Safety and first aid

Hazards after a flood

Flooding increases the risk to your health. These include:

  • floodwater contaminated with bacteria and debris
  • damaged power lines, electrical equipment and gas supplies
  • damaged buildings. 

Take care when cleaning up after a flood:

Follow clean-up advice from emergency and response recovery agencies, including your local government (shire).

List of hazards


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.

Utilities and services

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.


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:

Snakes, rodents and other wildlife

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


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


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.


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.


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.


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.


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.

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. 

More information

Last reviewed: 20-10-2023

This publication is provided for education and information purposes only. It is not a substitute for professional advice. Information about a service, product or treatment does not imply endorsement and is not intended to replace professional advice. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified professional for answers to their questions.

Questions? Ask your local government environmental health services