly clean it.

Medicine

Throw out any medicine that has come into contact with floodwater.

If the power goes out for more than four hours, your medicines that need to be stored in the fridge may need to be thrown out.

Call your doctor or medical clinic for advice about binning and replacing refrigerated medicines.

Vegetable gardens

Floodwater may contaminate your vegetable or herb garden with bacteria, chemicals or other dangerous substances.

Discard all leafy greens such as lettuce, kale and watercress.

Vegetables and herbs, such as capsicum, chilli, zucchini, cucumber, basil and parsley should be left in the garden to grow for a month after the flooding, when they will be suitable to eat. If they cannot be left to grow in the garden, discard them into compost.

After growing for one month:

• wash the vegetables or herbs
• sanitise in a weak bleach solution made of 1 tablespoon of bleach to 2 litres of water
• rinse in drinking-quality water
• peel and use.

Following a flood, many animals, particularly farm animals may not survive.

It is important to promptly dispose of 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.

How to dispose of dead animals

• Cover a carcass with crude oil or kerosene to keep away dogs, scavenging birds and vermin.
• 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 animal 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 to 120cm deep, so predatory animals won't be able to reach them.
• If quicklime (Builder’s Lime) is available, cover the carcasses with it before backfilling. Quicklime speeds up the decomposition process.

Contact your local government (external site) animal control officer for further guidelines.

Stagnant water following a flood or rainfall provides an excellent breeding ground for mosquitoes. This increases the risk of diseases transmitted by mosquitoes, such as Ross River virus (RRV), Barmah Forest virus (BFV), Murray Valley encephalitis virus (MVE) and Kunjin (KUIN) virus. It is also possible that mosquitoes may be carrying Japanese encephalitis virus (JEV), which has been detected in feral pigs and chickens in the Kimberley.

In the north of Western Australia, the risk of infection with the rare but potentially fatal Murray Valley encephalitisvirus (MVE) is considered to be increased at this time. It is important that individuals take extra precautions to prevent mosquito bites.

Mosquito breeding can occur over huge areas after flooding.

Prevent mosquitoes breeding around your home:

• empty all water containers, including buckets, bird baths and palm fronds.
• check rainwater tank screens and replace if damaged.
• ensure swimming pools are not left untreated, otherwise empty them.

For more information, see:

• Mosquito bites can make you sick flier (PDF 2MB)
• Mosquitoes can make you sick. Protect yourself audio, Plain English (MP3 585KB)
• Mosquitoes can make you sick. Protect yourself audio, Kriol (MP3 733KB)
• Applying mosquito repellent video, Plain English (external site)
• Applying mosquito repellent video, Kroil (external site)
• Applying mosquito repellent video, Walmajarri (external site)

Snakes, rodents and other wildlife can be displaced during a flood, seeking shelter and food inside houses, storage sheds and other buildings.

Snakes

After a flood, damaged structures and debris are more accessible to snakes.

Outdoors

Wear work boots and long trousers to protect your legs and watch where you place your hands and feet..

Remove debris from around your home as soon as possible as it can attract rodents, lizards and insects on which snakes feed.

If you see a snake, step back from it slowly and allow it to proceed on its way – do not touch it.

Be aware of snakes that may be swimming in the water trying to get to higher ground. They may also try to get into boats. Stop them from getting in by using an oar or other long stake.

Indoors

If you find a snake in your house do not panic. Ask the Department of Biodiversity, Conservation and Attractions (external site) how to get in contact with the nearest licensed snake catcher.

If you are bitten by a snake, get medical treatment immediately.

Spiders

Red back spiders

If bitten by a red back spider:

• wash the affected area well and soothe the pain with an ice packs or clean iced water
• do not apply pressure – this is not recommended for red back spider bites and can worsen the pain
• get medical help immediately

Other spiders

If bitten by another spider:

• 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 needed. Contact your doctor if symptoms develop or persist.

If possible and safe to do so, catch the spider for positive identification.

Read more on First aid for bites and stings.

Rodents

To discourage rodents and the spread of disease:

• remove foods and items that can provide shelter for rodents
• wash dishes immediately after use
• get rid of garbage and debris as soon as possible
• lay rodent baits or traps.

Flies

To discourage flies and the spread of disease:

• do not let food and garbage build up as this becomes a breeding ground for flies
• clean up food waste as soon as possible.

• Asbestos safety after a flood flyer (PDF 3.5MB)
• Asbestos hazards following a cyclone or flooding fact sheet (PDF 461KB)
• Chemicals, poisons or pesticide hazards following a cyclone or flooding fact sheet (PDF 456KB)
• Damaged onsite wastewater systems following a cyclone or flooding fact sheet (PDF 454KB)
• Safer homes after an emergency fact sheet (PDF 682KB)
• Tips for cleaning up safely after a flood fact sheet (PDF 1.95MB)
• Mould can make you sick flyer (PDF 1.15MB)