Water damage vs mould: How do they differ from each other?

Mould and water damage are persistent issues in homes, especially if you live in the coastal and tropical regions of Australia, where the weather is hot and it rains a lot. Immediately addressing these issues is vital to maintaining the structural integrity of your home while keeping your family’s health safe. 

Although both water damage and mould occur due to excessive moisture, these are still two different issues requiring specific treatments and preventive measures. Learn more about their differences in this water damage vs mould guide to avoid costly repairs.

What is mould? Mould buildup on ceiling. (Source: iStock)

Mould is a type of fungus that grows in areas with high humidity. It appears in a wide range of colours, but the most common indoor mould is blackish green with a fuzzy and slimy texture and rotten smell. Mould comes in many colours, which can help identify its type, but it can also be hidden from plain sight.

What looks like a fine white mould could be something different. The type of material can hide the mould, but the cross-contamination would still affect the area.

Seeing mould on surfaces like carpet, flooring, plaster boards, walls and ceilings usually means it’s too late. It can develop on these materials in 1 to 2 days, and once it takes hold, the surface can be deeply affected. That’s why prevention is always better than treatment. The key is to dry and clean the surface immediately and thoroughly to stop any potential growth before it starts. 

If left untreated, mould spores spread, and they may destroy your furniture, walls, and floors. Moreover, mould is a health hazard that can cause many respiratory problems and allergic reactions. 

There are many types of mould on walls, floors, and other surfaces, including:

Allergenic moulds

These are common indoor moulds in damp areas such as wet carpets, wood surfaces, showers, and under-sinks. They quickly spread and cause mild allergic reactions and lung issues. 

Toxigenic moulds

These are the most dangerous and can cause various health risks, such as skin and nail infections. Toxic mould typically grows in contaminated humidifiers and window sealants. 

Pathogenic moulds

These are moulds that can cause infections and diseases. The most common pathogenic mould is Aspergillus, an allergenic mould. However, some other Aspergillus mould species are pathogenic and can cause infections and lung diseases. 

What is a water damage? 

What water damage looks like. (Source: iStock) 

Water damage results from dampness or the accumulated moisture trapped on surfaces. This can happen when houses lack ventilation and insulation, causing the moist air to condense and build up on cold surfaces. Some visible signs of water damage at home include visible discoloration on walls and windows, peeling wallpaper or paint, and rotting skirting boards. 

Moreover, water damage becomes a problem during heavy rains and floods. Much of this is due to contaminated water from sewage backflows or blocked drains. Another source is rainwater seeping from the ground, which also carries contaminants, resulting in water damage. If left untreated, this can quickly lead to mould growth. 

Other factors, such as roof leaks and routine tasks such as cooking and showering, can also cause water damage. If not fixed, damp surfaces might occur, causing mould and bacteria to grow. 

Mould vs water damage: What are their key differences? 

Since mould grows in damp areas caused by water damage, you probably think, is water damage and mould the same thing? Or, does water damage mean mould? No, they’re not the same. Here are some factors to consider that can help you differentiate these two common household issues. 

In terms of smell and appearance

Like mildew, mould has a distinct earthy, musty smell because it emits microbial volatile organic compounds (MVOCs) as it spreads. However, when comparing mould vs mildew, the latter has a more overpowering pungent smell that can make you easily gag! 

As for appearance, indoor mould growth looks black or green. Other mould types may appear brightly yellow, brown, white, purple, and even pink! You don’t have to be worried about the colour because it doesn’t indicate how toxic a mould is. It’s normal for mould to change colour depending on its surrounding environment.

Meanwhile, water-damaged areas have a similar distinctly musty smell, but it’s not as strong as mould. Water damage can also look like a brownish or slightly yellow wet patch on the wall after it rains.

In terms of causes

What causes mould on walls? Excessive moisture and lack of ventilation. Kitchens and bathrooms are some areas in the house that exhibit this kind of environment. Steam from cooking and showering causes most air to build up on cold surfaces, creating a perfect breeding ground for mould growth.

Mould growth can also appear on paper, wood, and carpets because these are organic porous materials that mould spores feed into. When these organic materials become wet and moist, irregular stains appear, signalling mould formation.

