Health Information

​Environmental health risks during and after a bushfire

Bushfires have the potential to cause a number of environmental health concerns beyond the immediate damage caused
by the fire.

For a full list of potential health risks, please read this document from the Department of Health.

Water contamination

If you have a water tank, be aware that the water is most likely to be contaminated either indirectly by ash, smoke, debris or directly by fire and the fire fighting activities. Do not use the water for drinking, preparing food, making ice, washing, bathing or cleaning teeth. Do not provide it to animals.

Please use the water instead to flush toilets, water the garden, wash cars and fight fires. It is dangerous to attempt to remove the contamination so we do not recommend this. Using any rainwater contaminated with ash or other debris to fill swimming pools or in evaporative air conditioners may clog filters and pumps. Contact the air conditioners, filter, or pump manufacturer for advice.

Water testing

Water testing is usually not necessary as contamination after a bushfire is usually obvious. It is usually very difficult and expensive to remove effectively any contamination caused by fire suppressants or any other potentially harmful by-products caused by ash from burnt bush, plastics and metals.

To test the chemical quality of watern in a water tank, contact a National Association of Testing Authorities (NATA) accredited chemical laboratory.

Refer to the Department of Health Publication, Standard Drinking Water test 

Refilling a rainwater tank

The tank may need to be drained and refilled with water from a commercial water carting company. Before you do, make sure that:

  • the tank or any associated pipework has not been damaged by fire;
  • the tank has been desludged and cleaned, if contaminated, by a specialist contractor; and
  • Do not reconnect your down pipes until your roof and gutters have been cleaned or rainwater from the first rains after the fire has been run to waste.

Make sure that the commercial carting company:

  • uses the tanker exclusively for drinking water;
  • gets the water from a scheme drinking water supply;
  • has treated the water with at least 1 milligram per litre of chlorine while in transit; and
  • follows the Department's water carting guideline.

Other sources of water

Water drawn from deep bores or wells should be safe to use. More information here.

Do not obtain water from a creek or stream that has been affected by bushfire as the water may be contaminated.

First rains

Ensure that all rainwater from the first good rainfall event after the fire is run to waste, as this may be contaminated by ash and other pollutants from the fire.

Further information: Rainwater tanks after a bushfire: see the Healthy WA website at Rainwater tanks after a bushfire (

Water tanks on your property: see the Healthy WA website at Water tanks on your property (

On-site wastewater systems

On-site wastewater systems such as septic tanks, secondary treatment systems, aerated wastewater treatment systems and their land application systems (leach drains, sprinklers and below ground drippers and connection pipes), can be easily damaged during a bushfire.

Avoid driving or walking near a fire-affected system until it is assessed by a licensed plumber or service technician familiar with on-site wastewater systems.

Contact with effluent or untreated wastewater from damaged on-site wastewater systems can cause illness and should be avoided at all times.

Wastewater systems

Plastic and fibreglass on-site wastewater systems, or systems made with plastic components, are more susceptible to damage than concrete tanks particularly if installed above ground. This includes shallow PVC pipes, plastic tanks and sumps, and plastic irrigation pipework which may be installed above or below ground. Pumps and other equipment with electrical components may also be damaged.

It is recommended that damaged on-site wastewater systems are not used until repaired or replaced.

Due to the risks associated with using systems after a bushfire, the following actions are recommended:

  • If the on-site systems are damaged, make arrangements to repair the system as soon as possible to prevent sewage from backing up into the house;

  • Avoid driving or walking near underground pipes, tanks and tank covers and their land application systems, which may have been weakened or damaged;

  • Reduce water use as much as possible until the system is inspected and repaired by:

         *   Reducing the frequency of toilet flushing for liquid waste;
         *   Taking shorter showers or shower elsewhere;
         *   Limiting laundry and dishwashing as much as possible. If possible avoid using automatic clothes washers and 

  • If the power has not been restored, the septic tank can be used as a temporary holding tank and pumped out periodically, provided the tank is not damaged. You may need to disconnect the pump (if present) and block the outlet to the land application area. If the tank is significantly damaged and can't be used as a temporary holding tank, do not use the system until it is repaired or replaced;

  • Once power is restored, ponding may occur near the wastewater system and these areas should be avoided. Contact a licenced plumber or authorised service technician to reassess the system;

  • Replace shallow PVC pipes if they have melted as they may cause blockages;
  • Repair or replace damaged electrical components and pumps as soon as possible.

