They are both types of fungi but have similar treatments. Both are unsightly, and exposure to mould may be especially harmful for people with allergies or weakened immune systems.


This is a type of microscopic fungus that travels through the air in the form of tiny spores. When these spores land in damp or humid environments, mildew begins to colonise and grow. But it doesn’t penetrate surfaces and grow into the materials it lands on like mould does. Instead, it grows on top of flat surfaces and it’s generally much easier to spot and get rid of than mould. It is typically white, grey or yellow grows on the surface, and has a fluffy or powdery texture.


This also is a type of fungus made up of microscopic spores that float in the air too. Some, if left to grow indoors, can cause damage to your home and make you ill. Because it loves the damp, you can find it in bathrooms, basements and kitchens, and will often grow near leaks in roofs and windows or behind appliances where water has collected, and will penetrate wood and drywalls. It shows up as irregular patches commonly of green, black or brown, and often appears fuzzy - typically accompanied by a musty smell.

Can you use bleach to kill mould?

Bleach is commonly used as a solution for eliminating mould, but it only works against mould on nonporous surfaces, like bathtubs, tiles and sinks. It doesn’t work on porous surfaces because mould spreads its roots deep into porous surfaces and continues to grow beneath.

While it may be impossible to fully remove mould from porous surfaces with bleach, you can still use it to eliminate mould from nonporous surfaces. Before you start, open the windows, as the fumes are powerful. Put on some protective clothing, including gloves and a mask. Mix one part bleach and three parts water, and using a spray bottle, spray the affected areas and allow it to set in, scrubbing if necessary. Rinse with clean water, and allow to airdry. Bleach is also very corrosive, and shouldn’t be mixed with any acids such as ammonia, because it causes dangerous fumes that can kill with just a few breaths. Chlorine gas, nitrogen trichloride and/or hydrazine will be produced when these two are mixed.

While household bleach isn’t considered corrosive or toxic, prolonged exposure to it may cause irritation to the eyes, mouth, lungs, and skin. This may be especially true if you live with a respiratory condition such as asthma. Bleach can also damage your skin, especially if you don’t rinse after immediate exposure. Don’t forget those gloves!

Hydrogen peroxide and other alternatives

An alternative option is to use hydrogen peroxide. Combine 1-part hydrogen peroxide and 1-part water in a spray bottle. Apply to mould and allow to sit before removal.

Baking soda is another option. Combine 2 tbsp. baking soda with 2 cups water in a spray bottle and shake until it’s completely dissolved. Spray onto the mould and let it sit before scrubbing. Afterwards, rinse the area and apply the solution again, allowing it to fully air dry.

Vinegar is another – spray undiluted white vinegar to the mould and allow to sit for 1 hour. Wipe the surface and allow to air dry. This is particularly better at killing mould because it can work on both porous and nonporous surfaces, as it terminates moulds at their roots so it won't return. It can even be combined with baking soda to make it more effective.

Two options I haven’t tried – mixing 2 tsp of tea tree oil with either 2 cups water or 2 cups distilled white vinegar, spraying it onto the mould, allowing it to sit for at least 1 hour, then scrubbing. An unusual option is Grapefruit seed extract - mix 10 drops of extract into 1 cup water into a spray and let it sit for 10 to 15 minutes.


Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man. 

Marilyn Sheridan