Black grout in shower keeps returning, fix myself?« Back to Previous Page

That black grout is a classic sign of mould growth, not just dirt. Dubai's high humidity, especially during summer, creates a perfect environment for it in bathrooms. Bleach only removes the surface colour but doesn't kill the mould's root structure (hyphae) penetrating the porous grout, which is why it returns so quickly.

For a small, recurring patch, you can try a targeted approach. Use a hydrogen peroxide-based mould remover or a paste of baking soda and vinegar; these can penetrate better than bleach. Scrub it into the grout lines with a stiff brush. The key is to significantly reduce the moisture. Run your bathroom exhaust fan for at least 30 minutes after every shower and ensure your AC is functioning properly, as it dehumidifies the air. Wiping down the wet walls and squeegeeing the shower after use can also help.

If the mould is widespread, has spread up the wall, or returns persistently despite these efforts, the issue is likely behind the tiles or in the wall cavity. In many Dubai buildings, persistent shower leaks can feed mould growth in the cavity, which is impossible to address with surface cleaning. At that point, a professional inspection is needed to assess the extent of the moisture source and growth. They can perform tests, like moisture mapping, to find the root cause. Remediation often involves removing the affected grout, treating the area, and resealing it with a high-quality, mould-resistant sealant to prevent recurrence.