Residents should not use any toilets, laundry, kitchen, bathroom or clean-up equipment connected to the onsite wastewater disposal system until:

  • All parts of the wastewater treatment and disposal system have been professionally inspected and repaired;
  •  Your onsite wastewater disposal system has been approved for use by the local authority environmental health officer.

Only trained specialists are suitably equipped to clean or repair onsite waste disposal systems. This is because tanks may contain dangerous gases and other harmful materials.

Onsite wastewater disposal systems should be pumped out by a licensed septic tank operator as soon as possible after the flood.

Further information: What should I do if my on-site wastewater system has been damaged by bushfire? Find out here.

Air quality from bushfire smoke
The elderly, very young and people with respiratory and heart conditions need to take extra precautions to avoid exposure to bushfire smoke and smoke haze as it can worsen asthma and other respiratory conditions, cause coughing, shortness of breath, irritate eyes, nose and throat.

People with a heart condition or lung problems, should make sure they always have at least five days' worth of medication if there is a bushfire nearby.

What should you do if I am exposed to bushfire smoke and smoke haze?

  • Stay indoors and shut the doors (particularly if you have a heart and circulation conditions, asthma and other respiratory conditions);

  • Reduce outdoor activity –  limit outdoor exercise to reduce breathing in air pollutants;

  • Use air conditioners and filters – air conditioners that circulate indoor air. Switch off evaporative air conditioners and air conditioners that do not allow the fresh air intake to be turned off;

  • Use a room air cleaner – A high powered portable air cleaner (with a high-efficiency particular air (HEPA) filter) may improve the air quality in a bedroom, which may be helpful to an individual with asthma. Room air cleaners will provide the most protection when placed in an enclosed room where people spend most of their time;

  • Use respiratory protection – if you must venture outdoors wear a P1 or P2/N95 face mask that has a tight seal around the mouth and nose and can filter airborne contaminants;

  • Keep hydrated - Drink plenty of water;

  • Look out for the elderly.
Anyone with an urgent smoke-related health condition should seek medical attention by dialling 000. People with other medical conditions or who are feeling unwell due to the smoke impact are advised to contact their GP or health direct on 1800 022 222.

Once the bushfire is contained, the smoke risk should decrease and no longer present a risk to the community. 

For more information on smoke alerts see The Department ofBiodiversity, Conservation and Attractions

For information about health hazards from bushfires see Health WA.


Asbestos damage and contamination
If your home or structure on your property was built before 1990, particularly between the 1970s and 80's, it should be suspected of containing asbestos, typically as flat or corrugated cement sheeting.

If you suspect or know your home or dwelling contains asbestos, please contact the Shire's Environmental Health team on 9290 6666.

Chemicals and other hazards

Houses, sheds, and other buildings or structures that are burnt in a bushfire can leave health hazards in the remaining rubble and ash including:

  • Asbestos
  • Ash from burnt treated timbers, such as copper chrome arsenate timber
  • electrical hazards
  • medicines
  • garden or farm chemicals and pesticides
  • other general chemicals, such as cleaning products or pool chlorine
  • metals and other residues from burnt household appliances
  • ash and dust.
More information: See the HealthyWA website: After a bushfire – hazards on your property (

Hazards on your property after a bush fire. Click Microsoft Word - Enviromental Health Guide _2_.doc

Contaminated swimming pools

After a bushfire a swimming pool may contain ash. This may affect the chemical balance of the water. Swimming pools should either be emptied or kept chlorinated to prevent the water quality from deteriorating.

You may need to make an assessment as to whether it is safe to empty the pool. Advice from a building consultant may also be required. If it safe to empty the pool, all water ad residue should be removed. Where it is not safe to do so, a trained technical operator will need to inspect the pool.

