• Mould is a type of fungi that lives on plant and animal matter.
  • Mould grows best in damp and poorly ventilated areas, and reproduces by making spores.
  • Airborne mould spores are commonly found in both indoor and outdoor environments.
  • For further information and advice on  mould issues, contact the Environmental Health section of your local council.
  • Before cleaning or disposing of water or mould-damaged items after a flood, always seek expert advice from your insurance company.
  • If you’ve decided to remove mould, make sure there is good ventilation and wear protective clothing.
Mould is a type of fungi that lives on plant and animal matter. Mould grows best in damp and poorly ventilated areas, and reproduces by making spores.

Airborne mould spores are commonly found in both indoor and outdoor environments. When they land on damp spots indoors, they may begin to grow and spread. There is no practical way to eliminate all mould indoors; the way to control indoor mould growth is to control the source of moisture.

Mould appearance

Mould is not always easy to recognise. It often looks like ‘fuzz’ or appears to be a stain, smudge or discoloration. The most common moulds are black, green or white. However, mould can be many other colours, ranging from grey to orange to brown.

Effects of mould

Mould associated with damp buildings can trigger nasal congestion, sneezing, cough, wheeze, respiratory infections and worsen asthma and allergic conditions.

People who are more susceptible to these symptoms and other serious health effects include those with:
  • weakened immune systems
  • allergies
  • severe asthma
  • chronic, obstructive, or allergic lung diseases.
You should seek medical advice if you are concerned about the effects of mould.

Controlling mould growth

Generally, if you can see or smell mould, you need to clean up and remove the mould immediately, as mould can damage surfaces it grows on. The longer it grows the more damage it can cause.

Mould only grows when there is sufficient moisture. When mould appears, the first task is to try to establish where the moisture is coming from.

Parts of a house that get wet or have poor ventilation are prone to mould growth, such as:
  • kitchens, bathrooms and laundries – due to condensation or high humidity and leaking pipes
  • cupboards and corners – due to restricted ventilation
  • walls or windows that are exposed to hot indoor air and cold outdoor air
  • walls and ceilings – due to insufficient insulation or rain seeping through the roof.
Avoid conditions encouraging mould growth, by using heat, insulation and ventilation. The cheapest and easiest way of reducing moisture and humidity levels is by ventilating a room by opening a door or window. Use exhaust fans where available.

Rising damp issues

Rising damp is ground moisture rising up a brick or stone wall. Poor sub-floor ventilation or moisture in the sub-floor area will worsen the problem.

Rising damp can be fixed by installing a new damp-course or waterproof barrier in the wall. Make sure the weep holes and air vents at the base of your home are uncovered. An experienced building consultant can recommend ways to fix the problem.

Actions you can take to reduce mould

There are some things that you can do to help prevent mould in your home, including:
  • Fix leaky plumbing and other building faults.
  • Use exhaust fans or open windows in the bathroom and kitchen when showering, cooking or using the dishwasher.
  • Vent clothes dryers to the outside.
  • Avoid conditions that encourage mould growth by using heat insulation and ventilation.
  • Use a vacuum cleaner with a HEPA (high efficiency particulate air) filter.
  • Clean up mould

Rental properties with mould issues

When a rental property has mould, the owner should fix any mould caused by faults in gutters or other fixtures, but the tenant must make sure there is adequate ventilation throughout, to help avoid mould problems during winter.

Sometimes, the cause of the mould growth may be due to a building fault that may not be easily rectified.

If as a tenant, you have taken measures to make sure the building is properly ventilated and mould is still growing, you should raise the issue with the owner. Tenants seeking further advice on their rights can contact the Tenants Union of Victoria on 03 9416 2577.

Testing for mould in your home

It is generally not considered necessary to test for mould in the home, as it is usually visible and easily identified. However, not all mould is visible, as contamination may be in cavities or the ceiling.

If you suspect mould contamination but cannot find the source of the problem, or if you have already taken measures to prevent mould from growing and you are still having problems, you could employ an occupational hygienist or environmental health and safety professional. For a fee, these professionals can provide specialist mould testing and consultancy services.

Mould growth after flooding

Flooding, excess moisture and pooled water can contribute to the growth of mould in your home, which may be a health risk for you and your family.

When returning to your home, be aware of any visible mould or a musty smell. High mould levels are likely if the house has been flooded for more than two days. The key to preventing mould growth is to clean up and dry out the house as quickly as possible (within 24 to 48 hours).

If you are visiting your house to collect belongings, visually inspect for damage or to do basic clean-up over short periods:
  • wear sturdy footwear, and rubber or leather gloves
  • it is preferable that footwear is waterproof and has rubber soles
  • it is not usually necessary to wear a respirator unless you are sensitive to mould.
Before cleaning or disposing of water or mould-damaged items, always seek expert advice from your insurance company.

Before you plan your clean-up, remember that not everyone is suited to working in damp, potentially mouldy conditions. Check that family members and volunteers who offer to help are not sensitive to mould.

People who should avoid being present during post-flood cleaning or repair works include:
  • children (under 12 years, particularly infants)
  • pregnant women
  • people over 65 years
  • those with weakened immune systems, allergies, severe asthma, and chronic, obstructive, or allergic lung diseases.
You do not need to test for mould. You can assume that the building’s interior is contaminated with mould when:
  • it has been flooded for more than two days
  • visible mould growth is extensive (more than before the flood)
  • visible water damage is present or musty odours are strong.
If you’ve decided to remove mould, make sure there is good ventilation, wear protective clothing such as a shower cap, rubber gloves, eye protection, overalls, suitable footwear and a P1 or P2 face mask (available from your hardware store).

The more extensive the contamination, the greater the personal risk of exposure during the clean-up process. Consider using professional cleaners who can remove the mould if the area to clean is large.

Steps to minimise mould growth after flooding

Mould removal efforts after flooding should focus on:
  • removing all sources of pooled water or excessive moisture from the home
  • removing all wet or flood damaged 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 (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 (for example, using fans or dehumidifiers once safe, reliable power has been restored to the property).
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.

Where to get help

  • In an emergency, always call triple zero (000)
  • State Emergency Service Victoria (SES) Tel. 132 500 – for emergency flood or storm assistance
  • SES Victoria Flood and Storm Information Line Tel. 1300 842 737
  • Environmental health section of your local council
  • Your insurance company
  • Tenants Union of Victoria Tel. 03 9416 2577

After a flood: mould and your health Community information, 2010 Department of Health, State Government of Victoria, Melbourne. More information here.

More information


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This page has been produced in consultation with and approved by: Department of Health and Human Services - RHP&R - Health Protection - Environmental Health Unit

Last updated: October 2015

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