Meanwhile, the root cause of water damage is the moisture that has penetrated the walls and floors due to poor building structure and lack of insulation. This is highly likely to happen after a series of rainfalls and snowstorms.

You may also encounter a condition known as a rising damp. It occurs when groundwater seeps through and travels up the walls, causing the timber to rot. Signs of rising dampness include peeling paint and bubbling wallpaper on walls. 

In terms of health risks

Is mould from water damage dangerous? Yes, because it can cause adverse health effects and trigger allergic reactions. Mould produces airborne spores that contain allergens, irritants, and even toxic substances. Inhaling these microscopic mould spores can make you cough and sneeze, and you’ll have difficulty breathing. You should also avoid touching mould spores because the spores can cause skin rashes and trigger eczema. 

Prolonged mould exposure can be even more dangerous for people with a weakened immune system. If they accidentally inhale mould spores, they may experience severe respiratory and airway infections.

Aside from affecting your physical health, living in a damp and mouldy place can also significantly impact your mental health. These unpleasant living conditions reduce indoor air quality, so you’ll most likely feel more stressed, anxious, and depressed. 

In terms of treatment

Treating mould on the wall. (Source: iStock)

Finding and eliminating the source is the first step in water damage cleaning. Start inspecting the roof and gutters because these moisture prone areas are likely to leak. Consider hiring expert local roofers to help you quickly find the source of water leaks. 

Penetrating dampness can also occur in water-damaged areas. This happens when the moisture from the exterior wall moves into the interior, causing the wooden panels in the walls to rot. Some treatments for penetrating dampness include adding a damp-proof course (DPC) or injecting a specialised damp-proof cream into walls. These serve as extra barriers to protect the walls from moisture and further damage.

On the other hand, treating mould involves removing the spores with potent cleaning agents like a bleach based mould cleaner. You can do this yourself, but wear protective gear like gloves and masks to avoid inhaling and touching mould spores. If you don’t want to risk it, seeking help from mould removal experts is the best. 

Anti-mould paints could help prevent new growth from mould as a last step in the treatment. But before you use them, make sure to identify and fix the source of the mould to get rid of hidden moisture, then clean, remove, or replace the affected materials. Only after that should you consider using anti-mould paints. 

In terms of removal cost

The cost difference between water damage and mould removal services depends on the severity of the issue and the required treatments. However, water damage treatment can be a bit more expensive because this involves fixing your leaky pipes, roof gutters, replacing affected materials, and other water-damaged home maintenance and repair tasks. In Australia, water damage restoration costs can range from $150 to $6,000. 

Meanwhile, mould removal costs range from $500 to $4,000. Removing molds is generally cheaper since they don’t require expensive structural repairs, unlike when treating dampness and water damages in homes. 

However, professional mould remediation and removals can still get expensive, especially if your entire home is infested. You might need advanced containment methods such as negative air pressure to prevent mould from growing back. 

In terms of prevention methods

Using a cleaning solution on the walls. (Source: iStock)

Since one of the causes of water damage is moisture, using dehumidifiers and air conditioners in areas with high humidity can help. You can also install exhaust fans to improve ventilation and reduce moisture in these areas.

Waterproofing the roof, walls, and floors is another way you can help prevent water damage. This includes adding sealants and insulation to reduce condensation damp on surfaces. 

The methods for preventing mould damage are similar. You'll also have to use dehumidifiers and exhaust fans to improve ventilation and inhibit mould growth. 

If you have an air conditioning system but have mould in the house, you’ll want a professional cleaning done on it first. Leaving your AC unit untreated when there’s mould presence in your home can quickly spread mould spores throughout the house once it’s turned on.

However, mould growth prevention requires more thorough cleaning maintenance. For example, when mopping the floors, you must always ensure wet surfaces are completely dry after 24 to 48 hours to prevent mould infestation. 

If you have something that’s been affected by mould but you’d like to keep, you must clean it regularly. Say you have a leather lounge that has mould growth. You’d have to vacuum it and use a leather cleaner to keep this favourite item. You’ll still need to be aware that the leather will deteriorate faster than a lounge that was never affected.

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