More information:

What is bushfire smoke and how harmful is it? (


2020_Bushfire_Smoke_Fact_infographic_v06_AW_EW (

Fire waste disposal 
Skip bins have been placed at the Mayo Road Reserve for disposal of fire damaged products. 

Access is available at all times as site will be left open. 

A separate bin will be allocated for wire and metal. Household hazardous products such as paint, poisons, batteries, gas cylinders can be taken to the Redhill hazardous waste facility for free. 

Other hazardous material such as asbestos please contact the Shire for more information.

Dead animal control

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. Where disposal or burial of any significant biomass, this must be undertaken in a consistent and appropriate manner in coordination with the local government.

Procedures to dispose of dead animals

  • Cover the animal 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 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 animal with it before backfilling. Quicklime speeds up the decomposition process.
  • Work with the Shire's animal control officer for further guidelines.

Contact the Shire's Environmental Health Department on 9290 6666 before undertaking disposal or burial of any large animals, to be sure that is being done in the appropriate manner to avoid ongoing risks to water table and the environment.

Use of retardant and a-class foams during bushfire operation

The Department of Fire and Emergency Services have provided information on the use of retardant and A-class foams during bushfire operations. Things to remember:

  • Retardant is coloured so firefighters can easily see where it has landed. A-Class foam is not coloured;

  • If fire suppressants come into contact with skin, wash with a gentle soap and fresh water;

  • If in eyes, rinse with fresh water for 15 minutes, then consult a doctor;

  • If swallowed, rinse your mouth out with fresh water, then consult a doctor;

  • When cleaning surfaces wear safety glasses, disposable gloves and disposable face mask (such as a P2 mask), and wash hands regularly;

  • Fire suppressants will degrade with exposure to the sun.

What are they made of? 

Short-term fire suppressant foams are a combination of wetting agents and foaming chemicals, mixed with water. This allows the water to penetrate surfaces more easily.

Long-term suppressants are essentially fertilisers (ammonium and diammonium sulphate and ammonium polyphosphate), with thickeners (guar gum) and corrosion inhibitors (to protect aircraft).

Sometimes a red coloured pigment, made from iron oxide, is added to show where retardant has been applied. Due to interstate firefighting arrangements, brands and types of water additives may vary slightly.

What are the environmental effects?

Current evidence does not suggest any significant effects on birds or mammals. However, in Australia, long-term fire retardants have been observed to cause effects on some species of native plants (leading to low level damage to new growth).

Water plants and animals are more sensitive to the effects of fire retardants. A-Class foams can be moderately toxic to aquatic life. For this reason, pilots try not to apply fire suppressant retardants within 100 metres of waterways, but these agents can drift.

What are the health effects?

Irritancy testing on animals shows these chemicals have little effect. The concentrated powder may cause minor respiratory irritation to workers who are handling it. This health effect does not occur once it is mixed into slurry. Workers require gloves, goggles and dust masks when handling the powder.

If you or your pets (and livestock) come into contact with a firefighting water additive, wash the skin with mild soap and cold water as soon as possible. Remove any contaminated clothing and, using disposable gloves, hand wash in cold water.

If you begin to feel unwell, contact the Poisons Information Centre on 13 11 26.

Tips on cleaning up fire retardant residue?

If aerial fire suppressants or firefighting foam residue is present on the house and/or cars, use a mild detergent and brushes to scrub and dilute the dried residue and flush it from the surfaces. 

Rinse with clean water. Take care – it could be slippery. Gloves and non-slip shoes should be worn.

Where downpipes are connected to water tanks, these should be disconnected to stop further retardant being washed into tanks. Wash the roof down and let the first rain flush through before reattaching the roof runoff to the rainwater tank.

If the fire retardant does enter your water tank, do not drink it. High levels of retardant in water will make it smell terrible and taste salty. It will not be suitable as drinking water for humans or animals (pets or livestock). The water can still be used for irrigation and firefighting. The tank should be drained and thoroughly washed out, then rinsed with fresh water before refilling for use.

You can read and download the full information sheet here.

For more information contact the WA Department of Health and see Disaster Management (

The Place for Sustainable Living. Sitemap  |   Copyright Shire of Mundaring 2018