Preventing Mould and Mildew in Your Bathroom

Few household problems are as persistent and frustrating as bathroom mould and mildew. These unwelcome guests thrive in the warm, humid conditions that bathrooms naturally create, and once established, they can be remarkably difficult to eliminate. Beyond being unsightly, mould poses genuine health risks—from allergic reactions and respiratory irritation to more serious conditions for those with compromised immune systems. This comprehensive guide explains why mould grows, how to prevent it, and what to do if it appears in your bathroom.

Understanding Mould and Mildew

Before we can effectively combat mould, we need to understand what we're dealing with. Mould and mildew are both types of fungi that reproduce through microscopic spores floating through the air. When these spores land on damp surfaces, they can begin growing within 24 to 48 hours under the right conditions.

The terms "mould" and "mildew" are often used interchangeably, but they have distinctions. Mildew is typically white or grey and grows on surfaces in flat patterns. It's usually easier to clean and less destructive. Mould can be black, green, red, or other colours, often appears fuzzy or slimy, and penetrates deeper into materials. Both require similar conditions to grow: moisture, warmth, and organic material to feed on.

Health Impacts of Bathroom Mould

The health effects of mould exposure vary depending on the type of mould, the extent of exposure, and individual sensitivity. Common symptoms include:

• Nasal congestion and sinus irritation
• Sneezing and runny nose
• Eye irritation (itching, redness, watering)
• Throat irritation and coughing
• Skin rashes or irritation
• Headaches and fatigue

For people with asthma, allergies, or weakened immune systems, mould exposure can trigger more severe reactions including asthma attacks, serious respiratory infections, and other complications. Infants, elderly individuals, and those with chronic respiratory conditions are particularly vulnerable.

This is why prevention is so important—it's far easier to stop mould from growing than to deal with the health consequences and remediation efforts once it's established.

Ventilation: Your Primary Defence

Proper ventilation is the single most effective weapon against bathroom mould. By removing humid air and allowing fresh, dry air to circulate, you eliminate the moisture that mould needs to survive.

Exhaust Fans

Every bathroom should have an exhaust fan, and it should be used properly. Run the fan during every shower or bath and keep it running for at least 15-20 minutes afterward—this is crucial for removing residual humidity. If your bathroom tends to stay humid, consider running the fan for 30 minutes or more.

If your exhaust fan isn't effectively removing humidity, it may be undersized for your bathroom, blocked by dust, or venting into the roof space rather than outside. Have it checked and upgraded if necessary—a powerful exhaust fan is one of the best investments you can make for bathroom health.

Windows and Doors

If your bathroom has a window, open it during and after bathing when weather permits. Even a small opening allows humid air to escape and fresh air to enter. In cooler months when opening windows isn't practical, rely on your exhaust fan and consider leaving the bathroom door open after use to allow humidity to dissipate into the rest of the house.

Smart Bathroom Practices

Your daily habits significantly impact mould risk. Small changes to your routine can make a substantial difference:

After Every Shower

• Squeegee shower walls: This removes the water that would otherwise evaporate and raise humidity. It takes less than a minute and dramatically reduces moisture levels
• Hang towels to dry: Spread towels out completely rather than bunching them. Consider a heated towel rail if your bathroom struggles with dampness
• Hang bath mats to dry: Never leave bath mats flat on the floor between uses. Hang them over the shower screen or bath edge to allow air circulation
• Leave the shower door open: If you have a glass shower enclosure, leave the door open after use to allow air circulation inside

General Practices

• Take shorter showers and use cooler water when practical—both reduce humidity
• Spread out household showers rather than back-to-back to give the bathroom time to dry between uses
• Don't leave wet items in the bathroom—move wet clothes, towels, or other items to appropriate drying areas
• Check for and repair leaks promptly—even small drips create persistent moisture problems

Choosing Mould-Resistant Products

The products you use in your bathroom can either help or hinder your mould prevention efforts.

Bath Mats

Some bath mat materials are naturally more mould-resistant than others. Diatomaceous earth mats dry within minutes and naturally inhibit mould growth. Bamboo mats drain water through rather than absorbing it, and bamboo's natural antimicrobial properties resist mould. If you prefer fabric mats, choose quick-drying microfiber options over slow-drying memory foam, especially if your bathroom has ventilation challenges.

Shower Curtains and Liners

Fabric shower curtains can harbour mould in their folds. Consider a mould-resistant liner or a curtain made from materials like PEVA or EVA that resist mould growth. Whatever material you choose, spread the curtain out fully after showering rather than bunching it to one side.

Grout and Sealant

When renovating or resealing, choose mould-resistant grout and silicone sealants. These products contain additives that inhibit mould growth and can make a significant difference in tile and corner areas that are prone to mould problems.

Regular Cleaning Routine

Consistent cleaning prevents the buildup of soap scum, body oils, and other organic materials that mould feeds on. Establish a routine that includes:

Weekly Tasks

• Clean all surfaces with a bathroom cleaner or a mixture of white vinegar and water
• Wash bath mats (or clean according to material type)
• Clean exhaust fan cover to ensure proper airflow
• Check corners, grout lines, and ceiling for early signs of mould

Monthly Tasks

• Deep clean grout lines with a grout cleaner or baking soda paste
• Clean or replace shower curtain liner
• Check and clean exhaust fan blades
• Inspect silicone seals around the bath and shower for deterioration

Dealing with Existing Mould

If mould has already established itself in your bathroom, you'll need to remove it before prevention strategies can be effective.

For small areas of surface mould (less than about one square metre), you can often clean it yourself. White vinegar kills most mould species and is safer than bleach. Spray undiluted white vinegar on the affected area, leave for at least an hour, then scrub with a brush and wipe clean. For stubborn mould, a paste of baking soda and water can be effective, or commercial mould removers for more serious cases.

Wear protective equipment when cleaning mould: rubber gloves, safety glasses, and a face mask rated for mould spores (N95 or P2 rating). Open windows and run exhaust fans to ventilate the area.

For extensive mould growth, mould that has penetrated porous materials like drywall, or situations where mould keeps returning despite your efforts, consider hiring a professional mould remediation service. They have the expertise and equipment to fully address the problem and identify underlying causes.

When to Seek Professional Help

Contact a professional if:

• Mould covers an area larger than one square metre
• Mould is growing inside walls, ceilings, or other hidden areas
• You or family members are experiencing persistent health symptoms
• Mould returns quickly after cleaning
• You suspect water damage or leaks you can't locate

Professional assessment can identify problems you might miss, such as hidden leaks, inadequate building ventilation, or structural issues contributing to moisture problems. The investment in professional help often saves money in the long run by addressing root causes rather than symptoms.

Preventing mould is an ongoing effort, but it's far easier than dealing with an established infestation. By maintaining proper ventilation, making smart product choices, establishing regular cleaning routines, and addressing moisture issues promptly, you can keep your bathroom healthy, hygienic, and mould-free.